| 摘要 |
A computer system 10 comprises a processor unit 14, a keyboard 16, a screen 12 and a mouse 18. A user uses the mouse to control the position of a cursor 20 on the screen, and also to indicate a selected cursor position. To correlate this position with shapes 40, 42 on the display, to determine which if any shapes have been selected, the computer first determines whether a pick rectangle around the selected cursor position overlaps a bounding rectangle 40, 42 around a shape. Those shapes for which an overlap is found are re-drawn into a bit map in memory, which is then examined to see if this drawing process has resulted in a change to the bit map. Any shapes which produce a change in the bit map must overlap the pick rectangle, and so are correlated with the cursor position. <IMAGE> |
