Abstract:
A background thread can be used to process events, e.g., a touch, gesture, pinch, or swipe, that are received on a touch sensitive device, or events, e.g., mouse scroll wheel events that are received on a input device, e.g., a mouse. The background thread can be used to process events when a main thread assigned to the Graphical User Interface (GUI) is interrupted. In such situations, the background thread can continue processing events. In cases where the main thread is interrupted and the event is scroll input, the background thread can draw content on the GUI in response to the scroll, so that the response to the scroll input observed by the user is unaffected by the interrupted main thread. By processing events and drawing content using the background thread while the main thread is blocked, the GUI can be navigated without having the user experience a stall or stutter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Application No. 61/658,884, filed Jun. 12, 2012, and titled “Input Device Event Processing,” which is incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This subject matter is generally related to processing events for navigating content in graphical user interface (GUI). 
       BACKGROUND 
       [0003]    Graphical user interfaces (GUIs) are often used to display content, e.g., graphical representations of electronic documents, images, and text. Users can navigate between pages of the displayed content by interacting with a touch sensitive surface using one or more fingers and/or making gestures, or by a mouse or mouse scroll wheel. 
       SUMMARY 
       [0004]    This disclosure describes systems, methods, and computer program products for scrolling content that is displayed on a GUI. 
         [0005]    In multithreaded computing environments, a device running an operating system can execute one or more processes for performing various jobs, e.g., executing a computer program. Each process can spawn one or more threads that can be used to execute various sub-tasks. Generally, a thread of execution is the smallest unit of processing that can be scheduled by an operating system. In some implementations, a first or “main” thread is assigned to process tasks relating to a GUI. For example, the main thread can be used to draw content on the GUI and to process user feedback, e.g., process input device events that are received on a touch sensitive surface or generated by a mouse, e.g., mouse scroll wheel. 
         [0006]    In some implementations, one or more other threads (hereinafter also referred to as “background” threads) can be used to process input device events, e.g., a touch, gesture, pinch, swipe, or finger move, as received on a touch sensitive surface, or a mouse scroll wheel move, as received on a mouse. A background thread runs separately from the main thread and is able to process its own tasks concurrently with the tasks being processed by the main thread. The one or more background threads can be used to process input device events in situations when a main thread assigned to the GUI is interrupted, e.g., stalled. In such situations, the one or more background threads can continue processing input device events when the main thread is not responding. In cases where the main thread is interrupted and the input device event is a scroll input, i.e., input that moves graphical content displayed on a user interface, the one or more background threads can draw content on the GUI in response to the scroll input, so that the processing of the scroll input observed by the user is unaffected by the main thread being interrupted. In some implementations, the one or more background threads draw content that was cached during processing of input device events by the main thread before it became interrupted. In some implementations, when cached content is unavailable, the drawn content can be a placeholder graphic, e.g., a checkerboard graphic. By processing input device events and drawing content using the one or more background threads while the main thread is blocked, the GUI can be navigated without having the user experience a stall or stutter. 
         [0007]    In some implementations, a method includes: receiving one or more input device events for navigating content presented on a graphical user interface; storing the one or more input device events in an event queue, the event queue including one or more events relating to the graphical user interface; processing events stored in the event queue using a first processing thread; determining an interrupt in the processing of the events by the first processing thread; and in response to the determination, spawning a second processing thread, wherein the second processing thread processes the one or more input device events from the event queue, wherein the method is performed by one or more hardware processors. 
         [0008]    In some implementations, a method includes: receiving one or more input device events for navigating content presented on a graphical user interface; storing the one or more input device events in an event queue, the event queue including one or more events relating to the graphical user interface; processing the one or more events from the event queue using a first processing thread; and processing the one or more input device events from the event queue using a second processing thread; wherein the method is performed by one or more hardware processors. 
         [0009]    In some implementations, a method includes: receiving one or more input device events for navigating content presented on a graphical user interface; storing the one or more input device events in an event queue, the event queue including one or more events relating to the graphical user interface; processing the one or more events from the event queue using a first processing thread; predicting an interrupt in the processing of the one or more events by the first processing thread; and in response to the prediction, instructing a second processing thread to process the one or more events from the event queue, wherein the method is performed by one or more hardware processors. 
         [0010]    Other implementations are disclosed which are directed to systems, methods and computer-readable mediums. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  illustrates exemplary architecture for processing events for navigating content in a GUI. 
