PATENT DOCUMENT

Publication Number: US-12174006-B2
Application Number: US-202318372606-A
Country: US
Kind Code: B2

Title: Devices and methods for measuring using augmented reality

Abstract:
A computer system displays an annotation placement user interface that includes a representation of a field of view of one or more cameras that is updated over time based on changes in the field of view, a placement user interface element indicating a virtual annotation placement location. If the placement user interface element is over a representation of a physical feature in the physical environment that can be measured, the appearance of the placement user interface element changes in accordance with one or more aspects of the representation of the physical feature, and, in response to an input to perform one or more measurements of the physical feature: if the physical feature is a first type of feature, measurements of a first measurement type are made; and, if a second, different type of physical feature, measurements of a second, different measurement type are made.

Claims:
What is claimed is: 
     
       1. A method, comprising:
 at a computer system with a display device and one or more cameras: 
 displaying, via the display device, an annotation placement user interface, the annotation placement user interface including:
 a representation of a field of view of the one or more cameras, including a representation of a portion of a three-dimensional physical environment that is in the field of view of the one or more cameras, wherein the representation of the field of view is updated over time based on changes in the field of view of the one or more cameras; and 
 a placement user interface element that indicates a location at which a virtual annotation would be placed in the representation of the field of view in response to receiving an annotation placement input; 
 
 while displaying the annotation placement user interface, detecting a first movement of the one or more cameras relative to the three-dimensional physical environment; 
 in response to detecting the first movement of the one or more cameras relative to the three-dimensional physical environment, updating the representation of the field of view based on the first movement of the one or more cameras; 
 in accordance with a determination that the placement user interface element is over at least a portion of a representation of a physical feature in the three-dimensional physical environment that can be measured, changing an appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical feature; 
 while displaying the annotation placement user interface, receiving an annotation placement input comprising a request to perform one or more measurements of the physical feature; and 
 in response to receiving the annotation placement input comprising a request to perform one or more measurements of the physical feature:
 in accordance with a determination that the physical feature is a first type of physical feature, displaying, over the representation of the physical feature, a first set of one or more representations of measurements of a first measurement type; and 
 in accordance with a determination that the physical feature is a second type of physical feature, different from the first type of physical feature, displaying, over the representation of the physical feature, a second set of one or more representations of measurements of a second measurement type different from the first measurement type. 
 
 
     
     
       2. The method of  claim 1 , wherein the physical feature is a first respective type of physical feature, the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and a second portion of the physical object is at most partially in the field of view of the one or more cameras, and the method includes:
 after displaying, over the representation of the physical feature, a first respective set of one or more representations of measurements of a first respective measurement type:
 detecting a second movement of the one or more cameras relative to the three-dimensional physical environment such that the second portion of the physical object is in the field of view of the one or more cameras; 
 in response to detecting the second movement of the one or more cameras:
 updating the representation of the field of view based on the second movement of the one or more cameras, including displaying, in the representation of the field of view, a representation of the physical object that includes a representation of the second portion of the physical object; 
 
 in accordance with a determination that the placement user interface element is over at least a portion of the representation of the physical object, changing the appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical object including the second portion of the physical object; 
 while displaying the annotation placement user interface including the representation of the physical object, receiving a second annotation placement input comprising a request to perform one or more measurements of the physical object; and 
 in response to receiving the second annotation placement input corresponding to the request to perform one or more measurements of the physical object:
 displaying, over the representation of the physical object, a second respective set of one or more representations of measurements of a second respective measurement type that is based on the second portion of the physical object. 
 
 
 
     
     
       3. The method of  claim 1 , wherein the determination that the physical feature is the first type of physical feature includes a determination that the physical feature is a piece of furniture, and the measurements of the first measurement type include one or more of: a height, a width, a depth, and a volume of the physical feature. 
     
     
       4. The method of  claim 1 , including:
 while displaying a respective set of one or more representations of measurements over the representation of the physical feature, wherein the respective set includes a first representation of a measurement, the first representation including a first measurement label and a first measurement segment that is displayed using a first level of detail while the one or more cameras are located a first distance from the physical feature, detecting movement of the one or more cameras that places the one or more cameras at a second distance, less than the first distance, from the physical feature; and 
 while the one or more cameras are located at the second distance from the physical feature:
 enlarging display of the first measurement label; and 
 displaying the first measurement segment using a second level of detail that is different from the first level of detail. 
 
 
     
     
       5. The method of  claim 4 , including:
 detecting a first touch input; and 
 in response to detecting the first touch input, adding and displaying a first measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional physical environment, wherein the first measurement point at the first location in the representation of the field of view is a most-recently-added measurement point in the representation of the field of view. 
 
     
     
       6. The method of  claim 4 , wherein displaying the first measurement segment using the first level of detail includes displaying one or more first scale markers along the representation of the first measurement segment at a first scale; and displaying the first measurement segment using the second level of detail includes displaying one or more second scale markers along at least a portion of the representation of the first measurement segment at a second scale that is distinct from the first scale. 
     
     
       7. The method of  claim 4 , wherein displaying the first measurement segment using the second level of detail includes displaying a set of scale markers at intervals along the first measurement segment, and the method includes:
 while displaying the first measurement segment using the second level of detail, detecting a second touch input; and 
 in response to receiving the second touch input, enlarging display of at least a portion of the representation of the field of view. 
 
     
     
       8. The method of  claim 7 , wherein the display device is a touch-sensitive display, and the method includes:
 while displaying the enlarged display of at least the portion of the representation of the field of view, detecting a third touch input that includes detecting movement of a contact across the touch-sensitive display; and 
 in response to detecting the movement of the contact across the touch-sensitive display:
 moving a measurement point across the representation of the field of view in accordance with the movement of the contact in the third touch input. 
 
 
     
     
       9. The method of  claim 4 , including:
 while displaying the first measurement segment using the second level of detail, detecting movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature; 
 in response to detecting the movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature:
 updating the representation of the field of view based on the movement of the one or more cameras; and 
 
 while the one or more cameras are located at the first distance from the physical feature:
 displaying the first measurement segment using the first level of detail; and 
 displaying the first measurement label. 
 
 
     
     
       10. The method of  claim 4 , wherein:
 the computer system is an electronic device; 
 the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras; and 
 the method includes:
 in accordance with a determination that the first distance between the electronic device and the physical object is less than a first threshold distance, the first measurement label is displayed at a first threshold size; 
 in accordance with a determination that the first distance between the electronic device and the physical object is greater than a second threshold distance that is greater than the first threshold distance, the first measurement label is displayed at a second threshold size that is smaller than the first threshold size; and 
 in accordance with a determination that the first distance between the electronic device and the physical object is between the first threshold distance and the second threshold distance, the first measurement label is displayed at a size, between the first threshold size and the second threshold size, that depends on the first distance between the electronic device and the physical object. 
 
 
     
     
       11. The method of  claim 1 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the annotation placement user interface includes an affordance, which, when activated, adds a measurement point in the representation of the field of view at a location in the representation of the field of view over which the placement user interface element is displayed, and receiving the annotation placement input comprising a request to perform one or more measurements of the physical object includes:
 detecting a fourth touch input activating the affordance; and 
 in response to detecting the fourth touch input activating the affordance, adding and displaying the measurement point in the representation of the field of view at the location in the representation of the field of view over which the placement user interface element is displayed. 
 
     
     
       12. The method of  claim 1 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the method includes:
 determining a classification of the physical object; and 
 displaying a label indicating the classification of the physical object. 
 
     
     
       13. A computer system, comprising:
 a display device; 
 one or more cameras; 
 one or more processors; and 
 memory storing one or more programs, wherein the one or more programs are configured to be executed by the one or more processors, the one or more programs including instructions for:
 displaying, via the display device, an annotation placement user interface, the annotation placement user interface including:
 a representation of a field of view of the one or more cameras, including a representation of a portion of a three-dimensional physical environment that is in the field of view of the one or more cameras, wherein the representation of the field of view is updated over time based on changes in the field of view of the one or more cameras; and 
 a placement user interface element that indicates a location at which a virtual annotation would be placed in the representation of the field of view in response to receiving an annotation placement input; 
 
 while displaying the annotation placement user interface, detecting a first movement of the one or more cameras relative to the three-dimensional physical environment; 
 in response to detecting the first movement of the one or more cameras relative to the three-dimensional physical environment, updating the representation of the field of view based on the first movement of the one or more cameras; 
 in accordance with a determination that the placement user interface element is over at least a portion of a representation of a physical feature in the three-dimensional physical environment that can be measured, changing an appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical feature; 
 while displaying the annotation placement user interface, receiving an annotation placement input comprising a request to perform one or more measurements of the physical feature; and 
 in response to receiving the annotation placement input comprising a request to perform one or more measurements of the physical feature:
 in accordance with a determination that the physical feature is a first type of physical feature, displaying, over the representation of the physical feature, a first set of one or more representations of measurements of a first measurement type; and 
 in accordance with a determination that the physical feature is a second type of physical feature, different from the first type of physical feature, displaying, over the representation of the physical feature, a second set of one or more representations of measurements of a second measurement type different from the first measurement type. 
 
 
 
     
     
       14. The computer system of  claim 13 , wherein the physical feature is a first respective type of physical feature, the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and a second portion of the physical object is at most partially in the field of view of the one or more cameras, and the one or more programs include instructions for:
 after displaying, over the representation of the physical feature, a first respective set of one or more representations of measurements of a first respective measurement type:
 detecting a second movement of the one or more cameras relative to the three-dimensional physical environment such that the second portion of the physical object is in the field of view of the one or more cameras; 
 in response to detecting the second movement of the one or more cameras:
 updating the representation of the field of view based on the second movement of the one or more cameras, including displaying, in the representation of the field of view, a representation of the physical object that includes a representation of the second portion of the physical object; 
 
 in accordance with a determination that the placement user interface element is over at least a portion of the representation of the physical object, changing the appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical object including the second portion of the physical object; 
 while displaying the annotation placement user interface including the representation of the physical object, receiving a second annotation placement input comprising a request to perform one or more measurements of the physical object; and 
 in response to receiving the second annotation placement input corresponding to the request to perform one or more measurements of the physical object:
 displaying, over the representation of the physical object, a second respective set of one or more representations of measurements of a second respective measurement type that is based on the second portion of the physical object. 
 
 
 
     
     
       15. The computer system of  claim 13 , wherein the determination that the physical feature is the first type of physical feature includes a determination that the physical feature is a piece of furniture, and the measurements of the first measurement type include one or more of: a height, a width, a depth, and a volume of the physical feature. 
     
     
       16. The computer system of  claim 13 , wherein the one or more programs include instructions for:
 while displaying a respective set of one or more representations of measurements over the representation of the physical feature, wherein the respective set includes a first representation of a measurement, the first representation including a first measurement label and a first measurement segment that is displayed using a first level of detail while the one or more cameras are located a first distance from the physical feature, detecting movement of the one or more cameras that places the one or more cameras at a second distance, less than the first distance, from the physical feature; and 
 while the one or more cameras are located at the second distance from the physical feature:
 enlarging display of the first measurement label; and 
 displaying the first measurement segment using a second level of detail that is different from the first level of detail. 
 
 
     
     
       17. The computer system of  claim 16 , wherein the one or more programs include instructions for:
 detecting a first touch input; and 
 in response to detecting the first touch input, adding and displaying a first measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional physical environment, wherein the first measurement point at the first location in the representation of the field of view is a most-recently-added measurement point in the representation of the field of view. 
 
     
     
       18. The computer system of  claim 16 , wherein displaying the first measurement segment using the first level of detail includes displaying one or more first scale markers along the representation of the first measurement segment at a first scale; and displaying the first measurement segment using the second level of detail includes displaying one or more second scale markers along at least a portion of the representation of the first measurement segment at a second scale that is distinct from the first scale. 
     
     
       19. The computer system of  claim 16 , wherein displaying the first measurement segment using the second level of detail includes displaying a set of scale markers at intervals along the first measurement segment, and the one or more programs include instructions for:
 while displaying the first measurement segment using the second level of detail, detecting a second touch input; and 
 in response to receiving the second touch input, enlarging display of at least a portion of the representation of the field of view. 
 
     
     
       20. The computer system of  claim 19 , wherein the display device is a touch-sensitive display, and the one or more programs include instructions for:
 while displaying the enlarged display of at least the portion of the representation of the field of view, detecting a third touch input that includes detecting movement of a contact across the touch-sensitive display; and 
 in response to detecting the movement of the contact across the touch-sensitive display:
 moving a measurement point across the representation of the field of view in accordance with the movement of the contact in the third touch input. 
 
 
     
     
       21. The computer system of  claim 16 , wherein the one or more programs include instructions for:
 while displaying the first measurement segment using the second level of detail, detecting movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature; 
 in response to detecting the movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature:
 updating the representation of the field of view based on the movement of the one or more cameras; and 
 
 while the one or more cameras are located at the first distance from the physical feature:
 displaying the first measurement segment using the first level of detail; and 
 displaying the first measurement label. 
 
 
     
     
       22. The computer system of  claim 16 , wherein:
 the computer system is an electronic device; 
 the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras; and 
 the one or more programs include instructions for:
 in accordance with a determination that the first distance between the electronic device and the physical object is less than a first threshold distance, the first measurement label is displayed at a first threshold size; 
 in accordance with a determination that the first distance between the electronic device and the physical object is greater than a second threshold distance that is greater than the first threshold distance, the first measurement label is displayed at a second threshold size that is smaller than the first threshold size; and 
 in accordance with a determination that the first distance between the electronic device and the physical object is between the first threshold distance and the second threshold distance, the first measurement label is displayed at a size, between the first threshold size and the second threshold size, that depends on the first distance between the electronic device and the physical object. 
 
 
     
     
       23. The computer system of  claim 13 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the annotation placement user interface includes an affordance, which, when activated, adds a measurement point in the representation of the field of view at a location in the representation of the field of view over which the placement user interface element is displayed, and receiving the annotation placement input comprising a request to perform one or more measurements of the physical object includes:
 detecting a fourth touch input activating the affordance; and 
 in response to detecting the fourth touch input activating the affordance, adding and displaying the measurement point in the representation of the field of view at the location in the representation of the field of view over which the placement user interface element is displayed. 
 
     
     
       24. The computer system of  claim 13 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the one or more programs include instructions for:
 determining a classification of the physical object; and 
 displaying a label indicating the classification of the physical object. 
 
     
     
       25. A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions that, when executed by a computer system that includes a display device and one or more cameras, cause the computer system to perform operations including:
 displaying, via the display device, an annotation placement user interface, the annotation placement user interface including:
 a representation of a field of view of the one or more cameras, including a representation of a portion of a three-dimensional physical environment that is in the field of view of the one or more cameras, wherein the representation of the field of view is updated over time based on changes in the field of view of the one or more cameras; 
 a placement user interface element that indicates a location at which a virtual annotation would be placed in the representation of the field of view in response to receiving an annotation placement input; 
 
 while displaying the annotation placement user interface, detecting a first movement of the one or more cameras relative to the three-dimensional physical environment; and 
 in response to detecting the first movement of the one or more cameras relative to the three-dimensional physical environment, updating the representation of the field of view based on the first movement of the one or more cameras; 
 in accordance with a determination that the placement user interface element is over at least a portion of a representation of a physical feature in the three-dimensional physical environment that can be measured, changing an appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical feature; 
 while displaying the annotation placement user interface, receiving an annotation placement input comprising a request to perform one or more measurements of the physical feature; and 
 in response to receiving the annotation placement input comprising a request to perform one or more measurements of the physical feature:
 in accordance with a determination that the physical feature is a first type of physical feature, displaying, over the representation of the physical feature, a first set of one or more representations of measurements of a first measurement type; and 
 in accordance with a determination that the physical feature is a second type of physical feature, different from the first type of physical feature, displaying, over the representation of the physical feature, a second set of one or more representations of measurements of a second measurement type different from the first measurement type. 
 
 
     
     
       26. The non-transitory computer readable storage medium of  claim 25 , wherein the physical feature is a first respective type of physical feature, the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and a second portion of the physical object is at most partially in the field of view of the one or more cameras, and the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 after displaying, over the representation of the physical feature, a first respective set of one or more representations of measurements of a first respective measurement type:
 detecting a second movement of the one or more cameras relative to the three-dimensional physical environment such that the second portion of the physical object is in the field of view of the one or more cameras; 
 in response to detecting the second movement of the one or more cameras:
 updating the representation of the field of view based on the second movement of the one or more cameras, including displaying, in the representation of the field of view, a representation of the physical object that includes a representation of the second portion of the physical object; 
 
 in accordance with a determination that the placement user interface element is over at least a portion of the representation of the physical object, changing the appearance of the placement user interface element in accordance with one or more aspects of the representation of the physical object including the second portion of the physical object; 
 while displaying the annotation placement user interface including the representation of the physical object, receiving a second annotation placement input comprising a request to perform one or more measurements of the physical object; and 
 in response to receiving the second annotation placement input corresponding to the request to perform one or more measurements of the physical object:
 displaying, over the representation of the physical object, a second respective set of one or more representations of measurements of a second respective measurement type that is based on the second portion of the physical object. 
 
 
 
     
     
       27. The non-transitory computer readable storage medium of  claim 25 , wherein the determination that the physical feature is the first type of physical feature includes a determination that the physical feature is a piece of furniture, and the measurements of the first measurement type include one or more of: a height, a width, a depth, and a volume of the physical feature. 
     
     
       28. The non-transitory computer readable storage medium of  claim 25 , wherein the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 while displaying a respective set of one or more representations of measurements over the representation of the physical feature, wherein the respective set includes a first representation of a measurement, the first representation including a first measurement label and a first measurement segment that is displayed using a first level of detail while the one or more cameras are located a first distance from the physical feature, detecting movement of the one or more cameras that places the one or more cameras at a second distance, less than the first distance, from the physical feature; and 
 while the one or more cameras are located at the second distance from the physical feature:
 enlarging display of the first measurement label; and 
 displaying the first measurement segment using a second level of detail that is different from the first level of detail. 
 
 
     
     
       29. The non-transitory computer readable storage medium of  claim 28 , wherein the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 detecting a first touch input; and 
 in response to detecting the first touch input, adding and displaying a first measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional physical environment, wherein the first measurement point at the first location in the representation of the field of view is a most-recently-added measurement point in the representation of the field of view. 
 
     
     
       30. The non-transitory computer readable storage medium of  claim 28 , wherein displaying the first measurement segment using the first level of detail includes displaying one or more first scale markers along the representation of the first measurement segment at a first scale; and displaying the first measurement segment using the second level of detail includes displaying one or more second scale markers along at least a portion of the representation of the first measurement segment at a second scale that is distinct from the first scale. 
     
     
       31. The non-transitory computer readable storage medium of  claim 28 , wherein displaying the first measurement segment using the second level of detail includes displaying a set of scale markers at intervals along the first measurement segment, and the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 while displaying the first measurement segment using the second level of detail, detecting a second touch input; and 
 in response to receiving the second touch input, enlarging display of at least a portion of the representation of the field of view. 
 
     
     
       32. The non-transitory computer readable storage medium of  claim 31 , wherein the display device is a touch-sensitive display, and the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 while displaying the enlarged display of at least the portion of the representation of the field of view, detecting a third touch input that includes detecting movement of a contact across the touch-sensitive display; and 
 in response to detecting the movement of the contact across the touch-sensitive display:
 moving a measurement point across the representation of the field of view in accordance with the movement of the contact in the third touch input. 
 
 
     
     
       33. The non-transitory computer readable storage medium of  claim 28 , wherein the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 while displaying the first measurement segment using the second level of detail, detecting movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature; 
 in response to detecting the movement of the one or more cameras that places the one or more cameras at the first distance from the physical feature:
 updating the representation of the field of view based on the movement of the one or more cameras; and 
 
 while the one or more cameras are located at the first distance from the physical feature:
 displaying the first measurement segment using the first level of detail; and 
 displaying the first measurement label. 
 
 
     
     
       34. The non-transitory computer readable storage medium of  claim 28 , wherein:
 the computer system is an electronic device; 
 the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras; and 
 the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 in accordance with a determination that the first distance between the electronic device and the physical object is less than a first threshold distance, the first measurement label is displayed at a first threshold size; 
 in accordance with a determination that the first distance between the electronic device and the physical object is greater than a second threshold distance that is greater than the first threshold distance, the first measurement label is displayed at a second threshold size that is smaller than the first threshold size; and 
 in accordance with a determination that the first distance between the electronic device and the physical object is between the first threshold distance and the second threshold distance, the first measurement label is displayed at a size, between the first threshold size and the second threshold size, that depends on the first distance between the electronic device and the physical object. 
 
 
     
     
       35. The non-transitory computer readable storage medium of  claim 25 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the annotation placement user interface includes an affordance, which, when activated, adds a measurement point in the representation of the field of view at a location in the representation of the field of view over which the placement user interface element is displayed, and receiving the annotation placement input comprising a request to perform one or more measurements of the physical object includes:
 detecting a fourth touch input activating the affordance; and 
 in response to detecting the fourth touch input activating the affordance, adding and displaying the measurement point in the representation of the field of view at the location in the representation of the field of view over which the placement user interface element is displayed. 
 
     
     
