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From: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
Newsgroups: comp.windows.x
Subject: Re: problem with colormap
Message-ID: <2702@gazette.bcm.tmc.edu>
Date: 9 Nov 90 17:46:40 GMT
References: <273A3E4E.7858@ics.uci.edu>
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Reply-To: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
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In article <273A3E4E.7858@ics.uci.edu>, tolani@buckaroo.ics.uci.edu (Deepak Tolani) writes:
|> 
|> 
|> Being completely unfamiliar with Xlib. I'd appreciate any assistance from you
|> X hackers out there. I was trying to get a ray tracing program that someone else
|> wrote to work on my DECStation 5000/200. The program fails when it attempts to
|> display an image and I traced the problem down to a section of code
|> that creates a new colormap. Below is the code fragment that I think is
|> causing problems.
|> 
|> 
|> 	i = XMatchVisualInfo(display, theScreen, depth, PseudoColor, &visualinfo);
|> 	if (!i)
|> 		i = XMatchVisualInfo(display, theScreen, depth, TrueColor, &visualinfo);
|> 
|> 	if (!i)
|> 		exit(1);
|> 
|> 	visual = visualinfo.visual;
|> 
|> 	rootw = RootWindow(display, theScreen);
|> 	theGC = DefaultGC(display, theScreen);
|> 	cmap = XCreateColormap(display, rootw, visual, AllocAll);
|> 	...
|> 
|> 	XStoreColors(display, cmap, carray, CMAPSIZE);
|> 
|> 
|> 

This section of code can not run with a TrueColor Visual.  The documentation says that XCreateColormap can not be given AllocNone with a TrueColor Visual.  Also, XStoreColors is horribly wrong with  a TrueColor visual (TrueColor is READ ONLY!).  This code must be re-thoughtout to deal with a TrueColor visual.
--
					Eric Taylor
					Baylor College of Medicine
					etaylor@wilkins.bmc.tmc.edu
					(713) 798-3776