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From: maunsell@cvs.rochester.edu (John Maunsell)
Newsgroups: comp.sys.mac.programmer
Subject: Saving/Restoring screen using off-screen pixMap
Keywords: Color QuickDraw, CLUT, off-screen
Message-ID: <11659@ur-cc.UUCP>
Date: 16 Jan 91 17:29:53 GMT
Sender: news@uhura.cc.rochester.edu
Distribution: na
Organization: Center for Visual Science, U. of Rochester
Lines: 16

I have several programs that save portions of the screen to an
off-screen bitMap so that screen contents can be updated quickly
at a later time.  I've had no problems using bitMaps,i but I can't 
get off-screen pixMaps to work properly.  The contents (lines, ovals, 
etc) of the restored region are returned intact, but the colors are 
often changed.

My guess is that I am not handling the offscreen pixMap CLUT properly, 
but I don't know what to change.  I am setting up the offscreen pixMap 
CLUT as described in Tech Note 120 (I haven't got a copy of Tech Note 
277).  Drawing off-screen and then copying to the screen seems to work.
Any suggestions?

John Maunsell
University of Rochester
maunsell@cvs.rochester.edu