           [0012]      FIG. 2  illustrates an exemplary process for processing events for navigating content in a GUI. 
           [0013]      FIG. 3  illustrates another exemplary process for processing events for navigating content in a GUI. 
           [0014]      FIGS. 4A-4B  are exemplary diagrams illustrating processing of an event relating to a graphical user interface. 
           [0015]      FIG. 5  is a block diagram of an exemplary architecture for a device capable of processing events for navigating content in a GUI. 
       
    
    
       [0016]    The same reference symbol used in various drawings indicates like elements. 
       DETAILED DESCRIPTION 
     Example Device Architecture for Processing Events 
       [0017]    Hereafter, when the disclosure refers “to select” or “selecting” user interface elements in a GUI, these terms are understood to include clicking or “hovering” with a mouse or other input device over a user interface element, or touching, tapping or gesturing with one or more fingers or stylus on a user interface element. User interface elements can be virtual buttons, menus, selectors, switches, sliders, scrubbers, knobs, thumbnails, links, icons, radial buttons, checkboxes and any other mechanism for receiving input from a user. 
         [0018]      FIG. 1  illustrates exemplary architecture  100  for processing events for navigating content in a graphical user interface (GUI). The example device architecture  100  can include a touch component  102 , e.g., a touch sensitive or enabled device or touch sensitive surface, an input device  103 , e.g., a mouse or track ball, an event dispatch module  104 , and an event processing module  108 . 
         [0019]    The touch component  102  can receive input data generated by touch-sensitive surface  101 . Touch component  102  can implement a touch event model that maps the received touch input into input device events. Touch-sensitive surface  101  can process multiple simultaneous points of input, e.g., input device events, including processing data related to the pressure, degree or position of each point of input. Such processing facilitates gestures with multiple fingers, including pinching and swiping. The input device  103 , e.g., a mouse, can generate input data, e.g., input device events. 
         [0020]    Event dispatch module  104  can receive data describing events from the touch component  102  and the input device  103 , and can store the received data describing the input device events in event queue  106 . For example, a user interacting with touch-sensitive surface  101  can provide touch input, e.g., a swipe, pinch, and tap, on content displayed on a GUI or other touch surface (e.g., a touch pad) and, in response, event queue  106  can store data describing the input device events in the order they were performed. In addition to storing the received input device events, event queue  106  can store data describing other events relating to the GUI, e.g., messages to be displayed at a particular position on the GUI. 
         [0021]    Events stored in event queue  106  can be processed by an event processing module  108  in the order in which they were stored in event queue  106 . In some implementations, event processing module  108  can spawn a first thread, such as a main user interface (UI) thread  110  for processing events from event queue  106 . Main UI thread  110  can process events stored in event queue  106  in the order in which the events were received by the event dispatch module  104 . 
         [0022]    In various implementations, event processing module  108  can spawn one or more other threads, such as one or more background threads  112  that can process events from event queue  106 . In some implementations, the one or more background threads  112  process events stored in event queue  106  when main UI thread  110  is interrupted, e.g., main UI thread  110  has stalled or has stopped responding while processing events. 
         [0023]    In some implementations, one or more background threads  112  process input device events that are stored in event queue  106  when the processing by main UI thread  110  is interrupted. In some other implementations, main UI thread  110  can predict when processing is going to be interrupted and, in response to the prediction, can instruct one or more background threads  112  to process events stored in event queue  106 . In some implementations, event dispatch module  104  can store input device events that were received after main UI thread  110  has been interrupted in one or more secondary event queues  114 . In such implementations, one or more background threads  112  can process input device events that were stored in one or more secondary event queues  114 . 
       Exemplary Process for Processing Events for Navigating Content 
       [0024]      FIG. 2  is a flow diagram of an example process for processing events for navigating content in a GUI. In some implementations, process  200  can be implemented using the architecture described in reference to  FIG. 1 . 
         [0025]    In some implementations, process  200  can begin by receiving data describing input device events, e.g., from touch component  102  or input device  103 , as described in reference to  FIG. 1  ( 202 ). The data can describe the type of input device event, e.g., a touch, gesture, pinch, scroll, or swipe, and how the input device event affects the GUI, e.g., the speed and distance of a scroll. Other types of input device events include a mouse move, e.g., movement of content presented on a UI by clicking one or more buttons on the UI or by dragging the content with the mouse, a mouse scroll wheel event, e.g., scrolling content using a mouse scroll wheel, or a keyboard move, e.g., moving the content using one or more keys on a keyboard. 