       36. The non-transitory computer readable storage medium of  claim 25 , wherein the physical feature is a first portion of a physical object in the three-dimensional physical environment that is in the field of view of the one or more cameras, and the one or more programs include instructions that when executed by the computer system cause the computer system to perform operations including:
 determining a classification of the physical object; and 
 displaying a label indicating the classification of the physical object.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/750,133, filed May 20, 2022, which is a continuation of U.S. application Ser. No. 17/307,957, filed May 4, 2021, now U.S. Pat. No. 11,391,561, which is continuation of U.S. application Ser. No. 16/841,550, filed Apr. 6, 2020, now U.S. Pat. No. 11,073,375, which is a continuation of U.S. application Ser. No. 16/138,779, filed Sep. 21, 2018, now U.S. Pat. No. 10,612,908, which claims priority to U.S. Provisional Application Ser. No. 62/679,952, filed Jun. 3, 2018, and U.S. Provisional Application Ser. No. 62/668,249, filed May 7, 2018, all of which are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     This relates generally to electronic devices for virtual/augmented reality, including but not limited to electronic devices for measuring physical spaces and/or objects using virtual/augmented reality environments. 
     BACKGROUND 
     Augmented reality environments are useful for making measurements of physical spaces and objects therein, by providing a view of the physical space and enabling a user to superimpose measurements on the physical space and objects therein. But conventional methods of measuring using augmented reality are cumbersome, inefficient, and limited. In some cases, conventional methods of measuring using augmented reality are limited in functionality. In some cases, conventional methods of measuring using augmented reality require multiple separate inputs (e.g., a sequence of gestures and button presses, etc.) to achieve an intended outcome (e.g., through activation of numerous displayed user interface elements to access different measurement functions). In addition, conventional methods take longer than necessary, thereby wasting energy. This latter consideration is particularly important in battery-operated devices. 
     SUMMARY 
     Accordingly, there is a need for computer systems with improved methods and interfaces for measuring using virtual/augmented reality environments. Such methods and interfaces optionally complement or replace conventional methods for measuring using virtual/augmented reality environments. Such methods and interfaces reduce the number, extent, and/or nature of the inputs from a user and produce a more efficient human-machine interface. For battery-operated devices, such methods and interfaces conserve power and increase the time between battery charges. 
     The above deficiencies and other problems associated with user interfaces for measuring using virtual/augmented reality are reduced or eliminated by the disclosed computer systems. In some embodiments, the computer system includes a desktop computer. In some embodiments, the computer system is portable (e.g., a notebook computer, tablet computer, or handheld device). In some embodiments, the computer system includes a personal electronic device (e.g., a wearable electronic device, such as a watch). In some embodiments, the computer system has (and/or is in communication with) a touchpad. In some embodiments, the computer system has (and/or is in communication with) a touch-sensitive display (also known as a “touch screen” or “touch-screen display”). In some embodiments, the computer system has a graphical user interface (GUI), one or more processors, memory and one or more modules, programs or sets of instructions stored in the memory for performing multiple functions. In some embodiments, the user interacts with the GUI in part through stylus and/or finger contacts and gestures on the touch-sensitive surface. In some embodiments, in addition to an augmented reality-based measurement function, the functions optionally include game playing, image editing, drawing, presenting, word processing, spreadsheet making, telephoning, video conferencing, e-mailing, instant messaging, workout support, digital photographing, digital videoing, web browsing, digital music playing, note taking, and/or digital video playing. Executable instructions for performing these functions are, optionally, included in a non-transitory computer readable storage medium or other computer program product configured for execution by one or more processors. 
     In accordance with some embodiments, a method is performed at an electronic device with a touch-sensitive display and one or more cameras. The method includes displaying, on the touch-sensitive display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is displayed at a first magnification, and the representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The field of view includes at least a portion of a three-dimensional space. The method includes, while displaying the representation of the field of view, detecting a first touch input on the touch-sensitive display, and, in response to detecting the first touch input, adding and displaying a measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional space. The method also includes, after adding the measurement point and while continuing to display the representation of the field of view: as at least one of the one or more cameras moves, displaying the measurement point at a location in the representation of the field of view that corresponds to the first location in the three-dimensional space; detecting a second touch input at a location on the touch-sensitive display that corresponds to a current location of the measurement point in the representation of the field of view; and, in response to detecting the second touch input, enlarging display of at least a portion of the representation of the field of view from the first magnification to a second magnification, greater than the first magnification, wherein the enlarged display of the portion of the representation of the field of view includes the measurement point. 
     In accordance with some embodiments, a method is performed at an electronic device with a touch-sensitive display, one or more sensors to detect intensities of contacts with the touch-sensitive display, and one or more cameras. The method includes displaying, on the touch-sensitive display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The user interface also includes a measurement-point-creation indicator that is displayed over the representation of the field of view. The field of view includes at least a portion of a three-dimensional space. The method includes detecting a contact on the touch-sensitive display, and, while continuously detecting the contact on the touch-sensitive display, while the measurement-point-creation indicator is displayed over a first location in the representation of the field of view that corresponds to a first location in the three-dimensional space, and in accordance with a determination that first criteria are met, where the first criteria include a requirement that an intensity of the contact meet a respective intensity threshold in order for the first criteria to be met, adding and displaying a first measurement point in the representation of the field of view that corresponds to the first location in the three-dimensional space. The method also includes, after adding the first measurement point, updating the representation of the field of view as the electronic device is moved. The method further includes, after the electronic device is moved, while the measurement-point-creation indicator is displayed over a second location in the representation of the field of view that corresponds to a second location in the three-dimensional space, in accordance with a determination that the first criteria are met while the measurement-point-creation indicator is displayed over the second location in the representation of the field of view that corresponds to the second location in the three-dimensional space: adding and displaying a second measurement point in the representation of the field of view that corresponds to the second location in the three-dimensional space; and displaying a first measurement segment connecting the first measurement point and the second measurement point. 
     In accordance with some embodiments, a method is performed at an electronic device with a touch-sensitive display and one or more cameras. The method includes displaying, on the touch-sensitive display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The user interface includes a measurement-point-creation indicator that is displayed over the representation of the field of view. The field of view includes at least a portion of a three-dimensional space. The method includes, while displaying the representation of the field of view, determining an anchor point at a location in the representation of the field of view that corresponds to a first location in the three-dimensional space. The method also includes, as at least one of the one or more cameras move, while the measurement-point-creation indicator is over the anchor point, changing a visual appearance of the measurement-point-creation indicator to indicate that a measurement point will be added at the anchor point if a touch input meets first criteria. The method further includes, detecting a first touch input on the touch-sensitive display that meets the first criteria, and, in response to detecting the first touch input that meets the first criteria: in accordance with a determination that the measurement-point-creation indicator is over the anchor point when the first criteria are met, adding and displaying a first measurement point at the anchor point in the representation of the field of view that corresponds to the first location in the three-dimensional space; and in accordance with a determination that the measurement-point-creation indicator is not over the anchor point when the first criteria are met, adding and displaying a first measurement point at a first location in the representation of the field of view that is away from the anchor point. 
     In accordance with some embodiments, a method is performed at an electronic device with a display, an input device, and one or more cameras. The method includes displaying, on the display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The field of view includes a physical object in a three-dimensional space. The method includes, while displaying the representation of the field of view, detecting one or more user inputs, via the input device, that add, over the representation of the field of view, a representation of a first measurement that corresponds to the physical object. The method also includes concurrently displaying, over the representation of the field of view, the representation of the first measurement and a first label that describes the first measurement, where: in accordance with a determination that a first distance between the electronic device and the physical object is less than a first threshold distance, the first label is displayed at a first threshold size; in accordance with a determination that the first distance between the electronic device and the physical object is greater than a second threshold distance that is greater than the first threshold distance, the first label is displayed at a second threshold size that is smaller than the first threshold size; and in accordance with a determination that the first distance between the electronic device and the physical object is between the first threshold distance and the second threshold distance, the first label is displayed at a size, between the first threshold size and the second threshold size, that depends on the first distance between the electronic device and the physical object. 
     In accordance with some embodiments, a method is performed at an electronic device with a display, an input device, and one or more cameras. The method includes displaying, on the display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The field of view includes a physical object in a three-dimensional space. The method includes, while displaying the representation of the field of view, detecting one or more user inputs, via the input device, that add, over the representation of the field of view, a representation of a first measurement that corresponds to the physical object, where the representation of the first measurement includes a first endpoint that corresponds to a first location on the physical object, the representation of the first measurement includes a second endpoint that corresponds to a second location on the physical object; and the representation of the first measurement includes a first line segment connecting the first endpoint and the second endpoint. The method also includes determining, based in part on the first measurement, a first area in the representation of the field of view that adjoins the first line segment of the first measurement, where the first area corresponds to a physical rectangular area in the three-dimensional space. The method further includes displaying an indication of the first area in the user interface, where the indication is overlaid on the first area in the representation of the field of view. 
     In accordance with some embodiments, a method is performed at an electronic device with a touch-sensitive display and one or more cameras. The method includes displaying, on the touch-sensitive display, a first user interface of an application. The first user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The field of view includes a physical object in a three-dimensional space. A representation of a measurement of the physical object is superimposed on an image of the physical object in the representation of the field of view. The method includes, while displaying the first user interface, detecting a first touch input on the touch-sensitive display on the representation of the measurement. The method further includes, in response to detecting the first touch input on the touch-sensitive display on the representation of the measurement, initiating a process for sharing information about the measurement. 
     In accordance with some embodiments, a method is performed at an electronic device with a display, an input device, and one or more cameras. The method includes displaying, on the display, a user interface of an application. The user interface includes a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras. The field of view includes at least a portion of a three-dimensional space. The method includes detecting movement of the electronic device that moves the field of view of at least one of the one or more cameras in a first direction. The method also includes, while detecting the movement of the electronic device that moves the field of view in the first direction: updating the representation of the field of view in accordance with the movement of the electronic device; identifying one or more first elements in the representation of the field of view that extend along the first direction; and, based at least in part on the determination of the one or more first elements, displaying, in the representation of the field of view, a first guide that extends in the first direction and that corresponds to one of the one or more first identified elements. 
     In accordance with some embodiments, a method is performed at an electronic device with one or more input devices, one or more display devices, and one or more cameras: The method includes displaying, via the one or more display devices, a user interface that includes a representation of a physical space. The method includes, while displaying the representation of the physical space, receiving a first set of one or more inputs to create a virtual annotation in the representation of the physical space. The method also includes, in response to receiving the first set of one or more inputs, adding a first virtual annotation to the representation of the physical space. The first virtual annotation is linked to a portion of the representation of the physical space. The method also includes, after adding the first virtual annotation to the representation of the physical space, receiving a second set of one or more inputs associated with the representation of the physical space. The method further includes, in response to receiving the second set of one or more inputs associated with the representation of the physical space: in accordance with a determination that the second set of one or more inputs corresponds to a request to create a virtual annotation in the representation of the physical space that is within a threshold distance from the first virtual annotation, creating a second virtual annotation in the representation of the physical space while maintaining the first virtual annotation in the representation of the physical space; and, in accordance with a determination that the second set of one or more inputs corresponds to a request to create a virtual annotation in the representation of the physical space that is outside of the threshold distance from the first virtual annotation, creating a second virtual annotation in the representation of the physical space and removing the first virtual annotation from the representation of the physical space. 
     In accordance with some embodiments, a method is performed at an electronic device with one or more input devices, one or more display devices, and one or more cameras. The method includes displaying, via the one or more display devices, an annotation placement user interface. The annotation placement user interface includes: a representation of a physical space; and a placement user interface element that indicates a location at which a virtual annotation will be placed in the representation of the physical space in response to detecting an annotation placement input. The method includes, while displaying the annotation placement user interface, detecting movement of at least one of the one or more cameras relative to the physical space. The movement of at least one of the one or more cameras starts while the placement user interface element is displayed at a location in the representation of the physical space that corresponds to a first portion of the physical space. The method includes, in response to detecting the movement of at least one of the one or more cameras relative to the physical space, moving the placement user interface element to a location in the representation of the physical space that corresponds to a second portion of the physical space that is different from the first portion of the physical space, and updating an appearance of the annotation placement user interface in accordance with the movement of at least one of the one or more cameras relative to the physical space, including: in accordance with a determination that the electronic device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, ceasing to display at least a portion of the placement user interface element; and in accordance with a determination that the device has identified an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, maintaining display of the placement user interface element. 
     In accordance with some embodiments, a computer system (e.g., an electronic device) includes (and/or is in communication with) a display generation component (e.g., a display, a projector, a heads-up display, or the like), one or more cameras (e.g., video cameras that continuously provide a live preview of at least a portion of the contents that are within the field of view of the cameras and optionally generate video outputs including one or more streams of image frames capturing the contents within the field of view of the cameras), and one or more input devices (e.g., a touch-sensitive surface, such as a touch-sensitive remote control, or a touch-screen display that also serves as the display generation component, a mouse, a joystick, a wand controller, and/or cameras tracking the position of one or more features of the user such as the user&#39;s hands), optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, optionally one or more tactile output generators, one or more processors, and memory storing one or more programs; the one or more programs are configured to be executed by the one or more processors and the one or more programs include instructions for performing or causing performance of the operations of any of the methods described herein. In accordance with some embodiments, a computer readable storage medium has stored therein instructions, which, when executed by a computer system that includes (and/or is in communication with) a display generation component, one or more cameras, one or more input devices, optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, and optionally one or more tactile output generators, cause the computer system to perform or cause performance of the operations of any of the methods described herein. In accordance with some embodiments, a graphical user interface on a computer system that includes (and/or is in communication with) a display generation component, one or more cameras, one or more input devices, optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, optionally one or more tactile output generators, a memory, and one or more processors to execute one or more programs stored in the memory includes one or more of the elements displayed in any of the methods described herein, which are updated in response to inputs, as described in any of the methods described herein. In accordance with some embodiments, a computer system includes (and/or is in communication with) a display generation component, one or more cameras, one or more input devices, optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, optionally one or more tactile output generators, and means for performing or causing performance of the operations of any of the methods described herein. In accordance with some embodiments, an information processing apparatus, for use in a computer system that includes (and/or is in communication with) a display generation component, one or more cameras, one or more input devices, optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, and optionally one or more tactile output generators, includes means for performing or causing performance of the operations of any of the methods described herein. 
     Thus, computer systems that have (and/or are in communication with) a display generation component, one or more cameras, one or more input devices, optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, and optionally one or more tactile output generators, are provided with improved methods and interfaces for measuring physical objects using virtual/augmented reality environments, thereby increasing the effectiveness, efficiency, and user satisfaction with such computer systems. Such methods and interfaces may complement or replace conventional methods for measuring physical objects using virtual/augmented reality environments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the various described embodiments, reference should be made to the Description of Embodiments below, in conjunction with the following drawings in which like reference numerals refer to corresponding parts throughout the figures. 
         FIG.  1 A  is a block diagram illustrating a portable multifunction device with a touch-sensitive display in accordance with some embodiments. 
         FIG.  1 B  is a block diagram illustrating example components for event handling in accordance with some embodiments. 
         FIG.  1 C  is a block diagram illustrating a tactile output module in accordance with some embodiments. 
         FIG.  2    illustrates a portable multifunction device having a touch screen in accordance with some embodiments. 
         FIG.  3 A  is a block diagram of an example multifunction device with a display and a touch-sensitive surface in accordance with some embodiments. 
         FIGS.  3 B- 3 C  are block diagrams of example computer systems in accordance with some embodiments. 
         FIG.  4 A  illustrates an example user interface for a menu of applications on a portable multifunction device in accordance with some embodiments. 
         FIG.  4 B  illustrates an example user interface for a multifunction device with a touch-sensitive surface that is separate from the display in accordance with some embodiments. 
         FIGS.  4 C- 4 E  illustrate examples of dynamic intensity thresholds in accordance with some embodiments. 
         FIGS.  4 F- 4 K  illustrate a set of sample tactile output patterns in accordance with some embodiments. 
         FIGS.  5 A- 5 CO  illustrate example user interfaces for making measurements of a physical space using an augmented reality environment in accordance with some embodiments. 
         FIGS.  6 A- 6 C  are flow diagrams of a process for interacting with an application for making measurements of a physical space using an augmented reality environment in accordance with some embodiments. 
         FIGS.  7 A- 7 E  are flow diagrams of a process for adding measurements to a displayed representation of a physical space in an augmented reality environment in accordance with some embodiments. 
         FIGS.  8 A- 8 C  are flow diagrams of a process for adding virtual measurement points at automatically determined anchor points in an augmented reality environment in accordance with some embodiments. 
         FIGS.  9 A- 9 B  are flow diagrams of a process for displaying labels for measurements of a physical space in an augmented reality environment in accordance with some embodiments. 
         FIGS.  10 A- 10 B  are flow diagrams of a process for measuring and interacting with rectangular areas in a physical space in an augmented reality environment in accordance with some embodiments. 
         FIGS.  11 A- 11 B  are flow diagrams of a process for interacting with and managing measurement information in an augmented reality environment in accordance with some embodiments. 
         FIGS.  12 A- 12 C  are flow diagrams of a process for providing automatically determined alignment guides in an augmented reality environment in accordance with some embodiments. 
         FIGS.  13 A- 13 C  are flow diagrams of a process for automatically removing previously-added virtual annotations in an augmented reality environment in accordance with some embodiments. 
         FIGS.  14 A- 14 D  are flow diagrams of a process for indicating whether objects in a physical space have been identified as objects whose corresponding representations in an augmented reality environment can be tracked in accordance with some embodiments. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     As noted above, augmented reality environments are useful for making measurements of physical spaces and objects therein, by providing a view of the physical space and enabling a user to superimpose measurements on the physical space and physical objects therein. Conventional methods of measuring with augmented reality environments are often limited in functionality. In some cases, conventional methods require multiple separate inputs (e.g., a sequence of gestures and button presses, etc.) to achieve an intended outcome (e.g., through activation of numerous displayed user interface elements to access different measurement functions). The embodiments disclosed herein provide an intuitive way for a user to make measurements with an augmented reality environment (e.g., by enabling the user to perform different operations in the augmented reality environment with fewer inputs, and/or by simplifying the user interface). Additionally, the embodiments herein provide improved visual and tactile feedback that provide additional information to the user about the physical objects being measured and about the operations being performed in the augmented reality environment. 
     The systems, methods, and GUIs described herein improve user interface interactions with virtual/augmented reality environments in multiple ways. For example, they make it easier to measure features in a physical space using an augmented reality environment, by providing automatic detection of features in the physical space, improved labeling, and alignment guides (e.g., for improved measurement point placement and area recognition), and by enabling the user to interact with and manage measurement information. 
     Below,  FIGS.  1 A- 1 B,  2 , and  3 A- 3 C  provide a description of example devices.  FIGS.  4 A- 4 B and  5 A- 5 CO  illustrate example contexts and example user interfaces for making measurements of a physical space using an augmented reality environment.  FIGS.  6 A- 6 C  illustrate a flow diagram of a method of interacting with an application for making measurements of a physical space using an augmented reality environment.  FIGS.  7 A- 7 E  illustrate a flow diagram of a method of adding measurements to a displayed representation of a physical space in an augmented reality environment.  FIGS.  8 A- 8 C  illustrate a flow diagram of a method of adding virtual measurement points at automatically determined anchor points in an augmented reality environment.  FIGS.  9 A- 9 B  illustrate a flow diagram of a method of displaying labels for measurements of a physical space in an augmented reality environment.  FIGS.  10 A- 10 B  illustrate a flow diagram of a method of measuring and interacting with rectangular areas in a physical space in an augmented reality environment.  FIGS.  11 A- 11 B  illustrate a flow diagram of a method of interacting with and managing measurement information in an augmented reality environment.  FIGS.  12 A- 12 C  illustrate a flow diagram of a method of providing automatically determined alignment guides in an augmented reality environment.  FIGS.  13 A- 13 C  are flow diagrams of a process for automatically removing previously-added virtual annotations in an augmented reality environment.  FIGS.  14 A- 14 D  are flow diagrams of a process for indicating whether objects in a physical space have been identified as objects whose corresponding representations in an augmented reality environment can be tracked. The user interfaces in  FIGS.  5 A- 5 CO  are used to illustrate the processes in  FIGS.  6 A- 6 C,  7 A- 7 E,  8 A- 8 C,  9 A- 9 B,  10 A- 10 B,  11 A- 11 B,  12 A- 12 C,  13 A- 13 C, and  14 A- 14 D . 
     Example Devices 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. 
     It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both contacts, but they are not the same contact, unless the context clearly indicates otherwise. 
     The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     As used herein, the term “if” is, optionally, construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” is, optionally, construed to mean “upon determining” or “in response to determining” or “upon detecting [the stated condition or event]” or “in response to detecting [the stated condition or event],” depending on the context. 
     Computer systems for virtual/augmented reality include electronic devices that produce virtual/augmented reality environments. Embodiments of electronic devices, user interfaces for such devices, and associated processes for using such devices are described. In some embodiments, the device is a portable communications device, such as a mobile telephone, that also contains other functions, such as PDA and/or music player functions. Example embodiments of portable multifunction devices include, without limitation, the iPhone®, iPod Touch®, and iPad® devices from Apple Inc. of Cupertino, California. Other portable electronic devices, such as laptops or tablet computers with touch-sensitive surfaces (e.g., touch-screen displays and/or touchpads), are, optionally, used. It should also be understood that, in some embodiments, the device is not a portable communications device, but is a desktop computer with a touch-sensitive surface (e.g., a touch-screen display and/or a touchpad) that also includes, or is in communication with, one or more cameras. 
     In the discussion that follows, a computer system that includes an electronic device that has (and/or is in communication with) a display and a touch-sensitive surface is described. It should be understood, however, that the computer system optionally includes one or more other physical user-interface devices, such as a physical keyboard, a mouse, a joystick, a wand controller, and/or cameras tracking the position of one or more features of the user such as the user&#39;s hands. 
     The device typically supports a variety of applications, such as one or more of the following: a gaming application, a note taking application, a drawing application, a presentation application, a word processing application, a spreadsheet application, a telephone application, a video conferencing application, an e-mail application, an instant messaging application, a workout support application, a photo management application, a digital camera application, a digital video camera application, a web browsing application, a digital music player application, and/or a digital video player application. 
     The various applications that are executed on the device optionally use at least one common physical user-interface device, such as the touch-sensitive surface. One or more functions of the touch-sensitive surface as well as corresponding information displayed by the device are, optionally, adjusted and/or varied from one application to the next and/or within a respective application. In this way, a common physical architecture (such as the touch-sensitive surface) of the device optionally supports the variety of applications with user interfaces that are intuitive and transparent to the user. 
     Attention is now directed toward embodiments of portable devices with touch-sensitive displays.  FIG.  1 A  is a block diagram illustrating portable multifunction device  100  with touch-sensitive display system  112  in accordance with some embodiments. Touch-sensitive display system  112  is sometimes called a “touch screen” for convenience, and is sometimes simply called a touch-sensitive display. Device  100  includes memory  102  (which optionally includes one or more computer readable storage mediums), memory controller  122 , one or more processing units (CPUs)  120 , peripherals interface  118 , RF circuitry  108 , audio circuitry  110 , speaker  111 , microphone  113 , input/output (I/O) subsystem  106 , other input or control devices  116 , and external port  124 . Device  100  optionally includes one or more optical sensors  164  (e.g., as part of one or more cameras). Device  100  optionally includes one or more intensity sensors  165  for detecting intensities of contacts on device  100  (e.g., a touch-sensitive surface such as touch-sensitive display system  112  of device  100 ). Device  100  optionally includes one or more tactile output generators  163  for generating tactile outputs on device  100  (e.g., generating tactile outputs on a touch-sensitive surface such as touch-sensitive display system  112  of device  100  or touchpad  355  of device  300 ). These components optionally communicate over one or more communication buses or signal lines  103 . 
     As used in the specification and claims, the term “tactile output” refers to physical displacement of a device relative to a previous position of the device, physical displacement of a component (e.g., a touch-sensitive surface) of a device relative to another component (e.g., housing) of the device, or displacement of the component relative to a center of mass of the device that will be detected by a user with the user&#39;s sense of touch. For example, in situations where the device or the component of the device is in contact with a surface of a user that is sensitive to touch (e.g., a finger, palm, or other part of a user&#39;s hand), the tactile output generated by the physical displacement will be interpreted by the user as a tactile sensation corresponding to a perceived change in physical characteristics of the device or the component of the device. For example, movement of a touch-sensitive surface (e.g., a touch-sensitive display or trackpad) is, optionally, interpreted by the user as a “down click” or “up click” of a physical actuator button. In some cases, a user will feel a tactile sensation such as an “down click” or “up click” even when there is no movement of a physical actuator button associated with the touch-sensitive surface that is physically pressed (e.g., displaced) by the user&#39;s movements. As another example, movement of the touch-sensitive surface is, optionally, interpreted or sensed by the user as “roughness” of the touch-sensitive surface, even when there is no change in smoothness of the touch-sensitive surface. While such interpretations of touch by a user will be subject to the individualized sensory perceptions of the user, there are many sensory perceptions of touch that are common to a large majority of users. Thus, when a tactile output is described as corresponding to a particular sensory perception of a user (e.g., an “up click,” a “down click,” “roughness”), unless otherwise stated, the generated tactile output corresponds to physical displacement of the device or a component thereof that will generate the described sensory perception for a typical (or average) user. Using tactile outputs to provide haptic feedback to a user enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device) which, additionally, reduces power usage and improves battery life of the device by enabling the user to use the device more quickly and efficiently. 
     In some embodiments, a tactile output pattern specifies characteristics of a tactile output, such as the amplitude of the tactile output, the shape of a movement waveform of the tactile output, the frequency of the tactile output, and/or the duration of the tactile output. 
     When tactile outputs with different tactile output patterns are generated by a device (e.g., via one or more tactile output generators that move a moveable mass to generate tactile outputs), the tactile outputs may invoke different haptic sensations in a user holding or touching the device. While the sensation of the user is based on the user&#39;s perception of the tactile output, most users will be able to identify changes in waveform, frequency, and amplitude of tactile outputs generated by the device. Thus, the waveform, frequency and amplitude can be adjusted to indicate to the user that different operations have been performed. As such, tactile outputs with tactile output patterns that are designed, selected, and/or engineered to simulate characteristics (e.g., size, material, weight, stiffness, smoothness, etc.); behaviors (e.g., oscillation, displacement, acceleration, rotation, expansion, etc.); and/or interactions (e.g., collision, adhesion, repulsion, attraction, friction, etc.) of objects in a given environment (e.g., a user interface that includes graphical features and objects, a simulated physical environment with virtual boundaries and virtual objects, a real physical environment with physical boundaries and physical objects, and/or a combination of any of the above) will, in some circumstances, provide helpful feedback to users that reduces input errors and increases the efficiency of the user&#39;s operation of the device. Additionally, tactile outputs are, optionally, generated to correspond to feedback that is unrelated to a simulated physical characteristic, such as an input threshold or a selection of an object. Such tactile outputs will, in some circumstances, provide helpful feedback to users that reduces input errors and increases the efficiency of the user&#39;s operation of the device. 
     In some embodiments, a tactile output with a suitable tactile output pattern serves as a cue for the occurrence of an event of interest in a user interface or behind the scenes in a device. Examples of the events of interest include activation of an affordance (e.g., a real or virtual button, or toggle switch) provided on the device or in a user interface, success or failure of a requested operation, reaching or crossing a boundary in a user interface, entry into a new state, switching of input focus between objects, activation of a new mode, reaching or crossing an input threshold, detection or recognition of a type of input or gesture, etc. In some embodiments, tactile outputs are provided to serve as a warning or an alert for an impending event or outcome that would occur unless a redirection or interruption input is timely detected. Tactile outputs are also used in other contexts to enrich the user experience, improve the accessibility of the device to users with visual or motor difficulties or other accessibility needs, and/or improve efficiency and functionality of the user interface and/or the device. Tactile outputs are optionally accompanied with audio outputs and/or visible user interface changes, which further enhance a user&#39;s experience when the user interacts with a user interface and/or the device, and facilitate better conveyance of information regarding the state of the user interface and/or the device, and which reduce input errors and increase the efficiency of the user&#39;s operation of the device. 
       FIGS.  4 F- 4 H  provide a set of sample tactile output patterns that may be used, either individually or in combination, either as is or through one or more transformations (e.g., modulation, amplification, truncation, etc.), to create suitable haptic feedback in various scenarios and for various purposes, such as those mentioned above and those described with respect to the user interfaces and methods discussed herein. This example of a palette of tactile outputs shows how a set of three waveforms and eight frequencies can be used to produce an array of tactile output patterns. In addition to the tactile output patterns shown in this figure, each of these tactile output patterns is optionally adjusted in amplitude by changing a gain value for the tactile output pattern, as shown, for example for FullTap 80 Hz, FullTap 200 Hz, MiniTap 80 Hz, MiniTap 200 Hz, MicroTap 80 Hz, and MicroTap 200 Hz in  FIGS.  4 I- 4 K , which are each shown with variants having a gain of 1.0, 0.75, 0.5, and 0.25. As shown in  FIGS.  4 I- 4 K , changing the gain of a tactile output pattern changes the amplitude of the pattern without changing the frequency of the pattern or changing the shape of the waveform. In some embodiments, changing the frequency of a tactile output pattern also results in a lower amplitude as some tactile output generators are limited by how much force can be applied to the moveable mass and thus higher frequency movements of the mass are constrained to lower amplitudes to ensure that the acceleration needed to create the waveform does not require force outside of an operational force range of the tactile output generator (e.g., the peak amplitudes of the FullTap at 230 Hz, 270 Hz, and 300 Hz are lower than the amplitudes of the FullTap at 80 Hz, 100 Hz, 125 Hz, and 200 Hz). 
       FIGS.  4 F- 4 K  show tactile output patterns that have a particular waveform. The waveform of a tactile output pattern represents the pattern of physical displacements relative to a neutral position (e.g., x zero ) versus time that a moveable mass goes through to generate a tactile output with that tactile output pattern. For example, a first set of tactile output patterns shown in  FIG.  4 F  (e.g., tactile output patterns of a “FullTap”) each have a waveform that includes an oscillation with two complete cycles (e.g., an oscillation that starts and ends in a neutral position and crosses the neutral position three times). A second set of tactile output patterns shown in  FIG.  4 G  (e.g., tactile output patterns of a “MiniTap”) each have a waveform that includes an oscillation that includes one complete cycle (e.g., an oscillation that starts and ends in a neutral position and crosses the neutral position one time). A third set of tactile output patterns shown in  FIG.  4 H  (e.g., tactile output patterns of a “MicroTap”) each have a waveform that includes an oscillation that include one half of a complete cycle (e.g., an oscillation that starts and ends in a neutral position and does not cross the neutral position). The waveform of a tactile output pattern also includes a start buffer and an end buffer that represent the gradual speeding up and slowing down of the moveable mass at the start and at the end of the tactile output. The example waveforms shown in  FIGS.  4 F- 4 K  include x min  and x max  values which represent the maximum and minimum extent of movement of the moveable mass. For larger electronic devices with larger moveable masses, there may be larger or smaller minimum and maximum extents of movement of the mass. The examples shown in  FIGS.  4 F- 4 K  describe movement of a mass in 1 dimension, however similar principles would also apply to movement of a moveable mass in two or three dimensions. 
     As shown in  FIGS.  4 F- 4 H , each tactile output pattern also has a corresponding characteristic frequency that affects the “pitch” of a haptic sensation that is felt by a user from a tactile output with that characteristic frequency. For a continuous tactile output, the characteristic frequency represents the number of cycles that are completed within a given period of time (e.g., cycles per second) by the moveable mass of the tactile output generator. For a discrete tactile output, a discrete output signal (e.g., with 0.5, 1, or 2 cycles) is generated, and the characteristic frequency value specifies how fast the moveable mass needs to move to generate a tactile output with that characteristic frequency. As shown in  FIGS.  4 F- 4 H , for each type of tactile output (e.g., as defined by a respective waveform, such as FullTap, MiniTap, or MicroTap), a higher frequency value corresponds to faster movement(s) by the moveable mass, and hence, in general, a shorter time to complete the tactile output (e.g., including the time to complete the required number of cycle(s) for the discrete tactile output, plus a start and an end buffer time). For example, a FullTap with a characteristic frequency of 80 Hz takes longer to complete than FullTap with a characteristic frequency of 100 Hz (e.g., 35.4 ms vs. 28.3 ms in  FIG.  4 F ). In addition, for a given frequency, a tactile output with more cycles in its waveform at a respective frequency takes longer to complete than a tactile output with fewer cycles its waveform at the same respective frequency. For example, a FullTap at 150 Hz takes longer to complete than a MiniTap at 150 Hz (e.g., 19.4 ms vs. 12.8 ms), and a MiniTap at 150 Hz takes longer to complete than a MicroTap at 150 Hz (e.g., 12.8 ms vs. 9.4 ms). However, for tactile output patterns with different frequencies this rule may not apply (e.g., tactile outputs with more cycles but a higher frequency may take a shorter amount of time to complete than tactile outputs with fewer cycles but a lower frequency, and vice versa). For example, at 300 Hz, a FullTap takes as long as a MiniTap (e.g., 9.9 ms). 
     As shown in  FIGS.  4 F- 4 H , a tactile output pattern also has a characteristic amplitude that affects the amount of energy that is contained in a tactile signal, or a “strength” of a haptic sensation that may be felt by a user through a tactile output with that characteristic amplitude. In some embodiments, the characteristic amplitude of a tactile output pattern refers to an absolute or normalized value that represents the maximum displacement of the moveable mass from a neutral position when generating the tactile output. In some embodiments, the characteristic amplitude of a tactile output pattern is adjustable, e.g., by a fixed or dynamically determined gain factor (e.g., a value between 0 and 1), in accordance with various conditions (e.g., customized based on user interface contexts and behaviors) and/or preconfigured metrics (e.g., input-based metrics, and/or user-interface-based metrics). In some embodiments, an input-based metric (e.g., an intensity-change metric or an input-speed metric) measures a characteristic of an input (e.g., a rate of change of a characteristic intensity of a contact in a press input or a rate of movement of the contact across a touch-sensitive surface) during the input that triggers generation of a tactile output. In some embodiments, a user-interface-based metric (e.g., a speed-across-boundary metric) measures a characteristic of a user interface element (e.g., a speed of movement of the element across a hidden or visible boundary in a user interface) during the user interface change that triggers generation of the tactile output. In some embodiments, the characteristic amplitude of a tactile output pattern may be modulated by an “envelope” and the peaks of adjacent cycles may have different amplitudes, where one of the waveforms shown above is further modified by multiplication by an envelope parameter that changes over time (e.g., from  0  to  1 ) to gradually adjust amplitude of portions of the tactile output over time as the tactile output is being generated. 
     Although specific frequencies, amplitudes, and waveforms are represented in the sample tactile output patterns in  FIGS.  4 F- 4 H  for illustrative purposes, tactile output patterns with other frequencies, amplitudes, and waveforms may be used for similar purposes. For example, waveforms that have between 0.5 to 4 cycles can be used. Other frequencies in the range of 60 Hz-400 Hz may be used as well. 
     It should be appreciated that device  100  is only one example of a portable multifunction device, and that device  100  optionally has more or fewer components than shown, optionally combines two or more components, or optionally has a different configuration or arrangement of the components. The various components shown in  FIG.  1 A  are implemented in hardware, software, firmware, or a combination thereof, including one or more signal processing and/or application specific integrated circuits. 
     Memory  102  optionally includes high-speed random access memory and optionally also includes non-volatile memory, such as one or more magnetic disk storage devices, flash memory devices, or other non-volatile solid-state memory devices. Access to memory  102  by other components of device  100 , such as CPU(s)  120  and the peripherals interface  118 , is, optionally, controlled by memory controller  122 . 
     Peripherals interface  118  can be used to couple input and output peripherals of the device to CPU(s)  120  and memory  102 . The one or more processors  120  run or execute various software programs and/or sets of instructions stored in memory  102  to perform various functions for device  100  and to process data. 
     In some embodiments, peripherals interface  118 , CPU(s)  120 , and memory controller  122  are, optionally, implemented on a single chip, such as chip  104 . In some other embodiments, they are, optionally, implemented on separate chips. 
     RF (radio frequency) circuitry  108  receives and sends RF signals, also called electromagnetic signals. RF circuitry  108  converts electrical signals to/from electromagnetic signals and communicates with communications networks and other communications devices via the electromagnetic signals. RF circuitry  108  optionally includes well-known circuitry for performing these functions, including but not limited to an antenna system, an RF transceiver, one or more amplifiers, a tuner, one or more oscillators, a digital signal processor, a CODEC chipset, a subscriber identity module (SIM) card, memory, and so forth. RF circuitry  108  optionally communicates with networks, such as the Internet, also referred to as the World Wide Web (WWW), an intranet and/or a wireless network, such as a cellular telephone network, a wireless local area network (LAN) and/or a metropolitan area network (MAN), and other devices by wireless communication. The wireless communication optionally uses any of a plurality of communications standards, protocols and technologies, including but not limited to Global System for Mobile Communications (GSM), Enhanced Data GSM Environment (EDGE), high-speed downlink packet access (HSDPA), high-speed uplink packet access (HSUPA), Evolution, Data-Only (EV-DO), HSPA, HSPA+, Dual-Cell HSPA (DC-HSPA), long term evolution (LTE), near field communication (NFC), wideband code division multiple access (W-CDMA), code division multiple access (CDMA), time division multiple access (TDMA), Bluetooth, Wireless Fidelity (Wi-Fi) (e.g., IEEE 802.11a, IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11b, IEEE 802.11g and/or IEEE 802.11n), voice over Internet Protocol (VoIP), Wi-MAX, a protocol for e-mail (e.g., Internet message access protocol (IMAP) and/or post office protocol (POP)), instant messaging (e.g., extensible messaging and presence protocol (XMPP), Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIMPLE), Instant Messaging and Presence Service (IMPS)), and/or Short Message Service (SMS), or any other suitable communication protocol, including communication protocols not yet developed as of the filing date of this document. 
     Audio circuitry  110 , speaker  111 , and microphone  113  provide an audio interface between a user and device  100 . Audio circuitry  110  receives audio data from peripherals interface  118 , converts the audio data to an electrical signal, and transmits the electrical signal to speaker  111 . Speaker  111  converts the electrical signal to human-audible sound waves. Audio circuitry  110  also receives electrical signals converted by microphone  113  from sound waves. Audio circuitry  110  converts the electrical signal to audio data and transmits the audio data to peripherals interface  118  for processing. Audio data is, optionally, retrieved from and/or transmitted to memory  102  and/or RF circuitry  108  by peripherals interface  118 . In some embodiments, audio circuitry  110  also includes a headset jack (e.g.,  212 ,  FIG.  2   ). The headset jack provides an interface between audio circuitry  110  and removable audio input/output peripherals, such as output-only headphones or a headset with both output (e.g., a headphone for one or both ears) and input (e.g., a microphone). 
     I/O subsystem  106  couples input/output peripherals on device  100 , such as touch-sensitive display system  112  and other input or control devices  116 , with peripherals interface  118 . I/O subsystem  106  optionally includes display controller  156 , optical sensor controller  158 , intensity sensor controller  159 , haptic feedback controller  161 , and one or more input controllers  160  for other input or control devices. The one or more input controllers  160  receive/send electrical signals from/to other input or control devices  116 . The other input or control devices  116  optionally include physical buttons (e.g., push buttons, rocker buttons, etc.), dials, slider switches, joysticks, click wheels, and so forth. In some alternate embodiments, input controller(s)  160  are, optionally, coupled with any (or none) of the following: a keyboard, infrared port, USB port, stylus, and/or a pointer device such as a mouse. The one or more buttons (e.g.,  208 ,  FIG.  2   ) optionally include an up/down button for volume control of speaker  111  and/or microphone  113 . The one or more buttons optionally include a push button (e.g.,  206 ,  FIG.  2   ). 
     Touch-sensitive display system  112  provides an input interface and an output interface between the device and a user. Display controller  156  receives and/or sends electrical signals from/to touch-sensitive display system  112 . Touch-sensitive display system  112  displays visual output to the user. The visual output optionally includes graphics, text, icons, video, and any combination thereof (collectively termed “graphics”). In some embodiments, some or all of the visual output corresponds to user interface objects. As used herein, the term “affordance” refers to a user-interactive graphical user interface object (e.g., a graphical user interface object that is configured to respond to inputs directed toward the graphical user interface object). Examples of user-interactive graphical user interface objects include, without limitation, a button, slider, icon, selectable menu item, switch, hyperlink, or other user interface control. 
     Touch-sensitive display system  112  has a touch-sensitive surface, sensor or set of sensors that accepts input from the user based on haptic and/or tactile contact. Touch-sensitive display system  112  and display controller  156  (along with any associated modules and/or sets of instructions in memory  102 ) detect contact (and any movement or breaking of the contact) on touch-sensitive display system  112  and converts the detected contact into interaction with user-interface objects (e.g., one or more soft keys, icons, web pages or images) that are displayed on touch-sensitive display system  112 . In some embodiments, a point of contact between touch-sensitive display system  112  and the user corresponds to a finger of the user or a stylus. 
     Touch-sensitive display system  112  optionally uses LCD (liquid crystal display) technology, LPD (light emitting polymer display) technology, or LED (light emitting diode) technology, although other display technologies are used in other embodiments. Touch-sensitive display system  112  and display controller  156  optionally detect contact and any movement or breaking thereof using any of a plurality of touch sensing technologies now known or later developed, including but not limited to capacitive, resistive, infrared, and surface acoustic wave technologies, as well as other proximity sensor arrays or other elements for determining one or more points of contact with touch-sensitive display system  112 . In some embodiments, projected mutual capacitance sensing technology is used, such as that found in the iPhone®, iPod Touch®, and iPad® from Apple Inc. of Cupertino, California. 
     Touch-sensitive display system  112  optionally has a video resolution in excess of 100 dpi. In some embodiments, the touch screen video resolution is in excess of 400 dpi (e.g., 500 dpi, 800 dpi, or greater). The user optionally makes contact with touch-sensitive display system  112  using any suitable object or appendage, such as a stylus, a finger, and so forth. In some embodiments, the user interface is designed to work with finger-based contacts and gestures, which can be less precise than stylus-based input due to the larger area of contact of a finger on the touch screen. In some embodiments, the device translates the rough finger-based input into a precise pointer/cursor position or command for performing the actions desired by the user. 
     In some embodiments, in addition to the touch screen, device  100  optionally includes a touchpad (not shown) for activating or deactivating particular functions. In some embodiments, the touchpad is a touch-sensitive area of the device that, unlike the touch screen, does not display visual output. The touchpad is, optionally, a touch-sensitive surface that is separate from touch-sensitive display system  112  or an extension of the touch-sensitive surface formed by the touch screen. 
     Device  100  also includes power system  162  for powering the various components. Power system  162  optionally includes a power management system, one or more power sources (e.g., battery, alternating current (AC)), a recharging system, a power failure detection circuit, a power converter or inverter, a power status indicator (e.g., a light-emitting diode (LED)) and any other components associated with the generation, management and distribution of power in portable devices. 
     Device  100  optionally also includes one or more optical sensors  164  (e.g., as part of one or more cameras).  FIG.  1 A  shows an optical sensor coupled with optical sensor controller  158  in I/O subsystem  106 . Optical sensor(s)  164  optionally include charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) phototransistors. Optical sensor(s)  164  receive light from the environment, projected through one or more lens, and converts the light to data representing an image. In conjunction with imaging module  143  (also called a camera module), optical sensor(s)  164  optionally capture still images and/or video. In some embodiments, an optical sensor is located on the back of device  100 , opposite touch-sensitive display system  112  on the front of the device, so that the touch screen is enabled for use as a viewfinder for still and/or video image acquisition. In some embodiments, another optical sensor is located on the front of the device so that the user&#39;s image is obtained (e.g., for selfies, for videoconferencing while the user views the other video conference participants on the touch screen, etc.). 
     Device  100  optionally also includes one or more contact intensity sensors  165 .  FIG.  1 A  shows a contact intensity sensor coupled with intensity sensor controller  159  in I/O subsystem  106 . Contact intensity sensor(s)  165  optionally include one or more piezoresistive strain gauges, capacitive force sensors, electric force sensors, piezoelectric force sensors, optical force sensors, capacitive touch-sensitive surfaces, or other intensity sensors (e.g., sensors used to measure the force (or pressure) of a contact on a touch-sensitive surface). Contact intensity sensor(s)  165  receive contact intensity information (e.g., pressure information or a proxy for pressure information) from the environment. In some embodiments, at least one contact intensity sensor is collocated with, or proximate to, a touch-sensitive surface (e.g., touch-sensitive display system  112 ). In some embodiments, at least one contact intensity sensor is located on the back of device  100 , opposite touch-screen display system  112  which is located on the front of device  100 . 
     Device  100  optionally also includes one or more proximity sensors  166 .  FIG.  1 A  shows proximity sensor  166  coupled with peripherals interface  118 . Alternately, proximity sensor  166  is coupled with input controller  160  in I/O subsystem  106 . In some embodiments, the proximity sensor turns off and disables touch-sensitive display system  112  when the multifunction device is placed near the user&#39;s ear (e.g., when the user is making a phone call). 
     Device  100  optionally also includes one or more tactile output generators  163 .  FIG.  1 A  shows a tactile output generator coupled with haptic feedback controller  161  in I/O subsystem  106 . In some embodiments, tactile output generator(s)  163  include one or more electroacoustic devices such as speakers or other audio components and/or electromechanical devices that convert energy into linear motion such as a motor, solenoid, electroactive polymer, piezoelectric actuator, electrostatic actuator, or other tactile output generating component (e.g., a component that converts electrical signals into tactile outputs on the device). Tactile output generator(s)  163  receive tactile feedback generation instructions from haptic feedback module  133  and generates tactile outputs on device  100  that are capable of being sensed by a user of device  100 . In some embodiments, at least one tactile output generator is collocated with, or proximate to, a touch-sensitive surface (e.g., touch-sensitive display system  112 ) and, optionally, generates a tactile output by moving the touch-sensitive surface vertically (e.g., in/out of a surface of device  100 ) or laterally (e.g., back and forth in the same plane as a surface of device  100 ). In some embodiments, at least one tactile output generator sensor is located on the back of device  100 , opposite touch-sensitive display system  112 , which is located on the front of device  100 . 
     Device  100  optionally also includes one or more accelerometers  167 , gyroscopes  168 , and/or magnetometers  169  (e.g., as part of an inertial measurement unit (IMU)) for obtaining information concerning the position (e.g., attitude) of the device. FIG.  1 A shows sensors  167 ,  168 , and  169  coupled with peripherals interface  118 . Alternately, sensors  167 ,  168 , and  169  are, optionally, coupled with an input controller  160  in I/O subsystem  106 . In some embodiments, information is displayed on the touch-screen display in a portrait view or a landscape view based on an analysis of data received from the one or more accelerometers. Device  100  optionally includes a GPS (or GLONASS or other global navigation system) receiver (not shown) for obtaining information concerning the location of device  100 . 
     In some embodiments, the software components stored in memory  102  include operating system  126 , communication module (or set of instructions)  128 , contact/motion module (or set of instructions)  130 , graphics module (or set of instructions)  132 , haptic feedback module (or set of instructions)  133 , text input module (or set of instructions)  134 , Global Positioning System (GPS) module (or set of instructions)  135 , and applications (or sets of instructions)  136 . Furthermore, in some embodiments, memory  102  stores device/global internal state  157 , as shown in  FIGS.  1 A and  3   . Device/global internal state  157  includes one or more of: active application state, indicating which applications, if any, are currently active; display state, indicating what applications, views or other information occupy various regions of touch-sensitive display system  112 ; sensor state, including information obtained from the device&#39;s various sensors and other input or control devices  116 ; and location and/or positional information concerning the device&#39;s location and/or attitude. 
     Operating system  126  (e.g., iOS, Android, Darwin, RTXC, LINUX, UNIX, OS X, WINDOWS, or an embedded operating system such as VxWorks) includes various software components and/or drivers for controlling and managing general system tasks (e.g., memory management, storage device control, power management, etc.) and facilitates communication between various hardware and software components. 
     Communication module  128  facilitates communication with other devices over one or more external ports  124  and also includes various software components for handling data received by RF circuitry  108  and/or external port  124 . External port  124  (e.g., Universal Serial Bus (USB), FIREWIRE, etc.) is adapted for coupling directly to other devices or indirectly over a network (e.g., the Internet, wireless LAN, etc.). In some embodiments, the external port is a multi-pin (e.g., 30-pin) connector that is the same as, or similar to and/or compatible with the 30-pin connector used in some iPhone®, iPod Touch®, and iPad® devices from Apple Inc. of Cupertino, California. In some embodiments, the external port is a Lightning connector that is the same as, or similar to and/or compatible with the Lightning connector used in some iPhone®, iPod Touch®, and iPad® devices from Apple Inc. of Cupertino, California. In some embodiments, the external port is a USB Type-C connector that is the same as, or similar to and/or compatible with the USB Type-C connector used in some electronic devices from Apple Inc. of Cupertino, California. 
     Contact/motion module  130  optionally detects contact with touch-sensitive display system  112  (in conjunction with display controller  156 ) and other touch-sensitive devices (e.g., a touchpad or physical click wheel). Contact/motion module  130  includes various software components for performing various operations related to detection of contact (e.g., by a finger or by a stylus), such as determining if contact has occurred (e.g., detecting a finger-down event), determining an intensity of the contact (e.g., the force or pressure of the contact or a substitute for the force or pressure of the contact), determining if there is movement of the contact and tracking the movement across the touch-sensitive surface (e.g., detecting one or more finger-dragging events), and determining if the contact has ceased (e.g., detecting a finger-up event or a break in contact). Contact/motion module  130  receives contact data from the touch-sensitive surface. Determining movement of the point of contact, which is represented by a series of contact data, optionally includes determining speed (magnitude), velocity (magnitude and direction), and/or an acceleration (a change in magnitude and/or direction) of the point of contact. These operations are, optionally, applied to single contacts (e.g., one finger contacts or stylus contacts) or to multiple simultaneous contacts (e.g., “multitouch”/multiple finger contacts). In some embodiments, contact/motion module  130  and display controller  156  detect contact on a touchpad. 
     Contact/motion module  130  optionally detects a gesture input by a user. Different gestures on the touch-sensitive surface have different contact patterns (e.g., different motions, timings, and/or intensities of detected contacts). Thus, a gesture is, optionally, detected by detecting a particular contact pattern. For example, detecting a finger tap gesture includes detecting a finger-down event followed by detecting a finger-up (lift off) event at the same position (or substantially the same position) as the finger-down event (e.g., at the position of an icon). As another example, detecting a finger swipe gesture on the touch-sensitive surface includes detecting a finger-down event followed by detecting one or more finger-dragging events, and subsequently followed by detecting a finger-up (lift off) event. Similarly, tap, swipe, drag, and other gestures are optionally detected for a stylus by detecting a particular contact pattern for the stylus. 
     In some embodiments, detecting a finger tap gesture depends on the length of time between detecting the finger-down event and the finger-up event, but is independent of the intensity of the finger contact between detecting the finger-down event and the finger-up event. In some embodiments, a tap gesture is detected in accordance with a determination that the length of time between the finger-down event and the finger-up event is less than a predetermined value (e.g., less than 0.1, 0.2, 0.3, 0.4 or 0.5 seconds), independent of whether the intensity of the finger contact during the tap meets a given intensity threshold (greater than a nominal contact-detection intensity threshold), such as a light press or deep press intensity threshold. Thus, a finger tap gesture can satisfy particular input criteria that do not require that the characteristic intensity of a contact satisfy a given intensity threshold in order for the particular input criteria to be met. For clarity, the finger contact in a tap gesture typically needs to satisfy a nominal contact-detection intensity threshold, below which the contact is not detected, in order for the finger-down event to be detected. A similar analysis applies to detecting a tap gesture by a stylus or other contact. In cases where the device is capable of detecting a finger or stylus contact hovering over a touch sensitive surface, the nominal contact-detection intensity threshold optionally does not correspond to physical contact between the finger or stylus and the touch sensitive surface. 
     The same concepts apply in an analogous manner to other types of gestures. For example, a swipe gesture, a pinch gesture, a depinch gesture, and/or a long press gesture are optionally detected based on the satisfaction of criteria that are either independent of intensities of contacts included in the gesture, or do not require that contact(s) that perform the gesture reach intensity thresholds in order to be recognized. For example, a swipe gesture is detected based on an amount of movement of one or more contacts; a pinch gesture is detected based on movement of two or more contacts towards each other; a depinch gesture is detected based on movement of two or more contacts away from each other; and a long press gesture is detected based on a duration of the contact on the touch-sensitive surface with less than a threshold amount of movement. As such, the statement that particular gesture recognition criteria do not require that the intensity of the contact(s) meet a respective intensity threshold in order for the particular gesture recognition criteria to be met means that the particular gesture recognition criteria are capable of being satisfied if the contact(s) in the gesture do not reach the respective intensity threshold, and are also capable of being satisfied in circumstances where one or more of the contacts in the gesture do reach or exceed the respective intensity threshold. In some embodiments, a tap gesture is detected based on a determination that the finger-down and finger-up event are detected within a predefined time period, without regard to whether the contact is above or below the respective intensity threshold during the predefined time period, and a swipe gesture is detected based on a determination that the contact movement is greater than a predefined magnitude, even if the contact is above the respective intensity threshold at the end of the contact movement. Even in implementations where detection of a gesture is influenced by the intensity of contacts performing the gesture (e.g., the device detects a long press more quickly when the intensity of the contact is above an intensity threshold or delays detection of a tap input when the intensity of the contact is higher), the detection of those gestures does not require that the contacts reach a particular intensity threshold so long as the criteria for recognizing the gesture can be met in circumstances where the contact does not reach the particular intensity threshold (e.g., even if the amount of time that it takes to recognize the gesture changes). 
     Contact intensity thresholds, duration thresholds, and movement thresholds are, in some circumstances, combined in a variety of different combinations in order to create heuristics for distinguishing two or more different gestures directed to the same input element or region so that multiple different interactions with the same input element are enabled to provide a richer set of user interactions and responses. The statement that a particular set of gesture recognition criteria do not require that the intensity of the contact(s) meet a respective intensity threshold in order for the particular gesture recognition criteria to be met does not preclude the concurrent evaluation of other intensity-dependent gesture recognition criteria to identify other gestures that do have criteria that are met when a gesture includes a contact with an intensity above the respective intensity threshold. For example, in some circumstances, first gesture recognition criteria for a first gesture—which do not require that the intensity of the contact(s) meet a respective intensity threshold in order for the first gesture recognition criteria to be met—are in competition with second gesture recognition criteria for a second gesture—which are dependent on the contact(s) reaching the respective intensity threshold. In such competitions, the gesture is, optionally, not recognized as meeting the first gesture recognition criteria for the first gesture if the second gesture recognition criteria for the second gesture are met first. For example, if a contact reaches the respective intensity threshold before the contact moves by a predefined amount of movement, a deep press gesture is detected rather than a swipe gesture. Conversely, if the contact moves by the predefined amount of movement before the contact reaches the respective intensity threshold, a swipe gesture is detected rather than a deep press gesture. Even in such circumstances, the first gesture recognition criteria for the first gesture still do not require that the intensity of the contact(s) meet a respective intensity threshold in order for the first gesture recognition criteria to be met because if the contact stayed below the respective intensity threshold until an end of the gesture (e.g., a swipe gesture with a contact that does not increase to an intensity above the respective intensity threshold), the gesture would have been recognized by the first gesture recognition criteria as a swipe gesture. As such, particular gesture recognition criteria that do not require that the intensity of the contact(s) meet a respective intensity threshold in order for the particular gesture recognition criteria to be met will (A) in some circumstances ignore the intensity of the contact with respect to the intensity threshold (e.g. for a tap gesture) and/or (B) in some circumstances still be dependent on the intensity of the contact with respect to the intensity threshold in the sense that the particular gesture recognition criteria (e.g., for a long press gesture) will fail if a competing set of intensity-dependent gesture recognition criteria (e.g., for a deep press gesture) recognize an input as corresponding to an intensity-dependent gesture before the particular gesture recognition criteria recognize a gesture corresponding to the input (e.g., for a long press gesture that is competing with a deep press gesture for recognition). 
     Attitude module  131 , in conjunction with accelerometers  167 , gyroscopes  168 , and/or magnetometers  169 , optionally detects attitude information concerning the device, such as the device&#39;s attitude (e.g., roll, pitch, and/or yaw) in a particular frame of reference. Attitude module  131  includes software components for performing various operations related to detecting the position of the device and detecting changes to the attitude of the device. 
     Graphics module  132  includes various known software components for rendering and displaying graphics on touch-sensitive display system  112  or other display, including components for changing the visual impact (e.g., brightness, transparency, saturation, contrast or other visual property) of graphics that are displayed. As used herein, the term “graphics” includes any object that can be displayed to a user, including without limitation text, web pages, icons (such as user-interface objects including soft keys), digital images, videos, animations and the like. 
     In some embodiments, graphics module  132  stores data representing graphics to be used. Each graphic is, optionally, assigned a corresponding code. Graphics module  132  receives, from applications etc., one or more codes specifying graphics to be displayed along with, if necessary, coordinate data and other graphic property data, and then generates screen image data to output to display controller  156 . 
     Haptic feedback module  133  includes various software components for generating instructions (e.g., instructions used by haptic feedback controller  161 ) to produce tactile outputs using tactile output generator(s)  163  at one or more locations on device  100  in response to user interactions with device  100 . 
     Text input module  134 , which is, optionally, a component of graphics module  132 , provides soft keyboards for entering text in various applications (e.g., contacts module  137 , e-mail client module  140 , IM module  141 , browser module  147 , and any other application that needs text input). 
     GPS module  135  determines the location of the device and provides this information for use in various applications (e.g., to telephone module  138  for use in location-based dialing, to camera module  143  as picture/video metadata, and to applications that provide location-based services such as weather widgets, local yellow page widgets, and map/navigation widgets). 
     Virtual/augmented reality module  145  provides virtual and/or augmented reality logic to applications  136  that implement augmented reality, and in some embodiments virtual reality, features. Virtual/augmented reality module  145  facilitates superposition of virtual content, such as a virtual user interface object (e.g., a virtual measuring tape for making augmented reality-based measurements), on a representation of at least a portion of a field of view of the one or more cameras. For example, with assistance from the virtual/augmented reality module  145 , the representation of at least a portion of a field of view of the one or more cameras may include a respective physical object and the virtual user interface object may be displayed at a location, in a displayed augmented reality environment, that is determined based on the respective physical object in the field of view of the one or more cameras or a virtual reality environment that is determined based on the attitude of at least a portion of a computer system (e.g., an attitude of a display device that is used to display the user interface to a user of the computer system). 
     Applications  136  optionally include the following modules (or sets of instructions), or a subset or superset thereof:
         contacts module  137  (sometimes called an address book or contact list);   telephone module  138 ;   video conferencing module  139 ;   e-mail client module  140 ;   instant messaging (IM) module  141 ;   workout support module  142 ;   camera module  143  for still and/or video images;   image management module  144 ;   browser module  147 ;   calendar module  148 ;   widget modules  149 , which optionally include one or more of: weather widget  149 - 1 , stocks widget  149 - 2 , calculator widget  149 - 3 , alarm clock widget  149 - 4 , dictionary widget  149 - 5 , and other widgets obtained by the user, as well as user-created widgets  149 - 6 ;   widget creator module  150  for making user-created widgets  149 - 6 ;   search module  151 ;   video and music player module  152 , which is, optionally, made up of a video player module and a music player module;   notes module  153 ;   map module  154 ; and/or   measurement module  155 .       

