jrs@cs.williams.edu (04/22/89)
I recently changed a graph editor program I'm working on so that the animation is done with locking and batching in a retained pixwin, which makes everything much smoother. When you start up the program, everything works fine. However, if a user does a resize, all subsequent locked & batched draws come out in purple, the foreground color. But it's even weirder than that. I didn't lock & batch the screen refresh, so after the resize the colors are all fine. When the user drags a vertex across the screen (which is done with locking & batching), however, the affected rectangle turns purple. (By the affected rectangle I mean the smallest rectangular region enclosing all the pixels that are changed in one batched draw.) It would actually be quite a neat effect if I could control it: it looks like a purple piece of cellophane whose corner is connected to the cursor is being dragged accross the screen (it doesn't move back with the cursor, however-- once a pixel has become purple it doesn't change back). One person suggested that maybe the routines copying the block of pixels to the screen when pw_batch_off is called for some reason think that the screen is only one bit deep. This sounds plausible to me. Does anyone know how to tell it to update in 8-bits (or however many I'm using) or does anyone have any other explanations, fixes etc? Feel free to contact me directly. Thanks. Josh Smith jrs@cs.williams.edu (413) 597-6716 SU box 1964 Williams College Williamstown, MA 01267