         [0026]    Process  200  can continue by storing the received data describing the input device events in an event queue, e.g., event queue  106 , as described in reference to  FIG. 1  ( 204 ). As described in  FIG. 1 , event queue  106  can store other events that generally relate to the GUI, e.g., presentation of content on the GUI, as well as input device events affecting the GUI. 
         [0027]    Process  200  can continue by processing data describing events stored in the event queue ( 206 ). The data describing events stored in the event queue can be executed, using, e.g., event processing module  108 , as described in reference to  FIG. 1 . Event processing module  108  can use a run loop to monitor event  106  queue to determine when data describing an event has been stored in event queue  106 . Upon determining that data describing an event has been stored in event queue  106 , event processing module  108  can use one or more threads of execution, e.g., main user interface (UI) thread  110 , to execute the data describing the event. 
         [0028]    For example, a run loop can be used to monitor event queue  106  to determine when data describing input device events, e.g., a swipe, pinch, scroll, and tap, is received and stored by event queue  106 . In response to the determination, event processing module  108  can use, e.g., main UI thread  110  for processing events from the event queue. 
         [0029]    Process  200  can continue by determining that an interrupt occurred in the processing of an event ( 208 ). For example, the main UI thread can become interrupted, e.g., stalled, while executing an event when the execution is particularly memory and/or processor intensive, or when the execution takes longer than a particular period of time. In some implementations, a main UI thread interrupt, or stall, can be detected by maintaining a time stamp of when the last event was processed by the main UI thread. If a subsequent event in the event queue is not processed with a specified time period, as measured from the time stamp, then the main UI thread is considered stalled. 
         [0030]    Process  200  can continue by processing events using one or more background threads ( 210 ) (e.g., background threads  112 ). In some implementations, one or more background threads can execute data describing events from the event queue upon determining that the main UI thread has become interrupted. In some implementations, input device events received after the main UI thread has been interrupted are stored in a second event queue (e.g., a secondary event queue  114 ) and one or more background threads are used to execute data describing input device events that were stored in the second event queue. 
         [0031]    In some implementations, process  200  determines that the main UI thread is no longer interrupted and, in response to the determination, process  200  communicates data to the main UI thread describing the input device events that were processed by the one or more background threads. For example, process  200  can determine that the main UI thread is no longer interrupted when the main UI thread completes its processing of an event. In some implementations, the main UI thread uses the communicated data describing the input device events that were processed by the one or more background threads to update the GUI. For example, the communicated data may indicate that content on the GUI has scrolled to a new position, and the main UI thread can use the communicated data to determine where to display a message on the GUI. 
         [0032]    When executing data describing input device events, the one or more background threads may update the GUI, e.g., by drawing content, in response to a input device event. For example, when executing data describing a downward scroll, a background thread may need to update the position of content, e.g., a document or web page, being presented on the GUI by drawing additional content. In some implementations, the background thread draws content that was cached during processing of input device events by the main UI thread. In some implementations, when cached content is unavailable, the background thread draws a placeholder graphic, e.g., a checkerboard. The placeholder graphic can serve as an indicator that a scroll has occurred but that the following content is not yet available for presentation. 
         [0033]    In some implementations, the main UI thread can predict when processing is going to be interrupted and, in response to the prediction, can instruct the one or more background threads to process events stored in the event queue. In some implementations, an interrupt can be predicted by having an application that is being processed by the main UI thread communicate information to the application framework indicating that a particularly intensive memory and/or processor operation is about to, or is scheduled to, be performed. 
       Another Exemplary Process for Processing Events for Navigating Content 
       [0034]      FIG. 3  is a flow diagram of an example process for processing events for navigating content in GUI. In some implementations, process  300  can be implemented using the architecture described in reference to  FIG. 1 . 
         [0035]    In some implementations, process  300  can begin by receiving data describing input device events, e.g., from a touch component  102  or input device  103 , as described in reference to  FIG. 1  ( 302 ). 