     Examples of other applications  136  that are, optionally, stored in memory  102  include other word processing applications, other image editing applications, drawing applications, presentation applications, JAVA-enabled applications, encryption, digital rights management, voice recognition, and voice replication. 
     In conjunction with touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , and text input module  134 , contacts module  137  includes executable instructions to manage an address book or contact list (e.g., stored in application internal state  192  of contacts module  137  in memory  102  or memory  370 ), including: adding name(s) to the address book; deleting name(s) from the address book; associating telephone number(s), e-mail address(es), physical address(es) or other information with a name; associating an image with a name; categorizing and sorting names; providing telephone numbers and/or e-mail addresses to initiate and/or facilitate communications by telephone module  138 , video conference module  139 , e-mail client module  140 , or IM module  141 ; and so forth. 
     In conjunction with RF circuitry  108 , audio circuitry  110 , speaker  111 , microphone  113 , touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , and text input module  134 , telephone module  138  includes executable instructions to enter a sequence of characters corresponding to a telephone number, access one or more telephone numbers in address book  137 , modify a telephone number that has been entered, dial a respective telephone number, conduct a conversation and disconnect or hang up when the conversation is completed. As noted above, the wireless communication optionally uses any of a plurality of communications standards, protocols and technologies. 
     In conjunction with RF circuitry  108 , audio circuitry  110 , speaker  111 , microphone  113 , touch-sensitive display system  112 , display controller  156 , optical sensor(s)  164 , optical sensor controller  158 , contact module  130 , graphics module  132 , text input module  134 , contact list  137 , and telephone module  138 , videoconferencing module  139  includes executable instructions to initiate, conduct, and terminate a video conference between a user and one or more other participants in accordance with user instructions. 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , and text input module  134 , e-mail client module  140  includes executable instructions to create, send, receive, and manage e-mail in response to user instructions. In conjunction with image management module  144 , e-mail client module  140  makes it very easy to create and send e-mails with still or video images taken with camera module  143 . 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , and text input module  134 , the instant messaging module  141  includes executable instructions to enter a sequence of characters corresponding to an instant message, to modify previously entered characters, to transmit a respective instant message (for example, using a Short Message Service (SMS) or Multimedia Message Service (MMS) protocol for telephony-based instant messages or using XMPP, SIMPLE, Apple Push Notification Service (APNs) or IMPS for Internet-based instant messages), to receive instant messages, and to view received instant messages. In some embodiments, transmitted and/or received instant messages optionally include graphics, photos, audio files, video files and/or other attachments as are supported in a MMS and/or an Enhanced Messaging Service (EMS). As used herein, “instant messaging” refers to both telephony-based messages (e.g., messages sent using SMS or MMS) and Internet-based messages (e.g., messages sent using XMPP, SIMPLE, APNs, or IMPS). 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , text input module  134 , GPS module  135 , map module  154 , and video and music player module  152 , workout support module  142  includes executable instructions to create workouts (e.g., with time, distance, and/or calorie burning goals); communicate with workout sensors (in sports devices and smart watches); receive workout sensor data; calibrate sensors used to monitor a workout; select and play music for a workout; and display, store and transmit workout data. 
     In conjunction with touch-sensitive display system  112 , display controller  156 , optical sensor(s)  164 , optical sensor controller  158 , contact module  130 , graphics module  132 , and image management module  144 , camera module  143  includes executable instructions to capture still images or video (including a video stream) and store them into memory  102 , modify characteristics of a still image or video, and/or delete a still image or video from memory  102 . 
     In conjunction with touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , text input module  134 , and camera module  143 , image management module  144  includes executable instructions to arrange, modify (e.g., edit), or otherwise manipulate, label, delete, present (e.g., in a digital slide show or album), and store still and/or video images. 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , and text input module  134 , browser module  147  includes executable instructions to browse the Internet in accordance with user instructions, including searching, linking to, receiving, and displaying web pages or portions thereof, as well as attachments and other files linked to web pages. 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , text input module  134 , e-mail client module  140 , and browser module  147 , calendar module  148  includes executable instructions to create, display, modify, and store calendars and data associated with calendars (e.g., calendar entries, to do lists, etc.) in accordance with user instructions. 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , text input module  134 , and browser module  147 , widget modules  149  are mini-applications that are, optionally, downloaded and used by a user (e.g., weather widget  149 - 1 , stocks widget  149 - 2 , calculator widget  149 - 3 , alarm clock widget  149 - 4 , and dictionary widget  149 - 5 ) or created by the user (e.g., user-created widget  149 - 6 ). In some embodiments, a widget includes an HTML (Hypertext Markup Language) file, a CSS (Cascading Style Sheets) file, and a JavaScript file. In some embodiments, a widget includes an XML (Extensible Markup Language) file and a JavaScript file (e.g., Yahoo! Widgets). 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , text input module  134 , and browser module  147 , the widget creator module  150  includes executable instructions to create widgets (e.g., turning a user-specified portion of a web page into a widget). 
     In conjunction with touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , and text input module  134 , search module  151  includes executable instructions to search for text, music, sound, image, video, and/or other files in memory  102  that match one or more search criteria (e.g., one or more user-specified search terms) in accordance with user instructions. 
     In conjunction with touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , audio circuitry  110 , speaker  111 , RF circuitry  108 , and browser module  147 , video and music player module  152  includes executable instructions that allow the user to download and play back recorded music and other sound files stored in one or more file formats, such as MP3 or AAC files, and executable instructions to display, present or otherwise play back videos (e.g., on touch-sensitive display system  112 , or on an external display connected wirelessly or via external port  124 ). In some embodiments, device  100  optionally includes the functionality of an MP3 player, such as an iPod (trademark of Apple Inc.). 
     In conjunction with touch-sensitive display system  112 , display controller  156 , contact module  130 , graphics module  132 , and text input module  134 , notes module  153  includes executable instructions to create and manage notes, to do lists, and the like in accordance with user instructions. 
     In conjunction with RF circuitry  108 , touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , text input module  134 , GPS module  135 , and browser module  147 , map module  154  includes executable instructions to receive, display, modify, and store maps and data associated with maps (e.g., driving directions; data on stores and other points of interest at or near a particular location; and other location-based data) in accordance with user instructions. 
     In conjunction with touch-sensitive display system  112 , display system controller  156 , contact module  130 , graphics module  132 , and virtual/augmented reality module  145 , measurement module  155  includes executable instructions that allow the user to measure physical spaces and/or objects therein in an augmented reality environment, as described in more detail herein. 
     Each of the above identified modules and applications correspond to a set of executable instructions for performing one or more functions described above and the methods described in this application (e.g., the computer-implemented methods and other information processing methods described herein). These modules (i.e., sets of instructions) need not be implemented as separate software programs, procedures or modules, and thus various subsets of these modules are, optionally, combined or otherwise re-arranged in various embodiments. In some embodiments, memory  102  optionally stores a subset of the modules and data structures identified above. Furthermore, memory  102  optionally stores additional modules and data structures not described above. 
     In some embodiments, device  100  is a device where operation of a predefined set of functions on the device is performed exclusively through a touch screen and/or a touchpad. By using a touch screen and/or a touchpad as the primary input control device for operation of device  100 , the number of physical input control devices (such as push buttons, dials, and the like) on device  100  is, optionally, reduced. 
     The predefined set of functions that are performed exclusively through a touch screen and/or a touchpad optionally include navigation between user interfaces. In some embodiments, the touchpad, when touched by the user, navigates device  100  to a main, home, or root menu from any user interface that is displayed on device  100 . In such embodiments, a “menu button” is implemented using a touch-sensitive surface. In some other embodiments, the menu button is a physical push button or other physical input control device instead of a touch-sensitive surface. 
       FIG.  1 B  is a block diagram illustrating example components for event handling in accordance with some embodiments. In some embodiments, memory  102  (in  FIG.  1 A ) or  370  ( FIG.  3 A ) includes event sorter  170  (e.g., in operating system  126 ) and a respective application  136 - 1  (e.g., any of the aforementioned applications  136 ,  137 - 155 ,  380 - 390 ). 
     Event sorter  170  receives event information and determines the application  136 - 1  and application view  191  of application  136 - 1  to which to deliver the event information. Event sorter  170  includes event monitor  171  and event dispatcher module  174 . In some embodiments, application  136 - 1  includes application internal state  192 , which indicates the current application view(s) displayed on touch-sensitive display system  112  when the application is active or executing. In some embodiments, device/global internal state  157  is used by event sorter  170  to determine which application(s) is (are) currently active, and application internal state  192  is used by event sorter  170  to determine application views  191  to which to deliver event information. 
     In some embodiments, application internal state  192  includes additional information, such as one or more of: resume information to be used when application  136 - 1  resumes execution, user interface state information that indicates information being displayed or that is ready for display by application  136 - 1 , a state queue for enabling the user to go back to a prior state or view of application  136 - 1 , and a redo/undo queue of previous actions taken by the user. 
     Event monitor  171  receives event information from peripherals interface  118 . Event information includes information about a sub-event (e.g., a user touch on touch-sensitive display system  112 , as part of a multi-touch gesture). Peripherals interface  118  transmits information it receives from I/O subsystem  106  or a sensor, such as proximity sensor  166 , accelerometer(s)  167 , and/or microphone  113  (through audio circuitry  110 ). Information that peripherals interface  118  receives from I/O subsystem  106  includes information from touch-sensitive display system  112  or a touch-sensitive surface. 
     In some embodiments, event monitor  171  sends requests to the peripherals interface  118  at predetermined intervals. In response, peripherals interface  118  transmits event information. In other embodiments, peripheral interface  118  transmits event information only when there is a significant event (e.g., receiving an input above a predetermined noise threshold and/or for more than a predetermined duration). 
     In some embodiments, event sorter  170  also includes a hit view determination module  172  and/or an active event recognizer determination module  173 . 
     Hit view determination module  172  provides software procedures for determining where a sub-event has taken place within one or more views, when touch-sensitive display system  112  displays more than one view. Views are made up of controls and other elements that a user can see on the display. 
     Another aspect of the user interface associated with an application is a set of views, sometimes herein called application views or user interface windows, in which information is displayed and touch-based gestures occur. The application views (of a respective application) in which a touch is detected optionally correspond to programmatic levels within a programmatic or view hierarchy of the application. For example, the lowest level view in which a touch is detected is, optionally, called the hit view, and the set of events that are recognized as proper inputs are, optionally, determined based, at least in part, on the hit view of the initial touch that begins a touch-based gesture. 
     Hit view determination module  172  receives information related to sub-events of a touch-based gesture. When an application has multiple views organized in a hierarchy, hit view determination module  172  identifies a hit view as the lowest view in the hierarchy which should handle the sub-event. In most circumstances, the hit view is the lowest level view in which an initiating sub-event occurs (i.e., the first sub-event in the sequence of sub-events that form an event or potential event). Once the hit view is identified by the hit view determination module, the hit view typically receives all sub-events related to the same touch or input source for which it was identified as the hit view. 
     Active event recognizer determination module  173  determines which view or views within a view hierarchy should receive a particular sequence of sub-events. In some embodiments, active event recognizer determination module  173  determines that only the hit view should receive a particular sequence of sub-events. In other embodiments, active event recognizer determination module  173  determines that all views that include the physical location of a sub-event are actively involved views, and therefore determines that all actively involved views should receive a particular sequence of sub-events. In other embodiments, even if touch sub-events were entirely confined to the area associated with one particular view, views higher in the hierarchy would still remain as actively involved views. 
     Event dispatcher module  174  dispatches the event information to an event recognizer (e.g., event recognizer  180 ). In embodiments including active event recognizer determination module  173 , event dispatcher module  174  delivers the event information to an event recognizer determined by active event recognizer determination module  173 . In some embodiments, event dispatcher module  174  stores in an event queue the event information, which is retrieved by a respective event receiver module  182 . 
     In some embodiments, operating system  126  includes event sorter  170 . Alternatively, application  136 - 1  includes event sorter  170 . In yet other embodiments, event sorter  170  is a stand-alone module, or a part of another module stored in memory  102 , such as contact/motion module  130 . 
     In some embodiments, application  136 - 1  includes a plurality of event handlers  190  and one or more application views  191 , each of which includes instructions for handling touch events that occur within a respective view of the application&#39;s user interface. Each application view  191  of the application  136 - 1  includes one or more event recognizers  180 . Typically, a respective application view  191  includes a plurality of event recognizers  180 . In other embodiments, one or more of event recognizers  180  are part of a separate module, such as a user interface kit (not shown) or a higher level object from which application  136 - 1  inherits methods and other properties. In some embodiments, a respective event handler  190  includes one or more of: data updater  176 , object updater  177 , GUI updater  178 , and/or event data  179  received from event sorter  170 . Event handler  190  optionally utilizes or calls data updater  176 , object updater  177  or GUI updater  178  to update the application internal state  192 . Alternatively, one or more of the application views  191  includes one or more respective event handlers  190 . Also, in some embodiments, one or more of data updater  176 , object updater  177 , and GUI updater  178  are included in a respective application view  191 . 
     A respective event recognizer  180  receives event information (e.g., event data  179 ) from event sorter  170 , and identifies an event from the event information. Event recognizer  180  includes event receiver  182  and event comparator  184 . In some embodiments, event recognizer  180  also includes at least a subset of: metadata  183 , and event delivery instructions  188  (which optionally include sub-event delivery instructions). 
     Event receiver  182  receives event information from event sorter  170 . The event information includes information about a sub-event, for example, a touch or a touch movement. Depending on the sub-event, the event information also includes additional information, such as location of the sub-event. When the sub-event concerns motion of a touch, the event information optionally also includes speed and direction of the sub-event. In some embodiments, events include rotation of the device from one orientation to another (e.g., from a portrait orientation to a landscape orientation, or vice versa), and the event information includes corresponding information about the current orientation (also called device attitude) of the device. 
     Event comparator  184  compares the event information to predefined event or sub-event definitions and, based on the comparison, determines an event or sub-event, or determines or updates the state of an event or sub-event. In some embodiments, event comparator  184  includes event definitions  186 . Event definitions  186  contain definitions of events (e.g., predefined sequences of sub-events), for example, event  1  ( 187 - 1 ), event  2  ( 187 - 2 ), and others. In some embodiments, sub-events in an event  187  include, for example, touch begin, touch end, touch movement, touch cancellation, and multiple touching. In one example, the definition for event  1  ( 187 - 1 ) is a double tap on a displayed object. The double tap, for example, comprises a first touch (touch begin) on the displayed object for a predetermined phase, a first lift-off (touch end) for a predetermined phase, a second touch (touch begin) on the displayed object for a predetermined phase, and a second lift-off (touch end) for a predetermined phase. In another example, the definition for event  2  ( 187 - 2 ) is a dragging on a displayed object. The dragging, for example, comprises a touch (or contact) on the displayed object for a predetermined phase, a movement of the touch across touch-sensitive display system  112 , and lift-off of the touch (touch end). In some embodiments, the event also includes information for one or more associated event handlers  190 . 
     In some embodiments, event definition  187  includes a definition of an event for a respective user-interface object. In some embodiments, event comparator  184  performs a hit test to determine which user-interface object is associated with a sub-event. For example, in an application view in which three user-interface objects are displayed on touch-sensitive display system  112 , when a touch is detected on touch-sensitive display system  112 , event comparator  184  performs a hit test to determine which of the three user-interface objects is associated with the touch (sub-event). If each displayed object is associated with a respective event handler  190 , the event comparator uses the result of the hit test to determine which event handler  190  should be activated. For example, event comparator  184  selects an event handler associated with the sub-event and the object triggering the hit test. 
     In some embodiments, the definition for a respective event  187  also includes delayed actions that delay delivery of the event information until after it has been determined whether the sequence of sub-events does or does not correspond to the event recognizer&#39;s event type. 
     When a respective event recognizer  180  determines that the series of sub-events do not match any of the events in event definitions  186 , the respective event recognizer  180  enters an event impossible, event failed, or event ended state, after which it disregards subsequent sub-events of the touch-based gesture. In this situation, other event recognizers, if any, that remain active for the hit view continue to track and process sub-events of an ongoing touch-based gesture. 
     In some embodiments, a respective event recognizer  180  includes metadata  183  with configurable properties, flags, and/or lists that indicate how the event delivery system should perform sub-event delivery to actively involved event recognizers. In some embodiments, metadata  183  includes configurable properties, flags, and/or lists that indicate how event recognizers interact, or are enabled to interact, with one another. In some embodiments, metadata  183  includes configurable properties, flags, and/or lists that indicate whether sub-events are delivered to varying levels in the view or programmatic hierarchy. 
     In some embodiments, a respective event recognizer  180  activates event handler  190  associated with an event when one or more particular sub-events of an event are recognized. In some embodiments, a respective event recognizer  180  delivers event information associated with the event to event handler  190 . Activating an event handler  190  is distinct from sending (and deferred sending) sub-events to a respective hit view. In some embodiments, event recognizer  180  throws a flag associated with the recognized event, and event handler  190  associated with the flag catches the flag and performs a predefined process. 
     In some embodiments, event delivery instructions  188  include sub-event delivery instructions that deliver event information about a sub-event without activating an event handler. Instead, the sub-event delivery instructions deliver event information to event handlers associated with the series of sub-events or to actively involved views. Event handlers associated with the series of sub-events or with actively involved views receive the event information and perform a predetermined process. 
     In some embodiments, data updater  176  creates and updates data used in application  136 - 1 . For example, data updater  176  updates the telephone number used in contacts module  137 , or stores a video file used in video and music player module  152 . In some embodiments, object updater  177  creates and updates objects used in application  136 - 1 . For example, object updater  177  creates a new user-interface object or updates the position of a user-interface object. GUI updater  178  updates the GUI. For example, GUI updater  178  prepares display information and sends it to graphics module  132  for display on a touch-sensitive display. 
     In some embodiments, event handler(s)  190  includes or has access to data updater  176 , object updater  177 , and GUI updater  178 . In some embodiments, data updater  176 , object updater  177 , and GUI updater  178  are included in a single module of a respective application  136 - 1  or application view  191 . In other embodiments, they are included in two or more software modules. 
     It shall be understood that the foregoing discussion regarding event handling of user touches on touch-sensitive displays also applies to other forms of user inputs to operate multifunction devices  100  with input-devices, not all of which are initiated on touch screens. For example, mouse movement and mouse button presses, optionally coordinated with single or multiple keyboard presses or holds; contact movements such as taps, drags, scrolls, etc., on touch-pads; pen stylus inputs; inputs based on real-time analysis of video images obtained by one or more cameras; movement of the device; oral instructions; detected eye movements; biometric inputs; and/or any combination thereof are optionally utilized as inputs corresponding to sub-events which define an event to be recognized. 
       FIG.  1 C  is a block diagram illustrating a tactile output module in accordance with some embodiments. In some embodiments, I/O subsystem  106  (e.g., haptic feedback controller  161  ( FIG.  1 A ) and/or other input controller(s)  160  ( FIG.  1 A )) includes at least some of the example components shown in  FIG.  1 C . In some embodiments, peripherals interface  118  includes at least some of the example components shown in  FIG.  1 C . 
     In some embodiments, the tactile output module includes haptic feedback module  133 . In some embodiments, haptic feedback module  133  aggregates and combines tactile outputs for user interface feedback from software applications on the electronic device (e.g., feedback that is responsive to user inputs that correspond to displayed user interfaces and alerts and other notifications that indicate the performance of operations or occurrence of events in user interfaces of the electronic device). Haptic feedback module  133  includes one or more of: waveform module  123  (for providing waveforms used for generating tactile outputs), mixer  125  (for mixing waveforms, such as waveforms in different channels), compressor  127  (for reducing or compressing a dynamic range of the waveforms), low-pass filter  129  (for filtering out high frequency signal components in the waveforms), and thermal controller  181  (for adjusting the waveforms in accordance with thermal conditions). In some embodiments, haptic feedback module  133  is included in haptic feedback controller  161  ( FIG.  1 A ). In some embodiments, a separate unit of haptic feedback module  133  (or a separate implementation of haptic feedback module  133 ) is also included in an audio controller (e.g., audio circuitry  110 ,  FIG.  1 A ) and used for generating audio signals. In some embodiments, a single haptic feedback module  133  is used for generating audio signals and generating waveforms for tactile outputs. 
     In some embodiments, haptic feedback module  133  also includes trigger module  121  (e.g., a software application, operating system, or other software module that determines a tactile output is to be generated and initiates the process for generating the corresponding tactile output). In some embodiments, trigger module  121  generates trigger signals for initiating generation of waveforms (e.g., by waveform module  123 ). For example, trigger module  121  generates trigger signals based on preset timing criteria. In some embodiments, trigger module  121  receives trigger signals from outside haptic feedback module  133  (e.g., in some embodiments, haptic feedback module  133  receives trigger signals from hardware input processing module  146  located outside haptic feedback module  133 ) and relays the trigger signals to other components within haptic feedback module  133  (e.g., waveform module  123 ) or software applications that trigger operations (e.g., with trigger module  121 ) based on activation of a user interface element (e.g., an application icon or an affordance within an application) or a hardware input device (e.g., a home button or an intensity-sensitive input surface, such as an intensity-sensitive touch screen). In some embodiments, trigger module  121  also receives tactile feedback generation instructions (e.g., from haptic feedback module  133 ,  FIGS.  1 A and  3   ). In some embodiments, trigger module  121  generates trigger signals in response to haptic feedback module  133  (or trigger module  121  in haptic feedback module  133 ) receiving tactile feedback instructions (e.g., from haptic feedback module  133 ,  FIGS.  1 A and  3   ). 
     Waveform module  123  receives trigger signals (e.g., from trigger module  121 ) as an input, and in response to receiving trigger signals, provides waveforms for generation of one or more tactile outputs (e.g., waveforms selected from a predefined set of waveforms designated for use by waveform module  123 , such as the waveforms described in greater detail below with reference to  FIGS.  4 F- 4 G ). 
     Mixer  125  receives waveforms (e.g., from waveform module  123 ) as an input, and mixes together the waveforms. For example, when mixer  125  receives two or more waveforms (e.g., a first waveform in a first channel and a second waveform that at least partially overlaps with the first waveform in a second channel) mixer  125  outputs a combined waveform that corresponds to a sum of the two or more waveforms. In some embodiments, mixer  125  also modifies one or more waveforms of the two or more waveforms to emphasize particular waveform(s) over the rest of the two or more waveforms (e.g., by increasing a scale of the particular waveform(s) and/or decreasing a scale of the rest of the waveforms). In some circumstances, mixer  125  selects one or more waveforms to remove from the combined waveform (e.g., the waveform from the oldest source is dropped when there are waveforms from more than three sources that have been requested to be output concurrently by tactile output generator  163 ). 
     Compressor  127  receives waveforms (e.g., a combined waveform from mixer  125 ) as an input, and modifies the waveforms. In some embodiments, compressor  127  reduces the waveforms (e.g., in accordance with physical specifications of tactile output generators  163  ( FIG.  1 A ) or  357  ( FIG.  3   )) so that tactile outputs corresponding to the waveforms are reduced. In some embodiments, compressor  127  limits the waveforms, such as by enforcing a predefined maximum amplitude for the waveforms. For example, compressor  127  reduces amplitudes of portions of waveforms that exceed a predefined amplitude threshold while maintaining amplitudes of portions of waveforms that do not exceed the predefined amplitude threshold. In some embodiments, compressor  127  reduces a dynamic range of the waveforms. In some embodiments, compressor  127  dynamically reduces the dynamic range of the waveforms so that the combined waveforms remain within performance specifications of the tactile output generator  163  (e.g., force and/or moveable mass displacement limits). 
     Low-pass filter  129  receives waveforms (e.g., compressed waveforms from compressor  127 ) as an input, and filters (e.g., smooths) the waveforms (e.g., removes or reduces high frequency signal components in the waveforms). For example, in some instances, compressor  127  includes, in compressed waveforms, extraneous signals (e.g., high frequency signal components) that interfere with the generation of tactile outputs and/or exceed performance specifications of tactile output generator  163  when the tactile outputs are generated in accordance with the compressed waveforms. Low-pass filter  129  reduces or removes such extraneous signals in the waveforms. 
     Thermal controller  181  receives waveforms (e.g., filtered waveforms from low-pass filter  129 ) as an input, and adjusts the waveforms in accordance with thermal conditions of device  100  (e.g., based on internal temperatures detected within device  100 , such as the temperature of haptic feedback controller  161 , and/or external temperatures detected by device  100 ). For example, in some cases, the output of haptic feedback controller  161  varies depending on the temperature (e.g. haptic feedback controller  161 , in response to receiving same waveforms, generates a first tactile output when haptic feedback controller  161  is at a first temperature and generates a second tactile output when haptic feedback controller  161  is at a second temperature that is distinct from the first temperature). For example, the magnitude (or the amplitude) of the tactile outputs may vary depending on the temperature. To reduce the effect of the temperature variations, the waveforms are modified (e.g., an amplitude of the waveforms is increased or decreased based on the temperature). 
     In some embodiments, haptic feedback module  133  (e.g., trigger module  121 ) is coupled to hardware input processing module  146 . In some embodiments, other input controller(s)  160  in  FIG.  1 A  includes hardware input processing module  146 . In some embodiments, hardware input processing module  146  receives inputs from hardware input device  175  (e.g., other input or control devices  116  in  FIG.  1 A , such as a home button or an intensity-sensitive input surface, such as an intensity-sensitive touch screen). In some embodiments, hardware input device  175  is any input device described herein, such as touch-sensitive display system  112  ( FIG.  1 A ), keyboard/mouse  350  ( FIG.  3   ), touchpad  355  ( FIG.  3   ), one of other input or control devices  116  ( FIG.  1 A ), or an intensity-sensitive home button. In some embodiments, hardware input device  175  consists of an intensity-sensitive home button, and not touch-sensitive display system  112  ( FIG.  1 A ), keyboard/mouse  350  ( FIG.  3   ), or touchpad  355  ( FIG.  3   ). In some embodiments, in response to inputs from hardware input device  175  (e.g., an intensity-sensitive home button or a touch screen), hardware input processing module  146  provides one or more trigger signals to haptic feedback module  133  to indicate that a user input satisfying predefined input criteria, such as an input corresponding to a “click” of a home button (e.g., a “down click” or an “up click”), has been detected. In some embodiments, haptic feedback module  133  provides waveforms that correspond to the “click” of a home button in response to the input corresponding to the “click” of a home button, simulating a haptic feedback of pressing a physical home button. 
     In some embodiments, the tactile output module includes haptic feedback controller  161  (e.g., haptic feedback controller  161  in  FIG.  1 A ), which controls the generation of tactile outputs. In some embodiments, haptic feedback controller  161  is coupled to a plurality of tactile output generators, and selects one or more tactile output generators of the plurality of tactile output generators and sends waveforms to the selected one or more tactile output generators for generating tactile outputs. In some embodiments, haptic feedback controller  161  coordinates tactile output requests that correspond to activation of hardware input device  175  and tactile output requests that correspond to software events (e.g., tactile output requests from haptic feedback module  133 ) and modifies one or more waveforms of the two or more waveforms to emphasize particular waveform(s) over the rest of the two or more waveforms (e.g., by increasing a scale of the particular waveform(s) and/or decreasing a scale of the rest of the waveforms, such as to prioritize tactile outputs that correspond to activations of hardware input device  175  over tactile outputs that correspond to software events). 
     In some embodiments, as shown in  FIG.  1 C , an output of haptic feedback controller  161  is coupled to audio circuitry of device  100  (e.g., audio circuitry  110 ,  FIG.  1 A ), and provides audio signals to audio circuitry of device  100 . In some embodiments, haptic feedback controller  161  provides both waveforms used for generating tactile outputs and audio signals used for providing audio outputs in conjunction with generation of the tactile outputs. In some embodiments, haptic feedback controller  161  modifies audio signals and/or waveforms (used for generating tactile outputs) so that the audio outputs and the tactile outputs are synchronized (e.g., by delaying the audio signals and/or waveforms). In some embodiments, haptic feedback controller  161  includes a digital-to-analog converter used for converting digital waveforms into analog signals, which are received by amplifier  185  and/or tactile output generator  163 . 
     In some embodiments, the tactile output module includes amplifier  185 . In some embodiments, amplifier  185  receives waveforms (e.g., from haptic feedback controller  161 ) and amplifies the waveforms prior to sending the amplified waveforms to tactile output generator  163  (e.g., any of tactile output generators  163  ( FIG.  1 A ) or  357  ( FIG.  3   )). For example, amplifier  185  amplifies the received waveforms to signal levels that are in accordance with physical specifications of tactile output generator  163  (e.g., to a voltage and/or a current required by tactile output generator  163  for generating tactile outputs so that the signals sent to tactile output generator  163  produce tactile outputs that correspond to the waveforms received from haptic feedback controller  161 ) and sends the amplified waveforms to tactile output generator  163 . In response, tactile output generator  163  generates tactile outputs (e.g., by shifting a moveable mass back and forth in one or more dimensions relative to a neutral position of the moveable mass). 
     In some embodiments, the tactile output module includes sensor  189 , which is coupled to tactile output generator  163 . Sensor  189  detects states or state changes (e.g., mechanical position, physical displacement, and/or movement) of tactile output generator  163  or one or more components of tactile output generator  163  (e.g., one or more moving parts, such as a membrane, used to generate tactile outputs). In some embodiments, sensor  189  is a magnetic field sensor (e.g., a Hall effect sensor) or other displacement and/or movement sensor. In some embodiments, sensor  189  provides information (e.g., a position, a displacement, and/or a movement of one or more parts in tactile output generator  163 ) to haptic feedback controller  161  and, in accordance with the information provided by sensor  189  about the state of tactile output generator  163 , haptic feedback controller  161  adjusts the waveforms output from haptic feedback controller  161  (e.g., waveforms sent to tactile output generator  163 , optionally via amplifier  185 ). 
       FIG.  2    illustrates a portable multifunction device  100  having a touch screen (e.g., touch-sensitive display system  112 ,  FIG.  1 A ) in accordance with some embodiments. The touch screen optionally displays one or more graphics within user interface (UI)  200 . In these embodiments, as well as others described below, a user is enabled to select one or more of the graphics by making a gesture on the graphics, for example, with one or more fingers  202  (not drawn to scale in the figure) or one or more styluses  203  (not drawn to scale in the figure). In some embodiments, selection of one or more graphics occurs when the user breaks contact with the one or more graphics. In some embodiments, the gesture optionally includes one or more taps, one or more swipes (from left to right, right to left, upward and/or downward) and/or a rolling of a finger (from right to left, left to right, upward and/or downward) that has made contact with device  100 . In some implementations or circumstances, inadvertent contact with a graphic does not select the graphic. For example, a swipe gesture that sweeps over an application icon optionally does not select the corresponding application when the gesture corresponding to selection is a tap. 
     Device  100  optionally also includes one or more physical buttons, such as “home” or menu button  204 . As described previously, menu button  204  is, optionally, used to navigate to any application  136  in a set of applications that are, optionally executed on device  100 . Alternatively, in some embodiments, the menu button is implemented as a soft key in a GUI displayed on the touch-screen display. 
     In some embodiments, device  100  includes the touch-screen display, menu button  204  (sometimes called home button  204 ), push button  206  for powering the device on/off and locking the device, volume adjustment button(s)  208 , Subscriber Identity Module (SIM) card slot  210 , head set jack  212 , and docking/charging external port  124 . Push button  206  is, optionally, used to turn the power on/off on the device by depressing the button and holding the button in the depressed state for a predefined time interval; to lock the device by depressing the button and releasing the button before the predefined time interval has elapsed; and/or to unlock the device or initiate an unlock process. In some embodiments, device  100  also accepts verbal input for activation or deactivation of some functions through microphone  113 . Device  100  also, optionally, includes one or more contact intensity sensors  165  for detecting intensities of contacts on touch-sensitive display system  112  and/or one or more tactile output generators  163  for generating tactile outputs for a user of device  100 . 
       FIG.  3 A  is a block diagram of an example multifunction device with a display and a touch-sensitive surface in accordance with some embodiments. Device  300  need not be portable. In some embodiments, device  300  is a laptop computer, a desktop computer, a tablet computer, a multimedia player device, a navigation device, an educational device (such as a child&#39;s learning toy), a gaming system, or a control device (e.g., a home or industrial controller). Device  300  typically includes one or more processing units (CPU&#39;s)  310 , one or more network or other communications interfaces  360 , memory  370 , and one or more communication buses  320  for interconnecting these components. Communication buses  320  optionally include circuitry (sometimes called a chipset) that interconnects and controls communications between system components. Device  300  includes input/output (I/O) interface  330  comprising display  340 , which is optionally a touch-screen display. I/O interface  330  also optionally includes a keyboard and/or mouse (or other pointing device)  350  and touchpad  355 , tactile output generator  357  for generating tactile outputs on device  300  (e.g., similar to tactile output generator(s)  163  described above with reference to  FIG.  1 A ), sensors  359  (e.g., optical, acceleration, proximity, touch-sensitive, and/or contact intensity sensors similar to contact intensity sensor(s)  165  described above with reference to FIG.  1 A). Memory  370  includes high-speed random access memory, such as DRAM, SRAM, DDR RAM or other random access solid state memory devices; and optionally includes non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. Memory  370  optionally includes one or more storage devices remotely located from CPU(s)  310 . In some embodiments, memory  370  stores programs, modules, and data structures analogous to the programs, modules, and data structures stored in memory  102  of portable multifunction device  100  ( FIG.  1 A ), or a subset thereof. Furthermore, memory  370  optionally stores additional programs, modules, and data structures not present in memory  102  of portable multifunction device  100 . For example, memory  370  of device  300  optionally stores drawing module  380 , presentation module  382 , word processing module  384 , website creation module  386 , disk authoring module  388 , and/or spreadsheet module  390 , while memory  102  of portable multifunction device  100  ( FIG.  1 A ) optionally does not store these modules. 
     Each of the above identified elements in  FIG.  3 A  are, optionally, stored in one or more of the previously mentioned memory devices. Each of the above identified modules corresponds to a set of instructions for performing a function described above. The above identified modules or programs (e.g., sets of instructions) need not be implemented as separate software programs, procedures or modules, and thus various subsets of these modules are, optionally, combined or otherwise re-arranged in various embodiments. In some embodiments, memory  370  optionally stores a subset of the modules and data structures identified above. Furthermore, memory  370  optionally stores additional modules and data structures not described above. 
       FIGS.  3 B- 3 C  are block diagrams of example computer systems  301  in accordance with some embodiments. 
     In some embodiments, computer system  301  includes and/or is in communication with:
         input device(s) ( 302  and/or  307 , e.g., a touch-sensitive surface, such as a touch-sensitive remote control, or a touch-screen display that also serves as the display generation component, a mouse, a joystick, a wand controller, and/or cameras tracking the position of one or more features of the user such as the user&#39;s hands);   virtual/augmented reality logic  303  (e.g., virtual/augmented reality module  145 );   display generation component(s) ( 304  and/or  308 , e.g., a display, a projector, a heads-up display, or the like) for displaying virtual user interface elements to the user;   camera(s) (e.g.,  305  and/or  311 ) for capturing images of a field of view of the device, e.g., images that are used to determine placement of virtual user interface elements, determine an attitude of the device, and/or display a portion of the physical environment in which the camera(s) are located; and   attitude sensor(s) (e.g.,  306  and/or  311 ) for determining an attitude of the device relative to the physical environment and/or changes in attitude of the device.       

     In some computer systems (e.g.,  301 - a  in  FIG.  3 B ), input device(s)  302 , virtual/augmented reality logic  303 , display generation component(s)  304 , camera(s)  305 ; and attitude sensor(s)  306  are all integrated into the computer system (e.g., portable multifunction device  100  in  FIGS.  1 A- 1 B  or device  300  in  FIG.  3    such as a smartphone or tablet). 
     In some computer systems (e.g.,  301 - b ), in addition to integrated input device(s)  302 , virtual/augmented reality logic  303 , display generation component(s)  304 , camera(s)  305 ; and attitude sensor(s)  306 , the computer system is also in communication with additional devices that are separate from the computer system, such as separate input device(s)  307  such as a touch-sensitive surface, a wand, a remote control, or the like and/or separate display generation component(s)  308  such as virtual reality headset or augmented reality glasses that overlay virtual objects on a physical environment. 
     In some computer systems (e.g.,  301 - c  in  FIG.  3 C ), the input device(s)  307 , display generation component(s)  309 , camera(s)  311 ; and/or attitude sensor(s)  312  are separate from the computer system and are in communication with the computer system. In some embodiments, other combinations of components in computer system  301  and in communication with the computer system are used. For example, in some embodiments, display generation component(s)  309 , camera(s)  311 , and attitude sensor(s)  312  are incorporated in a headset that is either integrated with or in communication with the computer system. 
     In some embodiments, all of the operations described below with reference to  FIGS.  5 A- 5 CO  are performed on a single computing device with virtual/augmented reality logic  303  (e.g., computer system  301 - a  described below with reference to  FIG.  3 B ). However, it should be understood that frequently multiple different computing devices are linked together to perform the operations described below with reference to  FIGS.  5 A- 5 CO  (e.g., a computing device with virtual/augmented reality logic  303  communicates with a separate computing device with a display  450  and/or a separate computing device with a touch-sensitive surface  451 ). In any of these embodiments, the computing device that is described below with reference to  FIGS.  5 A- 5 CO  is the computing device (or devices) that contain(s) the virtual/augmented reality logic  303 . Additionally, it should be understood that the virtual/augmented reality logic  303  could be divided between a plurality of distinct modules or computing devices in various embodiments; however, for the purposes of the description herein, the virtual/augmented reality logic  303  will be primarily referred to as residing in a single computing device so as not to unnecessarily obscure other aspects of the embodiments. 
     In some embodiments, the virtual/augmented reality logic  303  includes one or more modules (e.g., one or more event handlers  190 , including one or more object updaters  177  and one or more GUI updaters  178  as described in greater detail above with reference to  FIG.  1 B ) that receive interpreted inputs and, in response to these interpreted inputs, generate instructions for updating a graphical user interface in accordance with the interpreted inputs which are subsequently used to update the graphical user interface on a display. In some embodiments, an interpreted input for an input that has been detected (e.g., by a contact motion module  130  in  FIGS.  1 A and  3   ), recognized (e.g., by an event recognizer  180  in  FIG.  1 B ) and/or distributed (e.g., by event sorter  170  in  FIG.  1 B ) is used to update the graphical user interface on a display. In some embodiments, the interpreted inputs are generated by modules at the computing device (e.g., the computing device receives raw contact input data so as to identify gestures from the raw contact input data). In some embodiments, some or all of the interpreted inputs are received by the computing device as interpreted inputs (e.g., a computing device that includes the touch-sensitive surface  451  processes raw contact input data so as to identify gestures from the raw contact input data and sends information indicative of the gestures to the computing device that includes the virtual/augmented reality logic  303 ). 
     In some embodiments, both a display and a touch-sensitive surface are integrated with the computer system (e.g.,  301 - a  in  FIG.  3 B ) that contains the virtual/augmented reality logic  303 . For example, the computer system may be a desktop computer or laptop computer with an integrated display (e.g.,  340  in  FIG.  3   ) and touchpad (e.g.,  355  in  FIG.  3   ). As another example, the computing device may be a portable multifunction device  100  (e.g., a smartphone, PDA, tablet computer, etc.) with a touch screen (e.g.,  112  in  FIG.  2   ). 
     In some embodiments, a touch-sensitive surface is integrated with the computer system while a display is not integrated with the computer system that contains the virtual/augmented reality logic  303 . For example, the computer system may be a device  300  (e.g., a desktop computer or laptop computer) with an integrated touchpad (e.g.,  355  in  FIG.  3   ) connected (via wired or wireless connection) to a separate display (e.g., a computer monitor, television, etc.). As another example, the computer system may be a portable multifunction device  100  (e.g., a smartphone, PDA, tablet computer, etc.) with a touch screen (e.g.,  112  in  FIG.  2   ) connected (via wired or wireless connection) to a separate display (e.g., a computer monitor, television, etc.). 
     In some embodiments, a display is integrated with the computer system while a touch-sensitive surface is not integrated with the computer system that contains the virtual/augmented reality logic  303 . For example, the computer system may be a device  300  (e.g., a desktop computer, laptop computer, television with integrated set-top box) with an integrated display (e.g.,  340  in  FIG.  3   ) connected (via wired or wireless connection) to a separate touch-sensitive surface (e.g., a remote touchpad, a portable multifunction device, etc.). As another example, the computer system may be a portable multifunction device  100  (e.g., a smartphone, PDA, tablet computer, etc.) with a touch screen (e.g.,  112  in  FIG.  2   ) connected (via wired or wireless connection) to a separate touch-sensitive surface (e.g., a remote touchpad, another portable multifunction device with a touch screen serving as a remote touchpad, etc.). 
     In some embodiments, neither a display nor a touch-sensitive surface is integrated with the computer system (e.g.,  301 - c  in  FIG.  3 C ) that contains the virtual/augmented reality logic  303 . For example, the computer system may be a stand-alone computing device  300  (e.g., a set-top box, gaming console, etc.) connected (via wired or wireless connection) to a separate touch-sensitive surface (e.g., a remote touchpad, a portable multifunction device, etc.) and a separate display (e.g., a computer monitor, television, etc.). 
     In some embodiments, the computer system has an integrated audio system (e.g., audio circuitry  110  and speaker  111  in portable multifunction device  100 ). In some embodiments, the computing device is in communication with an audio system that is separate from the computing device. In some embodiments, the audio system (e.g., an audio system integrated in a television unit) is integrated with a separate display. In some embodiments, the audio system (e.g., a stereo system) is a stand-alone system that is separate from the computer system and the display. 
     Attention is now directed towards embodiments of user interfaces (“UI”) that are, optionally, implemented on portable multifunction device  100 . 
       FIG.  4 A  illustrates an example user interface for a menu of applications on portable multifunction device  100  in accordance with some embodiments. Similar user interfaces are, optionally, implemented on device  300 . In some embodiments, user interface  400  includes the following elements, or a subset or superset thereof:
         Signal strength indicator(s) for wireless communication(s), such as cellular and Wi-Fi signals;   Time;   a Bluetooth indicator;   a Battery status indicator;   Tray  408  with icons for frequently used applications, such as:
           Icon  416  for telephone module  138 , labeled “Phone,” which optionally includes an indicator  414  of the number of missed calls or voicemail messages;   Icon  418  for e-mail client module  140 , labeled “Mail,” which optionally includes an indicator  410  of the number of unread e-mails;   Icon  420  for browser module  147 , labeled “Browser”; and   Icon  422  for video and music player module  152 , labeled “Music”; and   
           Icons for other applications, such as:
           Icon  424  for IM module  141 , labeled “Messages”;   Icon  426  for calendar module  148 , labeled “Calendar”;   Icon  428  for image management module  144 , labeled “Photos”;   Icon  430  for camera module  143 , labeled “Camera”;   Icon  432  for measurement module  155 , labeled “Measurement”;   Icon  434  for stocks widget  149 - 2 , labeled “Stocks”;   Icon  436  for map module  154 , labeled “Maps”;   Icon  438  for weather widget  149 - 1 , labeled “Weather”;   Icon  440  for alarm clock widget  149 - 4 , labeled “Clock”;   Icon  442  for workout support module  142 , labeled “Workout Support”;   Icon  444  for notes module  153 , labeled “Notes”; and   Icon  446  for a settings application or module, labeled “Settings,” which provides access to settings for device  100  and its various applications  136 .   
               

