AWCTTYPA@UIAMVS.BITNET ("David A. Lyons") (03/15/89)
>Date: Tue, 14 Mar 89 16:44:32 EST >From: mcgurrin@MWUNIX.MITRE.ORG >Subject: Re: offscreen bitmaps on GS > >I confess considerable ignorance on this topic, but isn't there also >a tool for copying memory blocks? If so, couldn't it be used to copy >the offscreen bitmap into the memory used for display? This would >seem much changing whole page displays (assuming one wasn't doing >windows, menus, etc., in which case you could cause one heck of a lot >of problems). There are indeed several toolbox calls specifically designed to copy blocks of memory: BlockMove, HandToPtr, PtrToHand, and HandToHand. For copying pixelmaps, it is most appropriate to use PaintPixels, PPToPort, or CopyPixels. In very simple cases (like when the part of the pixel map you are copying is rectangular and has the same width as both the source and destination ports, and when everything is still rectangular after taking into account the Visisble Region and Clip Region of both ports), the only exciting thing done by a toolbox call like PaintPixels will be a memory copy. But in general, you won't be copying pixel maps that are as wide as your ports, and they may be partly obscured. If you use the appropriate toolbox calls, everything is taken care of _for_ you--no need to worry about whether other windows overlap yours, whether your window is partly off the screen, etc. --David A. Lyons bitnet: awcttypa@uiamvs DAL Systems CompuServe: 72177,3233 P.O. Box 287 GEnie mail: D.LYONS2 North Liberty, IA 52317 AppleLinkPE: Dave Lyons