         [0036]    Process  300  can continue by storing the received data describing the input device events in an event queue, e.g., an event queue  106 , as described in reference to  FIG. 1  ( 304 ). As described in  FIG. 1 , the event queue can store events that generally relate to the GUI, e.g., presentation of content on the GUI, as well as input device events affecting the GUI. In some implementations, the events describe operations relating to the GUI, e.g., messages to be displayed on the GUI or content to be drawn on the GUI, and the input device events reference a touch, gesture, pinch, swipe, mouse input, or mouse scroll, as described in reference to  FIG. 1 . 
         [0037]    In some implementations, the data describing events is executed by a first thread and data describing input device events is executed by a second thread. Thus, for example, input device events can be processed exclusively by one or more dedicated background threads. In some implementations, the event queue is shared between the first and second threads. In some implementations, the event queue is partitioned so that the input device events are stored in a specified address space. For example, for an event queue of size 100, the address space defined by the first 50 slots can be allocated to data describing events, and the address space defined by the last 50 slots can be allocated to data describing input device events. 
         [0038]    Process  300  can continue by processing data describing events stored in the event queue using a first thread ( 306 ). For example, the process  300  can use a main user interface (UI) thread for processing data describing events stored in the event queue, as described in reference to  FIG. 2 . 
         [0039]    Process  300  can continue by processing input device events using a second thread ( 308 ). For example, one or more background threads can execute data describing input device events stored in the event queue. 
         [0040]    In some implementations, input device events received after the main UI thread has been interrupted are stored in a second event queue and one or more background threads are used to execute data describing input device events that were stored in the second event queue. 
       Exemplary Sequence Diagrams 
       [0041]      FIG. 4A  is an exemplary sequence diagram  400  illustrating processing of an event, e.g., a scroll, relating to a graphical user interface (GUI) by a main user interface (UI) thread  402 . At  404 , the main UI thread is interrupted and, as result, the main UI thread  402  is no longer processing the event relating to the GUI stalled  406  for a period of time  406 . At  408 , the main UI thread  402  resumes processing of the event relating to the GUI and processes the event until completion  410 . 
         [0042]      FIG. 4B  is an exemplary diagram  450  illustrating processing of an event, e.g., a scroll, relating to a GUI according to an implementation described in this specification. In  FIG. 4B , the event is processed by a main user interface thread  452 . At  454 , a determination is made that the main UI thread  452  is interrupted. In response to the determination, a background thread  456  is spawned and the background thread  456  processes the event until completion  460 . 
       Exemplary Device Architecture 
       [0043]      FIG. 5  is a block diagram of an exemplary architecture for a device capable of input device event processing. Architecture  500  can be implemented in any device for generating the features described in reference to  FIGS. 1-4 , including but not limited to portable or desktop computers, smart phones and electronic tablets, television systems, game consoles, kiosks and the like. Architecture  500  can include memory interface  502 , data processor(s), image processor(s) or central processing unit(s)  504 , and peripherals interface  506 . Memory interface  502 , processor(s)  504  or peripherals interface  506  can be separate components or can be integrated in one or more integrated circuits. The various components can be coupled by one or more communication buses or signal lines. 
         [0044]    Sensors, devices, and subsystems can be coupled to peripherals interface  506  to facilitate multiple functionalities. For example, motion sensor  510 , light sensor  512 , and proximity sensor  514  can be coupled to peripherals interface  506  to facilitate orientation, lighting, and proximity functions of the device. For example, in some implementations, light sensor  512  can be utilized to facilitate adjusting the brightness of touch surface  546 . In some implementations, motion sensor  510  (e.g., an accelerometer, gyros) can be utilized to detect movement and orientation of the device. Accordingly, display objects or media can be presented according to a detected orientation (e.g., portrait or landscape). 
         [0045]    Other sensors can also be connected to peripherals interface  506 , such as a temperature sensor, a biometric sensor, or other sensing device, to facilitate related functionalities. 
         [0046]    Location processor  515  (e.g., GPS receiver) can be connected to peripherals interface  506  to provide geo-positioning. Electronic magnetometer  516  (e.g., an integrated circuit chip) can also be connected to peripherals interface  506  to provide data that can be used to determine the direction of magnetic North. Thus, electronic magnetometer  516  can be used as an electronic compass. 
         [0047]    Camera subsystem  520  and an optical sensor  522 , e.g., a charged coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) optical sensor, can be utilized to facilitate camera functions, such as recording photographs and video clips. 