     It should be noted that the icon labels illustrated in  FIG.  4 A  are merely examples. For example, other labels are, optionally, used for various application icons. In some embodiments, a label for a respective application icon includes a name of an application corresponding to the respective application icon. In some embodiments, a label for a particular application icon is distinct from a name of an application corresponding to the particular application icon. 
       FIG.  4 B  illustrates an example user interface on a device (e.g., device  300 ,  FIG.  3 A ) with a touch-sensitive surface  451  (e.g., a tablet or touchpad  355 ,  FIG.  3 A ) that is separate from the display  450 . Although many of the examples that follow will be given with reference to inputs on touch screen display  112  (where the touch sensitive surface and the display are combined), in some embodiments, the device detects inputs on a touch-sensitive surface that is separate from the display, as shown in  FIG.  4 B . In some embodiments, the touch-sensitive surface (e.g.,  451  in  FIG.  4 B ) has a primary axis (e.g.,  452  in  FIG.  4 B ) that corresponds to a primary axis (e.g.,  453  in  FIG.  4 B ) on the display (e.g.,  450 ). In accordance with these embodiments, the device detects contacts (e.g.,  460  and  462  in  FIG.  4 B ) with the touch-sensitive surface  451  at locations that correspond to respective locations on the display (e.g., in  FIG.  4 B,  460    corresponds to  468  and  462  corresponds to  470 ). In this way, user inputs (e.g., contacts  460  and  462 , and movements thereof) detected by the device on the touch-sensitive surface (e.g.,  451  in  FIG.  4 B ) are used by the device to manipulate the user interface on the display (e.g.,  450  in  FIG.  4 B ) of the multifunction device when the touch-sensitive surface is separate from the display. It should be understood that similar methods are, optionally, used for other user interfaces described herein. 
     Additionally, while the following examples are given primarily with reference to finger inputs (e.g., finger contacts, finger tap gestures, finger swipe gestures, etc.), it should be understood that, in some embodiments, one or more of the finger inputs are replaced with input from another input device (e.g., a mouse based input or a stylus input). For example, a swipe gesture is, optionally, replaced with a mouse click (e.g., instead of a contact) followed by movement of the cursor along the path of the swipe (e.g., instead of movement of the contact). As another example, a tap gesture is, optionally, replaced with a mouse click while the cursor is located over the location of the tap gesture (e.g., instead of detection of the contact followed by ceasing to detect the contact). Similarly, when multiple user inputs are simultaneously detected, it should be understood that multiple computer mice are, optionally, used simultaneously, or a mouse and finger contacts are, optionally, used simultaneously. 
     As used herein, the term “focus selector” refers to an input element that indicates a current part of a user interface with which a user is interacting. In some implementations that include a cursor or other location marker, the cursor acts as a “focus selector,” so that when an input (e.g., a press input) is detected on a touch-sensitive surface (e.g., touchpad  355  in  FIG.  3 A  or touch-sensitive surface  451  in  FIG.  4 B ) while the cursor is over a particular user interface element (e.g., a button, window, slider or other user interface element), the particular user interface element is adjusted in accordance with the detected input. In some implementations that include a touch-screen display (e.g., touch-sensitive display system  112  in  FIG.  1 A  or the touch screen in  FIG.  4 A ) that enables direct interaction with user interface elements on the touch-screen display, a detected contact on the touch-screen acts as a “focus selector,” so that when an input (e.g., a press input by the contact) is detected on the touch-screen display at a location of a particular user interface element (e.g., a button, window, slider or other user interface element), the particular user interface element is adjusted in accordance with the detected input. In some implementations, focus is moved from one region of a user interface to another region of the user interface without corresponding movement of a cursor or movement of a contact on a touch-screen display (e.g., by using a tab key or arrow keys to move focus from one button to another button); in these implementations, the focus selector moves in accordance with movement of focus between different regions of the user interface. Without regard to the specific form taken by the focus selector, the focus selector is generally the user interface element (or contact on a touch-screen display) that is controlled by the user so as to communicate the user&#39;s intended interaction with the user interface (e.g., by indicating, to the device, the element of the user interface with which the user is intending to interact). For example, the location of a focus selector (e.g., a cursor, a contact, or a selection box) over a respective button while a press input is detected on the touch-sensitive surface (e.g., a touchpad or touch screen) will indicate that the user is intending to activate the respective button (as opposed to other user interface elements shown on a display of the device). In some embodiments, a focus indicator (e.g., a cursor or selection indicator) is displayed via the display device to indicate a current portion of the user interface that will be affected by inputs received from the one or more input devices. 
     As used in the specification and claims, the term “intensity” of a contact on a touch-sensitive surface refers to the force or pressure (force per unit area) of a contact (e.g., a finger contact or a stylus contact) on the touch-sensitive surface, or to a substitute (proxy) for the force or pressure of a contact on the touch-sensitive surface. The intensity of a contact has a range of values that includes at least four distinct values and more typically includes hundreds of distinct values (e.g., at least 256). Intensity of a contact is, optionally, determined (or measured) using various approaches and various sensors or combinations of sensors. For example, one or more force sensors underneath or adjacent to the touch-sensitive surface are, optionally, used to measure force at various points on the touch-sensitive surface. In some implementations, force measurements from multiple force sensors are combined (e.g., a weighted average or a sum) to determine an estimated force of a contact. Similarly, a pressure-sensitive tip of a stylus is, optionally, used to determine a pressure of the stylus on the touch-sensitive surface. Alternatively, the size of the contact area detected on the touch-sensitive surface and/or changes thereto, the capacitance of the touch-sensitive surface proximate to the contact and/or changes thereto, and/or the resistance of the touch-sensitive surface proximate to the contact and/or changes thereto are, optionally, used as a substitute for the force or pressure of the contact on the touch-sensitive surface. In some implementations, the substitute measurements for contact force or pressure are used directly to determine whether an intensity threshold has been exceeded (e.g., the intensity threshold is described in units corresponding to the substitute measurements). In some implementations, the substitute measurements for contact force or pressure are converted to an estimated force or pressure and the estimated force or pressure is used to determine whether an intensity threshold has been exceeded (e.g., the intensity threshold is a pressure threshold measured in units of pressure). Using the intensity of a contact as an attribute of a user input allows for user access to additional device functionality that may otherwise not be readily accessible by the user on a reduced-size device with limited real estate for displaying affordances (e.g., on a touch-sensitive display) and/or receiving user input (e.g., via a touch-sensitive display, a touch-sensitive surface, or a physical/mechanical control such as a knob or a button). 
     In some embodiments, contact/motion module  130  uses a set of one or more intensity thresholds to determine whether an operation has been performed by a user (e.g., to determine whether a user has “clicked” on an icon). In some embodiments, at least a subset of the intensity thresholds are determined in accordance with software parameters (e.g., the intensity thresholds are not determined by the activation thresholds of particular physical actuators and can be adjusted without changing the physical hardware of device  100 ). For example, a mouse “click” threshold of a trackpad or touch-screen display can be set to any of a large range of predefined thresholds values without changing the trackpad or touch-screen display hardware. Additionally, in some implementations a user of the device is provided with software settings for adjusting one or more of the set of intensity thresholds (e.g., by adjusting individual intensity thresholds and/or by adjusting a plurality of intensity thresholds at once with a system-level click “intensity” parameter). 
     As used in the specification and claims, the term “characteristic intensity” of a contact refers to a characteristic of the contact based on one or more intensities of the contact. In some embodiments, the characteristic intensity is based on multiple intensity samples. The characteristic intensity is, optionally, based on a predefined number of intensity samples, or a set of intensity samples collected during a predetermined time period (e.g., 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10 seconds) relative to a predefined event (e.g., after detecting the contact, prior to detecting liftoff of the contact, before or after detecting a start of movement of the contact, prior to detecting an end of the contact, before or after detecting an increase in intensity of the contact, and/or before or after detecting a decrease in intensity of the contact). A characteristic intensity of a contact is, optionally based on one or more of: a maximum value of the intensities of the contact, a mean value of the intensities of the contact, an average value of the intensities of the contact, a top 10 percentile value of the intensities of the contact, a value at the half maximum of the intensities of the contact, a value at the 90 percent maximum of the intensities of the contact, a value produced by low-pass filtering the intensity of the contact over a predefined period or starting at a predefined time, or the like. In some embodiments, the duration of the contact is used in determining the characteristic intensity (e.g., when the characteristic intensity is an average of the intensity of the contact over time). In some embodiments, the characteristic intensity is compared to a set of one or more intensity thresholds to determine whether an operation has been performed by a user. For example, the set of one or more intensity thresholds may include a first intensity threshold and a second intensity threshold. In this example, a contact with a characteristic intensity that does not exceed the first intensity threshold results in a first operation, a contact with a characteristic intensity that exceeds the first intensity threshold and does not exceed the second intensity threshold results in a second operation, and a contact with a characteristic intensity that exceeds the second intensity threshold results in a third operation. In some embodiments, a comparison between the characteristic intensity and one or more intensity thresholds is used to determine whether or not to perform one or more operations (e.g., whether to perform a respective option or forgo performing the respective operation) rather than being used to determine whether to perform a first operation or a second operation. 
     In some embodiments, a portion of a gesture is identified for purposes of determining a characteristic intensity. For example, a touch-sensitive surface may receive a continuous swipe contact transitioning from a start location and reaching an end location (e.g., a drag gesture), at which point the intensity of the contact increases. In this example, the characteristic intensity of the contact at the end location may be based on only a portion of the continuous swipe contact, and not the entire swipe contact (e.g., only the portion of the swipe contact at the end location). In some embodiments, a smoothing algorithm may be applied to the intensities of the swipe contact prior to determining the characteristic intensity of the contact. For example, the smoothing algorithm optionally includes one or more of: an unweighted sliding-average smoothing algorithm, a triangular smoothing algorithm, a median filter smoothing algorithm, and/or an exponential smoothing algorithm. In some circumstances, these smoothing algorithms eliminate narrow spikes or dips in the intensities of the swipe contact for purposes of determining a characteristic intensity. 
     The user interface figures described herein optionally include various intensity diagrams that show the current intensity of the contact on the touch-sensitive surface relative to one or more intensity thresholds (e.g., a contact detection intensity threshold IT 0 , a light press intensity threshold IT L , a deep press intensity threshold IT D  (e.g., that is at least initially higher than IT L ), and/or one or more other intensity thresholds (e.g., an intensity threshold IT H  that is lower than IT L )). This intensity diagram is typically not part of the displayed user interface, but is provided to aid in the interpretation of the figures. In some embodiments, the light press intensity threshold corresponds to an intensity at which the device will perform operations typically associated with clicking a button of a physical mouse or a trackpad. In some embodiments, the deep press intensity threshold corresponds to an intensity at which the device will perform operations that are different from operations typically associated with clicking a button of a physical mouse or a trackpad. In some embodiments, when a contact is detected with a characteristic intensity below the light press intensity threshold (e.g., and above a nominal contact-detection intensity threshold IT 0  below which the contact is no longer detected), the device will move a focus selector in accordance with movement of the contact on the touch-sensitive surface without performing an operation associated with the light press intensity threshold or the deep press intensity threshold. Generally, unless otherwise stated, these intensity thresholds are consistent between different sets of user interface figures. 
     In some embodiments, the response of the device to inputs detected by the device depends on criteria based on the contact intensity during the input. For example, for some “light press” inputs, the intensity of a contact exceeding a first intensity threshold during the input triggers a first response. In some embodiments, the response of the device to inputs detected by the device depends on criteria that include both the contact intensity during the input and time-based criteria. For example, for some “deep press” inputs, the intensity of a contact exceeding a second intensity threshold during the input, greater than the first intensity threshold for a light press, triggers a second response only if a delay time has elapsed between meeting the first intensity threshold and meeting the second intensity threshold. This delay time is typically less than 200 ms (milliseconds) in duration (e.g., 40, 100, or 120 ms, depending on the magnitude of the second intensity threshold, with the delay time increasing as the second intensity threshold increases). This delay time helps to avoid accidental recognition of deep press inputs. As another example, for some “deep press” inputs, there is a reduced-sensitivity time period that occurs after the time at which the first intensity threshold is met. During the reduced-sensitivity time period, the second intensity threshold is increased. This temporary increase in the second intensity threshold also helps to avoid accidental deep press inputs. For other deep press inputs, the response to detection of a deep press input does not depend on time-based criteria. 
     In some embodiments, one or more of the input intensity thresholds and/or the corresponding outputs vary based on one or more factors, such as user settings, contact motion, input timing, application running, rate at which the intensity is applied, number of concurrent inputs, user history, environmental factors (e.g., ambient noise), focus selector position, and the like. Example factors are described in U.S. patent application Ser. Nos. 14/399,606 and 14/624,296, which are incorporated by reference herein in their entireties. 
     For example,  FIG.  4 C  illustrates a dynamic intensity threshold  480  that changes over time based in part on the intensity of touch input  476  over time. Dynamic intensity threshold  480  is a sum of two components, first component  474  that decays over time after a predefined delay time p 1  from when touch input  476  is initially detected, and second component  478  that trails the intensity of touch input  476  over time. The initial high intensity threshold of first component  474  reduces accidental triggering of a “deep press” response, while still allowing an immediate “deep press” response if touch input  476  provides sufficient intensity. Second component  478  reduces unintentional triggering of a “deep press” response by gradual intensity fluctuations of in a touch input. In some embodiments, when touch input  476  satisfies dynamic intensity threshold  480  (e.g., at point  481  in  FIG.  4 C ), the “deep press” response is triggered. 
       FIG.  4 D  illustrates another dynamic intensity threshold  486  (e.g., intensity threshold IT D ).  FIG.  4 D  also illustrates two other intensity thresholds: a first intensity threshold IT H  and a second intensity threshold IT L . In  FIG.  4 D , although touch input  484  satisfies the first intensity threshold IT H  and the second intensity threshold IT L  prior to time p 2 , no response is provided until delay time p 2  has elapsed at time  482 . Also in  FIG.  4 D , dynamic intensity threshold  486  decays over time, with the decay starting at time  488  after a predefined delay time p 1  has elapsed from time  482  (when the response associated with the second intensity threshold IT L  was triggered). This type of dynamic intensity threshold reduces accidental triggering of a response associated with the dynamic intensity threshold ITS immediately after, or concurrently with, triggering a response associated with a lower intensity threshold, such as the first intensity threshold IT H  or the second intensity threshold IT L . 
       FIG.  4 E  illustrate yet another dynamic intensity threshold  492  (e.g., intensity threshold IT D ). In  FIG.  4 E , a response associated with the intensity threshold IT L  is triggered after the delay time p 2  has elapsed from when touch input  490  is initially detected. Concurrently, dynamic intensity threshold  492  decays after the predefined delay time p 1  has elapsed from when touch input  490  is initially detected. So a decrease in intensity of touch input  490  after triggering the response associated with the intensity threshold IT L , followed by an increase in the intensity of touch input  490 , without releasing touch input  490 , can trigger a response associated with the intensity threshold IT D  (e.g., at time  494 ) even when the intensity of touch input  490  is below another intensity threshold, for example, the intensity threshold IT L . 
     An increase of characteristic intensity of the contact from an intensity below the light press intensity threshold IT L  to an intensity between the light press intensity threshold IT L  and the deep press intensity threshold IT D  is sometimes referred to as a “light press” input. An increase of characteristic intensity of the contact from an intensity below the deep press intensity threshold IT D  to an intensity above the deep press intensity threshold IT D  is sometimes referred to as a “deep press” input. An increase of characteristic intensity of the contact from an intensity below the contact-detection intensity threshold IT 0  to an intensity between the contact-detection intensity threshold IT 0  and the light press intensity threshold IT L  is sometimes referred to as detecting the contact on the touch-surface. A decrease of characteristic intensity of the contact from an intensity above the contact-detection intensity threshold IT 0  to an intensity below the contact-detection intensity threshold IT 0  is sometimes referred to as detecting liftoff of the contact from the touch-surface. In some embodiments IT 0  is zero. In some embodiments, IT 0  is greater than zero. In some illustrations a shaded circle or oval is used to represent intensity of a contact on the touch-sensitive surface. In some illustrations, a circle or oval without shading is used represent a respective contact on the touch-sensitive surface without specifying the intensity of the respective contact. 
     In some embodiments, described herein, one or more operations are performed in response to detecting a gesture that includes a respective press input or in response to detecting the respective press input performed with a respective contact (or a plurality of contacts), where the respective press input is detected based at least in part on detecting an increase in intensity of the contact (or plurality of contacts) above a press-input intensity threshold. In some embodiments, the respective operation is performed in response to detecting the increase in intensity of the respective contact above the press-input intensity threshold (e.g., the respective operation is performed on a “down stroke” of the respective press input). In some embodiments, the press input includes an increase in intensity of the respective contact above the press-input intensity threshold and a subsequent decrease in intensity of the contact below the press-input intensity threshold, and the respective operation is performed in response to detecting the subsequent decrease in intensity of the respective contact below the press-input threshold (e.g., the respective operation is performed on an “up stroke” of the respective press input). 
     In some embodiments, the device employs intensity hysteresis to avoid accidental inputs sometimes termed “jitter,” where the device defines or selects a hysteresis intensity threshold with a predefined relationship to the press-input intensity threshold (e.g., the hysteresis intensity threshold is X intensity units lower than the press-input intensity threshold or the hysteresis intensity threshold is 75%, 90%, or some reasonable proportion of the press-input intensity threshold). Thus, in some embodiments, the press input includes an increase in intensity of the respective contact above the press-input intensity threshold and a subsequent decrease in intensity of the contact below the hysteresis intensity threshold that corresponds to the press-input intensity threshold, and the respective operation is performed in response to detecting the subsequent decrease in intensity of the respective contact below the hysteresis intensity threshold (e.g., the respective operation is performed on an “up stroke” of the respective press input). Similarly, in some embodiments, the press input is detected only when the device detects an increase in intensity of the contact from an intensity at or below the hysteresis intensity threshold to an intensity at or above the press-input intensity threshold and, optionally, a subsequent decrease in intensity of the contact to an intensity at or below the hysteresis intensity, and the respective operation is performed in response to detecting the press input (e.g., the increase in intensity of the contact or the decrease in intensity of the contact, depending on the circumstances). 
     For ease of explanation, the description of operations performed in response to a press input associated with a press-input intensity threshold or in response to a gesture including the press input are, optionally, triggered in response to detecting: an increase in intensity of a contact above the press-input intensity threshold, an increase in intensity of a contact from an intensity below the hysteresis intensity threshold to an intensity above the press-input intensity threshold, a decrease in intensity of the contact below the press-input intensity threshold, or a decrease in intensity of the contact below the hysteresis intensity threshold corresponding to the press-input intensity threshold. Additionally, in examples where an operation is described as being performed in response to detecting a decrease in intensity of a contact below the press-input intensity threshold, the operation is, optionally, performed in response to detecting a decrease in intensity of the contact below a hysteresis intensity threshold corresponding to, and lower than, the press-input intensity threshold. As described above, in some embodiments, the triggering of these responses also depends on time-based criteria being met (e.g., a delay time has elapsed between a first intensity threshold being met and a second intensity threshold being met). 
     Although only specific frequencies, amplitudes, and waveforms are represented in the sample tactile output patterns in  FIGS.  4 F- 4 K  for illustrative purposes, tactile output patterns with other frequencies, amplitudes, and waveforms may be used for similar purposes. For example, waveforms that have between 0.5 to 4 cycles can be used. Other frequencies in the range of 60 Hz-400 Hz may be used as well. 
     User Interfaces and Associated Processes 
     Attention is now directed towards embodiments of user interfaces (“UI”) and associated processes that may be implemented on a computer system (e.g., an electronic device such as portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes (and/or is in communication with) a display generation component (e.g., a display, a projector, a heads-up display, or the like), one or more cameras (e.g., video cameras that continuously provide a live preview of at least a portion of the contents that are within the field of view of at least one of the cameras and optionally generate video outputs including one or more streams of image frames capturing the contents within the field of view of at least one of the cameras), and one or more input devices (e.g., a touch-sensitive surface, such as a touch-sensitive remote control, or a touch-screen display that also serves as the display generation component, a mouse, a joystick, a wand controller, and/or cameras tracking the position of one or more features of the user such as the user&#39;s hands), optionally one or more attitude sensors, optionally one or more sensors to detect intensities of contacts with the touch-sensitive surface, and optionally one or more tactile output generators. 
       FIGS.  5 A- 5 CO  illustrate example user interfaces for making measurements of a physical space using an augmented reality environment in accordance with some embodiments. The user interfaces in these figures are used to illustrate the processes described below, including the processes in  FIGS.  6 A- 6 C,  7 A- 7 E,  8 A- 8 C,  9 A- 9 B,  10 A- 10 B,  11 A- 11 B,  12 A- 12 C,  13 A- 13 C, and  14 A- 14 D . For convenience of explanation, some of the embodiments will be discussed with reference to operations performed on a device with a touch-sensitive display system  112 . In such embodiments, the focus selector is, optionally: a respective finger or stylus contact, a representative point corresponding to a finger or stylus contact (e.g., a centroid of a respective contact or a point associated with a respective contact), or a centroid of two or more contacts detected on the touch-sensitive display system  112 . However, analogous operations are, optionally, performed on a device with a display  450  and a separate touch-sensitive surface  451  in response to detecting the contacts on the touch-sensitive surface  451  while displaying the user interfaces shown in the figures on the display  450 , along with a focus selector. 
       FIG.  5 A  illustrates a context in which user interfaces described with respect to  FIGS.  5 A- 5 CO  are used. In particular,  FIG.  5 A  illustrates a view of physical space  5000  in which table  5002  and device  100  are located. Device  100  is held by user  5004  to view physical space  5000 , including a portion of table  5002 , through touch screen  112  of device  100 . In particular, touch screen  112  displays a view of an augmented reality environment corresponding to physical space  5000 . User  5004  uses touch screen  112  of device  100  to interact with the augmented reality environment via displayed user interface  5006  (e.g., a user interface of an augmented reality measurement application). User interface  5006  includes a live preview of the field of view of at least one of one or more cameras of device  100  (sometimes referred to as “the camera” of device  100 , such as camera(s)  305 ,  FIGS.  3 A- 3 B  or camera(s)  311 ,  FIG.  3 C , optionally including optical sensors  164 ,  FIG.  1 A  as part of the one or more cameras). In some embodiments, the camera(s) are located on device  100  in region  5008 . In some embodiments, device  100  includes front-facing camera  305 - a  that is located in region  5008  next to and on the same side of device  100  as touch screen  112  (e.g., the side facing user  5004  in  FIG.  5 A ). In some embodiments, device  100  includes one or more cameras that are located in region  5008  behind touch screen  112  or on the opposite side of device  100  from touch screen  112  (e.g., the side facing away from user  5004  in  FIG.  5 A ). At least one camera continuously provides a live preview of contents that are within the field of view the camera, which may include one or more physical objects in physical space  5000  (e.g., table  5002 ). 
     In some embodiments, user interface  5006  includes one or more user interface elements for user interaction with the augmented reality environment. For example, in  FIG.  5 A , user interface  5006  includes reticle  5010  that indicates an area for user interaction with the augmented reality environment. In some embodiments, reticle  5010  includes focus point  5012  that indicates a particular point for user interaction. In some embodiments, user interface  5006  includes measurement addition button  5014  that is used for adding new measurements (e.g., new measurement points, new measurement segments, and/or new measurement regions) to user interface  5006  (e.g., as described in more detail herein). In some embodiments, reticle  5010  and focus point  5012  together form a measurement-point-creation indicator that indicates a location at which a new measurement will be added in response to activation of measurement addition button  5014 . 
     In some embodiments, user interface  5006  includes media capture button  5016  that is used for capturing media, such as a still image, or a video (that optionally includes corresponding audio), of the field of view, and any virtual measurements corresponding to physical objects in the field of view. In some embodiments, user interface  5006  includes undo button  5018  that is used for undoing (e.g., reversing the performance of) a most-recently-performed operation in user interface  5006 . In some embodiments, user interface  5006  includes redo button  5020  that is used for redoing a most-recently-undone operation (e.g., reversing the reversal of the most-recently-performed operation by activation of undo button  5018 ) in user interface  5006 . User interface  5006  may also include one or more virtual measurements that correspond to one or more physical objects in physical space  5000 , and that are displayed at least partially in response to user inputs on the user interface elements of user interface  5006 . In some embodiments, user interface  5006  includes clear button  5022  for removing virtual measurements displayed in user interface  5006  (and, optionally, also removing virtual measurements that are not displayed in user interface  5006  when clear button  5022  is activated, such as virtual measurements corresponding to physical object(s) that are outside of the field of view of the camera when clear button  5022  is activated). 
       FIG.  5 B  illustrates device  100  in a first landscape orientation, in contrast to its portrait orientation in  FIG.  5 A . While device  100  is in the first landscape orientation, as shown in  FIG.  5 B , the one or more cameras of device  100  are located in region  5008  on the left side of device  100 , and measurement addition button  5014  is displayed in user interface  5006  on the right side of device  100 , away from region  5008 , to reduce the chance that user  5004  will hold device  100  on the left side and obscure the field of view of the camera providing the live preview in user interface  5006 , and also to facilitate interaction with the augmented reality environment during single-handed operation by user  5004  while holding device  100  by its right side (e.g., while user  5004  holds device  100  with his/her right hand). 
       FIG.  5 C  illustrates device  100  in a second landscape orientation, different from the landscape orientation in  FIG.  5 B  (e.g., 180 degrees rotated from the landscape orientation in  FIG.  5 B ). While device  100  is in the second landscape orientation, as shown in  FIG.  5 C , the one or more cameras of device  100  are located in region  5008  on the right side of device  100 , and measurement addition button  5014  is displayed in user interface  100  on the left side of device  100 , away from region  5008 , to reduce the chance that user  5004  will hold device  100  on the right side and obscure the field of view of the camera providing the live preview in user interface  5006 , and also to facilitate interaction with the augmented reality environment during single-handed operation by user  5004  while holding device  100  by its left side (e.g., while user  5004  holds device  100  with his/her left hand). 
       FIG.  5 D  illustrates an example of an error condition of the augmented reality environment. In particular,  FIG.  5 D  shows a view of physical space  5000  when there is insufficient light available for device  100  to recognize distinct physical objects and physical features in the field of view of the camera. Device  100  displays error message  5024  (e.g., with the text “Too dark” and “Turn on lights to detect surface”) in user interface  5006  to indicate the error condition and to prompt user  5004  to increase the amount of light in physical space  5000 . In some embodiments, while an error condition exists such that device  100  is unable to identify a physical object or feature in the field of view of the camera, device  100  ceases to display reticle  5010  and/or focus point  5012  to indicate the error condition. 
       FIG.  5 E  illustrates another example of an error condition of the augmented reality environment. In particular,  FIG.  5 E  shows a view of physical space  5000  when there is sufficient light available (e.g., user  5004  has turned on the lights in response to error message  5024 ), but device  100  does not detect a surface of a physical object in physical space  5000  that is in the field of view of the camera. Device  100  displays error message  5026  (e.g., with the text “Move device from side to side to detect surface”) in user interface  5006  to indicate the error condition and to prompt user  5004  to move device  100  from side to side (e.g., to facilitate image processing by device  100  to detect a physical surface that is in the field of view of the camera). Movement arrows  5028  indicate side-to-side movement of device  100  by user  5004  in response to error message  5026 . In some embodiments, error message  5026  is displayed when device  100  does not detect a surface of a physical object at the location over which focus point  5012  is displayed in the live preview. In some embodiments, a different error message is displayed if user  5004  moves device  100  too quickly for a surface of a physical object to be detected, to indicate the error condition and to prompt user  5004  to move device  100  more slowly. 
       FIG.  5 F  illustrates a view of physical space  5000  when device  100  has detected a surface of physical object in physical space  5000 . In particular, in  FIG.  5 F , device  100  has detected the top surface of table  5002  (e.g., based on the side-to-side movement of device  100 , as described above with respect to  FIG.  5 E , while focus point  5012  is positioned over the top surface of table  5002  in the live preview). In accordance with detecting a surface, device  100  displays reticle  5010  in user interface  5006 , in addition to focus point  5012 . In some embodiments, reticle  5010  is displayed whenever focus point  5012  is positioned over a region in the live preview that corresponds to a detected surface of a physical object in physical space  5000  (e.g., to indicate that the region in the live preview over which focus point  5012  is positioned corresponds to a detected surface). In some embodiments, reticle  5010  is tilted to appear to be co-planar with the detected surface, as illustrated in  FIG.  5 F , to indicate the surface that has been detected by the device. 
       FIG.  5 G  illustrates a transition from  FIG.  5 F . In  FIG.  5 G , user  5004  has moved device  100  such that focus point  5012  is positioned over a point in the live preview that does not correspond to a detected surface (e.g., focus point  5012  is no longer positioned over the detected top surface of table  5002  in the live preview). Accordingly, device  100  changes the appearance of reticle  5010  (e.g., by no longer tilting the reticle  5010 , by changing the reticle to a solid circle, and/or by ceasing to display the reticle), while continuing to display focus point  5012 . 
       FIG.  5 H  illustrates a transition from  FIG.  5 G . In  FIG.  5 H , user  5004  has moved device  100  such that focus point  5012  and at least part of reticle  5010  are repositioned over the detected top surface of table  5002  in the live preview. Device  100  has detected edge  5030  of table  5002  in the live preview (e.g., an edge of the detected top surface). Edge  5030  is at least partially within reticle  5010  (e.g., focus point  5012  is within a predefined threshold distance of edge  5030 , where the predefined threshold distance is at most the radius of reticle  5010 ). Accordingly, the visual appearances of reticle  5010  and focus point  5012  are changed. In particular, focus point  5012  has been moved (e.g., vertically downward) to, or “snapped” to, a point along edge  5030 . In addition, a size of reticle  5010  is reduced to indicate that focus point  5012  has snapped to a detected feature in the live preview. In some embodiments, reticle  5010  is displayed at the size shown in  FIG.  5 H  whenever focus point  5012  is snapped to a detected feature in the live preview. In some embodiments, the visual appearances of reticle  5010  and focus point  5012  are changed when focus point  5012  snaps to a detected feature in the live preview that corresponds to an edge or a corner of a physical object in the field of view of the camera. In some embodiments, the visual appearances of reticle  5010  and focus point  5012  are not changed when reticle  5010  and focus point  5012  are positioned over a detected feature in the live preview that corresponds to a surface of a physical object in the field of view of the camera (but not an edge or a corner). In some embodiments, in conjunction with moving focus point  5012  to edge  5030 , device  100  optionally generates tactile output  5032  (e.g., using tactile output generators  163 ,  FIG.  1 A ) to indicate that point  5012  has been “snapped” to a detected feature in the live preview of the camera. 
       FIG.  5 I  illustrates a transition from  FIG.  5 H . In  FIG.  5 I , user  5004  has moved device  100  such that no portion of edge  5030  is within reticle  5010 . Accordingly, focus point  5012  is snapped away from edge  5030  and is redisplayed at the center of reticle  5010  (e.g., because there is no longer any feature within reticle  5010  to which focus point  5012  should snap). In addition, the size of reticle  5010  is increased back to its size as shown in  FIG.  5 F , prior to focus point  5012  snapping to edge  5030 . In some embodiments, reticle  5010  is displayed at the size shown in  FIGS.  5 F and  5 I  by default, whenever focus point  5012  is not snapped to any detected feature in the live preview. In some embodiments, focus point  5012  is displayed at the center of reticle  5010  by default, whenever focus point  5012  is not snapped to any detected feature in the live preview. In some embodiments, as shown in  FIG.  5 I , device  100  optionally generates tactile output  5034  in conjunction with moving focus point  5012  away from edge  5030 , to indicate focus point  5012  is no longer snapped to a detected feature in the live preview of the camera. In some embodiments, tactile output  5034  differs from tactile output  5032  ( FIG.  5 H ) in at least one tactile output property (e.g., frequency, amplitude, and/or pattern), such that tactile output  5032  ( FIG.  5 H ), which indicates snapping to a detected feature, provides a different tactile feedback to user  5004  than tactile output  5034 , which indicates snapping away from a detected feature. 
       FIGS.  5 J- 5 O  illustrate creation of a measurement of the horizontal upper-left edge of table  5002 .  FIG.  5 J  illustrates a transition from  FIG.  5 I  In  FIG.  5 J , user  5004  has moved device  100  such that the upper-back-left corner of table  5002 , as displayed in the live preview, is within reticle  5010 . Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-back-left corner of table  5002  in the live preview. In some embodiments, focus point  5012  is maintained on the anchor point in the live preview as long as the upper-back-left corner of table  5002  in the live preview is within reticle  5010  (e.g., although device  100  may move slightly due to unintentional movements of user  5004 , such as unsteadiness of user  5004 &#39;s hands). The size of reticle  5010  is decreased to indicate the snapping behavior (e.g., to the same size shown in and described above with reference to  FIG.  5 H ). In addition, tactile output  5036  is generated to indicate the snapping behavior. 
       FIGS.  5 K- 5 L  illustrate a transition from  FIG.  5 J  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 K  illustrates activation of measurement addition button  5014  by touch input  5038  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5042  to user interface  5006  at a current location of focus point  5012 . In conjunction with adding measurement point  5042  to user interface  5006 , device  100  optionally generates tactile output  5044  to indicate the addition of a measurement point. In some embodiments, tactile output  5044  differs from tactile output  5032  ( FIG.  5 H ) and tactile output  5034  ( FIG.  5 I ) in at least one tactile output property (e.g., frequency, amplitude, and/or pattern), such that tactile output  5032  ( FIG.  5 H ) and tactile output  5034  ( FIG.  5 I ), which indicate snapping behavior, provide different tactile feedback to user  5004  than tactile output  5044 , which indicates the addition of a measurement point.  FIG.  5 L  illustrates liftoff of touch input  5038  from measurement addition button  5014 . 
       FIG.  5 M  illustrates a transition from  FIG.  5 L . In  FIG.  5 M , user  5004  has moved device  100  diagonally downward and toward the right such that reticle  5010  is positioned over a different location in physical space  5000  as displayed in the live preview. In particular, in  FIG.  5 M , reticle  5010  is positioned over the upper-front-left corner of table  5002  as displayed in the live preview. Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-front-left corner of table  5002  in the live preview. The size of reticle  5010  is decreased to indicate the snapping behavior (e.g., to the same size shown in and described above with reference to  FIG.  5 J ). Tactile output  5046  is generated to indicate the snapping behavior. In addition, measurement point  5042  continues to be displayed over the upper-back-left corner of table  5002  in the live preview (e.g., measurement point  5042  is associated with the upper-back-left corner of table  5002  and is displayed over that position in the live preview even while the position of the upper-back-left corner of table  5002  in the live preview changes as device  100  moves). 
     In response to the movement of device  100  such that reticle  5010  and focus point  5012  are positioned over a different location in physical space  5000 , measurement segment  5048  is displayed between measurement point  5042  (the most-recently-added measurement point) and focus point  5012 . Measurement segment  5048  is displayed with label  5049  that indicates a distance between the point in physical space  5000  corresponding to measurement point  5042  and the point in physical space  5000  corresponding to focus point  5012  (e.g., “3 ft”). Before the second endpoint of measurement segment  5048  is added, measurement segment  5048  is a dynamic measurement segment having a first endpoint that is measurement point  5042  and a second endpoint that is the current position of focus point  5012  (e.g., the length of measurement segment  5048  and the distance indicated by label  5049  corresponding to measurement segment  5048  are both updated in accordance with movement of device  100  that changes the point in physical space  5000  to which the current location of focus point  5012  corresponds). In addition, virtual guide  5050  is displayed along a feature in physical space  5000  that extends in the direction of movement of device  100  from the most-recently-added measurement point, measurement point  5042 . Specifically, virtual guide  5050  is displayed along the horizontal upper-left edge of table  5002  that extends diagonally downward and toward the right in the live preview. Note that the upper-left edge of table  5002 , and other edges of the top surface of table  5002 , are referred to herein as horizontal edges, because they are horizontal in physical space  5000  even though they may appear diagonal in the live preview, from the perspective of device  100 . 
       FIGS.  5 N- 5 O  illustrate a transition from  FIG.  5 M  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 N  illustrates activation of measurement addition button  5014  by touch input  5052  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5054  in user interface  5006  at a current location of focus point  5012  and as the second endpoint of measurement segment  5048 . In conjunction with adding measurement point  5054  to user interface  5006 , device  100  optionally generates tactile output  5056  to indicate the addition of a measurement point. In some embodiments, tactile output  5056  is the same type of tactile output as tactile output  5044  ( FIG.  5 K ), indicating the addition of a measurement point. In some embodiments, tactile output  5056  differs from tactile output  5044  ( FIG.  5 K ) in at least one tactile output property (e.g., frequency, amplitude, and/or pattern), such that tactile output  5056  provides different tactile feedback to user  5004  than tactile output  5044  ( FIG.  5 K ). In some such embodiments, tactile output  5044  ( FIG.  5 K ) indicates the addition of a measurement point that begins a new measurement segment, while tactile output  5056  indicates the addition of a measurement point that completes (e.g., ends) a measurement segment.  FIG.  5 O  illustrates liftoff of touch input  5052  from measurement addition button  5014 . After liftoff of touch input  5052 , device  100  continues to display measurement point  5042 , measurement point  5054 , measurement segment  5048  connecting measurement points  5042  and  5054  in user interface  5006 , and label  5049  (corresponding to a measurement of the horizontal upper-left edge of table  5002 ). In some embodiments, as shown in  FIG.  5 O , upon the completion of a measurement segment, device  100  ceases to display virtual guides such as virtual guide  5050 . 
       FIG.  5 P  illustrates a transition from  FIG.  5 O . In  FIG.  5 P , user  5004  has moved device  100  such that reticle  5010  is positioned over a side surface of table  5002  in the live preview that is adjacent to measurement segment  5048 . Device  100  has determined (e.g., based in part on measurement segment  5048 ) that the region over which reticle  5010  (or more specifically, focus point  5012 ) is positioned corresponds to a physical rectangular area in physical space  5000  (e.g., although the detected region appears trapezoidal in the live preview, from the perspective of device  100 ). Accordingly, device  100  displays indicator  5058  to indicate that the detected region corresponds to a physical rectangular area. In addition, device  100  continues to display measurement point  5042 , measurement point  5054 , measurement segment  5048 , and label  5049  over the horizontal upper-left edge of table  5002 . In some embodiments, measurement elements (e.g., measurement point  5042 , measurement  5054 , measurement segment  5048 , and label  5049 ) that are part of a virtual measurement are displayed in user interface  5006  whenever the physical object corresponding to the virtual measurement (e.g., the horizontal upper-left edge of table  5002 ) is visible in the live preview, until the corresponding virtual measurement is cleared. 
       FIG.  5 Q- 5 X  illustrate creation of a measurement of the vertical front-left edge of table  5002 .  FIG.  5 Q  illustrates a transition from  FIG.  5 P . In  FIG.  5 Q , user  5004  has moved device  100  such that reticle  5010  is repositioned over the upper-front-left corner of table  5002  as displayed in the live preview. Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-front-left corner of table  5002  in the live preview, and corresponding to measurement point  5054 . The size of reticle  5010  is decreased to indicate the snapping behavior (e.g., to the same size shown in and described above with reference to  FIG.  5 M ). Tactile output  5060  is generated to indicate the snapping behavior. Device  100  ceases to display indicator  5058  (e.g., because focus point  5012  has snapped to the anchor point corresponding to the upper-front-left corner of table  5002 , and is no longer displayed over the detected region in the live preview that corresponds to the physical rectangular area of the side surface of table  5002 ). 
       FIG.  5 R  illustrates a transition from  FIG.  5 Q  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 R  illustrates activation of measurement addition button  5014  by touch input  5062  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In some embodiments, as shown in  FIG.  5 R , in response to the activation of measurement addition button  5014 , device  100  uses measurement point  5054  as the starting point for a new measurement segment to be added. In some embodiments, in response to the activation of measurement addition button  5014 , device  100  adds and displays another (virtual) measurement point, at the same location as measurement point  5054 , as the starting point for a new measurement segment. In conjunction with establishing either of the aforementioned starting points for a new measurement segment, device  100  optionally generates tactile output  5064  to indicate the addition of a measurement point (and, in some embodiments, to indicate that the added measurement point begins a new measurement segment). 
       FIG.  58    illustrates a transition from  FIG.  5 R . In  FIG.  5 S , user  5004  has moved device  100  horizontally toward the right such that reticle  5010  is positioned over a location along the horizontal front edge of table  5002 , and such that the upper-front-left corner of table  5002  in the live preview is no longer within reticle  5010 . Accordingly, focus point  5012  is displayed on an anchor point corresponding to the horizontal front edge of table  5002  (e.g., at the midpoint of the portion of the front edge of table  5002  that is within reticle  5010 , which is the point along the portion of the front edge of table  5002  within reticle  5010  that is the shortest distance from the center of reticle  5010 ). Reticle  5010  is displayed at its decreased size (e.g., at the same size as in  FIG.  5 R ) to indicate that focus point  5012  is snapped to a detected feature in the live preview. In addition, measurement point  5054  continues to be displayed over the upper-front-left corner of table  5002  in the live preview, and dynamic measurement segment  5066  is displayed between measurement point  5054  and focus point  5012 . Label  5068  indicates a distance between the point in physical space  5000  corresponding to measurement point  5054  and the point in physical space  5000  corresponding to focus point  5012 . In addition, in response to the horizontal movement of device  100 , device  100  displays virtual guide  5070  extending horizontally from measurement point  5054 . 
     In some embodiments, as shown in  FIG.  5 S , a tactile output is not generated to indicate the snapping behavior. For example, while at least some portion of the horizontal front edge of table  5002  is been maintained within reticle  5010 , such that focus point  5012  has not snapped away from the horizontal front edge of table  5002  at any time during the movement of device  100 , although the particular anchor point to which focus point  5012  is snapped changes while device  100  moves, device  100  forgoes generating a tactile output so as to avoid continuous generation of tactile outputs as focus point  5012  moves along the detected edge. 
       FIG.  5 T  illustrates a transition from  FIG.  5 S . In  FIG.  5 T , the direction of movement of device  100  has changed from horizontally toward the right to vertically downward. In response to the change in direction of movement from horizontal movement to vertical movement, device  100  ceases to display (horizontal) virtual guide  5070  ( FIG.  5 S ) and instead displays (vertical) virtual guide  5072  extending vertically from measurement point  5054  in the direction of movement of device  100 . Focus point  5012  is snapped to an anchor point corresponding to vertical inner-left edge  5074  of table  5002 , and in some embodiments, as shown in  FIG.  5 T , device  100  generates tactile output  5076  to indicate the snapping behavior. Dynamic measurement segment  5066  is continually updated in accordance with the movement of device  100  so as to be displayed between measurement point  5054  and a current location of focus point  5012 . In addition, label  5068  is continually updated in accordance with the movement of device and the updating of dynamic measurement segment  5066  so that label  5068  is displayed at a midpoint of dynamic measurement segment  5066 . 
       FIG.  5 U  illustrates a transition from  FIG.  5 T  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 U  illustrates activation of measurement addition button  5014  by touch input  5078  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5080  to user interface  5006  at a current location of focus point  5012  and as the second endpoint of measurement segment  5066 , which becomes a completed measurement segment (e.g., whose second endpoint is now measurement point  5080  and no longer focus point  5012 ) rather than a dynamic measurement segment. In conjunction with adding measurement point  5080  to user interface  5006 , device  100  optionally generates tactile output  5082  indicating the addition of a measurement point (and optionally to indicate in particular the addition of a measurement point that completes a measurement segment, for example using the same type of tactile output as tactile output  5056 ,  FIG.  5 N ). In some embodiments, as shown in  FIG.  5 U , device  100  continues to display virtual guides such as virtual guide  5072  even after the completion of a measurement segment (e.g., until the device  100  is moved away from its current position). 
       FIG.  5 V  illustrates a transition from  FIG.  5 U  that includes performing an “undo” operation to reverse the most-recently-performed operation in user interface  5006 . In particular,  FIG.  5 V  illustrates activation of undo button  5018  by touch input  5084  to reverse the addition of measurement point  5080  ( FIG.  5 U ). Accordingly, measurement point  5080  is removed from user interface  5006 . Measurement segment  5066  is now (again) a dynamic measurement segment whose second endpoint is focus point  5012  and that is updated as focus point  5012  moves. 
