seth@CS.UCLA.EDU (12/18/87)
Well it's time for another naive mac programming question. I'm trying to do following: Set up two offscreen bitmaps A and B. Do all my drawing on A and B (rectangles, lines, and text) and then bitblt from A and B onto the window I've created on the screen W. I want the images in A and B to persist so that if W gets messed up I can update it just by blitting from A and B. I'm using Allegro CommonLisp but have access to the entire toolbox as needed. I'm confused about whether A and B can just be bitmaps or need to be full-fledged grafports in their own right. I've checked IM and it talks about using SetPortBits to draw to offscreen bitmaps and then using CopyBits to update the screen but I can't figure it out and there are no examples. I would greatly appreciate it if someone could take a little time and explain it to me. I have various versions of my code which behave strangely but the one where I thought I had it right resulting in nothing being drawn. How do I create a real offscreen bitmap? What are the bounds for that bitmap (i.e. off the screen?). What is the portrect if the offscreen bitmap needs to be a grafport? Thanks, Seth Goldman ARPA: seth@CS.UCLA.EDU UUCP: ...!{ihnp4,cepu,trwspp,sdcrdcf,ucbvax}!ucla-cs!seth USMail: A.I. Lab, 3531 Boelter Hall, UCLA, Los Angeles, CA 90024 MaBell: (213) 825-5199