         [0048]    Communication functions can be facilitated through one or more communication subsystems  524 . Communication subsystem(s)  524  can include one or more wireless communication subsystems. Wireless communication subsystems  524  can include radio frequency receivers and transmitters and/or optical (e.g., infrared) receivers and transmitters. Wired communication system can include a port device, e.g., a Universal Serial Bus (USB) port or some other wired port connection that can be used to establish a wired connection to other computing devices, such as other communication devices, network access devices, a personal computer, a printer, a display screen, or other processing devices capable of receiving or transmitting data. The specific design and implementation of the communication subsystem  524  can depend on the communication network(s) or medium(s) over which the device is intended to operate. For example, a device may include wireless communication subsystems designed to operate over a global system for mobile communications (GSM) network, a GPRS network, an enhanced data GSM environment (EDGE) network, 802.x communication networks (e.g., WiFi, WiMax, or 3G networks), code division multiple access (CDMA) networks, and a Bluetooth™ network. Communication subsystems  524  may include hosting protocols such that the device may be configured as a base station for other wireless devices. As another example, the communication subsystems can allow the device to synchronize with a host device using one or more protocols, such as, for example, the TCP/IP protocol, HTTP protocol, UDP protocol, and any other known protocol. 
         [0049]    Audio subsystem  526  can be coupled to a speaker  528  and one or more microphones  530  to facilitate voice-enabled functions, such as voice recognition, voice replication, digital recording, and telephony functions. 
         [0050]    I/O subsystem  540  can include touch controller  542  and/or other input controller(s)  544 . Touch controller  542  can be coupled to a touch surface  546 . Touch surface  546  and touch controller  542  can, for example, detect contact and movement or break thereof using any of a number of touch sensitivity technologies, 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 surface  546 . In one implementation, touch surface  546  can display virtual or soft buttons and a virtual keyboard, which can be used as an input/output device by the user. 
         [0051]    Other input controller(s)  544  can be coupled to other input/control devices  548 , such as one or more buttons, rocker switches, thumb-wheel, infrared port, USB port, and/or a pointer device such as a stylus. The one or more buttons (not shown) can include an up/down button for volume control of speaker  528  and/or microphone  530 . 
         [0052]    In some implementations, device  500  can present recorded audio and/or video files, such as MP3, AAC, and MPEG files. In some implementations, device  500  can include the functionality of an MP3 player and may include a pin connector for tethering to other devices. Other input/output and control devices can be used. 
         [0053]    Memory interface  502  can be coupled to memory  550 . Memory  550  can include high-speed random access memory or non-volatile memory, such as one or more magnetic disk storage devices, one or more optical storage devices, or flash memory (e.g., NAND, NOR). Memory  550  can store operating system  552 , such as Darwin, RTXC, LINUX, UNIX, OS X, WINDOWS, or an embedded operating system such as VxWorks. Operating system  552  may include instructions for handling basic system services and for performing hardware dependent tasks. In some implementations, operating system  552  can include a kernel (e.g., UNIX kernel). 
         [0054]    Memory  550  may also store communication instructions  554  to facilitate communicating with one or more additional devices, one or more computers or servers. Communication instructions  554  can also be used to select an operational mode or communication medium for use by the device, based on a geographic location (obtained by the GPS/Navigation instructions  568 ) of the device. Memory  550  may include graphical user interface instructions  556  to facilitate graphic user interface processing, such as described in reference to  FIGS. 1-4 ; sensor processing instructions  558  to facilitate sensor-related processing and functions; phone instructions  560  to facilitate phone-related processes and functions; electronic messaging instructions  562  to facilitate electronic-messaging related processes and functions; web browsing instructions  564  to facilitate web browsing-related processes and functions and display GUIs; media processing instructions  566  to facilitate media processing-related processes and functions; GPS/Navigation instructions  568  to facilitate GPS and navigation-related processes; and camera instructions  570  to facilitate camera-related processes and functions. The memory  550  may also store other software instructions  572  for facilitating other processes, features and applications, such as applications related to navigation, social networking, location-based services or map displays. 
         [0055]    Each of the above identified instructions and applications can correspond to a set of instructions for performing one or more functions described above. These instructions need not be implemented as separate software programs, procedures, or modules. Memory  550  can include additional instructions or fewer instructions. Furthermore, various functions of the mobile device may be implemented in hardware and/or in software, including in one or more signal processing and/or application specific integrated circuits.