       FIG.  5 W  illustrates a transition from  FIG.  5 V . In  FIG.  5 W , user  5004  has moved device  100  downward such that reticle  5010  is positioned over the lower-front-left corner of table  5002  as displayed in the live preview. Accordingly, focus point  5012  is snapped to the anchor point corresponding to the lower-front-left corner of table  5002  (and optionally also to virtual guide  5072 ). Reticle  5010  is displayed at its decreased size (e.g., at the same size as in  FIG.  5 U ) to indicate that focus point  5012  is snapped to a detected feature in the live preview. Tactile output  5086  is generated to indicate the snapping behavior. In  FIG.  5 X , device  100  has moved such that only a portion of measurement segment  5048  is displayed in user interface  5006 , because the upper-back-left corner of table  5002  is no longer visible in the live preview and thus only a portion of the horizontal upper-left edge of table  5002  is visible in the live preview. Accordingly, label  5049  is displayed at a midpoint of only the displayed portion of measurement segment  5048 , rather than at the midpoint of the entire measurement segment  5048  (e.g., as shown in  FIG.  5 V ). 
       FIG.  5 X  illustrates a transition from  FIG.  5 W  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 X  illustrates activation of measurement addition button  5014  by touch input  5088  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5090  to user interface  5006  at a current location of focus point  5012  and as the second endpoint of measurement segment  5066 , which becomes a completed measurement segment. In conjunction with adding measurement point  5090  to user interface  5006 , device  100  optionally generates tactile output  5092  to indicate the addition of a measurement point (and optionally to indicate the addition of a measurement point that completes a measurement segment, for example using the same type of tactile output as tactile output  5056 ,  FIG.  5 N , or tactile output  5082 ,  FIG.  5 U ). 
       FIGS.  5 Y- 5 AF  illustrate the creation of measurement regions corresponding to physical rectangular areas in physical space  5000  (e.g., surfaces of table  5002 ). In particular,  FIGS.  5 Y- 5 Z  illustrate the creation of a measurement region corresponding to a physical rectangular area that is displayed in its entirety in the live preview at one time.  FIG.  5 Y  illustrates a transition from  FIG.  5 X . In  FIG.  5 Y , user  5004  has moved device  100  from its position in  FIG.  5 X  such that reticle  5010  is positioned over the side surface of table  5002  in the live preview that is adjacent to both measurement segment  5048  and to measurement segment  5066 . Device  100  has determined that the region in the live preview over which reticle  5010  (or more specifically, focus point  5012 ) is positioned corresponds to a physical rectangular area in physical space  5000  (e.g., the determination is based in part on measurement segment  5048  and measurement segment  5066  being adjacent sides of the detected region). Accordingly, device  100  displays indicator  5094  to indicate that the detected region in the live preview over which focus point  5012  is positioned corresponds to a physical rectangular area. In addition, device  100  continues to display measurement segment  5048 , corresponding label  5049 , measurement segment  5066 , corresponding label  5068 , and endpoints  5042 ,  5054 , and  5090 .  FIG.  5 Y  is similar to  FIG.  5 P , except that  FIG.  5 Y  includes (a second) measurement segment  5066 , with endpoints  5054  and  5090  and label  5068 , in addition to (a first) measurement segment  5048 , with endpoints  5042  and  5054  and label  5049 . 
       FIG.  5 Z  illustrates a transition from  FIG.  5 Y  showing the addition of a measurement region to user interface  5006 . In particular,  FIG.  5 Z  illustrates activation of measurement addition button  5014 , while focus point  5012  is over the detected region indicated by indicator  5094 , by touch input  5096  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds a measurement corresponding to the detected region and changes the appearance of indicator  5094  to indicate that the detected region has been confirmed as a measurement region. In addition, device  100  displays label  5098  that indicates an area of the physical rectangular area corresponding to the confirmed region (e.g., “7.5 f t2 ”). Optionally, in some embodiments, label  5098  is displayed with indicator  5094  prior to the detected region being confirmed as a measurement region (e.g., in some embodiments, label  5098  is displayed with indicator  5094  in  FIG.  5 Y ). 
       FIG.  5 AA  illustrates a transition from  FIG.  5 Z . In  FIG.  5 AA , user  5004  has moved device  100  vertically upwards such that reticle  5010  is positioned over the horizontal upper-left edge of table  5002  in the live preview and measurement segment  5048 . In particular, the midpoint of measurement segment  5048  is within reticle  5010 . In some embodiments, as shown in  FIG.  5 AA , the midpoint of a respective measurement segment displayed in user interface  5006  can be an anchor point to which focus point  5012  snaps. Accordingly, in  FIG.  5 AA , focus point  5012  is snapped to the anchor point corresponding to the midpoint of measurement segment  5048  (and also corresponding to the midpoint of the horizontal upper-left edge of table  5002 ). The size of reticle  5010  is decreased to indicate the snapping behavior, as previously described. Tactile output  5100  is generated to indicate the snapping behavior. In addition, device  100  continues to display confirmed-region indicator  5094  over the detected region that corresponds to the physical rectangular area in physical space  5000  (e.g., confirmed-region indicator  5094  is associated with the detected region that corresponds to the physical rectangular area and is displayed over the detected region in the live preview even while the detected region moves in the live preview as device  100  moves). 
       FIG.  5 AB- 5 AE  illustrate creation of a measurement region corresponding to a physical rectangular area in physical space  5000  that is partially visible in the live preview but not visible in its entirety at one time (e.g., a physical rectangular area of which only three sides, in whole or in part, are visible in the live preview).  FIG.  5 AB  illustrates a transition from  FIG.  5 AA . In  FIG.  5 AB , user  5004  has moved device  100  horizontally toward the right such that reticle  5010  is positioned over a region in the live preview that is adjacent to measurement segment  5048  and that corresponds to a partial view of the top surface of table  5002 . In particular, the left edge of the top surface of table  5002  is visible, a portion of the front edge of the top surface of table  5002  is visible, and a portion of the back edge of the top surface of table  5002  is visible, whereas the right edge of the top surface of table  5002  is not visible. Focus point  5012  has snapped away from the anchor point corresponding to the midpoint of measurement segment  5048  and is redisplayed at the center of reticle  5010 . Reticle  5010  is redisplayed at its increased size, and tactile output  5102  is optionally generated in conjunction with focus point  5012  moving away from the anchor point. In addition, device  100  has determined (e.g., based in part on measurement segment  5048 ) that the region over which reticle  5010  (or more specifically, focus point  5012 ) is positioned corresponds to a portion of a physical rectangular area in physical space  5000  (e.g., although the detected region does not appear rectangular in the live preview, from the perspective of device  100 ). Accordingly, device  100  displays indicator  5104  to indicate that the detected region corresponds to a physical rectangular area. Optionally, in accordance with the movement of device  100 , virtual guides  5106  are displayed. Virtual guides  5106  extend horizontally and correspond to features in the live preview identified as extending horizontally, in the direction of movement of device  100 . In some embodiments, where multiple features extend in the direction of movement of device  100 , multiple virtual guides that extend in the direction of movement are displayed. In some embodiments, virtual guides that extend in the direction of movement are displayed only for features over which corresponding measurement points have already been added in user interface  5006 . 
       FIGS.  5 AC- 5 AD  illustrate further horizontal movement of device  100  while reticle  510  is positioned over the top surface of table  5002  in the live preview. In  FIG.  5 AC , a portion of the front edge and a portion of the back edge of the top surface of table  5002  are visible, whereas neither the left edge nor the right edge of the top surface of table  5002  are visible. In  FIG.  5 AD , the right edge of the top surface of table  5002  is now visible, in addition to a portion of the front edge and a portion of the back edge. Device  100  continues to display indicator  5104  over the visible portion of the top surface of table  5002  in the live preview as well as horizontal virtual guides in accordance with the horizontal movement of device  100 . 
       FIG.  5 AE  illustrates a transition from  FIG.  5 AD  showing the addition of a measurement region to user interface  5006 . In particular,  FIG.  5 AE  illustrates activation of measurement addition button  5014 , while focus point  5012  is over the detected region indicated by indicator  5104 , by touch input  5108  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds a measurement corresponding to the entire detected region, although only a portion of the detected region is visible, and changes the appearance of indicator  5104  to indicate that the detected region has been confirmed as a measurement region. In addition, device  100  displays label  5110 , label  5112 , and label  5114 . Label  5110  indicates an area of the (entire) physical rectangular area corresponding to the (entire) confirmed region. Label  5112  indicates a length of a first side of the physical rectangular area corresponding to the confirmed region (e.g., the right edge of the top surface of table  5002 ). Label  5114  indicates a length of a second side, adjacent to the first side, of the physical rectangular area corresponding to the confirmed region (e.g., the front edge of the top surface of table  5002 ). Optionally, in some embodiments, label  5114  is displayed with indicator  5104  prior to the detected region being confirmed as a measurement region (e.g., in some embodiments, label  5114  is displayed with indicator  5104  in  FIG.  5 AD ). 
       FIG.  5 AF  illustrates a transition from  FIG.  5 AE . In  FIG.  5 AF , user  5004  has moved device  100  horizontally toward the left so that the left portion of table  5002  is visible in the live preview. Indicator  5094 , measurement segment  5048 , and measurement segment  5066  (along with their associated labels) are displayed in user interface  5006  at their respective locations corresponding to respective features of table  5002  (e.g., the side surface, the horizontal upper-left edge, and the vertical front-left edge, respectively, of table  5002 ), even though device  100  previously moved away from a position at which these elements and the corresponding features of table  5002  were visible in user interface  5006  and has now been moved back to a position (such as that shown in  FIG.  5 AF ) at which these elements and the corresponding features of table  5002  are (again) visible in user interface  5006 . In addition, indicator  5104  (along with its associated labels) is displayed over the visible portion of the top surface of table  5002 , even though the detected region corresponding to the top surface of table  5002  was confirmed while device  100  displayed a different portion of the top surface of table  5002  that is not currently visible in user interface  5006 . 
       FIG.  5 AG  illustrates clearing from user interface  5006  all measurements displayed over the live preview of and corresponding to physical space  5000  (e.g., including measurements corresponding to physical objects not currently in the field of view of the camera). In  FIG.  5 AG , in response to activation of clear button  5022  by touch input  5116 , measurement segments  5048  and  5066 , measurement points  5042 ,  5054 , and  5090 , indicators  5094  and  5104 , and all corresponding labels are removed from user interface  506 . 
       FIGS.  5 AH- 5 AS  illustrate continuous creation of measurements based on changes in intensity of a continuous touch input. In particular,  FIGS.  5 AH- 5 AM  illustrate creation of a measurement of the horizontal upper-left edge of table  5002 .  FIG.  5 AH  optionally illustrates a transition from  FIG.  5 AG . In  FIG.  5 AH , user  5004  has moved device  100  such that the upper-back-left corner of table  5002 , as displayed in the live preview, is within reticle  5010 . Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-back-left corner of table  5002  in the live preview. Reticle  5010  is displayed at its decreased size to indicate the snapping behavior. In addition, tactile output  5118  is optionally generated to indicate the snapping behavior. 
       FIG.  5 AI  illustrates a transition from  FIG.  5 AH  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 AI  illustrates activation of measurement addition button  5014  by touch input  5120  (e.g., a light press gesture) with a contact intensity that is above light press intensity threshold IT L , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5122  to user interface  5006  at the current location of focus point  5012 . In conjunction with adding measurement point  5122  to user interface  5006 , and in response to the increase in contact intensity of touch input  5120  above light press intensity threshold IT L , device  100  optionally generates tactile output  5124  to indicate the addition of a measurement point. In some embodiments, as shown in  FIG.  5 AI , the size of measurement addition button  5014  is decreased as the contact intensity of touch input  5120  increases (e.g., measurement addition button  5014  is smaller in  FIG.  5 AI , when the contact intensity of touch input  5120  is above light press intensity threshold IT L , than in  FIG.  5 K , when the contact intensity of touch input  5038  is between minimum contact detection threshold IT 0  and light press intensity threshold IT L ). 
       FIG.  5 AJ  illustrates a transition from  FIG.  5 AI  showing that touch input  5120  is maintained on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  but that has decreased below light press intensity threshold IT L . In some embodiments, device  100  generates a tactile output upon detecting the decrease in the contact intensity of touch input  5120  below light press intensity threshold IT L  (e.g., tactile output  5124  is not generated in response to the increase in contact intensity of touch input  5120  above light press intensity threshold IT L , as shown in  FIG.  5 AI , but instead is generated in response to the decrease in contact intensity of touch input  5120  below light press intensity threshold IT L , as shown in  FIG.  5 AJ ). 
       FIG.  5 AK  illustrates a transition from  FIG.  5 AJ . In  FIG.  5 AK , user  5004  has moved device  100  diagonally downward and toward the right while maintaining touch input  5120  on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  and below light press intensity threshold IT L . Device  100  has been moved such that reticle  5010  is positioned over the upper-front-left corner of table  5002  as displayed in the live preview. Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-front-left corner of table  5002  in the live preview. Reticle  5010  is displayed at its decreased size to indicate the snapping behavior, and, optionally, tactile output  5126  is generated to indicate the snapping behavior. Measurement point  5122  continues to be displayed over the upper-back-left corner of table  5002  in the live preview, and dynamic measurement segment  5128  is displayed between the current position of focus point  5012  and measurement point  5122 . In addition, in accordance with the movement of device  100 , virtual guide  5130  is displayed, where virtual guide  5130  extends diagonally from measurement point  5122  and along the horizontal upper-left edge of table  5002  in user interface  5006 . 
       FIG.  5 AL  illustrates a transition from  FIG.  5 AK  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 AL  illustrates activation of measurement addition button  5014 , while touch input  5120  is maintained on measurement addition button  5014 , by an increase in the contact intensity of touch input  5120  to above light press intensity threshold IT L , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5132  to user interface  5006  at the current location of focus point  5012  and as the second endpoint of measurement segment  5128 . In conjunction with adding measurement point  5132  to user interface  5006 , and in response to the increase in contact intensity of touch input  5120  above light press intensity threshold IT L , device  100  optionally generates tactile output  5134  to indicate the addition of a measurement point. In some embodiments, as shown in  FIG.  5 AL  (and as previously described with reference to  FIG.  5 AI ), the size of measurement addition button  5014  is decreased as the contact intensity of touch input  5120  increases. Optionally, as shown in  FIG.  5 AL , upon the completion of measurement segment  5128 , device  100  ceases to display virtual guide  5130 . 
       FIG.  5 AM  illustrates a transition from  FIG.  5 AL  showing that touch input  5120  is maintained on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  but that has decreased below light press intensity threshold IT L . In some embodiments, device  100  generates a tactile output upon detecting the decrease in the contact intensity of touch input  5120  below light press intensity threshold IT L , as described herein with respect to  FIG.  5 AJ . 
       FIGS.  5 AN- 5 AR  illustrates a transition from  FIG.  5 AM  showing the addition of another measurement segment that is continuous with (e.g., has an endpoint in common with) measurement segment  5128 , using the same continuous touch input  5120 . In  FIG.  5 AN , user  5004  has moved device  100  diagonally upward and toward the right while maintaining touch input  5120  on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  and below light press intensity threshold IT L . Device  100  has been moved such that reticle  5010  is positioned over an area of the top surface of table  5002  that does not include any features to which focus point  5012  has snapped. Accordingly, focus point  5012  is displayed at the center of reticle  5010 , and reticle  5010  is displayed at its increased size. Measurement point  5122 , measurement segment  5128 , and measurement point  5132  continue to be displayed over the live preview, and dynamic measurement segment  5136  is displayed between the current position of focus point  5012  and measurement point  5122 . Because the live preview does not include any features that extend in the direction of movement of device  100 , no virtual guides are displayed. For example, the movement of device  100  is more than a predefined angle from horizontal, so virtual guides are not displayed for features in the live preview that extend horizontally; in addition, the movement of device  100  is more than a predefined angle from vertical, so virtual guides are not displayed for features in the live preview that extend vertically. 
       FIG.  5 AO  illustrates a transition from  FIG.  5 AN . In  FIG.  5 AO , user  5004  has moved device  100  horizontally toward the right while maintaining touch input  5120  on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  and below light press intensity threshold IT L . Device  100  has been moved such that measurement point  5122 , measurement segment  5128 , and measurement point  5132  are no longer displayed in user interface  5006  because the physical features to which they correspond are no longer within the live preview displayed in user interface  5006 . Dynamic measurement segment  5136  continues to be displayed extending from the current position of focus point  5012 . However, because measurement point  5132  (the other endpoint of dynamic measurement segment  5136 ) is no longer displayed in user interface  5006 , dynamic measurement segment  5136  extends only to the edge of user interface  5006  (e.g., toward a projected position of measurement point  5132 ). In addition, in accordance with the horizontal movement of device  100 , virtual guide  5138  is displayed, where virtual guide  5138  extends horizontally from (the projected position of) measurement point  5132  and along the horizontal front edge of table  5002  in user interface  5006 . 
       FIG.  5 AP  illustrates a transition from  FIG.  5 AO . In  FIG.  5 AP , user  5004  has moved device  100  toward the right and slightly downward while maintaining touch input  5120  on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  and below light press intensity threshold IT L . Device  100  has been moved such that virtual guide  5138 , corresponding to the horizontal front edge of table  5002  in the live preview, is at least partially within reticle  5010  (e.g., focus point  5012  is within a predefined distance (e.g., the predefined distance being the radius of reticle  5010 ) of virtual guide  5138  and the horizontal front edge of table  5002  in the live preview). Accordingly, focus point  5012  is snapped to virtual guide  5138  (e.g., to a point along virtual guide  5138  that is the shortest distance from the center of reticle  5010 ). Reticle  5010  is displayed at its decreased size, and, optionally, tactile output  5140  is generated, to indicate the snapping behavior. Dynamic measurement segment  5136  continues to be displayed extending from the current position of focus point  5012  to the edge of user interface  5006  (e.g., toward a projected position of measurement point  5132 ). In addition, in accordance with the continued movement of device  100  that is within a predefined angle of horizontal, horizontal virtual guide  5138  continues to be displayed along the front edge of table  5002  in user interface  5006 . 
       FIG.  5 AQ  illustrates a transition from  FIG.  5 AP . In  FIG.  5 AQ , user  5004  has moved device  100  horizontally toward the right while maintaining touch input  5120  on measurement addition button  5014  with a contact intensity that is above minimum contact detection threshold IT 0  and below light press intensity threshold IT L . Device  100  has been moved such that reticle  5010  is positioned over the upper-front-right corner of table  5002  as displayed in the live preview. Accordingly, focus point  5012  is snapped to the anchor point corresponding to the upper-front-right corner of table  5002  in the live preview. Reticle  5010  is displayed at its decreased size to indicate the snapping behavior. Dynamic measurement segment  5136  continues to be displayed extending from the current position of focus point  5012  to the edge of user interface  5006  (e.g., toward a projected position of measurement point  5132 ). In addition, in the sequence of  FIGS.  5 AN- 5 AQ , the label corresponding to measurement segment  5136  is updated to reflect the changes in the length of the measurement represented by dynamic measurement segment  5136  as device  100  is moved. In addition, in accordance with the continued horizontal movement of device  100 , horizontal virtual guide  5138  continues to be displayed along the front edge of table  5002  in user interface  5006 . 
       FIGS.  5 AR- 5 AS  illustrate a transition from  FIG.  5 AQ  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 AR  illustrates activation of measurement addition button  5014 , while touch input  5120  is maintained on measurement addition button  5014 , by an increase in the contact intensity of touch input  5120  to above light press intensity threshold IT L , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays (virtual) measurement point  5142  to user interface  5006  at the current location of focus point  5012  and as the second endpoint of measurement segment  5136 . In conjunction with adding measurement point  5142  to user interface  5006 , and in response to the increase in contact intensity of touch input  5120  above light press intensity threshold IT L , device  100  optionally generates tactile output  5144  to indicate the addition of a measurement point. In addition, the size of measurement addition button  5014  is (optionally) decreased as the contact intensity of touch input  5120  increases. Optionally, as shown in  FIG.  5 AR , device  100  continues to display virtual guide  5138  even after the completion of measurement segment  5136 . 
       FIG.  5 AS  illustrates liftoff of touch input  5120  from measurement addition button  5014 . In some embodiments, after the liftoff of touch input  5120  from measurement addition button  5014  (and before any subsequent touch inputs are detected), further movement of device  100  will not result in display of a new dynamic measurement segment that extends from measurement point  5142  (e.g., and that is continuous with measurement segment  5136 ). That is, the liftoff of continuous touch input  5120  ends the continuous creation of new measurement segments based on touch input  5120 . 
     In some embodiments, the device responds differently to a series of tap gestures (where contact is not maintained with the touch-sensitive surface) than to a series of pressing gestures (where contact is maintained with the touch-sensitive surface). For inputs that are discrete tap gestures (rather than pressing gestures made with a single continuously detected contact), measurement segments are not continuously created with each subsequently added measurement point. That is, for a series of tap gestures, if a user drops four points in succession, a measurement segment will be created between the first point and second point, and another measurement segment will be created between the third point and the fourth point, but a measurement segment will not be created between the second point and the third point. 
       FIG.  5 AT  illustrates a transition from  FIG.  5 AS . In  FIG.  5 AT , device  100  has been moved such that reticle  5010  is positioned over the upper-front-left corner of table  5002  as displayed in the live preview and over measurement point  5132 . Accordingly, focus point  5012  is snapped to measurement point  5132 , at the anchor point corresponding to the upper-front-left corner of table  5002  in the live preview. Reticle  5010  is displayed at its decreased size to indicate the snapping behavior. Measurement segment  5128  and measurement segment  5136  are displayed in user interface  5006  at their respective locations corresponding to respective features of table  5002  (e.g., the horizontal upper-left edge and the horizontal front edge, respectively, of table  5002 ), in accordance with the corresponding features of table  5002  being displayed (again) in the live preview in user interface  5006 . Measurement segment  5128  is displayed between its endpoints, measurement point  5122  and measurement point  5132 . Measurement segment  5136  is displayed extending from measurement point  5132  (one endpoint of measurement segment  5136 ) to the edge of user interface  5006  (e.g., toward a projected position of measurement point  5142 , which is the other endpoint of measurement segment  5136 , and which is not currently visible in user interface  5006 ). In addition, in accordance with reticle  5010  being positioned over measurement point  5132 , virtual guides  5146 ,  5148 , and  5150  extending from measurement point  5132  are displayed. Virtual guide  5146  extends in an x-direction (e.g., horizontally along the horizontal front edge of table  5002 ) from measurement point  5132 . Virtual guide  5148  extends in a y-direction (e.g., vertically along the vertical front-left edge of table  5002 ) from measurement point  5132 . Virtual guide  5150  extends in a z-direction (e.g., horizontally along the horizontal upper-left edge of table  5002 ) from measurement point  5132 . 
       FIGS.  5 AU- 5 AX  illustrate a transition from  FIG.  5 AT  showing the addition of a measurement segment to user interface  5006 .  FIG.  5 AU  illustrates activation of measurement addition button  5014  by touch input  5152  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  uses measurement point  5132  as the starting point for a new measurement segment to be added and, optionally, generates tactile output  5154  to indicate the beginning of a new measurement segment. 
       FIG.  5 AV  illustrates that (after liftoff of touch input  5152 ) user  5004  has moved device  100  downward along the vertical front-left edge of table  5002 . Focus point  5012  is snapped to an anchor point along the vertical front-left edge of table  5002  that is not the lower-front-left corner of table  5002 . Reticle  5010  is displayed at its decreased size to indicate the snapping behavior. Also, in accordance with the vertical movement, device  100  continues to display virtual guide  5148 , which extends vertically from measurement point  5132 , and has ceased to display virtual guides  5146  and  5150 , which do not extend vertically (or in a direction that is within a predefined angle of vertical) from measurement point  5132 . In addition, dynamic measurement segment  5156  is displayed between measurement point  5132  and the current position of focus point  5012 . 
       FIG.  5 AW  illustrates activation of measurement addition button  5014  by touch input  5158  (e.g., a tap gesture) with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to the activation of measurement addition button  5014 , device  100  adds and displays measurement point  5160  to user interface  5006  at the current location of focus point  5012  and as the second endpoint of measurement segment  5156 , which becomes a completed measurement segment. In conjunction with adding measurement point  5160  to user interface  5006 , device  100  optionally generates tactile output  5162  (e.g., to indicate the completion of a measurement segment).  FIG.  5 AX  illustrates liftoff of touch input  5158  from measurement addition button  5014 . 
       FIGS.  5 AY- 5 BE  illustrate example zoom interactions with the augmented reality environment in user interface  5006 . In particular,  FIG.  5 AY- 5 BA  illustrate zoom-assisted repositioning of a displayed measurement point.  FIG.  5 AY  illustrates touch input  5164  detected on measurement point  5160  with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 . In response to detecting touch input  5164  on measurement point  5160 , device  100  enlarges, or zooms into, a portion of the live preview that includes measurement point  5160  (e.g., the portion of the live preview that is centered on measurement point  5160 ). An amount of zoom of the live preview is based on the distance between device  100  and the point on table  5002  to which measurement point  5160  corresponds (e.g., a point on table  5002  just above the lower-front-left corner of table  5002 ). For example, in  FIG.  5 AY , when device  100  is a distance d 1  from the point on table  5002  to which measurement point  5160  corresponds, the live preview is enlarged by a zoom factor of 4×. 
       FIG.  5 AZ  illustrates a transition from  FIG.  5 AY  showing movement of touch input  5164  across touch screen  112  (e.g., a pan gesture or a drag gesture by the contact in touch input  5164 ) such that touch input  5164  is over an anchor point corresponding to the lower-front-left corner of table  5002 . Measurement point  5160  moves in user interface  5006  with the movement of touch input  5164  across touch screen  112 . In some embodiments, as shown in  FIG.  5 AZ , measurement point  5160  is snapped to the anchor point over which touch input  5164  has moved. Accordingly, measurement point  5160  is displayed at the anchor point corresponding to the lower-front-left corner of table  5002 . In conjunction with the movement of measurement point  5160 , measurement segment  5156  is extended and its label is updated accordingly (to indicate a length of the vertical front-left edge of table  5002 ). In addition, device  100  optionally generates tactile output  5166  to indicate the snapping behavior. 
     In some embodiments, device  100  determines a vector from the position of the camera to the location on a detected surface in physical space  5000  over which a measurement point is displayed. In some embodiments, device  100  determines an angle between the determined vector and the detected surface. In some embodiments, in accordance with a determination that the determined vector is within a predefined threshold angle of the detected surface (e.g., the determined angle is less than a predefined threshold angle, such as 15, 18, 20, 25, or 30 degrees), when receiving a set of one or more user inputs to move the measurement point, the measurement point is moved through locations in user interface  5006  that correspond to locations along the determined vector. 
       FIG.  5 BA  illustrates a transition from  FIG.  5 AZ . In some embodiments, as shown in  FIG.  5 BA , upon liftoff of touch input  5164 , device  100  ceases to display the enlarged (portion of the) live preview and redisplays the live preview without zoom. In some embodiments, after liftoff of touch input  5164 , device  100  continues to display the enlarged live preview until a subsequent input (to exit the zoomed live preview and return to the live preview displayed without zoom) is detected. 
     Because device  100  was maintained in the same position in  FIGS.  5 AX- 5 AZ , reticle  5010  is displayed in  FIG.  5 BA  at the same size and at the same position as it was in  FIG.  5 AX  (prior to the zoom-assisted repositioning of measurement point  5160 ). Because measurement point  5160  was repositioned to the anchor point corresponding to the lower-front-left corner of table  5002  as described with respect to  FIGS.  5 AY- 5 AZ , measurement point  5160  is displayed at that anchor point in the live preview that is displayed without zoom in  FIG.  5 BA , outside of reticle  5010 . Extended measurement segment  5156  and its corresponding updated label are also displayed. 
       FIG.  5 BB- 5 BC  illustrate another example zoom interaction.  FIG.  5 BB  is similar to  FIG.  5 AX , except that device  100  is positioned closer to table  5002  (or, more specifically, to the point on table  5002  to which measurement point  5160  corresponds) in  FIG.  5 BB  than in  FIG.  5 AX  (as indicated by the side view of user  5004 , device  100 , and table  5002  in  FIG.  5 AY ), at a distance d 2  that is less than the distance d 1  in  FIG.  5 AY . Accordingly, in response to detecting touch input  5168  on measurement point  5160 , as shown in  FIG.  5 BC , device  100  zooms into a portion of the live preview that includes measurement point  5160 . The amount of zoom of the live preview in  FIG.  5 BC  is based on the lesser distance d 2  between device  100  and table  5002 , and thus the amount of zoom of the live preview in  FIG.  5 BC , corresponding to a zoom factor of 2×, is less than the amount of zoom in  FIG.  5 AY , which corresponds to a zoom factor of 4×. In addition, because device  100  is closer to table  5002  in  FIG.  5 BB  than in  FIG.  5 AX , scale markers are displayed at one-foot intervals along measurement segment  5156  (e.g., as opposed to no scale markers being displayed in  FIG.  5 AX ). Also, because device  100  is closer to table  5002  in  FIG.  5 BB  than in  FIG.  5 AX , the size of the labels corresponding to the displayed measurements is larger in  FIG.  5 BB  than in  FIG.  5 AX . 
       FIG.  5 BD- 5 BE  illustrate another example zoom interaction.  FIG.  5 BD  is similar to  FIG.  5 BB , except that device  100  is positioned closer to table  5002  (or, more specifically, to the point on table  5002  to which measurement point  5160  corresponds) in  FIG.  5 BD  than in  FIG.  5 BB , at a distance d 3  that is less than the distance d 2  in  FIG.  5 BB . Accordingly, in response to detecting touch input  5170  on measurement point  5160 , as shown in  FIG.  5 BE , device  100  zooms into a portion of the live preview that includes measurement point  5160 . The amount of zoom of the live preview in  FIG.  5 BE  is based on the lesser distance d 3  between device  100  and table  5002 , and thus the amount of zoom of the live preview in  FIG.  5 BE , corresponding to a zoom factor of 1.5×, is less than the amount of zoom in  FIG.  5 BC , which corresponds to a zoom factor of 2×. In addition, because device  100  is closer to table  5002  in  FIG.  5 BD  than in  FIG.  5 BD , scale markers are displayed at one-inch intervals along measurement segment  5156  (e.g., as opposed to the scale markers displayed at one-foot intervals in  FIG.  5 BB ). Also, because device  100  is closer to table  5002  in  FIG.  5 BD  than in  FIG.  5 BB , the size of the labels corresponding to the displayed measurements is larger in  FIG.  5 BD  than in  FIG.  5 BB . In some embodiments, the scale at which markers are displayed along a measurement segment becomes finer as the distance between device  100  and the physical feature corresponding to the measurement segment decreases (e.g., at distances above a first distance, no scale markers are displayed; at distances between the first distance and a second distance (shorter than the first distance), scale markers are displayed at one-foot intervals; at distances between the second distance and a third distance (shorter than the second distance), scale markers are displayed at one-inch intervals; at distances shorter than the third distance, scale markers are displayed at quarter-inch intervals, and so on). 
     In some embodiments, the amount of zoom displayed in  FIG.  5 AY  is a maximum amount of zoom, such that when the distance between device  100  and table  5002  (or the point on table  5002  to which the displayed measurement point corresponds) is greater than the distance d 1  shown in  FIG.  5 AY , the amount of zoom of the live preview still corresponds to a zoom factor of 4×. In some embodiments, the amount of zoom displayed in  FIG.  5 BE  is a minimum amount of zoom, such that when the distance between device  100  and table  5002  (or the point on table  5002  to which the displayed measurement point corresponds) is less than the distance d 3  shown in  FIG.  5 BE , the amount of zoom of the live preview still corresponds to a zoom factor of 1.5×. 
     Similarly, in some embodiments, the size of the labels displayed in  FIG.  5 AY  is a minimum label size, such that when the distance between device  100  and table  5002  (or the point on table  5002  to which the displayed measurement point corresponds) is greater than the distance d 1  shown in  FIG.  5 AY , the size of the labels is the same as in  FIG.  5 AY . In some embodiments, the size of the labels displayed in  FIG.  5 BE  is a maximum label size, such that when the distance between device  100  and table  5002  (or the point on table  5002  to which the displayed measurement point corresponds) is less than the distance d 3  shown in  FIG.  5 BE , the size of the labels is the same as in  FIG.  5 BE . 
       FIG.  5 BF- 5 BK  illustrate capturing images of the augmented reality environment in user interface  5006 .  FIG.  5 BF  optionally illustrates a transition from  FIG.  5 BA . In  FIG.  5 BF , user  5004  has positioned device  100  such that measurement segments  5128 ,  5136 , and  5156 , and their corresponding endpoints and labels, are displayed in user interface  5006 , the corresponding features of table  5002  being visible in the live preview.  FIG.  5 BG  illustrates activation of media capture button  5016  by touch input  5172 , as indicated by the increase in intensity shown in intensity graph  5180 , which shows the contact intensity of touch input  5172  over time. 
       FIG.  5 BH  illustrates a transition from  FIG.  5 BG  based on liftoff of touch input  5172  before a predefined threshold time Tin (e.g., touch input  5172  is a tap gesture). Accordingly, intensity graph  5180  shows a corresponding decrease in the contact intensity of touch input  5172  to zero before time Tin. In response to detecting liftoff of touch input  5172  before the predefined threshold time Tin, device  100  captures image  5174  of the augmented reality environment. Captured image  5174  is a still image that includes an image of the field of view of the camera, corresponding to an instantaneous snapshot of the live preview, and measurement segments  5128 ,  5136 , and  5156 , along with their corresponding endpoints and labels, superimposed on the image of the field of view of the camera. In some embodiments, as shown in  FIG.  5 BH , captured image  5174  does not include images of the buttons/controls in user interface  5006 . 
       FIG.  5 BI  illustrates capture of an image in response to activation of media capture button  5016  while device  100  is at a different position relative to table  5002  (facing the left side surface of table  5002 ) such that a different perspective view of table  5002  is displayed in the live preview. In response to activation of media capture button  5016  by a touch input and liftoff of the touch input before the predefined threshold time T th , as indicated by intensity graph  5180 , device  100  captures image  5176  of the augmented reality environment. Captured image  5176  is a still image that includes an image of table  5002  from the perspective of device  100  at its position in  FIG.  5 BI  (e.g., facing the left side surface of table  5002 ). Measurement segments  5128 ,  5136 , and  5156  and their corresponding endpoints and labels are superimposed on the corresponding features of table  5002  in captured image  5176  based on the perspective of device  100  in  FIG.  5 BI . 
       FIG.  5 BJ  illustrates an alternate transition from  FIG.  5 BG . Together with  FIG.  5 BG ,  FIGS.  5 BJ- 5 BK  illustrate capture of a video of the augmented reality environment in response to a touch input maintained on media capture button  5016  (e.g., a long-press gesture). In  FIG.  5 BJ , touch input  5172  is maintained on media capture button  5016  past the predefined threshold time T th , as indicated by intensity graph  5180 . Accordingly, device  100  captures video of the field of view of the camera. Timer  5178  is displayed in user interface  5006  and indicates a current length of the captured video. In addition, the captured video includes any measurements in the field of view of the camera (e.g., measurement segments  5128 ,  5136 , and  5156 , and their corresponding endpoints and labels, are superimposed on the corresponding features of table  5002  in the captured video). In some embodiments, the captured video does not include images of the buttons/controls in user interface  5006 . 
       FIG.  5 BK  illustrates that device  100  has moved while touch input  5172  is maintained on media capture button  5016 . Accordingly, device  100  has continued to capture video of the field of view of the camera as device  100  moved, as indicated by the current video length shown by timer  5178  in  FIG.  5 BK  being longer than that shown by timer  5178  in  FIG.  5 BJ . The captured video includes additional portions of measurement segment  5136  superimposed over corresponding features in the field of view of the camera as device  100  moves to its position as shown in  FIG.  5 BK . 
       FIGS.  5 BL- 5 BM  illustrate displaying additional information about a selected measurement and options for sharing the information to another application, process, or device.  FIG.  5 BL  illustrates touch input  5182  (e.g., a tap gesture by a contact in the touch input) detected on measurement segment  5156  with a contact intensity that is above a minimum contact detection threshold IT 0 , as indicated by intensity meter  5040 .  FIG.  5 BM  illustrates that, in response to detecting touch input  5182  on measurement segment  5156 , device  100  displays measurement management interface  5184 . Measurement management interface  5184  includes a label that describes the physical object, table  5002 , to which measurement  5156  corresponds. For example, measurement management interface  5184  includes label  5186 - a  classifying table  5002  (e.g., identifying table  5002  as a “Table”). Measurement management interface  5184  also includes label  5186 - b  classifying the relationship between measurement  5156  and table  5002  (e.g., identifying measurement  5156  as a “height” of table  5002 ). In some embodiments, the relationship between measurement  5156  and table  5002  is classified as a “height” based on the vertical movement of device  100  while adding measurement  5156  to user interface  5006 . 
     In some embodiments, in response to touch input  5182 , information about measurement  5156  (e.g., the classification of the physical object to which measurement  5156  corresponds and the relationship between measurement  5156  and the physical object, a magnitude of measurement  5156  such as length or area, an image of measurement  5156 , etc.) is copied to a clipboard process executing on device  100 . In some embodiments, measurement management interface includes a plurality of destinations to which information about selected measurement  5156  can be transmitted (e.g., icon  5192  corresponding to e-mail client module  140  ( FIG.  1 A ), icon  5194  corresponding to IM module  141  ( FIG.  1 A ), and icon  5196  corresponding to a file transfer protocol between electronic devices). In some embodiments, measurement management interface  5184  is displayed in response to touch input  5182  satisfying an intensity threshold (e.g., light press intensity threshold IT L ) that is above minimum contact detection threshold IT 0  (e.g., in response to touch input  5182  being a light press or deep press gesture). 
       FIG.  5 BN  illustrates an example control center user interface  5188  that includes augmented reality measurement application icon  5190 . Activation of augmented reality measurement application icon  5190  launches the augmented reality measurement application and displays user interface  5006  (e.g., as described with reference to  FIG.  5 A ). 
       FIG.  5 BO  illustrates a context in which user interfaces described with respect to  FIGS.  5 BO- 5 CO  are used.  FIG.  5 BO  is similar to  FIG.  5 A  in that  FIG.  5 BO  illustrates a view of physical space  5000  that includes device  100 , except that physical space  5000  includes table  5200  on which object  5202  is placed (instead of table  5002 ). Object  5202  is in the field of view of the camera(s) of device  100  and is visible in the live preview of physical space  5000  displayed in user interface  5006  on device  100 . In some embodiments, as shown in  FIG.  5 BO , reticle  5010  in user interface  5006  is tilted to appear to be co-planar with the top surface of table  5200  to indicate the surface that has been detected and that corresponds to the current location of focus point  5012 . 
       FIGS.  5 BP- 5 BQ  illustrate a first way of adding a virtual measurement point to user interface  5006 , in accordance with some embodiments.  FIG.  5 BP  shows touch input  5204  on reticle  5010 . In accordance with some embodiments,  FIG.  5 BP  shows that, in response to touch input  5204 , device  100  adds and displays virtual measurement point  5206  to user interface  5006  at a current location of focus point  5012  (as shown in  FIG.  5 BO ).  FIG.  5 BQ  shows measurement point  5206  displayed at the same location as in  FIG.  5 BP  after liftoff of touch input  5204 . 
       FIGS.  5 BR- 5 B  S illustrate an alternate way of adding a virtual measurement point to user interface  5006 , in accordance with some embodiments.  FIG.  5 BR  shows touch input  5204  on reticle  5010 . In contrast to  FIG.  5 BP ,  FIG.  5 BR  shows that, in response to touch input  5204 , device  100  forgoes adding and displaying a virtual measurement point at the location of focus point  5012 . Instead, in  FIG.  5 BR , device  100  displays instruction message  5208  to prompt user  5004  to tap on measurement addition button  5014  (instead of tapping on reticle  5010 ) to add a measurement point.  FIG.  5 B  S illustrates activation of measurement addition button  5014  by touch input  5210 . In response to touch input  5210 , device  100  adds virtual measurement point  5206  to user interface  5006  at a current location of focus point  5012  (as shown in  FIG.  5 BQ ). 
       FIG.  5 BT- 5 BU  illustrate the creation of a measurement corresponding to object  5202  following the addition of measurement point  5206  (e.g., in either  FIG.  5 BQ  or  FIG.  5 BS ). In  FIG.  5 BT , user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a different location in physical space  5000 . Specifically, in  FIG.  5 BT , reticle  5010  and focus point  5012  are positioned over an edge of object  5202  (as displayed in the live preview) that is closer to device  100  than the edge over which reticle  5010  and focus point  5012  were positioned in  FIG.  5 BO . Accordingly, reticle  5010  is displayed at an increased size in  FIG.  5 BT  relative to its size in  FIG.  5 BO , and focus point  5012  is displayed at an increased size in  FIG.  5 BT  relative to its size in  FIG.  5 BO . In some embodiments, the size at which reticle  5010  is displayed is based on a distance between device  100  and the location in physical space  5000  over which reticle  5010  is displayed, optionally subject to a predefined minimum size (used for distances greater than a predefined maximum distance) and a predefined maximum size (used for distances less than a predefined minimum distance). Similarly, in some embodiments, the size at which focus point  5012  is displayed is based on a distance between device  100  and the location in physical space  5000  over which focus point  5012  is displayed, optionally subject to a predefined minimum size and a predefined maximum size. In addition, in accordance with the movement of device  100  such that reticle  5010  and focus point  5012  are positioned over a different location in physical space  5000 , (dynamic) measurement segment  5212 , indicated by a dashed line, is displayed between measurement point  5206  (the most-recently-added measurement point) and focus point  5012 . Measurement segment  5212  is displayed with an associated (dynamic) label that indicates a distance in physical space  5000  across which measurement segment  5212  appears to extend in user interface  5006 . 
       FIG.  5 BU  illustrates activation of measurement addition button  5014  by touch input  5214  (e.g., a tap gesture). In response to the activation of measurement addition button  5014 , device  100  adds and displays measurement point  5216  in user interface  5006  at a current location of focus point  5012  (as shown in  FIG.  5 BT ) and as the second endpoint of measurement segment  5212 . In accordance with the completion of measurement segment  5212 , the appearance of measurement segment  5212  is changed. In the example shown in  FIG.  5 BU , measurement segment  5212  is changed from a dashed line to a solid line. Because measurement point  5216  is positioned over an edge of object  5202  that is closer to device  100  than the edge of object  5202  over which measurement point  5206  is displayed, measurement point  5216  is displayed at an increased size relative to measurement point  5206 . 
       FIG.  5 BV- 5 BY  illustrate creation of a measurement corresponding to object  5202  that causes a prior measurement to be removed, in accordance with some embodiments.  FIG.  5 BV  illustrates a transition from  FIG.  5 BU . In  FIG.  5 BV , user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a different location in physical space  5000  than in  FIG.  5 BU . Specifically, in  FIG.  5 BV , reticle  5010  and focus point  5012  are positioned over a first corner of object  5202 . In some embodiments, as shown in  FIG.  5 BV , in accordance with reticle  5010  and focus point  5012  being moved away from measurement segment  5212 , device  100  ceases to display the label (“17 in”) associated with measurement segment  5212 . 
       FIG.  5 BW  illustrates a transition from  FIG.  5 BV  showing the addition of a measurement point to user interface  5006 . In particular,  FIG.  5 BW  illustrates activation of measurement addition button  5014  by touch input  5218 . In response, device  100  adds measurement point  5220  to user interface  5006  at the current location of focus point  5012  (as shown in  FIG.  5 BV ). In addition, in accordance with the addition of a new measurement point away from previously-created measurement segment  5212 , device  100  changes the appearance of measurement segment  5212  (e.g., to indicate that creating a measurement segment that is disconnected from measurement segment  5212  will cause measurement segment  5212  to be removed from user interface  5006 ). In the example shown in  FIG.  5 BW , measurement segment  5212  is changed from a solid line to a dashed line, and the color (and/or transparency) of measurement segment  5212  and its endpoints is changed. 
       FIG.  5 BX  illustrates a transition from  FIG.  5 BW  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a second corner of object  5202 . Accordingly, (dynamic) measurement segment  5222 , indicated by a dashed line, is displayed between measurement point  5206  (the most-recently-added measurement point) and focus point  5012 . Measurement segment  5222  is displayed with an associated (dynamic) label (e.g., “17 in”) that indicates a distance in physical space  5000  (e.g., along object  5202 ) across which measurement segment  5222  appears to extend in user interface  5006 . 
       FIG.  5 BY  illustrates a transition from  FIG.  5 BX  showing the addition of measurement point  5224  to user interface  5006  in response to activation of measurement addition button  5014  by touch input  5226 .  FIG.  5 BY  illustrates that measurement point  5224  has been added at a current location of focus point  5012  (as shown in Figure BX) as the second endpoint of measurement segment  5222 . Because measurement point  5224  is positioned over a location on object  5202  that is further from device  100  than the location on object  5202  over which measurement point  5220  is displayed, measurement point  5224  is displayed at a decreased size relative to measurement point  5220 . In accordance with the completion of measurement segment  5222 , the appearance of measurement segment  5222  is changed from a dashed line to a solid line. In addition, in accordance with the completion of measurement segment  5222 , and in accordance with measurement segment  5222  being disconnected from previously-placed measurement segment  5212 , device  100  ceases to display measurement segment  5212 . In some embodiments, measurement segment  5212  ceases to be displayed in accordance with a determination that measurement segment  5222  is at least a predefined threshold distance away from measurement segment  5212  (e.g., no point on measurement segment  5212  is within the predefined threshold distance of any point on measurement segment  5222 ). 
       FIGS.  5 BZ- 5 CF  illustrate creation of a measurement corresponding to object  5202  that connects to a prior measurement such that the prior measurement continues to be displayed, in accordance with some embodiments.  FIG.  5 BZ  illustrates a transition from  FIG.  5 BY  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a third corner of object  5202 . In some embodiments, as shown in  FIG.  5 BZ , even though reticle  5010  and focus point  5012  have been moved away from measurement segment  5222 , device  100  continues to display the label associated with measurement segment  5222  (in contrast to  FIG.  5 BV , which illustrates embodiments in which device  100  ceases to display the label associated with measurement segment  5212  when reticle  5010  and focus point  5012  are moved away from the measurement segment). 
       FIG.  5 CA  illustrates a transition from  FIG.  5 BZ  showing the addition of measurement point  5228  to user interface  5006  at a current location of focus point  5012  (as shown in  FIG.  5 BZ ) in response to activation of measurement addition button  5014  by touch input  5230 . In accordance with measurement point  5228  being added at a location in user interface  5006  that is away from previously-created measurement segment  5222 , device  100  changes the appearance of measurement segment  5222  (e.g., to indicate that creating a measurement segment that is disconnected from measurement segment  5222  will cause measurement segment  5222  to be removed from user interface  5006 ). In the example shown in  FIG.  5 CA , measurement segment  5222  is changed from a solid line to a dashed line, and the color (and/or transparency) of measurement segment  5222  is changed. 
