1.  Field of the Invention
The present invention relates generally to a method for designating selection of displayed characters and figures utilizing a pointing device such as mouse and pen, in an information processor having a display unit such as computer and word processor. 
2.  Description of the Related Art
In a text and a figure on the display picture plane of a display unit such as computer and word processor, a range for editing must be designated in the test in some cases.  In such a case, it is a common practice to designate a selection starting point and a selection ending point, by moving a cursor utilizing a keyboard.  In recent years, however such selection starting point and ending point are designated utilizing a pointing device such as mouse in many cases.  In such a case, generally, designation of the position of the starting point is performed first, and then designation of the ending point is performed as a separate operation.  However, recently, a method of designating starting time and ending time in a series of operations called "drag operation" has been employed. 
The drag operation proceeds as follows.  For a mouse, for example, the mouse cursor is positioned on a starting point and a switch provided to the mouse is pressed (the operation called "click"), the mouse cursor is moved to an ending position while the switch being pressed, and the switch is released at the ending position.  While the switch is pressed, the system always detects the position of the mouse cursor, and explicitly notifies the user of a range to be processed changing with the movement of the mouse cursor by inverting or changing the point representing the range moment by moment for display.  Herein, the drag operation will mainly be described. 
Referring to FIG.  1, a conventional apparatus of this kind includes a key CPU (Central Operation Unit) 2 for controlling a pointing device, a keyboard and the like.  Coordinate data input from the pointing device is once preserved in a memory 4 and transferred to CPU 1 at the same time.  CPU 1 extracts the coordinate data from memory 4 according to a program stored in a program memory 6 and stores the extracted data in a memory 8.  CPU 1 also refers to the coordinate data extracted from memory 4, extracts data on corresponding points (or region), and characters and figures from a VRAM (Video Random Access Memory) 3 and preserved the data as needed in a cut buffer 5. 
Conventionally, selection of an object displayed on a display device such as a character string requires the following operation.  Referring to FIG.  2, in step SA10, the user positions the mouse cursor on a starting point and clicks.  Thus, coordinates representing the position of the mouse cursor are taken.  At that time, the mouse cursor must be exactly within the display region of the object characters. 
Subsequently in step SA20, the obtained coordinate information on the display is transformed into a system of coordinates for use in a processing in the system.  This is a transformation from an absolute display on the picture plane to a relative display using the upper left part of a window as reference, for example when a window display is performed.  In the case of text display, transformation into a system of coordinates which represent the position of characters in row and column positions.  It is assumed that after the switch of the mouse is pressed in step SA10 the switch continuous to be pressed. 
Subsequently in step SA30, a processing of detecting the pointer position of the mouse cursor according to the movement of the mouse is performed.  Thus obtained information is also formed of the absolute coordinates of the pointer position of the mouse cursor on the picture plane. 
In step SA40, a processing of transforming the coordinates obtained in step SA30 into a system of coordinates used in the system is performed. 
In step SA50, a character string present between the starting position designated in step SA10 and the pointer position determined in step SA30 is determined as a selection region. 
In step SA60, all the characters within the region selected in step SA10 are inverted for display. 
In step SA70, a detection whether or not the drag operation of the mouse has been completed, in other words whether or not the pressing operation of the switch provided to the mouse has been completed is performed.  If the drag operation has been completed, the control proceeds to step SA80, and otherwise the control returns to step SA30.  As long as the drag operation continues, the processings in steps SA30-SA70 are repeatedly performed, the determination display of the selection region is repeatedly performed according to the movement of the pointer position of the mouse and further characters are selected if the selection region expands. 
When the drag operation has been completed and the control proceeds to step SA80, the user inputs a command representing what processing to be performed to the selection region.  In step SA90, the processing according to the command detected in step SA80 is issued to the selection region.  In the case of "cut and paste" processing, the character string in the selected region is transferred to a storage region called a cut buffer for exchanging data between applications. 
However, according to such a conventional method for designating objects, the point of the pointing device such a mouse cursor must correctly be positioned within the display region of the selected object.  However slightly it may be, if the pointer is shifted from the character of the selected object, the character can not be selected or a wrong object can be selected. 
If an object to be selected is relatively large, it is not very much difficult to position the point of the pointing device exactly on the object.  However, the resolution of display units increase and information for display increases, selection objects tend to be small.  As a selection object shrinks, the operation of moving the point of a pointing device exactly on the selection object becomes tremendously difficult, and as a result, wrong objects are often selected by mistakes.