       FIG.  5 CB  illustrates a transition from  FIG.  5 BZ  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned away from the third corner of object  5202 . Accordingly, (dynamic) measurement segment  5232 , indicated by a dashed line, is displayed between measurement point  5228  and focus point  5012 . Measurement segment  5232  is displayed with an associated (dynamic) label that indicates the distance along object  5202  across which measurement segment  5222  appears to extend in user interface  5006  (e.g., “8 in”). 
       FIG.  5 CC  illustrates a transition from  FIG.  5 CB  showing that user  5004  has moved device  100  such that the midpoint of measurement segment  5222  is within reticle  5010 . In some embodiments, as shown in  FIG.  5 CC , the midpoint of a respective measurement segment displayed in user interface  5006  can be an anchor point to which focus point  5012  snaps. Accordingly, in  FIG.  5 CC , focus point  5012  is snapped to the anchor point corresponding to the midpoint of measurement segment  5222 . To indicate the snapping behavior, focus point  5012  is displayed at an increased size relative to the size of focus point  5012  when focus point  5012  is not snapped to an anchor point (e.g., as shown in  FIG.  5 CB ). In some embodiments, as shown in  FIG.  5 CC , the size of reticle  5010  is not changed when the focus point is snapped to an anchor point. In some embodiments, the size of focus point  5012  when snapped to an anchor point is greater than the predefined maximum size of focus point  5012  that is used for changing the size of focus point  5012  based on the distance between device  100  and the location in physical space  5000  over which focus point  5012  is displayed (e.g., as described herein with respect to  FIG.  5 BT ). In addition, because focus point  5012  is snapped to a point along measurement segment  5222 , the appearance of measurement segment  5222  is changed to indicate that adding a measurement point at the current location of focus point  5012  will result in measurement segment  5222  continuing to be displayed instead of being removed. Specifically, measurement segment  5222  is changed from a dashed line (back) to a solid line, and the color (and/or transparency) of measurement segment  5222  is changed, such that measurement segment  5222  is redisplayed with its appearance as shown in  FIG.  5 BZ  (before measurement point  5228  was added). In addition, the length of dynamic measurement segment  5232  is updated in accordance with the movement of device  100  such that measurement segment  5232  continues to be displayed between measurement point  5228  and the current location of focus point  5012 . The label associated with measurement segment  5232  is updated to reflect the change in length of measurement segment  5232  (e.g., “12 in”). 
       FIG.  5 CD  illustrates a transition from  FIG.  5 CC  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned away from the midpoint of measurement segment  5222 . Accordingly, in  FIG.  5 CD , dynamic measurement segment  5232  and its associated label are updated to reflect the change in length of measurement segment  5232  due to the movement of focus point  5012  relative to measurement point  5228 . In addition, the appearance of measurement segment  5222  is updated to indicate that adding a measurement point at the current location of focus point  5012  will result in measurement segment  5222  being removed. 
       FIG.  5 CE  illustrates a transition from  FIG.  5 CD  showing that user  5004  has moved device  100  such that measurement point  5224  (as shown in  FIG.  5 CD ) is within reticle  5010 . In some embodiments, as shown in  FIG.  5 CE , the endpoint of a previously-added measurement segment can be an anchor point to which focus point  5012  snaps. Accordingly, in  FIG.  5 CE , focus point  5012  is snapped to the anchor point corresponding to measurement point  5224  (as shown in  FIG.  5 CD ). To indicate the snapping behavior, focus point  5012  is displayed at an increased size relative to its size when not snapped to an anchor point (e.g., as shown in  FIG.  5 CD ), although the size of reticle  5010  is not changed, as described herein with reference to  FIG.  5 CC . In addition, because focus point  5012  is snapped to a point along measurement segment  5222 , the appearance of measurement segment  5222  is changed to indicate that adding a measurement point at the current location of focus point  5012  will result in measurement segment  5222  continuing to be displayed, instead of being removed. Specifically, measurement segment  5222  is changed from a dashed line to a solid line, and the color (and/or transparency) of measurement segment  5222  is changed, such that measurement segment  5222  is redisplayed with its appearance as shown in  FIG.  5 BZ . In addition, dynamic measurement segment  5232  and its associated label are updated to reflect the change in length of measurement segment  5232  due to the movement of focus point  5012  relative to measurement point  5228 . 
       FIG.  5 CF  illustrates a transition from  FIG.  5 CE  showing the addition of measurement point  5234  to user interface  5006  at the current location of focus point  5012  (as shown in  FIG.  5 CE ) in response to activation of measurement addition button  5014  by touch input  5236 . In accordance with measurement point  5234  being added at a point along measurement segment  5222 , measurement segment  5222  continues to be displayed. In accordance with the completion of measurement segment  5232 , the appearance of measurement segment  5232  is changed from a dashed line to a solid line. 
       FIG.  5 CG- 5 CK  illustrate creation of a measurement that is close enough to (e.g., within a predefined threshold distance of, but not connected to) a prior measurement such that the prior measurement continues to be displayed, in accordance with some embodiments.  FIG.  5 CG  illustrates a transition from  FIG.  5 CF  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned away from object  5202  and over a first corner of table  5200 . In some embodiments, as shown in  FIG.  5 CG , even though reticle  5010  and focus point  5012  have been moved away from measurement segment  5222  and measurement segment  5232 , device  100  continues to display the labels associated with measurement segments  5222  and  5232  (in contrast to  FIG.  5 BV , which illustrates embodiments in which device  100  ceases to display the label associated with measurement segment  5212  when reticle  5010  and focus point  5012  are moved away from the measurement segment). 
       FIG.  5 CH  illustrates a transition from  FIG.  5 CG  showing the addition of measurement point  5238  to user interface  5006  at the current location of focus point  5012  (as shown in  FIG.  5 CH ) in response to activation of measurement addition button  5014  by touch input  5240 . In accordance with measurement point  5238  being added at a location in user interface  5006  that is away from previously-created measurement segments  5222  and  5232 , device  100  changes the appearance of measurement segments  5222  and  5232  to indicate that creating a measurement segment that is disconnected and more than a threshold distance from any point along measurement segment  5222  and any point along measurement segment  5232  will cause measurement segments  5222  and  5232  to be removed from user interface  5006 . In the example shown in  FIG.  5 CH , measurement segments  5222  and  5232  are changed from solid lines to dashed lines, and the color (and/or transparency) of measurement segments  5222  and  5232  and their endpoints is changed. 
       FIG.  5 CI  illustrates a transition from  FIG.  5 CH  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a side surface of table  5200 . In some embodiments, as shown in  FIG.  5 CI , reticle  5010  is tilted to appear to be co-planar with the side surface of table  5200  to indicate the surface that has been detected and that corresponds to the current location of focus point  5012 . Dynamic measurement segment  5242 , indicated by a dashed line, is displayed between measurement point  5238  and focus point  5012 , along with an associated dynamic label that indicates the distance along the side surface of table  5200  across which measurement segment  5242  appears to extend in user interface  5006  (e.g., “2 ft 10 in”). 
       FIG.  5 CJ  illustrates a transition from  FIG.  5 CI  showing that user  5004  has moved device  100  such that reticle  5010  and focus point  5012  are positioned over a second corner of table  5200 . In some embodiments, as shown in  FIG.  5 CJ , the appearance of measurement segments  5222  and  5232  are not changed even though adding a measurement point at the current location of focus point  5012  will result in measurement segments  5222  and  5232  continuing to be displayed instead of being removed (e.g., because the resulting measurement segment that would be created by the addition of a measurement point at the current location of focus point  5012  will be within a predefined threshold distance of both measurement segments  5222  and  5232 ). 
       FIG.  5 CK  illustrates a transition from  FIG.  5 CJ  showing the addition of measurement point  5244  at the current location of focus point  5012  (as shown in  FIG.  5 CJ ) in response to activation of measurement addition button  5014  by touch input  5246 . Measurement point  5244  is added at a location in user interface  5006  such that measurement segment  5242  is within a predefined threshold distance of measurement segment  5222  (e.g., measurement segment  5242  includes at least one point that is within a predefined threshold distance of at least one point along measurement segment  5222 ). Accordingly, measurement segment  5222  continues to be displayed after the addition of measurement point  5244 . In addition, measurement segment  5222  is changed from a dashed line (back) to a solid line, and the color (and/or transparency) of measurement segment  5222  is changed, such that measurement segment  5222  is redisplayed with its appearance as shown in  FIG.  5 CG . Similarly, measurement segment  5242  is within the predefined threshold distance of measurement segment  5232  (e.g., measurement segment  5242  includes at least one point that is within a predefined threshold distance of at least one point along measurement segment  5222 , such as endpoint measurement point  5234 ). Accordingly, like measurement segment  5222 , measurement segment  5232  continues to be displayed and is redisplayed with its appearance as shown in  FIG.  5 CG . In some embodiments, as long as at least one point in any of the currently displayed segments (e.g., previously connected segments  5222  and  5232 ) is within the predefined distance of a newly created segment (e.g., segment  5242 ), then all of the currently displayed segments remain displayed. 
       FIG.  5 CL- 5 CM  illustrate an example alert condition in the augmented reality environment.  FIG.  5 CL  illustrates a transition from  FIG.  5 CK  showing that user  5004  has moved device  100  such that field of view of the camera no longer includes the portion of physical space  5000  over which measurement segments  5222 ,  5232 , and  5242  were displayed (e.g., the left portion of table  5200 , as shown in  FIG.  5 CK ).  FIG.  5 CL  indicates that the amount of time that has elapsed since the field of view of the camera was moved away from the left portion of table  5200  is less than a first predefined threshold amount of time T th . 
       FIG.  5 CM  illustrates a transition from  FIG.  5 CL  showing that the amount of time that has elapsed since the field of view of the camera was moved away from the left portion of table  5200  has reached the first predefined threshold amount of time. Accordingly, device  100  displays alert message  5248  to indicate that measurement segments  5222 ,  5232 , and  5242  will soon be removed from user interface  5006 . In some embodiments, if device  100  is moved back to its position as shown in  FIG.  5 CK  within a second predefined threshold amount of time since alert message  5248  was displayed, measurement segments  5222 ,  5232 , and  5242  will be redisplayed in user interface  5006  over the corresponding features in physical space  5000  as shown in  FIG.  5 CG . In some embodiments, if device  100  is moved back to its position as shown in  FIG.  5 CK  after the second predefined threshold amount of time has elapsed since alert message  5248  was displayed, measurement segments  5222 ,  5232 ,  5242  will not be redisplayed in user interface  5006 . In some embodiments, alert message  5248  is displayed when device  100  has been moved such that the portion of physical space  5000  over which measurements  5222 ,  5232 , and  5242  were displayed is more than a threshold distance from the portion of physical space  5000  that is currently in the field of view of the camera. 
       FIG.  5 CN- 5 CO  illustrate another example alert condition in the augmented reality environment.  FIG.  5 CN  shows device  100  positioned at a first distance from table  5200 , where the first distance is less than a predefined (maximum) threshold distance an. Reticle  5010  and focus point  5012  are displayed, which indicates that device  100  has detected a surface at the location over which focus point  5012  is displayed.  FIG.  5 CO  shows device  100  positioned at a second distance from table  5200 , where the second distance is greater than the predefined (maximum) threshold distance D th . Accordingly, device  100  does not display reticle  5010  and focus point  5012 , which indicates that device  100  has not detected a surface at the location in physical space  5000  over which focus point  5012  would have been displayed. In addition, device  100  displays alert message  5250  to indicate that device  100  is too far away from the location in physical space  5000  over which focus point  5012  would have been displayed and to prompt user  5004  to move device  100  closer to that location. Similarly, in some embodiments, when device  100  is positioned at a distance from table  5200  that is less than a predefined minimum threshold distance, device  100  does not display reticle  5010  and focus point  5012  (to indicate that a surface has not been detected) and displays an alert message (e.g., with text such as “Move further”) to prompt user  5004  to move device  100  further away from the location in physical space  5000  over which focus point  5012  would have been displayed. 
       FIGS.  6 A- 6 C  are flow diagrams illustrating method  600  of interacting with an application for making measurements of a physical space using an augmented reality environment in accordance with some embodiments. Method  600  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a touch-sensitive display (e.g., touch screen  112  ( FIG.  1 A ), or display generation component(s)  304  in combination with input device(s)  302  ( FIG.  3 B )), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with the touch-sensitive display (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  600  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  600  provides an intuitive way to reposition a virtual measurement point in an augmented reality-based measurement. Zooming in on an area that includes the measurement point in response to an input directed to the measurement point makes it easy to reposition the measurement point more precisely. Method  600  reduces the number, extent, and/or nature of the inputs from a user when repositioning a virtual measurement point, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to reposition measurement points faster and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 602 ), on the touch-sensitive display, a user interface (e.g., user interface  5006 ,  FIG.  5 AX ) of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The user interface includes ( 604 ) a representation of a field of view of at least one of the one or more cameras (e.g., user interface  5006  includes a live preview of the field of view of the camera of device  100 ,  FIG.  5 AX ). The representation of the field of view is displayed at a first magnification and updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view from at least one of the one or more cameras). In addition, the field of view includes at least a portion of a three-dimensional space (e.g., a space in the physical world that includes physical objects). For example, the live preview is displayed without zoom (or with a zoom factor of 1×) and is updated as device  100  moves (e.g., as in  FIGS.  5 AU- 5 AV ). 
     While displaying the representation of the field of view, the electronic device detects ( 606 ) a first touch input on the touch-sensitive display (e.g., a tap gesture or press input on an affordance which, when activated, adds a measurement point to the displayed representation of the field of view) (e.g., touch input  5158 ,  FIG.  5 AW ). 
     In response to detecting the first touch input, the electronic device adds ( 608 ) and displays a (virtual) measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional space (e.g., measurement point  5160 ,  FIG.  5 AW ). 
     After adding the measurement point and while continuing to display the representation of the field of view ( 610 ), as at least one of the one or more cameras moves, the electronic device displays ( 612 ) the measurement point at a location in the representation of the field of view that corresponds to the first location in the three-dimensional space. For example, as the position and/or orientation of at least one of the one or more cameras change due to movement of the electronic device, the (virtual) measurement point continues to be displayed in the live view at a location that corresponds to the first location in the three-dimensional space, where the (virtual) measurement point was initially placed. In some embodiments, as at least one of the one or more cameras moves, the displayed measurement point appears to be attached or anchored to the location in the three-dimensional space where the (virtual) measurement point was initially placed. 
     After adding the measurement point and while continuing to display the representation of the field of view ( 610 ), the electronic device detects ( 614 ) a second touch input (e.g., touch input  5164 ,  FIG.  5 AY ) at a location on the touch-sensitive display that corresponds to a current location of the measurement point in the representation of the field of view (which, in turn, corresponds to the first location in the three-dimensional space, where the measurement point was initially placed). 
     In response to detecting the second touch input, the electronic device enlarges ( 616 ) display of at least a portion of the representation of the field of view from the first magnification to a second magnification, greater than the first magnification (e.g., the live preview is enlarged by a zoom factor of 4× in  FIG.  5 AY ). The enlarged display of the portion of the representation of the field of view includes the measurement point. In some embodiments, in response to a gesture on the measurement point (such as a tap, double tap, press, press and hold, or depinch gesture), the electronic device zooms in on an area that includes the measurement point, thereby enlarging an area that includes the measurement point from a first magnification to a second magnification. In some embodiments, zooming in on an area that includes the measurement point enables a user to reposition the measurement point more precisely, e.g., in response to gestures directed to the zoomed-in measurement point. 
     In some embodiments, the one or more cameras are ( 618 ) located on the electronic device adjacent to a portion of the touch-sensitive display that is near a side of the device on which the one or more cameras are positioned (e.g., the one or more cameras are located in region  5008 ,  FIG.  5 A ). In some embodiments, the one or more cameras are located on the electronic device adjacent to a first portion of the touch-sensitive display. In some embodiments, a surface of the touch-sensitive display extends along an xy-plane, and the one or more cameras are adjacent to the first portion of the touch-sensitive display along the xy-plane. In some embodiments, the one or more cameras are adjacent to the first portion of the touch-sensitive display in a z-direction that is perpendicular to the xy-plane. In some embodiments, the user interface includes a first affordance that is displayed in a portion of the touch-sensitive display that is away from a side of the device on which the one or more cameras are positioned and which, when activated, adds a measurement point to the displayed representation of the field of view (e.g., measurement addition button  5014 ,  FIG.  5 A ). In some embodiments, the first affordance is displayed in a second portion of the touch-sensitive display, where the second portion of the touch-sensitive display is distinct from the first portion of the touch-sensitive display, and where the second portion of the touch-sensitive display is located away from the side of the device on which the one or more cameras are positioned. In some embodiments, the user interface further includes one or more second affordances (e.g., buttons  5018 ,  5020 ,  5022 ,  FIG.  5 A ) displayed in accordance with a first orientation of the electronic device (e.g., portrait orientation, as shown in  FIG.  5 A ). In some embodiments, the electronic device detects movement (e.g., rotation) of the electronic device to a second orientation (e.g., rotation to a landscape orientation as shown in  FIG.  5 B  or  FIG.  5 C ). In some embodiments, in response to detecting the movement of the electronic device to the second orientation, the electronic device updates display of the one or more second affordances in accordance with the second orientation of the electronic device (e.g., buttons  5018 ,  5020 , and  5022  move to different regions of the user interface in FIG.  5 B or  FIG.  5 C  without regard to the positions of the one or more cameras) and continues to display the first affordance in the portion of the touch-sensitive display that is away from the side of the device on which the one or more cameras are positioned (e.g., measurement addition button  5014  is displayed away from region  5008  in  FIGS.  5 B and  5 C ). 
     In some embodiments, in the second orientation, the electronic device updates display of the first affordance such that the first affordance is displayed at a different position within the portion of the touch-sensitive display that is away from the side of the device on which the one or more cameras are positioned (e.g., at a position within a predefined distance of an edge or a corner of the touch-sensitive display, to facilitate activation of the first affordance during single-handed operation of the electronic device) (e.g., measurement addition button  5014 ). In some embodiments, the first affordance is restricted to positions within the portion of the touch-sensitive display that is away from the side of the device on which the one or more cameras are positioned, so as to deter a user from holding the electronic device in a manner in which the user&#39;s hand obscures the field of view. In some embodiments, while the electronic device is in a first orientation (e.g., a first landscape orientation) in which the one or more cameras are located on a left half of the electronic device, the first affordance is displayed in the user interface on a right half of the electronic device; and, while the electronic device is in a second orientation (e.g., a second landscape orientation in which the device is rotated 180 degrees from the first landscape orientation) in which the one or more cameras are located on the right half of the electronic device, the first affordance is displayed in the user interface on the left half of the electronic device (e.g., as shown in and described herein with reference to  FIGS.  5 B- 5 C ). 
     When the device orientation changes, automatically keeping an affordance that is used to place measurement points at a location on that touch sensitive display that is away from the one or more cameras reduces the chance that a user will hold the electronic device in a way that obscures the field of view of a camera that is providing the live view. Automatically repositioning an affordance in this manner when the device orientation changes enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device, such as obscuring the field of view). 
     In some embodiments, the user interface of the application includes ( 620 ) one or more affordances that correspond to operations of the application, including a capture affordance (e.g., an affordance such as a virtual shutter button which, when activated, initiates capture of media that corresponds to the representation of the field of view) (e.g., media capture button  5016 ,  FIG.  5 A ). In some embodiments, the electronic device detects a third touch input on the capture affordance, and, in accordance with a determination that the third touch input meets first media capture criteria, initiates capture of media of a first type (e.g., a video or a live photo) that includes a sequence of images of the field of view of at least one of the one or more cameras (and, in some embodiments, corresponding audio) (e.g., as described herein with reference to  FIGS.  5 BJ- 5 BK ). In some embodiments, the first media capture criteria include a first requirement that the third touch input be maintained on the touch-sensitive display for at least a predefined threshold amount of time, and a second requirement that an amount of movement of the third touch input across the touch-sensitive display be less than a predefined threshold amount of movement. In some embodiments, the first media capture criteria are satisfied by a stationary long-press or a press-and-hold gesture on the capture affordance. 
     In some embodiments, the captured sequence of images includes (virtual) measurement information displayed over the images (e.g., one or more (virtual) measurement points, lines between the measurement points, labels for the measurement points, and/or distances between measurement points) (e.g., as described herein with reference to  FIGS.  5 BJ- 5 BK ). In some embodiments, the captured sequence of images does not include display of other affordances (besides the measurement information displayed over the images) that are shown in the user interface of the application, such as the capture affordance. In other words, in some embodiments, instead of capturing a screen recording of everything being shown in the user interface of the application, the device just captures a video of the field of view with the (virtual) measurement information superimposed upon the field of view (e.g., as described herein with reference to  FIGS.  5 BJ- 5 BK ). 
     Providing a virtual shutter button or other capture affordance makes it easy to record a video of the objects being measured, along with the virtual measurement information that is displayed over the objects. Recording such a video, without also recording other elements in the user interface of the application, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to create recordings that show the objects and the measurements, without showing extraneous information that was displayed in the user interface during the recording). 
     In some embodiments, in accordance with a determination that the third touch input meets second media capture criteria, the electronic device initiates ( 622 ) capture of media of a second type (e.g., a still image) that includes a single image of the field of view of at least one of the one or more cameras (e.g., without corresponding audio) (e.g., as shown in and described herein with reference to  FIGS.  5 BH- 5 BI ). In some embodiments, the second media capture criteria include a first requirement that the third touch input cease to be detected on the touch-sensitive display before a predefined threshold amount of time elapses, and a second requirement that an amount of movement of the second touch input across the touch-sensitive display be less than a predefined threshold amount of movement. In some embodiments, the second media capture criteria are satisfied by a stationary tap gesture on the capture affordance. 
     In some embodiments, the captured still image does not include display of other affordances (besides the measurement information displayed over the images) that are shown in the user interface of the application, such as the capture affordance (e.g., as shown in and described herein with reference to  FIGS.  5 BH- 5 BI ). In other words, in some embodiments, instead of capturing a still image of everything being shown in the user interface of the application, the device just captures a still image of the field of view with the (virtual) measurement information superimposed upon the field of view. 
     Providing a capture affordance that can initiate capture of either a still image or a video makes it easy to obtain either a still image or a video of the objects being measured, along with the virtual measurement information that is displayed over the objects. Obtaining such a still image or video, without also including other elements in the user interface of the application, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to create a still image or video that shows the objects and the measurements, without showing extraneous information that was displayed in the user interface during the recording). In addition, providing additional control options for the capture affordance (e.g., to capture either a still image or a video, depending on the characteristics of the touch input on the capture affordance), without cluttering the user interface with additional displayed controls, enhances the operability of the device and makes the user-device interface more efficient. 
     In some embodiments, prior to displaying the user interface of the application, the electronic device displays ( 624 ) a control panel user interface that includes a plurality of controls (e.g., control center user interface  5188 ,  FIG.  5 BN ), where a first control in the plurality of controls corresponds to the application (e.g., augmented reality measurement application icon  5190 ,  FIG.  5 BN ). In some embodiments, the electronic device detects a touch input (e.g., a tap gesture or press input) activating the first control, and, in response to detecting the touch input activating the first control, displays the user interface of the application (e.g., as described herein with reference to  FIG.  5 BN ). Providing access to a measurement application via a control panel makes it easier to find and launch the application. Reducing the number of inputs needed to find and launch an application enhances the operability of the device and makes the user-device interface more efficient. 
     In some embodiments, the user interface is ( 626 ) a first user interface of a plurality of user interfaces in the application. In some embodiments, the first user interface corresponds to a measurement mode of the application. In some embodiments, a second user interface of the plurality of user interfaces corresponds to a levelling mode of the application. In some embodiments, an augmented reality measurement application or an application that includes augmented reality measurement functionality also includes level functionality. Providing both measurement and level functionality in the same application makes it easier to find and use these related functions. Providing multiple related functionalities in the same application enhances the operability of the device and makes the user-device interface more efficient. 
     In some embodiments, the electronic device determines ( 628 ) a distance between the electronic device and the first location in the three-dimensional space that corresponds to the measurement point (e.g., a distance from one of the cameras of the electronic device to the first location in the three-dimensional space that corresponds to the measurement point). In some embodiments, the distance from one of the cameras to the first location in the three-dimensional space is determined based on depth information captured by at least one of the one or more cameras (e.g., by depth sensors that are optionally part of the one or more cameras) and/or based on disparity information between multiple different cameras (e.g., determined by comparing information captured by multiple different cameras). In some embodiments, in accordance with a determination that the determined distance is less than a first threshold distance, a magnification factor between the first magnification and the second magnification (e.g., an amount of increase in magnification from the first magnification to the second magnification) is a first magnification factor (e.g., corresponding to a minimum amount of zoom, that does not change as the distance between the electronic device and the first location in the three-dimensional space decreases below the first threshold distance). In some embodiments, in accordance with a determination that the determined distance is greater than a second threshold distance, the magnification factor is a second magnification factor (e.g., corresponding to a maximum amount of zoom, that does not change as the distance between the electronic device and the first location in the three-dimensional space increases above the second threshold distance). In some embodiments, in accordance with a determination that the determined distance is between the first threshold distance and the second threshold distance, the magnification factor is a respective magnification factor, between the first magnification factor and the second magnification factor, that depends on the determined distance. For example, as shown in and described herein with reference to  FIGS.  5 AY- 5 BE , an amount of zoom of the live preview is based on the distance between device  100  and table  5002 , optionally with a maximum and/or a minimum limit on the amount of zoom. 
     More generally, in some embodiments, the amount of zoom is increased when the electronic device is further from the point of interest in the three-dimensional space (optionally subject to a maximum amount of zoom), and the amount of zoom is decreased when the electronic device is closer to the point of interest in the three-dimensional space (optionally subject to a minimum amount of zoom). In principle, a greater amount of zoom is needed when the electronic device is further from the point(s) of interest in the three-dimensional space, because features of interest are more difficult to discern (e.g., in the representation of the field of view) at greater distances, whereas a lesser amount of zoom is needed when the electronic device is closer to the point(s) of interest in the three-dimensional space, because features of interest are more readily perceived (e.g., in the representation of the field of view) at lesser distances. In some embodiments, a maximum amount of zoom is imposed in accordance with hardware specifications (e.g., zoom limitations) of the one or more cameras. 
     Automatically varying the amount of zooming based on the distance from the electronic device to a location in the three-dimensional space that corresponds to the measurement point makes it easier to reposition the measurement point, because the measurement point is displayed at an appropriate level of magnification for each distance. Performing a zoom operation with different magnification factors, which depend on an automatically measured distance, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient (e.g., by automatically displaying the measurement point at a magnification level where proper inputs can be provided to reposition the measurement point). 
     In some embodiments, while displaying the enlarged display of at least the portion of the representation of the field of view, the electronic device detects ( 630 ) a fourth touch input that includes detecting a contact at the current location of the measurement point and detecting movement of the contact across the touch-sensitive display (e.g., touch input  5164 ,  FIG.  5 AZ ). In some embodiments, the second touch input and the fourth touch input are different portions of an input by a single continuous contact (e.g., the second touch input is a first portion of the input that touches down the contact on the touch-sensitive display, and the fourth input is a second portion of the input that includes movement of the contact). In some embodiments, in response to detecting the movement of the contact across the touch-sensitive display, the electronic device moves the measurement point across the representation of the field of view in accordance with the movement of the contact in the fourth touch input (e.g., as described herein with reference to measurement point  5160 ,  FIG.  5 AZ ). Dragging the measurement point while viewing an enlarged area around the measurement point makes it easy to reposition the measurement point precisely with movement of a single contact. Reducing the number of inputs needed to perform a repositioning operation enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the first touch input is ( 632 ) detected on an affordance which, when activated, adds a measurement point to the displayed representation of the field of view. In some embodiments, the affordance is displayed in the user interface at a (fixed) predefined location. In some embodiments, a location in the representation of the field of view where the measurement point is initially added, in response to activation of the affordance, is distinct from the predefined location of the affordance. For example, in  FIGS.  5 AV- 5 AW , measurement point  5160  is added to user interface  5006  at a location that is away from the location of measurement addition button  5014 . Providing an affordance for adding measurement points that is located away from where the added measurement points are initially displayed makes it easy to see where a measurement point will be placed. Displaying an affordance for adding points away from the location where the points are initially added enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs for adding measurement points and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  6 A- 6 C  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  600  described above with respect to  FIGS.  6 A- 6 C . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  600  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  7 A- 7 E  are flow diagrams illustrating method  700  of adding measurements to a displayed representation of a physical space in an augmented reality environment in accordance with some embodiments. Method  700  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a touch-sensitive display (e.g., touch screen  112  ( FIG.  1 A ), or display generation component(s)  304  in combination with input device(s)  302  ( FIG.  3 B )), one or more sensors to detect intensities of contacts with the touch-sensitive display (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  700  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  700  provides an intuitive way to more precisely add virtual measurement points and segments in augmented reality-based measurements. For an electronic device with a touch-sensitive display, one or more sensors to detect intensities of contacts with the touch-sensitive display, and one or more cameras, repeated presses by a continuously detected contact on the touch-sensitive display make it easier to hold the electronic device steady (e.g., as compared to repeated taps on the touch-sensitive display) while positioning the locations of the measurement points with a live view from at least one of the cameras. Method  700  changes the nature of the inputs from a user when adding virtual measurement points and segments, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to add measurement points and segments more accurately and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 702 ), on the touch-sensitive display, a user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The user interface includes ( 704 ) a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view, which changes as the one or more cameras move and/or as the physical world in the field of view of the one or more cameras change). The user interface includes a measurement-point-creation indicator that is displayed over the representation of the field of view (e.g., reticle  5010  in conjunction with focus point  5012 ,  FIG.  5 AH  which are displayed within user interface  5006  on top of the live preview of the camera). In addition, the field of view includes at least a portion of a three-dimensional space (e.g., a space in the physical world that includes physical objects) (e.g., physical space  5000 ). 
     The electronic device detects ( 706 ) a contact on the touch-sensitive display (e.g., touch input  5120 ,  FIG.  5 AI ). 
     While continuously detecting the contact on the touch-sensitive display ( 708 ), and while the measurement-point-creation indicator is displayed over a first location in the representation of the field of view that corresponds to a first location in the three-dimensional space ( 710 ), in accordance with a determination that first criteria (e.g., measurement-point-creation criteria) are met, where the first criteria include a requirement that an intensity of the contact meet (e.g., reach or exceed) a respective intensity threshold in order for the first criteria to be met, the electronic device adds ( 712 ) and displays a first (virtual) measurement point (e.g., measurement point  5122 ,  FIG.  5 AI ) in the representation of the field of view that corresponds to the first location in the three-dimensional space. In some embodiments, the electronic device determines whether the first criteria are met. In some embodiments, the first criteria are met when the intensity of the contact exceeds an intensity threshold (e.g., a light press intensity threshold IT L , which is above a contact detection intensity threshold IT 0 ) (e.g., as indicated by intensity meter  5040 ,  FIG.  5 AI ). In some embodiments, the first criteria are met when the intensity of the contact falls below the intensity threshold (after exceeding the intensity threshold). In some embodiments, the first criteria include a requirement that, when other criteria of the first criteria are met, the contact be positioned on an affordance, which, when activated, adds a measurement point to the displayed representation of the field of view at the location over which the measurement-point-creation indicator is displayed (e.g., measurement addition button  5014 ,  FIG.  5 AI ). 
     While continuously detecting the contact on the touch-sensitive display ( 708 ), and after adding the first (virtual) measurement point, the electronic device updates ( 714 ) the representation of the field of view as the electronic device is moved (e.g., as the field of view of the one or more cameras changes). In some embodiments, in response to the electronic device being moved, the electronic device displays a dynamic measurement segment between the first (virtual) measurement point in the representation of the field of view (e.g., while the field of view of the one or more cameras includes the first location in the three-dimensional space) and the measurement-point-creation indicator in the user interface (e.g., dynamic measurement segment  5128 ,  FIG.  5 AK ). In some embodiments, the display of the dynamic measurement segment changes in accordance with the movement of the device (e.g., which changes the field of view of the one or more cameras). For example, when the measurement-point-creation indicator is centered at a fixed position within the representation of the field of view, a distance between the first measurement point in the representation of the field of view and a location in the representation of the field of view that corresponds to the measurement-point-creation indicator changes as the device (and the field of view of the one or more cameras) moves relative to the first location in the three-dimensional space and, accordingly, a length of the dynamic measurement segment changes as the device moves. 
     While continuously detecting the contact on the touch-sensitive display ( 708 ), after the electronic device is moved, and while the measurement-point-creation indicator is displayed over a second location in the representation of the field of view that corresponds to a second location in the three-dimensional space ( 716 ), in accordance with a determination that the first criteria are met while the measurement-point-creation indicator is displayed over the second location in the representation of the field of view that corresponds to the second location in the three-dimensional space ( 718 ): the electronic device adds ( 720 ) and displays a second (virtual) measurement point (e.g., as explained herein with respect to the addition of measurement point  5132 ,  FIG.  5 AL ) in the representation of the field of view that corresponds to the second location in the three-dimensional space. In some embodiments, the second location in the representation of the field of view is the same as the first location in the representation of the field of view, for example when the measurement-point-creation indicator is centered at a fixed position within the representation of the field of view. In some embodiments, the electronic device determines whether the first criteria are met. In addition, the electronic device displays ( 722 ) a first measurement segment connecting the first measurement point and the second measurement point. 
     In some embodiments, the first measurement segment (connecting the first measurement point and the second measurement point) is displayed in accordance with a determination that second criteria (e.g., measurement-segment-creation criteria) are met. In some embodiments, the second criteria include a requirement that, following a respective instance when the first criteria are met for adding and displaying a respective measurement point, the contact be maintained on the touch-sensitive display (e.g., on an affordance which, when activated, adds a measurement point to the displayed representation of the field of view at the location over which the measurement-point-creation indicator is displayed) until a next instance that the first criteria are met for adding and displaying a next measurement point (e.g., as shown in and described herein with reference to  FIGS.  5 AH- 5 AS ). That is, the second criteria include a requirement that the contact be maintained between the creation of successive measurement points that satisfy the (intensity-based) first criteria. In some embodiments, the intensity threshold for the first criteria is a second intensity threshold (e.g., a light press intensity threshold IT L ) that is above a first intensity threshold (e.g., a contact detection intensity threshold (IT 0 ), and the second criteria include a requirement that an intensity of the contact remain at or above the first intensity threshold while the contact is maintained. In some embodiments, the second criteria include a requirement that an intensity of the contact decrease to or below the second intensity threshold while the contact is maintained (e.g., if the first criteria require that the intensity of the contact exceed the second intensity threshold). In some embodiments, the second criteria include a requirement that an intensity of the contact remain at or below the second intensity threshold while the contact is maintained (e.g., if the first criteria require that the intensity of the contact fall below the intensity threshold (after exceeding the intensity threshold)). 
     More generally, in some embodiments, after a respective point is added and displayed in accordance with the first criteria being met, as long as the contact is maintained on the touch-sensitive display, one or more additional measurement points, as well as their corresponding measurement segments, are added and displayed in accordance with the first criteria being met for each additional measurement point. That is, as long as the contact is maintained on the touch-sensitive-display, each subsequent instance when the first criteria is met adds both an additional point and an additional measurement segment between the (newly-added) additional point and the most-recently-added prior point. Stated another way, after a respective point is added in accordance with the first criteria being met, the electronic device operates in a continuous measurement-(point-and-segment-)creation mode until the contact ceases to be maintained on the touch-sensitive display. 
     In some embodiments, while continuously detecting the contact on the touch-sensitive display, and after adding the second (virtual) measurement point, the electronic device updates ( 724 ) the representation of the field of view as the electronic device is moved again (e.g., as shown in and described herein with reference to  FIGS.  5 AN- 5 AQ ). In some embodiments, while continuously detecting the contact on the touch-sensitive display, after the electronic device is moved again, and while the measurement-point-creation indicator is displayed over a third location in the representation of the field of view that corresponds to a third location in the three-dimensional space, in accordance with a determination that the first criteria are met while the measurement-point-creation indicator is displayed over the third location in the representation of the field of view that corresponds to the third location in the three-dimensional space, the electronic device adds and displays a third (virtual) measurement point in the representation of the field of view that corresponds to the third location in the three-dimensional space (e.g., measurement point  5142 ,  FIG.  5 AR ), and displays a second measurement segment connecting the second measurement point and the third measurement point (e.g., completed measurement segment  5136 ,  FIG.  5 AR ). In some embodiments, the third location in the representation of the field of view is the same as the first location in the representation of the field of view, for example when the measurement-point-creation indicator is centered at a fixed position within the representation of the field of view. 
     In some embodiments, in accordance with a determination that the first criteria are not met while the measurement-point-creation indicator is displayed over the second location in the representation of the field of view that corresponds to the second location in the three-dimensional space, the electronic device forgoes ( 726 ) adding and displaying the second (virtual) measurement point in the representation of the field of view that corresponds to the second location in the three-dimensional space, and forgoes displaying the first measurement segment connecting the first measurement point and the second measurement point. 
     In some embodiments, after adding the second (virtual) measurement point, the electronic device updates ( 728 ) the representation of the field of view as the electronic device is moved again. In some embodiments, after the electronic device is moved again, while the measurement-point-creation indicator is displayed over a third location in the representation of the field of view that corresponds to the third location in the three-dimensional space, and in accordance with a determination that the first criteria are met while the measurement-point-creation indicator is displayed over the third location in the representation of the field of view that corresponds to the third location in the three-dimensional space, the electronic device adds and displays a third (virtual) measurement point in the representation of the field of view that corresponds to the third location in the three-dimensional space. In some embodiments, in accordance with a determination that second criteria (e.g., measurement-segment-creation criteria) are met, where the second criteria include a requirement that the contact is maintained between the first criteria being met for adding the second measurement point and the first criteria being met for adding the third measurement point, the electronic device displays a second measurement segment connecting the second measurement point and the third measurement point. In some embodiments, in accordance with a determination that the second criteria are not met, the electronic device forgoes displaying the second measurement segment connecting the second measurement point and the third measurement point (e.g., as shown in and described herein with reference to  FIGS.  5 AH- 5 AS ). In some embodiments, if a respective measurement point is a most-recently-added measurement point (e.g., the second measurement point) and is an endpoint of a measurement segment that is the most-recently-added measurement segment (e.g., the first measurement segment), then, in accordance with a determination that the first criteria (e.g., the measurement-point-creation criteria) are met and the second criteria are not met, the electronic device adds and displays an additional measurement point (e.g., the third measurement point) and forgoes displaying an additional measurement segment between the respective measurement point (the most-recently-added measurement point prior to displaying the additional measurement point) and the additional measurement point. 
     In some embodiments, while continuously detecting the contact on the touch-sensitive display, and while the electronic device is being moved, a dynamic measurement segment is displayed between a most-recently-added measurement point (e.g., the second measurement point) and a location in the representation of the field of view that corresponds to the measurement-point-creation indicator (e.g., a dynamic measurement segment as described herein with reference to operation  714 ), and the dynamic measurement segment continues to be displayed in accordance with a determination that the second criteria are met. In some embodiments, if the most-recently-added measurement point is an endpoint of another measurement segment that is the most-recently-added measurement segment prior to displaying the dynamic measurement segment (e.g., the first measurement segment), then the electronic device ceases to display the dynamic measurement segment in response to liftoff of the contact after the first criteria are met for adding the second measurement point (e.g., at any point before the first criteria are met for adding the third measurement point) (e.g., as shown in and described herein with reference to  FIGS.  5 AH- 5 AS ). 
     Adding a measurement point with or without a corresponding measurement segment to the immediately prior measurement point, depending on whether a contact has been maintained on the touch sensitive display, provides an additional option for adding a measurement point without adding a measurement segment (e.g., a user lifts off the contact to indicate that the next measurement point to be added is not connected to the prior measurement points and segments). Providing additional control options without cluttering the UI with additional displayed controls enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the electronic device includes one or more tactile output generators. In some embodiments, in accordance with a determination that the intensity of the contact meets (e.g., reaches (increases to) or exceeds) the respective intensity threshold, the electronic device generates ( 730 ) a tactile output (e.g., to indicate that the intensity of the contact is sufficient to add a measurement point) (e.g., as described herein with reference to tactile output  5124 ,  FIG.  5 AI ). In some embodiments, a tactile output is generated in accordance with the determination that the first criteria are met (e.g., that other requirements of the first criteria are also met, in addition to the requirement that the intensity of the contact meet the respective intensity threshold). In some embodiments, the electronic device provides a tactile output when the respective intensity threshold is met to indicate that the intensity of the contact is sufficient to add a measurement point and/or to indicate that the measurement point has been added. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments in which the electronic device includes one or more tactile output generators, the respective intensity threshold is ( 732 ) a second intensity threshold (e.g., a light press intensity threshold IT L ) that is above a first intensity threshold (e.g., a contact detection intensity threshold IT 0 ). In some embodiments, in accordance with a determination that the intensity of the contact ceases to meet the second intensity threshold (after meeting the second intensity threshold) (e.g., the intensity of the contact decreases to or below the second intensity threshold), and that the intensity of the contact meets the first intensity threshold (e.g., the intensity of the contact remains at or above the first intensity threshold), the electronic device generates a tactile output (e.g., to indicate addition of a measurement point) (e.g., as described herein with reference to  FIG.  5 AJ ). In some embodiments, the electronic device provides a tactile output when the intensity falls below the second intensity threshold to indicate that a measurement point has been added. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the adding and the displaying of the first measurement point is ( 734 ) performed when the intensity of the contact meets the respective intensity threshold, while the measurement-point-creation indicator is displayed over the first location in the representation of the field of view that corresponds to the first location in the three-dimensional space (e.g., as shown in and described herein with reference to  FIG.  5 AI ). In some embodiments, the adding and the displaying of the second measurement point is performed when the intensity of the contact meets the respective intensity threshold after the electronic device is moved, while the measurement-point-creation indicator is displayed over the second location in the representation of the field of view that corresponds to the second location in the three-dimensional space. 
     In some embodiments, the respective intensity threshold is ( 736 ) a second intensity threshold (e.g., a light press intensity threshold IT L ) that is above a first intensity threshold (e.g., a contact detection intensity threshold IT 0 ). In some embodiments, the first criteria include a requirement that the intensity of the contact falls below the respective intensity threshold, after meeting the respective intensity threshold, in order for the first criteria to be met. In some embodiments, the adding and the displaying of the first measurement point is performed when the intensity of the contact falls below the respective intensity threshold, while the measurement-point-creation indicator is displayed over the first location in the representation of the field of view that corresponds to the first location in the three-dimensional space. In some embodiments, the adding and the displaying of the second measurement point is performed when, after the electronic device is moved and while the measurement-point-creation indicator is displayed over the second location in the representation of the field of view that corresponds to the second location in the three-dimensional space, the intensity of the contact falls below the respective intensity threshold. 
     In some embodiments, while displaying the representation of the field of view of the one or more cameras, the electronic device determines ( 738 ) an anchor point in the representation of the field of view of the one or more cameras that corresponds to a respective location in the three-dimensional space. In some embodiments, as the one or more cameras move, while the measurement-point-creation indicator (or at least a portion thereof) is over (or proximate to) the anchor point, the electronic device changes a visual appearance of the measurement-point-creation indicator to indicate that a respective measurement point will be added at the anchor point if the contact meets the first criteria (e.g., as described herein with reference to reticle  5010  and focus point  5012  in  FIG.  5 AH ). Providing visual feedback that a measurement point will be added at the anchor point if the contact meets the first criteria makes it easy to add a measurement point at the anchor point. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the user interface includes ( 740 ) an affordance, which, when activated, adds a (virtual) measurement point in the representation of the field of view at a location in the representation of the field of view over which the measurement-point-creation indicator is displayed (e.g., measurement addition button  5014 ). In some embodiments, the electronic device detects a touch input (e.g., a tap gesture) activating the affordance, and, in response to detecting the touch input activating the affordance, adds and displays a measurement point in the representation of the field of view at the location in the representation of the field of view over which the measurement-point-creation indicator is displayed (e.g., as shown in and described herein with reference to  FIG.  5 K ). 
     It should be understood that the particular order in which the operations in  FIGS.  7 A- 7 E  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  800 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  700  described above with respect to  FIGS.  7 A- 7 E . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  700  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  800 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  8 A- 8 C  are flow diagrams illustrating method  800  of adding virtual measurement points at automatically determined anchor points in an augmented reality environment in accordance with some embodiments. Method  800  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a touch-sensitive display (e.g., touch screen  112  ( FIG.  1 A ), or display generation component(s)  304  in combination with input device(s)  302  ( FIG.  3 B )), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with the touch-sensitive display (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  800  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  800  provides an intuitive way to add virtual measurement points in augmented reality-based measurements, either at automatically determined anchor points or away from such anchor points. An electronic device provides visual feedback that a measurement point will be added at an anchor point if measurement-point-creation criteria, which makes it easy to add a measurement point at the anchor point. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). For battery-operated electronic devices, enabling a user to add measurement points at automatically determined anchor points (or add measurement points away from such anchor points) faster and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 802 ), on the touch-sensitive display, a user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The user interface includes ( 804 ) a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view). In addition, the user interface includes a measurement-point-creation indicator that is displayed over the representation of the field of view (e.g., reticle  5010  in combination with focus point  5012 ,  FIG.  5 K ). The field of view includes at least a portion of a three-dimensional space (e.g., a space in the physical world that includes physical objects). 
     While displaying the representation of the field of view ( 806 ), the electronic device determines ( 808 ) an anchor point at a location in the representation of the field of view that corresponds to a first location in the three-dimensional space. In some embodiments, the electronic device determines a plurality of anchor points that correspond to a plurality of locations in the three-dimensional space, such as a corner of a physical object in the three-dimensional space, points along an edge of a physical object in the three-dimensional space, or the like. 
     While displaying the representation of the field of view ( 806 ), as at least one of the one or more cameras move, and while the measurement-point-creation indicator (or at least a portion thereof) is over (or proximate to) the anchor point, the electronic device changes ( 810 ) a visual appearance of the measurement-point-creation indicator to indicate that a (virtual) measurement point will be added at the anchor point if a touch input meets first criteria (e.g., measurement point creation criteria) (e.g., as described herein with reference to reticle  5010  and focus point  5012  in  FIG.  5 AK ). 
     While displaying the representation of the field of view ( 806 ), the electronic device detects ( 812 ) a first touch input on the touch-sensitive display that meets the first criteria (e.g., a tap gesture on an affordance or a hard press input on an affordance, the hard press input meeting or exceeding an intensity threshold) (e.g., touch input  5038 ,  FIG.  5 K . 
     While displaying the representation of the field of view ( 806 ), in response to detecting the first touch input that meets the first criteria ( 814 ), and in accordance with a determination that the measurement-point-creation indicator (or at least a portion thereof) is over (or proximate to) the anchor point when the first criteria are met ( 816 ), the electronic device adds and displays a first (virtual) measurement point at the anchor point in the representation of the field of view that corresponds to the first location in the three-dimensional space (e.g., measurement point  5042 ,  FIG.  5 K ). 
     While displaying the representation of the field of view ( 806 ), in accordance with a determination that the measurement-point-creation indicator (or at least a portion thereof) is not over (or proximate to) the anchor point when the first criteria are met ( 818 ), the electronic device adds and displays a first (virtual) measurement point at a first location in the representation of the field of view that is away from the anchor point (e.g., at a location in the representation of the field of view that does not correspond to the first location in the three-dimensional space). 
     In some embodiments, the determined anchor point is ( 820 ) also an endpoint of a (currently) displayed representation of a measurement (e.g., as described herein with respect to the anchor point corresponding to measurement point  5054 ,  FIG.  5 Q ), and adding a measurement point at the anchor point, if a touch input meets first criteria, will not form a region, in the representation of the field of view, that is enclosed by a plurality of displayed measurement segments (e.g., and their associated endpoints). For example, a measurement segment that will be added in conjunction with or in response to adding the measurement point at the determined anchor point will not form a closed polygon that includes the added measurement segment as a final side of the closed polygon). Providing visual feedback that a measurement point will be added at the anchor point if measurement-point-creation criteria are met makes it easy to add a measurement point at the anchor point, including at an anchor point that is not just closing a loop of measurement points. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the electronic device displays ( 822 ), over the representation of the field of view, a representation of a first measurement. The representation of the first measurement includes a first endpoint that corresponds to a second location in the three-dimensional space, a second endpoint that corresponds to a third location in the three-dimensional space, and a first line segment connecting the first endpoint and the second endpoint. In addition, the determined anchor point is a midpoint of the first line segment (e.g., the first location, to which the anchor point corresponds, is halfway between the second location and the third location in the three-dimensional space) (e.g., as shown in and described herein with reference to  FIG.  5 AA ). Providing visual feedback that a measurement point will be added at an anchor point that is at the midpoint of a measurement segment if measurement-point-creation criteria are met makes it easy to add a measurement point at the midpoint of a measurement segment. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the electronic device includes one or more tactile output generators. In some embodiments, as at least one of the one or more cameras moves, and while the measurement-point-creation indicator (or at least a portion thereof) is over (or proximate to) the anchor point, the electronic device generates ( 824 ) a tactile output in conjunction with changing the visual appearance of the measurement-point-creation indicator (e.g., as described herein with respect to  FIG.  5 H ). In some embodiments, adding a measurement point at the anchor point, if a touch input meets first criteria, will not form a region enclosed by a plurality of displayed measurement segments (e.g., and their associated endpoints) in the representation of the field of view of the one or more cameras. For example, a measurement segment that will be added in conjunction with or in response to adding the measurement point will not form a closed polygon that includes the added measurement segment as a final side of the closed polygon. In some embodiments, a tactile output is generated when snapping to an identified physical feature in the three-dimensional space. In some embodiments, a tactile output is generated when snapping to a currently displayed representation of a measurement, to a respective measurement point (e.g., an endpoint) thereof, and/or to a midpoint of a measurement segment thereof. Providing both haptic and visual feedback that a measurement point will be added at the anchor point if measurement-point-creation criteria are met makes it easy to add a measurement point at the anchor point, including at an anchor point that is not just closing a loop of measurement points. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments in which the electronic device includes one or more tactile output generators, the electronic device detects ( 826 ) movement of the measurement-point-creation indicator away from the anchor point (e.g., so that the measurement-point-creation indicator is not over (or not proximate to) the anchor point) (e.g., due to movement of the one or more cameras that changes the field of view while the measurement-point-creation indicator remains at a fixed location within the user interface). In some embodiments, in response to detecting the movement of the measurement-point-creation indicator away from the anchor point, the electronic device generates a tactile output (e.g., as described herein with respect to  FIG.  5 I ). Providing haptic feedback that a measurement point will not be added at the anchor point if measurement-point-creation criteria are met helps guide a user while placing measurement points. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments in which the electronic device includes one or more tactile output generators, in response to detecting the first touch input that meets the first criteria, the electronic device adds ( 828 ) the first measurement point without adding a measurement segment connected to the first measurement point (e.g., the first measurement point is a first endpoint of a new measurement) and generates a first tactile output (e.g., a start-of-measurement tactile output) (e.g., as described herein with respect to measurement point  5042 ,  FIG.  5 K ). In some embodiments, the electronic device detects movement of the measurement-point-creation indicator to a second location in the representation of the field of view that corresponds to a second location in the three-dimensional space (e.g., as described herein with respect to  FIG.  5 M ). In some embodiments, while the measurement-point-creation indicator is over the second location in the representation of the field of view, the electronic device detecting a second touch input on the touch-sensitive display that meets the first criteria. In some embodiments, in response to detecting the second touch input that meets the first criteria, the electronic device adds a second measurement point at the second location in the representation of the field of view (e.g., as described herein with respect to measurement point  5054 ,  FIG.  5 N ). In some embodiments, in response to detecting the second touch input that meets the first criteria, the electronic device adds a measurement segment between the first measurement point and the second measurement point (e.g., the electronic device adds a representation of a measurement by adding a second measurement point and a measurement segment, where the representation of the measurement includes the first measurement point, the second measurement point, and the measurement segment) (e.g., as described herein with respect to measurement segment  5048 ,  FIG.  5 N ). In some embodiments, in response to detecting the second touch input that meets the first criteria, the electronic device generates a second tactile output (e.g., an end-of-measurement tactile output) that is different from the first tactile output (e.g., the second tactile output differs from the first tactile output in at least one tactile output property, such as frequency, amplitude, pattern, duration, etc.) (e.g., as described herein with respect to tactile output  5056 ,  FIG.  5 N ). Providing different haptic feedback at the start of a measurement (with just the first measurement point) versus when a measurement segment has been created helps guide a user while placing measurement points, by indicating where they are in the measurement process. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, as at least one of the one or more cameras moves, the electronic device displays ( 830 ) the measurement-point-creation indicator while the representation of the field of view includes a region corresponding to an identified physical feature in the three-dimensional space in the field of view of at least one of the one or more cameras, In addition, the electronic device ceases to display the measurement-point-creation indicator while the representation of the field of view does not include a region corresponding to an identified physical feature in the three-dimensional space (e.g., as described herein with reference to  FIGS.  5 E- 5 G ). Displaying or not displaying the measurement-point-creation indicator, depending on whether a live view includes a region that corresponds to an identified physical feature in the three-dimensional space, provides visual feedback about the presence or absence of automatically identified features. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  8 A- 8 C  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  800  described above with respect to  FIGS.  8 A- 8 C . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  800  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  900 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  9 A- 9 B  are flow diagrams illustrating method  900  of displaying labels for measurements of a physical space in an augmented reality environment in accordance with some embodiments. Method  900  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a display (e.g., touch screen  112  ( FIG.  1 A ), display  340  ( FIG.  3 A ), or display generation component(s)  304  ( FIG.  3 B )), an input device (e.g., touch screen  112  ( FIG.  1 A ), touchpad  355  ( FIG.  3 A ), input device(s)  302  ( FIG.  3 B ), or a physical button that is separate from the display), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with a touch-sensitive surface of the input device (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  900  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  900  provides an intuitive way to provide labels for different measurements, based on the distance between the electronic device and a given measurement. Providing maximum-size labels at short distances keeps these labels from getting too big and obscuring large portions of the representation of the field of view. Providing minimum-size labels at long distances keeps these labels legible. And providing variable-size labels at intermediate distances indicates the relative distances of the corresponding measurements in the representation of the field of view. Providing labels for different measurements at different distances in this manner enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to see and use measurement labels when operating/interacting with the device). 
     The electronic device displays ( 902 ), on the display, a user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The user interface includes ( 904 ) a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view). The field of view includes a physical object in a three-dimensional space (e.g., a space in the physical world). 
     While displaying the representation of the field of view, the electronic device detects ( 906 ) one or more user inputs (e.g., tap gestures or press inputs on an affordance which, when activated, adds a measurement point to the displayed representation of the field of view), via the input device, that add, over the representation of the field of view, a representation of a first measurement that corresponds to the physical object (e.g., a displayed line that corresponds to a measurement of the length, width, or other dimension of the physical object, where the displayed line is superimposed or overlaid on the representation of the field of view). In some embodiments, the electronic device concurrently displays ( 908 ), over the representation of the field of view, the representation of the first measurement and a first label that describes the first measurement. In some embodiments, in accordance with a determination that a first distance between the electronic device and the physical object (e.g., a distance from one of the cameras of the electronic device to the physical object) is less than a first threshold distance (e.g., a lower distance threshold), the first label is ( 910 ) displayed at a first threshold size (e.g., an upper size threshold, or a maximum size, that does not change as the distance between the electronic device and the physical object decreases below the first threshold distance). In some embodiments, in accordance with a determination that the first distance between the electronic device and the physical object is greater than a second threshold distance (e.g., an upper distance threshold) that is greater than the first threshold distance, the first label is displayed at a second threshold size that is smaller than the first threshold size (e.g., a lower size threshold, or a minimum size, that does not change as the distance between the electronic device and the physical object increases above the second threshold distance). In some embodiments, in accordance with a determination that the first distance between the electronic device and the physical object is between the first threshold distance and the second threshold distance, the first label is displayed at a size, between the first threshold size and the second threshold size, that depends on the first distance between the electronic device and the physical object. Variations in label size based on distance between the electronic device and the physical object are shown in and described herein with reference to  FIGS.  5 AX- 5 BE . 
     In some embodiments, while concurrently displaying, over the representation of the field of view, the representation of the measurement and the label that describes the measurement: while the electronic device (or one of the cameras of the electronic device) is the first distance from the physical object, the electronic device displays ( 912 ) one or more first scale markers along the representation of the measurement at a first scale (e.g., displaying the one or more first scale markers at intervals of a first predefined distance along the representation of the measurement, corresponding to intervals of a first predefined physical distance in the three-dimensional space). In some embodiments, the electronic device detects movement of the electronic device (or movement of the one or more cameras thereof) that moves the electronic device to a second distance from the physical object. In some embodiments, while the electronic device is the second distance from the physical object, the electronic device displays one or more second scale markers along at least a portion of the representation of the measurement at a second scale that is distinct from the first scale (e.g., the electronic device displays the one or more second scale markers at intervals of a second predefined distance along the representation of the measurement, corresponding to intervals of a second predefined physical distance in the three-dimensional space). Variations in the scale of displayed markers based on distance between the electronic device and the physical object are shown in and described herein with reference to  FIGS.  5 AX- 5 BE . 
     In some embodiments, the one or more first scale markers at the first scale are displayed along the representation of the measurement while the electronic device is within a first predefined range of distances from the physical object (e.g., distances greater than the second threshold distance, or distances between the first threshold distance and the second threshold distance), where the first predefined range of distances includes the first distance. In some embodiments, the one or more second scale markers at the second scale are displayed along at least a portion of the representation of the measurement (e.g., if only a portion of the representation of the measurement continues to be displayed in the user interface as a result of the movement of the electronic device closer to the physical object) while the electronic device is within a second predefined range of distances from the physical object (e.g., distances between the first threshold distance and the second threshold distance, or distances less than the first threshold distance), where the second predefined range of distances includes the second distance. 
     In an example, the detected movement of the electronic device moves the electronic device closer to the physical object, such that the first distance is greater than the second distance. While the electronic device is the first distance from the physical object, the one or more scale markers are displayed at intervals along the representation of the measurement corresponding to intervals of one foot in the three-dimensional space. In the same example, while the electronic device is the second distance from the physical object, the one or more scale markers are displayed at intervals along the representation of the measurement corresponding to intervals of one inch in the three-dimensional space. One of ordinary skill in the art will recognize that different predefined physical distances may be denoted by the scale markers displayed while the device is at a respective distance from the physical object, such as meters, decimeters, centimeters, millimeters, yards, feet, inches, quarter inches, or any other suitable distance. 
     Providing scale markers that automatically change scale as the distance from a measurement to the device changes is more efficient than requiring a user to change the scale manually. Performing an operation when a set of conditions has been met (e.g., distance conditions) without requiring further user input enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the electronic device detects ( 914 ) a second set of one or more user inputs that add, over the representation of the field of view, a representation of a second measurement that corresponds to a respective physical object (e.g., the same physical object to which the first measurement corresponds, or a different physical object in the three-dimensional space) in the three-dimensional space. In some embodiments, the electronic device concurrently displays, over the representation of the field of view, the representation of the second measurement and a second label that describes the second measurement. In some embodiments, in accordance with a determination that a second distance between the electronic device and the respective physical object is less than the first threshold distance, the second label is displayed at the first threshold size. In some embodiments, in accordance with a determination that the second distance between the electronic device and the respective physical object is greater than the second threshold distance, the second label is displayed at the second threshold size. In some embodiments, in accordance with a determination that the second distance between the electronic device and the respective physical object is between the first threshold distance and the second threshold distance, the second label is displayed at a size, between the first threshold size and the second threshold size, that depends on the second distance between the electronic device and the respective physical object. In some embodiments, the representation of the field of view concurrently displays multiple labels that change in size as the field of view changes. 
     In some embodiments, the first distance between the electronic device and the physical object to which the first measurement corresponds is ( 916 ) different from the second distance between the electronic device and the respective physical object to which the second measurement corresponds. In some embodiments, the first label is displayed at a first size (e.g., based on the first distance), the second label is displayed at a second size (e.g., based on the second distance), and the first size is different from the second size. In an example, the first distance is in a first predefined range of distances, and the second distance is in a second predefined range of distances (e.g., the first predefined range is one of: distances less than the first threshold distance, distances greater than the second threshold distance, or distances between the first threshold distance and the second threshold distance, and the second predefined range is a different one of the aforementioned ranges). In another example, the first distance and the second distances are different distances in the range of distances between the first threshold distance and the second threshold distance, and, accordingly, the respective sizes of their associated labels (e.g., the labels corresponding to the measurements at the first distance and the second distance) are different. 
     It should be understood that the particular order in which the operations in  FIGS.  9 A- 9 B  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  900  described above with respect to  FIGS.  9 A- 9 B . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  900  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  1000 ,  1100 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  10 A- 10 B  are flow diagrams illustrating method  1000  of measuring and interacting with rectangular areas in a physical space in an augmented reality environment in accordance with some embodiments. Method  1000  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a display (e.g., touch screen  112  ( FIG.  1 A ), display  340  ( FIG.  3 A ), or display generation component(s)  304  ( FIG.  3 B )), an input device (e.g., touch screen  112  ( FIG.  1 A ), touchpad  355  ( FIG.  3 A ), input device(s)  302  ( FIG.  3 B ), or a physical button that is separate from the display), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with a touch-sensitive surface of the input device (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  1000  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  1000  provides an intuitive way to detect and indicate a rectangle that adjoins a measurement. By having the detected rectangle adjoin a measurement made in response to user inputs, method  1000  reduces the risk that the device will detect and indicate rectangles that are not relevant to the user (e.g., are not being measured), thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling faster and more efficient detection and display of relevant rectangles conserves power and increases the time between battery charges. 
     The electronic device displays ( 1002 ), on the display, a user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The user interface includes ( 1004 ) a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view). The field of view includes a physical object (or portion thereof) in a three-dimensional space (e.g., a space in the physical world). 
     While displaying the representation of the field of view, the electronic device detects ( 1006 ) one or more user inputs (e.g., tap gestures or press inputs on an affordance which, when activated, adds a measurement point to the displayed representation of the field of view), via the input device, that add, over the representation of the field of view, a representation of a first measurement that corresponds to the physical object (e.g., the detected user inputs cause the electronic device to add a displayed line that corresponds to a measurement of an edge of the physical object, where the displayed line is superimposed or overlaid on the representation of the field of view). 
     The representation of the first measurement includes ( 1008 ) a first endpoint that corresponds to a first location on the physical object. The representation of the first measurement includes a second endpoint that corresponds to a second location on the physical object. The representation of the first measurement includes a first line segment connecting the first endpoint and the second endpoint. The addition of a representation of a measurement including two endpoints and a first line segment connecting the two endpoints is shown in and described herein with reference to  FIGS.  5 J- 5 O . 
     The electronic device determines ( 1010 ), based in part on the first measurement (or the representation thereof), a first area in the representation of the field of view that adjoins the first line segment of the first measurement. The first area corresponds to a physical rectangular area (e.g., the entire physical rectangular area or a portion thereof) in the three-dimensional space. For example, the first area corresponds to a physical rectangular area, or a portion thereof, of the physical object and the first measurement corresponds to one edge of the physical rectangular area of the physical object). In some embodiments, the first area in the representation of the field of view is not displayed as rectangular in the representation of the field of view, due to a viewing angle of at least one of the one or more cameras with respect to the physical rectangular area. In some embodiments, the electronic device determines that the physical area corresponding to the first area in the representation of the field of view is a rectangular area based on image processing (e.g., using depth estimation) of the representation of the field of view. In some embodiments, the field of view of at least one of the one or more cameras includes a first portion of the physical rectangular area without including one or more additional portions of the physical rectangular area. In some embodiments, viewing the one or more additional portions of the physical rectangular area requires movement of the device that moves the field of view of at least one of the one or more cameras to include the one or more additional portions of the physical rectangular area. 
     The electronic device displays ( 1012 ) an indication of the first area in the user interface (e.g., indicator  5058 ,  FIG.  5 P ). The indication is overlaid (e.g., superimposed) on the first area in the representation of the field of view. 
     In some embodiments, the user interface includes ( 1014 ) a measurement-point-creation indicator that is displayed over the representation of the field of view (e.g., reticle  5010  in combination with focus point  5012 ,  FIG.  5 Y ). In some embodiments, the indication of the first area is displayed in accordance with a determination that the measurement-point-creation indicator is displayed over the first area in the representation of the field of view of the one or more cameras (e.g., as shown in and described herein with reference to  FIG.  5 Y ). In some embodiments, while the measurement-point-creation indicator (or at least a portion thereof) is over the first area, the electronic device detects a user input via the input device (e.g., a tap gesture or press input on a touch-sensitive surface at a location corresponding to an affordance which, when activated, adds a measurement or measurement point to the displayed representation of the field of view). In some embodiments, in response to detecting the user input while the measurement-point-creation indicator is over the first area, the electronic device changes a visual appearance of the indication of the first area to indicate that the first area has been confirmed (e.g., as shown in and described herein with reference to  FIG.  5 Z ). 
     In some embodiments, the user input is detected while the measurement-point-creation indicator is over the first area and while the indication of the first area is displayed, and the visual appearance of the indication of the first area is changed in response to (e.g., in accordance with) detecting the user input both while the measurement-point-creation indicator is over the first area and while the indication of the first area is displayed. In some embodiments, the method includes displaying, over the representation of the field of view, one or more labels that describe the first area (e.g., concurrently displayed with the indication displayed with changed visual appearance). In some embodiments, the one or more labels that describe the first area include a label that indicates a length of a first side of the first area (e.g., a length of the physical rectangular area), a label that indicates a length of a second side of the first area (e.g., a width of the physical rectangular area), and/or a label that indicates an area of the first area (e.g., an area of the physical rectangular area) (e.g., as shown in and described herein with reference to  FIG.  5 Z ). 
     Changing the appearance of the indication of the first area provides visual feedback that the electronic device has detected the user&#39;s confirmation that the rectangle adjoining the first measurement is correct. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the one or more user inputs add ( 1016 ), over the representation of the field of view, a representation of a second measurement that corresponds to the physical object (e.g., the detected user inputs cause the electronic device to add a second displayed line that corresponds to a measurement of a second edge of the physical object, where the second displayed line is superimposed or overlaid on the representation of the field of view) (e.g., a measurement represented by measurement segment  5066  and its corresponding endpoints,  FIG.  5 Y ). In some embodiments, the representation of the second measurement includes the second endpoint that corresponds to the second location on the physical object (e.g., measurement point  5054 ,  FIG.  5 Y ). In some embodiments, the representation of the second measurement includes a third endpoint that corresponds to a third location on the physical object (e.g., the third location is different from the first location and the second location) (e.g., measurement point  5090 ,  FIG.  5 Y ). In some embodiments, the representation of the second measurement includes a second line segment connecting the second endpoint and the third endpoint (e.g., measurement segment  5066 ,  FIG.  5 Y ). In some embodiments, the first area in the representation of the field of view of the one or more cameras is determined based on the first measurement and the second measurement. In some embodiments, the first area adjoins the first line segment of the first measurement and the second line segment of the second measurement. Determining the first area based on two measurements reduces the risk that the device will detect and indicate rectangles that are not relevant to the user (e.g., are not being measured), thereby enhancing the operability of the device and making the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the field of view of at least one of the one or more cameras includes ( 1018 ) a first portion of the physical rectangular area, and the first area corresponds to the first portion of the physical rectangular area (e.g., as described with reference to the region indicated by indicator  5104 ,  FIG.  5 AB ). In some embodiments, the electronic device detects movement of the electronic device that moves the field of view of at least one of the one or more cameras (e.g., as shown in and described herein with reference to  FIGS.  5 AC- 5 AD ). In some embodiments, in response to detecting the movement of the electronic device that moves the field of view, the electronic device updates the representation of the field of view over time to display one or more indications of one or more additional areas that correspond to one or more additional portions of the physical rectangular area. In some embodiments, in accordance with a determination that an aggregate area, including the first area and the one or more additional areas displayed over time, corresponds to the entire physical rectangular area, the electronic device displays, over the representation of the field of view, a label that describes a measurement that corresponds to the physical rectangular area (e.g., as described herein with reference to label  5110 ,  FIG.  5 AE ). In some embodiments, the label indicates an area of the measurement (e.g., an area of the entire physical rectangular area). Automatically showing, as the field of view changes, indications of additional areas that correspond to the physical rectangular area provides visual feedback that the electronic device has correctly detected the physical rectangular area. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, after displaying, over the representation of the field of view, the label that describes the measurement that corresponds to the physical rectangular area in accordance with the determination that the aggregate area corresponds to the entire physical rectangular area, the electronic device detects ( 1020 ) further movement of the electronic device that moves the field of view of at least one of the one or more cameras such that the representation of the field of view includes the first area corresponding to the first portion of the physical rectangular area. In some embodiments, in accordance with the determination that the aggregate area corresponds to the entire physical rectangular area, the electronic device displays, over the first area corresponding to the first portion of the physical rectangular area, the label that describes the measurement that corresponds to the physical rectangular area (e.g., as described herein with reference to  FIG.  5 AF ). Displaying the label describing the measurement of the physical rectangular area at different portions of the physical rectangular area when those portions are (re)displayed provides visual feedback that the electronic device has correctly detected the physical rectangular area and that the measurement has been correctly associated with all portions of the physical rectangular area. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  10 A- 10 B  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1100 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  1000  described above with respect to  FIGS.  10 A- 10 B . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  1000  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1100 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  11 A- 11 B  are flow diagrams illustrating method  1100  of interacting with and managing measurement information in an augmented reality environment in accordance with some embodiments. Method  1100  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a touch-sensitive display (e.g., touch screen  112  ( FIG.  1 A ), or display generation component(s)  304  in combination with input device(s)  302  ( FIG.  3 B )), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with the touch-sensitive display (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  1100  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  1100  provides an intuitive way to share information about a measurement, by initiating a process for sharing the information in response to detecting a touch input on a representation of the measurement. Method  1100  reduces the number, extent, and/or nature of the inputs from a user when sharing information about a measurement, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to share information about a measurement faster and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 1102 ), on the touch-sensitive display, a first user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). 
     The first user interface includes ( 1104 ) a representation of a field of view of at least one of the one or more cameras. The representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view). The field of view includes a physical object in a three-dimensional space (e.g., a space in the physical world). A representation of a measurement of the physical object is superimposed on an image of the physical object in the representation of the field of view. 
     While displaying the first user interface, the electronic device detects ( 1106 ) a first touch input on the touch-sensitive display on the representation of the measurement (e.g., a tap, double tap, or press input on the displayed measurement) (e.g., touch-input  5182 ,  FIG.  5 BL ). 
     In response to detecting the first touch input on the touch-sensitive display on the representation of the measurement, the electronic device initiates ( 1108 ) a process for sharing information about the measurement (e.g., sending information about the measurement to a clipboard process or a communication application (e.g., a text messaging application, an e-mail application, a file transfer application), etc.) (e.g., as described herein with reference to  FIGS.  5 BL- 5 BM ). In some embodiments, the process includes adding the measurement information to a clipboard. In some embodiments, the process includes sending the information to a second application. In some embodiments, initiating the process includes displaying a second user interface that includes user-selectable options for sharing the information about the measurement, such as a share sheet user interface. In some embodiments, the second user interface includes the information describing the measurement. In some embodiments, the information includes an automatically generated semantic label classifying the physical object (e.g., as a window, wall, floor, or table) on which the measurement is superimposed. In some embodiments, the information includes an automatically generated semantic label classifying a relationship between the first measurement and the physical object (e.g., a length, width, height, or depth of the physical object). 
     In some embodiments, initiating the process for sharing information about the measurement includes ( 1110 ) copying the information about the measurement (e.g., to a clipboard process provided by an operating system of the electronic device). In some embodiments, after copying the information about the measurement, the electronic device detects one or more user inputs to paste the information about the measurement to a destination on the electronic device. In some embodiments, in response to detecting the one or more user inputs to paste the information about the measurement to the destination on the electronic device, the electronic device displays the information about the measurement at the destination on the electronic device. Enabling copying and pasting of the information about the measurement makes it easy to share the measurement within the same application and with other applications on the electronic device. Making information available to multiple applications enhances the operability of the device and makes the user-device interface more efficient (e.g., by making it easy to select an application for sharing or sending the measurement). 
     In some embodiments, initiating the process for sharing the information about the measurement includes ( 1112 ) displaying a second user interface (e.g., measurement management interface  5184 ,  FIG.  5 BM ) that includes one or more activatable user interface elements, where a respective activatable user interface element in the one or more activatable user interface elements corresponds to a respective destination for the information about the measurement (e.g., icons  5192 ,  5194 , and  5196 ,  FIG.  5 BM ). In some embodiments, each of the one or more activatable user interface elements corresponds to a respective application (other than the first application) or process on the electronic device (e.g., a messaging application (e.g., icon  5194 ,  FIG.  5 BM ), an email application (e.g., icon  5192 , FIG.  5 BM), a notetaking application, a file transfer protocol (e.g., icon  5196 ,  FIG.  5 BM ), etc.). In some embodiments, the electronic device detects a second touch input on the touch-sensitive display on a respective activatable user interface element in the second user interface. In some embodiments, in response to detecting the second touch input, the electronic device transmits the information about the measurement to the respective destination corresponding to the respective activatable user interface element. 
     In some embodiments, transmitting the information about the measurement to the respective destination includes transmitting the information to a second application (e.g., a notetaking application) on the electronic device. In some embodiments, transmitting the information about the measurement to the respective destination includes displaying a third user interface for reviewing, editing, and/or annotating the information about the measurement prior to transmitting the information to a subsequent destination (e.g., the third user interface includes an affordance upon selection of which the information, including any edits and annotations, is transmitted from the respective destination (e.g., a messaging application or an email application) to a subsequent destination (e.g., another electronic device)). In some embodiments, transmitting the information about the measurement to the respective destination includes transmitting the information to a second electronic device via a file transfer protocol between the electronic device and the second electronic device. 
     Providing a user interface with activatable user interface elements for multiple destinations for the shared measurement (e.g., a share sheet with destination icons) makes it easy to share the measurement with these destinations. Providing multiple sharing destination options enhances the operability of the device and makes the user-device interface more efficient (e.g., by making it easy to select an application for sharing or sending the measurement). 
     In some embodiments, in response to detecting the first touch input on the touch-sensitive display on the representation of the measurement, the electronic device displays ( 1114 ) the information about the measurement. In some embodiments, the information about the measurement includes a magnitude of the measurement (e.g., as shown in measurement management interface  5184 ,  FIG.  5 BM ). In some embodiments, the information about the measurement includes a semantic label classifying a relationship between the measurement and the physical object (e.g., a length, width, height, or depth of the physical object) (e.g., as described herein with reference to label  5186 - b  in measurement management interface  5184 ,  FIG.  5 BM ). In some embodiments, the information about the measurement includes a label (e.g., a text label) classifying a relationship between the measurement and an identified anchor feature of the three-dimensional space (e.g., whether an area in the representation of the field of view corresponds to a physical rectangular area that is parallel to the ground). In some embodiments, where the measurement corresponds to a physical rectangular area and includes a length measurement, a width measurement, and an area measurement, the length, width, and area are displayed, and the length and width are displayed more prominently than the area. Providing information about the measurement, in addition to initiating a process for sharing the information, in response to detecting a touch input on a representation of the measurement, provides visual feedback that the user has selected the correct measurement for sharing, and allows a user to see and use the information. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the displaying of the information about the measurement is ( 1116 ) performed in accordance with a determination that the first touch input meets first criteria, where the first criteria include a requirement that an intensity of a contact in the first touch input meet (e.g., reach or exceed) a respective intensity threshold in order for the first criteria to be met (e.g., as described herein with reference to  FIGS.  5 BL- 5 BM ). In some embodiments, the respective intensity threshold is a light-press intensity threshold IT L  that is above a contact detection intensity threshold IT 0 . Providing information about the measurement in response to detecting a touch input on a representation of the measurement that meets intensity criteria reduces accidental, unwanted display of the information. Performing an operation when intensity criteria have been met enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the electronic device determines ( 1118 ) a classification of the physical object (e.g., a classification of the physical object as a respective structural feature (such as a window, a wall, a floor, etc.) or as a respective piece of furniture or fixture (such as a table)). In some embodiments, the information about the measurement includes a label indicating the classification of the physical object (e.g., as described herein with reference to label  5186 - a  in measurement management interface  5184 ,  FIG.  5 BM ). In some embodiments, the electronic device classifies the physical object based on image processing (e.g., using feature recognition) of the representation of the field of view of the one or more cameras. Automatically classifying and labeling the physical object, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient by reducing (or eliminating) the need for the user to manually classify and label physical objects. 
     In some embodiments, the representation of the measurement was ( 1120 ) added to the user interface of the application based at least in part on movement of the electronic device in a first direction during the measurement. In some embodiments, the electronic device determines a classification of a relationship between the measurement and the physical object (e.g., a classification of the measurement as corresponding to a length, width, height, or depth of the physical object) based at least in part on the movement of the electronic device in the first direction during the measurement (e.g., as described herein with reference to  FIG.  5 BM ). 
     In some embodiments, the information about the measurement includes a label indicating the classification of the relationship between the measurement and the physical object. For example, the electronic device classifies the measurement as a height of the physical object based on the movement of the electronic device being in a vertical direction during the measurement, or as a width of the physical object based on the movement of the electronic device being in a horizontal direction during the measurement. In some embodiments, the electronic device classifies the relationship between the measurement and the physical object based further on image processing (e.g., feature recognition) of the representation of the field of view to determine respective distances between the electronic device and respective points on the physical object corresponding to respective points along the measurement. For example, the electronic device classifies the measurement as a depth of the physical object based further on a determination that a first point on the physical object, corresponding to a first endpoint of the measurement, is further from (or closer to) (e.g., in a z-direction) the electronic device than a second point on the physical object, corresponding to a second endpoint of the measurement. 
     Automatically classifying and labeling a measurement, based in part on the movement of the device during the measurement, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient, by reducing (or eliminating) the need for the user to manually classify and label measurements. 
     It should be understood that the particular order in which the operations in  FIGS.  11 A- 11 B  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1200 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  1100  described above with respect to  FIGS.  11 A- 11 B . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  1100  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1200 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  12 A- 12 C  are flow diagrams illustrating method  1200  of providing automatically determined alignment guides in an augmented reality environment in accordance with some embodiments. Method  1200  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes a display (e.g., touch screen  112  ( FIG.  1 A ), display  340  ( FIG.  3 A ), or display generation component(s)  304  ( FIG.  3 B )), an input device (e.g., touch screen  112  ( FIG.  1 A ), touchpad  355  ( FIG.  3 A ), or input device(s)  302  ( FIG.  3 B ), or a physical button that is separate from the display), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with a touch-sensitive surface of the input device (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  1200  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  1200  provides an intuitive way to provide (virtual) guides in an augmented reality-based measurement, with the guides extending along a direction of movement of a field of view of a camera. Providing measurement guides helps a user position and place (virtual) measurement points quickly and accurately. By automatically providing guides along a direction of movement of a field of view of a camera, method  1200  reduces the number, extent, and/or nature of the inputs from a user when making measurements, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to make measurements faster and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 1202 ), on the display, a user interface of an application (e.g., an augmented reality measurement application or an application that includes augmented reality measurement functionality). The user interface includes ( 1204 ) a representation of a field of view of at least one of the one or more cameras; the representation of the field of view is updated over time based on changes to current visual data detected by at least one of the one or more cameras (e.g., the representation of the field of view is a live view); and the field of view includes at least a portion of a three-dimensional space (e.g., a space in the physical world that includes physical objects). 
     The electronic device detects ( 1206 ) movement of the electronic device that moves the field of view of at least one of the one or more cameras in a first direction (e.g., horizontally, or vertically) (or, in some embodiments, in substantially the first direction (e.g., a direction that is within a predefined threshold angle of a first direction, such as within 10, 15, 20 or 25 degrees of the first direction)). 
     While detecting the movement of the electronic device that moves the field of view in the first direction ( 1208 ), the electronic device updates ( 1210 ) the representation of the field of view in accordance with the movement of the electronic device; identifies ( 1212 ) one or more first elements (or features) in the representation of the field of view that extend along the first direction (e.g., a detected edge, a detected plane, etc.); and, based at least in part on the determination of the one or more first elements, displays ( 1214 ), in the representation of the field of view, a first guide that extends in the first direction and that corresponds to one of the one or more first identified elements (e.g., as described herein with reference to virtual guide  5050 ,  FIG.  5 M ). In some embodiments, the electronic device displays a plurality of guides in the first direction (e.g., as described herein with reference to virtual guides  5106 ,  FIG.  5 AB ). In some embodiments, each of the plurality of guides corresponds to a respective identified element that extends along the first direction (e.g., a respective edge, of a respective physical object in the three-dimensional space, that extends along the first direction). In some embodiments, the electronic device displays one or more guides in the first direction while detecting the movement of the electronic device. 
     In some embodiments, the field of view includes ( 1216 ) a plurality of elements, and the plurality of elements includes one or more elements that extend in directions other than the first direction (e.g., directions perpendicular to or substantially perpendicular to (e.g., within a predefined threshold angle of being perpendicular to) the first direction, or directions that are greater than a predefined threshold angle from the first direction, such as greater than 10, 15, 20 or 25 degrees from the first direction). In some embodiments, while detecting the movement of the electronic device that moves the field of view in the first direction, the electronic device forgoes displaying guides that extend in directions other than the first direction (e.g., as described herein with reference to  FIGS.  5 AN- 5 AO and  5 AV ). For example, the electronic device determines an axis of a physical object (e.g., a table or a wall) along which to extend guides based on the direction of movement of the camera. In some embodiments, the electronic device displays one or more guides, corresponding to one or more elements in the field of view, that extend in the direction of movement of at least one camera, without displaying guides that extend in directions other than the direction of motion of the at least one camera. Providing one or more guides along the direction of movement of the field of view, without providing guides that extend in other directions, avoids displaying guides that are not likely to be relevant to the measurement being made. Reducing clutter in the user interface enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, prior to detecting the movement of the electronic device that moves the field of view in the first direction ( 1218 ), the electronic device detects a first touch input on the touch-sensitive display, and, in response to detecting the first touch input, adds and displays a first (virtual) measurement point at a first location in the representation of the field of view that corresponds to a first location in the three-dimensional space (e.g., measurement point  5054 ,  FIG.  5 R ). Displaying the first guide is further based on a determination that the one or more first elements correspond to the first location in the three-dimensional space (e.g., the first location is a point along a detected edge). In addition, the first guide includes the first location in the representation of the field of view (e.g., the guide overlaps with the measurement point, or extends from the measurement point in the first direction) (e.g., as described herein with reference to virtual guide  5070 ,  FIG.  5 S ). Providing a guide that extends from and/or includes a first measurement point along the direction of movement of the field of view helps a user to place a second measurement point, and thereby make a measurement. Providing this visual feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the first measurement point at the first location in the representation of the field of view is ( 1220 ) a most-recently-added measurement point in the representation of the field of view. Providing a guide that extends from and/or includes the most-recently-added measurement point along the direction of movement of the field of view helps a user to place the next measurement point, and thereby make a measurement between the two most-recently-added measurement points. Providing this visual feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, after detecting the movement of the electronic device that moves the field of view in the first direction (e.g., horizontally, as described herein with reference to  FIG.  5 S ), the electronic device ( 1222 ) detects movement of the electronic device that moves the field of view in a second direction (e.g., vertically, as described herein with reference to  FIG.  5 T ). In response to detecting the movement of the electronic device that moves the field of view in the second direction, the electronic device ceases to display the first guide that extends in the first direction. In some embodiments, the electronic device ceases to display any guides in any directions other than the second direction or within a predefined threshold angle of the second direction (e.g., as described herein with reference to  FIG.  5 T ). While detecting the movement of the electronic device that moves the field of view in the second direction, the electronic device updates the representation of the field of view in accordance with the movement of the electronic device, identifies one or more second elements in the representation of the field of view that extend along the second direction, and, based at least in part on the determination of the one or more second elements, displays, in the representation of the field of view, a second guide that extends in the second direction and that corresponds to one of the one or more identified second elements (e.g., virtual guide  5072 ,  FIG.  5 T ). Automatically changing guides, as the direction of movement of the field of view changes, displays guides that are more likely to be relevant to the measurement being made (and ceases to display guides that are less likely to be relevant to the measurement being made). Reducing clutter in the user interface enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, at least one of the one or more first identified elements to which the first guide corresponds is ( 1224 ) an element identified as an edge of a physical object in the three-dimensional space (e.g., as described herein with reference to  FIG.  5 S ). Automatically displaying a guide along an edge of a physical object that runs in the first direction helps a user to place measurement points and make measurements along the edge. Automatically providing a guide along an edge of an object, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, at least one of the one or more first identified elements to which the first guide corresponds is ( 1226 ) an element identified as a plane in the three-dimensional space (e.g., corresponding to a surface of a physical object in the three-dimensional space). Automatically displaying a guide along a plane that runs in the first direction helps a user to place measurement points and make measurements along the plane. Automatically providing a guide along a plane, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the user interface includes ( 1228 ) a measurement-point-creation indicator that is displayed over the representation of the field of view. In some embodiments, the electronic device displays a respective measurement point at a respective location in the representation of the field of view that corresponds to a respective location in the three-dimensional space. In some embodiments, the electronic device detects movement of the electronic device that moves the measurement-point-creation indicator over the respective measurement point in the representation of the field of view, and, in response to detecting the movement of the electronic device, while the measurement-point-creation indicator is displayed over the respective measurement point, the electronic device displays a plurality of guides. A first guide of the plurality of guides is perpendicular to a second guide of the plurality of guides, and the plurality of guides intersect at the respective measurement point. Display of perpendicular guides is described herein with reference to  FIG.  5 AT . 
     In some embodiments, a respective guide of the plurality of guides is displayed based at least in part on a determination that the respective guide extends along an element in the representation of the field of view that extends from the measurement point. For example, if the measurement point corresponds to a corner of a physical object in the three-dimensional space, the one or more guides include a guide that extends in a first direction (e.g., along an x-axis) from the corner of the physical object along an edge of the physical object that extends in the first direction (e.g., an edge corresponding to a (horizontal) length of the physical object), as displayed in the representation of the field of view. In some embodiments, the one or more guides include a guide that extends in a second direction (e.g., along a y-axis) from the corner of the physical object along an edge of the physical object that extends in the second direction (e.g., corresponding to a (vertical) height of the physical object), as displayed in the representation of the field of view. In some embodiments, the one or more guides include a guide that extends in a third direction (e.g., along a z-axis) from the corner of the physical object along an edge of the physical object that extends in the third direction (e.g., an edge corresponding to a depth of the physical object), as displayed in the representation of the field of view. 
     Automatically displaying a plurality of perpendicular guides at a measurement point, while a measurement-point-creation indicator is displayed over the measurement point, helps a user to place additional measurement points. Automatically providing perpendicular guides at a measurement point, without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the user interface includes ( 1230 ) a measurement-point-creation indicator that is displayed over a second location in the representation of the field of view. In some embodiments, while displaying the first guide that extends in the first direction, the electronic device detects a second touch input on the touch-sensitive display. In response to detecting the second touch input, and in accordance with a determination that a distance (e.g., a shortest distance) between the second location and the first guide is within a threshold distance, the electronic device adds and displays a second (virtual) measurement point at the location on the first guide that is the distance from the second location. For example,  FIG.  5 X  illustrates the addition of measurement point  5090  at a point on virtual guide  5072 . In response to detecting the second touch input, and in accordance with a determination that a distance between the second location and the first guide is not within the threshold distance, the electronic device adds and displays the second measurement point at the second location (e.g., measurement point  5080  is not within the threshold distance of virtual guide  5072 , and thus measurement point  5080  is not added to a point on virtual guide  5072 ). Automatically adding a measurement point on a guide (e.g., snapping the measurement point to a location on the guide) or adding the measurement point off the guide, depending on the distance between the location of a measurement-point-creation indicator and the guide, helps a user to place measurement points quickly and accurately. Performing an operation when a set of conditions has been met (e.g., a distance condition), without requiring further user input, enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper measurement inputs and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  12 A- 12 C  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1300 , and  1400 ) are also applicable in an analogous manner to method  1200  described above with respect to  FIGS.  12 A- 12 C . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  1200  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1300 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  13 A- 13 C  are flow diagrams illustrating method  1300  of automatically removing previously-added virtual annotations in accordance with some embodiments. Method  1300  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes one or more input devices (e.g., touch screen  112  ( FIG.  1 A ), touchpad  355  ( FIG.  3 A ), or input device(s)  302  ( FIG.  3 B ), or a physical button that is separate from the display), one or more display devices (e.g., touch screen  112  ( FIG.  1 A ), display  340  ( FIG.  3 A ), or display generation component(s)  304  ( FIG.  3 B )), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with a touch-sensitive surface of the input device (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  1300  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  1300  provides an intuitive way to automatically delete prior virtual annotations (such as prior augmented-reality-based measurements) that are not connected or related to current virtual annotations (such as current augmented-reality-based measurements). Automatically deleting prior, unrelated virtual annotations prevents the augmented reality user interface from becoming cluttered with earlier virtual annotations while making new virtual annotations. As described herein, method  1300  makes it easy to make individual virtual annotations without having to manually delete prior virtual annotations, and also makes it easy to take a series of related virtual annotations (e.g., connected virtual annotations) without deleting early virtual annotations in the series as new virtual annotations are added to the series. The method reduces the number, extent, and/or nature of the inputs from a user when making augmented-reality-based virtual annotations, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to make augmented-reality-based virtual annotations faster and more efficiently conserves power and increases the time between battery charges. 
     In particular, when the virtual annotations are augmented-reality-based measurements, automatically deleting prior, unrelated augmented-reality-based measurements prevents the measurement user interface from becoming cluttered with earlier measurements while making new measurements. These automatic deletions also remove measurements for which the electronic device may no longer have accurate mappings to the physical space. As described herein, method  1300  makes it easy to take individual measurements without having to manually delete prior measurements, and also makes it easy to take a series of related measurements (e.g., connected measurements) without deleting early measurements in the series as new measurements are added to the series. The method reduces the number, extent, and/or nature of the inputs from a user when making augmented-reality-based measurements, thereby creating a more efficient human-machine interface. For battery-operated electronic devices, enabling a user to make augmented-reality-based measurements faster and more efficiently conserves power and increases the time between battery charges. 
     The electronic device displays ( 1302 ), via the one or more display devices, a user interface that includes a representation of a physical space (e.g., a live preview of a portion of the physical space that is in the field of view of at least one of the one or more cameras). For example, user interface  5006  in  FIG.  5 B  S includes a representation of physical space  5000 . 
     While displaying the representation of the physical space, the electronic device receives ( 1304 ) a first set of one or more inputs to create a virtual annotation (e.g., a shape, line, rectangle, measurement, or the like) in the representation of the physical space (e.g., an input to drop a point followed by movement of the electronic device relative to the physical space followed by another input to drop a point). 
     In response to receiving the first set of one or more inputs, the electronic device adds ( 1306 ) a first virtual annotation to the representation of the physical space. The first virtual annotation is linked to a portion of the representation of the physical space. For example, as shown in  FIG.  5 BS- 5 BU , a virtual annotation that includes measurement segment  5212  and its associated endpoints  5206  and  5216  is created in user interface  5006  and linked to a representation of (physical) object  5202 . As another example, as shown in  FIGS.  5 BV- 5 BY , a virtual annotation that includes measurement segment  5222  and its associated endpoints  5220  and  5224  is created in user interface  5006  and linked to a representation of object  5202 . 
     In some embodiments, adding a virtual annotation to the representation of the physical space includes creating a virtual annotation and linking it to a position in the representation of the physical space, so that the virtual annotation appears fixed or substantially fixed in the representation of the physical space. In some embodiments, a virtual annotation “in” the representation of the physical space or “added to” the representation of the physical space is actually added to a model of the physical space and is drawn on top of camera images of the physical space when the portion of the representation of the physical space to which the virtual annotation is linked appears in the camera images of the physical space, to give the impression that the virtual annotation is in the physical space. In some embodiments, a virtual annotation “removed from” the representation of the physical space is actually removed from a model of the physical space and, once it has been “removed from” the representation of the physical space, it is no longer drawn on top of camera images of the physical space when the portion of the representation of the physical space to which the virtual annotation was linked appears in the camera images of the physical space, to give the impression that the virtual annotation is no longer in the physical space. 
     After adding the first virtual annotation to the representation of the physical space, the electronic device receives ( 1310 ) a second set of one or more inputs associated with the representation of the physical space. 
     In response to receiving the second set of one or more inputs associated with the representation of the physical space ( 1312 ), in accordance with a determination that the second set of one or more inputs corresponds to a request to create a virtual annotation in the representation of the physical space that is within a threshold distance from the first virtual annotation ( 1314 ), the electronic device creates a second virtual annotation in the representation of the physical space (e.g., linked to a second portion of the representation of the physical space) while maintaining the first virtual annotation in the representation of the physical space. In some embodiments, the first virtual annotation and the second virtual annotation are concurrently displayed. In some embodiments, the threshold distance is zero (e.g., the second virtual annotation must be connected with the first virtual annotation in order for the first virtual annotation to be maintained when the second virtual annotation is created). In some embodiments, the threshold distance is greater than zero (e.g., if the second virtual annotation is within a predetermined distance to the first virtual annotation, the first virtual annotation is maintained when the second virtual annotation is created, even if the second virtual annotation is not connected to or touching the first virtual annotation). For example, as shown in  FIGS.  5 BZ- 5 CF , because measurement segment  5232  is within a threshold distance from previously-added measurement segment  5222 , previously-added measurement segment  5222  is maintained in the representation of physical space  5000  in user interface  5006  when/after measurement segment  5232  is created. In another example, as shown in  FIGS.  5 CG- 5 CK , because measurement segment  5242  is within a threshold distance from previously-added measurement segments  5232  and  5222 , previously-added measurement segments  5232  and  5222  are maintained in the representation of physical space  5000  in user interface  5006  when/after measurement segment  5242  is created. 
     In addition, in response to receiving the second set of one or more inputs associated with the representation of the physical space ( 1312 ), in accordance with a determination that the second set of one or more inputs corresponds to a request to create a virtual annotation in the representation of the physical space that is outside of the threshold distance from the first virtual annotation ( 1316 ), the electronic device creates a second virtual annotation in the representation of the physical space (e.g., linked to a second portion of the representation of the physical space) and removes the first virtual annotation from the representation of the physical space. In some embodiments, the first virtual annotation is removed without an explicit request to remove the first virtual annotation (e.g., the device does not detect a user input, separate from the second set of inputs used to create the second virtual annotation, requesting deletion of the first virtual annotation). For example, as shown in  FIGS.  5 BV- 5 BY , because measurement segment  5222  is outside of the threshold distance from previously-added measurement segment  5212 , previously-added measurement segment  5212  is removed when/after measurement segment  5222  is added. 
     In some embodiments, creating the second virtual annotation in the representation of the physical space while maintaining the first virtual annotation in the representation of the physical space includes ( 1318 ) starting to create the second virtual annotation at a location that corresponds to at least a portion of the first virtual annotation (e.g., if the creation of measurement segment  5232  in  FIGS.  5 CA- 5 CF  had instead started with the placement of measurement point  5234  in  FIG.  5 CF  and ended with the placement of measurement point  5228  in  FIG.  5 CA ). Automatically keeping a prior virtual annotation when a subsequent virtual annotation starts on the prior virtual annotation enables the electronic device to make a series of related virtual annotations (e.g., a series of connected measurements), without deleting early annotations (e.g., measurements) in the series as new annotations are added to the series. Performing an operation when a set of conditions has been met (e.g., when a subsequent virtual annotation starts on the prior virtual annotation) without requiring further user input enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, creating the second virtual annotation in the representation of the physical space while maintaining the first virtual annotation in the representation of the physical space includes ( 1320 ) completing creation of the second virtual annotation at a location that corresponds to at least a portion of the first virtual annotation. For example, as shown in  FIGS.  5 BZ- 5 CF , creation of measurement segment  5232  is completed at a location that corresponds to an endpoint of measurement segment  5222 , and measurement segment  5222  is thus maintained in the representation of physical space  5000 . Automatically keeping a prior virtual annotation when a subsequent virtual annotation ends on the prior virtual annotation enables the electronic device to make a series of related virtual annotations (e.g., a series of connected measurements), without deleting early annotations (e.g., measurements) in the series as new annotations are added to the series. Performing an operation when a set of conditions has been met (e.g., when a subsequent virtual annotation ends on the prior virtual annotation) without requiring further user input enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, in response to receiving the second set of one or more inputs associated with the representation of the physical space ( 1322 ), in accordance with a determination that the second set of one or more inputs correspond to a request to shift a field of view of at least one of the one or more cameras by more than a threshold amount (e.g., shifting a field of view of at least one of the one or more cameras by an amount that causes a fidelity of tracking of the link between the first virtual annotation and the representation of the physical space to degrade by more than a threshold amount), the electronic device removes the first virtual annotation from the representation of the physical space. In some embodiments, the first virtual annotation is removed without an explicit request to remove the first virtual annotation (e.g., the electronic device does not detect a user input requesting deletion of the first virtual annotation). An example of removal of virtual annotations in accordance with movement of the camera(s) by more than a threshold amount is described herein with reference to  FIGS.  5 CL- 5 CM . Automatically removing a prior virtual annotation (e.g., measurement) when the field of view for a subsequent virtual annotation shifts by more than a threshold amount reduces clutter in the augmented reality user interface and avoids potential problems with the fidelity of tracking and displaying prior virtual annotations that are not near new virtual annotations. Performing an operation when a set of conditions has been met without requiring further user input enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, in response to receiving the second set of one or more inputs associated with the representation of the physical space ( 1324 ), in accordance with a determination that the second set of one or more inputs correspond to a request to shift a field of view of at least one of the one or more cameras so that the first virtual annotation is no longer visible for more than a threshold amount of time (e.g., shifting a field of view of at least one of the one or more cameras away from the portion of the physical space to which the first virtual annotation appears to be linked for more than a threshold amount of time), the electronic device removes the first virtual annotation from the representation of the physical space. In some embodiments, the first virtual annotation is removed without an explicit request to remove the first virtual annotation (e.g., the device does not detect a user input requesting deletion of the first virtual annotation). An example of removal of virtual annotations in accordance with movement of the camera(s) so that the virtual annotations are no longer visible for more than a threshold amount of time is described herein with reference to  FIGS.  5 CL- 5 CM . Automatically removing a prior virtual annotation (e.g., measurement) when the field of view for a subsequent virtual annotation shifts by more than a threshold amount of time reduces clutter in the augmented reality user interface and avoids potential problems with the fidelity of tracking and displaying prior virtual annotations that are not near new virtual annotations. Performing an operation when a set of conditions has been met without requiring further user input enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, while receiving the second set of one or more inputs and while the first virtual annotation is in the representation of the physical space, the electronic device outputs ( 1326 ) an indication that further input will cause the first virtual annotation to be removed from the representation of the physical space. In some embodiments, the indication includes a graphical indication, an audio indication, and/or a tactile indication. For example, as shown in  FIGS.  5 BW- 5 BX , device  100  changes the appearance of measurement segment  5212  to indicate that further input will cause measurement segment  5212  to be removed from the representation of physical space  5000  in user interface  5006 . In another example, as shown in  FIGS.  5 CA- 5 CB , device  100  changes the appearance of measurement segment  5222  to indicate that further input will cause measurement segment  5222  to be removed from the representation of physical space  5000  in user interface  5006 . Providing visual, audio, and/or haptic feedback that further input will delete the prior virtual annotation (e.g., measurement) provides an opportunity to alter the input so that the prior virtual annotation is not accidentally removed. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the indication is ( 1328 ) a visual indication that is displayed in a predetermined portion of the user interface that is used for displaying alerts (e.g., a designated alert area in the user interface, such as the area in user interface  5006  above reticle  5010  (e.g., the area in which error message  5248  is displayed in  FIG.  5 CM )). Providing visual feedback in a designated area of the user interface for displaying alerts increases the likelihood that a user will see and understand the feedback/alert. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the indication is ( 1330 ) a change in appearance of the first virtual annotation in the representation of the physical space (e.g., changing a line color, line style, line thickness, fill, opacity, etc.). For example, as shown in  FIGS.  5 BW- 5 BX , the appearance (e.g., line color and line style) of measurement segment  5212  is changed. In some embodiments, the change in appearance of the first virtual annotation increases in magnitude as a reticle for point placement moves away from the first virtual annotation). Providing visual feedback by changing the appearance of the first virtual annotation increases the likelihood that a user will see and understand that the first virtual annotation will be removed if the same input continues. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the first virtual annotation is ( 1332 ) a representation of a measurement that includes a description of the measurement (e.g., a text description of the distance or area measured by the measurement), and the change in appearance of the first virtual annotation includes removing the description from the representation of the measurement while maintaining at least a portion of the representation of the measurement. For example, as shown in  FIG.  5 BV , the label associated with measurement segment  5212  is removed when reticle  5010  is moved away from measurement segment  5212 . Providing visual feedback by removing a label or other description from a measurement while maintaining a line or other shape that represents the measurement increases the likelihood that a user will see and understand that the measurement will be removed if the same input continues. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, after displaying the change in appearance of the first virtual annotation in the representation of the physical space ( 1334 ), the electronic device detects an input at a location within a threshold distance (e.g., the same threshold distance that will be used to determine whether or not to remove the first virtual annotation from the display when the second virtual annotation is created) from the first virtual annotation (e.g., hovering the reticle for point placement on or near the first virtual annotation), and, in response to detecting the input at the location within the threshold distance form the first virtual annotation, reverses the change in appearance of the first virtual indication (e.g., to indicate that if the second virtual annotation includes a portion at the location within the threshold distance from the first virtual annotation, the first virtual annotation will not be removed when the second virtual annotation is created). For example, the change in appearance of measurement segment  5222  from  FIGS.  5 CA- 5 CB  is reversed in  FIG.  5 CC  when focus point  5012  snaps to a point on measurement segment  5222 . After providing visual feedback to indicate that the prior virtual annotation will be removed, and after a user alters their input by making the input closer to or on the prior virtual annotation, providing feedback to indicate that the prior virtual annotation will be maintained helps guide the user&#39;s input. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  13 A- 13 C  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 , and  1400 ) are also applicable in an analogous manner to method  1300  described above with respect to  FIGS.  13 A- 13 C . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  1300  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 , and  1400 ). For brevity, these details are not repeated here. 
       FIGS.  14 A- 14 D  are flow diagrams illustrating method  1400  of indicating whether objects in a physical space have been identified as objects whose corresponding representations in an augmented reality environment can be tracked in accordance with some embodiments. Method  1400  is performed at an electronic device (e.g., portable multifunction device  100  ( FIG.  1 A ), device  300  ( FIG.  3 A ), or computer system  301  ( FIG.  3 B )) that includes one or more input devices (e.g., touch screen  112  ( FIG.  1 A ), touchpad  355  ( FIG.  3 A ), or input device(s)  302  ( FIG.  3 B ), or a physical button that is separate from the display), one or more display devices (e.g., touch screen  112  ( FIG.  1 A ), display  340  ( FIG.  3 A ), or display generation component(s)  304  ( FIG.  3 B )), and one or more cameras (e.g., optical sensor(s)  164  ( FIG.  1 A ) or camera(s)  305  ( FIG.  3 B )), optionally one or more sensors to detect intensities of contacts with a touch-sensitive surface of the input device (e.g., contact intensity sensor(s)  165 ,  FIG.  1 A ), and optionally one or more tactile output generators (e.g., tactile output generator(s)  163  ( FIG.  1 A ) or tactile output generator(s)  357  ( FIG.  3 A )). Some operations in method  1400  are, optionally, combined and/or the order of some operations is, optionally, changed. 
     As described below, method  1400  provides visual feedback while placing virtual annotations (e.g., virtual measurements) in an augmented reality environment. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     The electronic device displays ( 1402 ), via the one or more display devices, an annotation placement user interface. The annotation placement user interface includes ( 1404 ): a representation of a physical space (e.g., a live preview of a portion of the physical space that is in the field of view of at least one of the one or more cameras); and a placement user interface element (e.g., a placement indicator) that indicates a location at which a virtual annotation will be placed in the representation of the physical space in response to detecting an annotation placement input (e.g., a tap on a drop point button or a tap on the placement user interface element). For example, as shown in  FIG.  5 CN , device  100  displays user interface  5006  that includes a representation of physical space  5000  and a placement user interface element in the form of reticle  5010  in conjunction with focus point  5012  that indicates a location at which a virtual annotation will be placed in the representation of physical space  5000  in response to detecting an annotation placement input (e.g., a tap on measurement addition button  5014  or, in some embodiments, a tap on reticle  5010  and/or focus point  5012 ). 
     While displaying the annotation placement user interface, the electronic device detects ( 1406 ) movement of at least one of the one or more cameras relative to the physical space. The movement of at least one of the one or more cameras starts ( 1408 ) while the placement user interface element is displayed at a location in the representation of the physical space that corresponds to a first portion of the physical space. In some embodiments, the movement includes one or more of moving laterally (e.g., moving up, down, left, right), rotating (e.g., rotating right, left, up, down), or moving forward or backward. 
     In response to detecting the movement of at least one of the one or more cameras relative to the physical space, the electronic device moves ( 1410 ) the placement user interface element to a location in the representation of the physical space that corresponds to a second portion of the physical space that is different from the first portion of the physical space, and updates an appearance of the annotation placement user interface in accordance with the movement of at least one of the one or more cameras relative to the physical space, including: in accordance with a determination that the electronic device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, ceasing ( 1412 ) to display at least a portion of the placement user interface element; and in accordance with a determination that the device has identified an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, maintaining ( 1414 ) display of the placement user interface element. For example, as shown in  FIG.  5 CN , reticle  5010  and focus point  5012  are displayed in accordance with a determination that device  100  has identified an object (table  5200 ) in physical space  5000  such that measurements can be added to the representation of table  5200  in user interface  5006 . In  FIG.  5 CO , reticle  5010  and focus point  5012  are not displayed in accordance with a determination that device  100  is unable to identify such an object in physical space  5000 . Providing visual feedback that the electronic device is unable to identify an object in the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation (e.g., by ceasing to display at least a portion of the placement user interface element) informs a user that the field of view needs to be changed (by moving the electronic device) until such an object is identified. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, in response to detecting the movement of at least one of the one or more cameras relative to the physical space ( 1416 ): in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that corresponds to a first object in the physical space that is a first distance away from one of the one or more cameras, the electronic device displays the placement user interface element at a first size; and in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that corresponds to a second object in the physical world that is a second distance away from one of the one or more cameras, the electronic device displays the placement user interface element at a second size. In some embodiments, the first distance is greater than the second distance and the first size is less than the second size. For example, as shown in  FIGS.  5 BO and  5 BT , reticle  5010  and focus point  5012  are displayed at smaller respective sizes when positioned over a location in the live preview that corresponds to a further point in physical space  5000  (as shown in  FIG.  5 BO ) than when positioned over a location in the live preview that corresponds to a closer point in physical space  5000  (as shown in  FIG.  5 BT ). In another example, as shown in  FIGS.  5 CG and  5 CJ , reticle  5010  and focus point  5012  are displayed at smaller respective sizes when positioned over a location in the live preview that corresponds to a further point in physical space  5000  (as shown in  FIG.  5 CG ) than when positioned over a location in the live preview that corresponds to a closer point in physical space  5000  (as shown in  FIG.  5 CJ ). When the placement user interface element is at the location of a given object in the live view from a camera, the electronic device adjusts the size of the placement user interface element based on the distance from the camera to the given object in the physical space. This visual feedback provides information to a user about the relative positions of objects in the physical space. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the first size of the placement user interface element in the representation of the physical space is ( 1418 ) larger relative to the first object in the physical space than the second size of the placement user interface element in the representation of the physical space relative to the second object in the physical space (e.g., as described herein with reference to  FIG.  5 BT ). Although in some embodiments the size of the placement user interface element is based on the distance from the camera to the given object in the physical space, to avoid having the size be too small when an object is far away from the camera (or be too large when the object is very close to the camera), the size in some embodiments does not scale precisely with distance. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the placement user interface element includes ( 1420 ) a first portion (e.g., a reticle, such as reticle  5010  in  FIG.  5 CC ) and a second portion (e.g., a dot, such as focus point  5012  in  FIG.  5 CC , or other marker). In some embodiments, in response to detecting the movement of at least one of the one or more cameras relative to the physical space: in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that corresponds to a predefined type of feature in the physical space (e.g., a corner, line or other feature that the second portion of the placement user interface element can snap to), the electronic device updates the appearance of the placement user interface element so that the second portion of the placement user interface element is enlarged relative to the first portion of the placement user interface element; and in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that does not correspond to a predefined type of feature in the physical space (e.g., a corner, line or other feature that the second portion of the placement user interface element can snap to), the electronic device maintains display of the placement user interface element without enlarging the second portion of the placement user interface element relative to the first portion of the placement user interface element. For example, as shown in  FIGS.  5 CC and  5 CE , when focus point is snapped to an anchor point (such as a point of interest on a previously-added measurement or a point of interest on a representation of a physical object), focus point  5012  is enlarged relative to reticle  5010  (and relative to the size of focus point  5012  when not snapped to an anchor point). Changing the appearance of the placement user interface element (e.g., by increasing the size of a placement dot relative to the rest of the placement user interface element) when it is over a feature that a virtual annotation point can be snapped to makes it easy to add a virtual annotation point at that feature. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments in which the placement user interface element includes ( 1422 ) a first portion (e.g., a reticle) and a second portion (e.g., a dot or other marker), in response to detecting the movement of at least one of the one or more cameras relative to the physical space: in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that corresponds to a predefined type of feature in the physical space (e.g., a corner, line or other feature that the second portion of the placement user interface element can snap to), the electronic device updates the appearance of the placement user interface element so that the second portion of the placement user interface element is shifted relative to the first portion of the placement user interface element; and in accordance with a determination that the placement user interface element is at a location in the representation of the physical space that does not correspond to a predefined type of feature in the physical space (e.g., a corner, line or other feature that the second portion of the placement user interface element can snap to), the electronic device maintains display of the placement user interface element without shifting the second portion of the placement user interface element relative to the first portion of the placement user interface element. For example, as shown in  FIGS.  5 CC and  5 CE , when focus point is snapped to an anchor point (such as a point of interest on a previously-added measurement or a point of interest on a representation of a physical object), focus point  5012  is shifted relative to reticle  5010  (and relative to the position of focus point  5012  within reticle  5010  when not snapped to an anchor point). Changing the appearance of the placement user interface element when it is over a feature that a virtual annotation point can be snapped to (e.g., by shifting the location of a placement dot relative to the rest of the placement user interface element, so that the placement dot snaps to the feature) makes it easy to add a virtual annotation point at that feature. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, in response to detecting the movement of at least one of the one or more cameras relative to the physical space ( 1424 ), in accordance with a determination that the device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, the electronic device displays an alert (e.g., separate from or overlaid on the annotation placement user interface) with information indicating that the electronic device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation. For example, as shown in  FIG.  5 CO , in response to movement of device  100  further away from table  5200  device  100  displays error message  5250  to indicate that device  100  is unable to identify an object in physical space  5000  whose corresponding object in the representation of physical space  5000  in user interface  5006  can be linked to a virtual annotation (e.g., a virtual measurement). Displaying an alert that the electronic device is unable to identify an object in the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation informs a user that the field of view needs to be changed (by moving the electronic device) until such an object is identified. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, in response to detecting the movement of at least one of the one or more cameras relative to the physical space ( 1426 ), in accordance with a determination that the device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, the electronic device displays an alert (e.g., separate from or overlaid on the placement user interface) with information indicating a reason that the electronic device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation. In some embodiments, the alert includes information describing steps that can be taken to improve the ability of the electronic device to identify objects in the physical space. For example, as shown in  FIG.  5 CO , in response to movement of device  100  further away from table  5200  device  100  displays error message  5250  to indicate that device  100  is unable to identify an object because device  100  needs to be moved closer to objects in the field of view of the camera. Displaying an alert that: (1) explains why the electronic device is unable to identify an object in the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation, and/or (2) informs a user how the field of view needs to be changed (e.g., by moving the electronic device) helps to correct this situation. Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, the information indicating the reason that the device is unable to identify an object in the second portion of the physical space whose corresponding object in the representation of the physical space can be linked to a virtual annotation includes ( 1428 ) one or more of: an indication that more light is required (e.g., as shown in  FIG.  5 D ), an indication that at least one of the one or more cameras (or the electronic device) is moving too fast, an indication that at least one of the one or more cameras (or the electronic device) needs to be moved to locate a surface in the physical space (e.g., as shown in  FIG.  5 E ), an indication that at least one of the one or more cameras (or the electronic device) needs to be moved further away from objects in the physical space, and an indication that at least one of the one or more cameras (or the electronic device) needs to be moved closer to objects in the physical space (e.g., as shown in  FIG.  5 CO ). 
     In some embodiments, while displaying the placement user interface element at a location over the representation of the physical space that corresponds to the second portion of the physical space, the electronic device detects ( 1430 ) a placement input (e.g., a tap gesture on the placement user interface element or a button that triggers placement of virtual annotations in the annotation placement user interface). In some embodiments, in response to detecting the placement input, the electronic device places at least a portion of a virtual annotation in the representation of the physical space at a location that corresponds to the placement user interface element. In some embodiments, the placement of the portion of the annotation includes dropping a first point in a measurement. In some embodiments, the placement of the portion of the annotation includes dropping a second or third point in a measurement. In some embodiments, the placement of the portion of the annotation includes completing placement of a measurement in the representation of the physical space. For example, as shown in  FIGS.  5 BP- 5 BQ , touch input  5204  (e.g., a tap gesture) on reticle  5010  and focus point  5012  triggers placement of measurement point  5206  in the representation of physical space  5000  in user interface  5006  at the location that corresponds to focus point  5012 . Placing a virtual annotation point at the displayed location of the placement user interface element, in response to a placement input, makes it easy to position the virtual annotation point at the correct location in the representation of the physical space. Providing improved visual feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     In some embodiments, while displaying the placement user interface element at a location over the representation of the physical space that corresponds to the second portion of the physical space, the electronic device detects ( 1432 ) an input at a location that corresponds to the placement user interface element (e.g., for an electronic device with a touch-sensitive display, a tap gesture on the placement user interface element). In some embodiments, in response to detecting the input at the location that corresponds to the placement user interface element, the electronic device displays a graphical indication adjacent to (or near) a different user interface element in the annotation placement user interface that indicates that activation of the different user interface element (e.g., for a touch-sensitive display, by a tap gesture on the different user interface element) will cause placement of at least a portion of a virtual annotation in the representation of the physical space at a location that corresponds to the placement user interface element (e.g., the electronic device displays instructions to tap a button to drop a point, where the button is different from the placement user interface element and is located away from the placement user interface element). For example, as shown in  FIG.  5 BR , touch input  5204  (e.g., a tap gesture) on reticle  5010  and focus point  5012  results in display of instruction message  5208  near measurement addition button  5014  to indicate that activation of measurement addition button  5014  will cause placement of a measurement point in the representation of physical space  5000  in user interface  5006  at the location that corresponds to focus point  5012 . In some embodiments, when a user tries to create a virtual annotation point by tapping on the placement user interface element (rather than tapping on a different element, such as a “+,” “add,” or similar element), the electronic device displays a message next to the “+,” “add,” or similar element indicating that this is the correct element to tap on to create a virtual annotation point (instead of tapping on the placement user interface element). Providing improved feedback enhances the operability of the device and makes the user-device interface more efficient (e.g., by helping the user to provide proper inputs and reducing user mistakes when operating/interacting with the device). 
     It should be understood that the particular order in which the operations in  FIGS.  14 A- 14 D  have been described is merely an example and is not intended to indicate that the described order is the only order in which the operations could be performed. One of ordinary skill in the art would recognize various ways to reorder the operations described herein. Additionally, it should be noted that details of other processes described herein with respect to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 , and  1300 ) are also applicable in an analogous manner to method  1400  described above with respect to  FIGS.  14 A- 14 D . For example, the inputs, user interface elements (e.g., measurement points, measurement segments, virtual annotations, representations of the physical space or field of view, affordances, alerts, indicators, labels, anchor points, and/or placement user interface elements such as a reticle and dot), tactile outputs, and intensity thresholds described above with reference to method  1400  optionally have one or more of the characteristics of the inputs, user interface elements, tactile outputs, and intensity thresholds described herein with reference to other methods described herein (e.g., methods  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 , and  1300 ). For brevity, these details are not repeated here. 
     The operations described above with reference to  FIGS.  6 A- 6 C,  7 A- 7 E,  8 A- 8 C,  9 A- 9 B,  10 A- 10 B,  11 A- 11 B,  12 A- 12 C,  13 A- 13 C, and  14 A- 14 D  are, optionally, implemented by components depicted in  FIGS.  1 A- 1 B . For example, detecting operations  606 ,  614 ,  706 ,  708 ,  812 ,  906 ,  1006 ,  1106 ,  1206 ,  1334 ,  1430 , and  1432 , and receiving operations  1304  and  1310  are, optionally, implemented by event sorter  170 , event recognizer  180 , and event handler  190 . Event monitor  171  in event sorter  170  detects a contact on touch-sensitive display  112 , and event dispatcher module  174  delivers the event information to application  136 - 1 . A respective event recognizer  180  of application  136 - 1  compares the event information to respective event definitions  186 , and determines whether a first contact at a first location on the touch-sensitive display (or whether rotation of the device) corresponds to a predefined event or sub-event, such as selection of an object on a user interface, or rotation of the device from one orientation to another. When a respective predefined event or sub-event is detected, event recognizer  180  activates an event handler  190  associated with the detection of the event or sub-event. Event handler  190  optionally uses or calls data updater  176  or object updater  177  to update the application internal state  192 . In some embodiments, event handler  190  accesses a respective GUI updater  178  to update what is displayed by the application. Similarly, it would be clear to a person having ordinary skill in the art how other processes can be implemented based on the components depicted in  FIGS.  1 A- 1 B . 
     The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best use the invention and various described embodiments with various modifications as are suited to the particular use contemplated.

Metadata:
Filing Date: 20230925
Publication Date: 20241224
Grant Date: 20241224
Priority Date: 20180507
Inventors: DRYER, ALLISON W.
PAUL, Grant R.
LEMAY, STEPHEN O.
FORSSELL, Lisa K.
Assignee: APPLE INC
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