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From: bmc@bmw.mayo.EDU
Newsgroups: comp.windows.x
Subject: Allocating color cells on a DEC5000pgx
Message-ID: <9102011532.AA28146@bmw.mayo.EDU>
Date: 1 Feb 91 15:32:41 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 44


Given the following workstation:
	DEC5000pgx
	Ultrix 4.1 & DECwindows

The following code failes (i.e. xncolors becomes = to 0):

cmap = XCreateColormap (display, window, visual, AllocNone);
xncolors = (unsigned int)visual->map_entries;
while (!XAllocColorCells (display, cmap, True, xplane_masks, 8, xpixels,
        xncolors)) {
	fprintf (stderr,"failed to allocate %d colorcells trying %d\n",xncolors,
		 xncolors-1);
	xncolors--;
	}
xmaxcolor = xncolors;

I am trying to find the maximum number of color cells I can get for my
application. According to xdpyinfo, if I use a PseudoColor visual I
should be able to get a maximum of 256 color cells and 8 planes.

I request a visual via:

vtemplate.class = PseudoColor;
vtemplate.depth = G_bits;
vtemplate.screen = DefaultScreen(display);
vlist = XGetVisualInfo (display, VisualScreenMask | VisualClassMask |  
                        VisualDepthMask, &vtemplate, &visuals_matched);

and set my window's visual to vlist[0] if the call is successful.

Can any kind soul point out what I am doing wrong? I need to get as
many colorcells as possible, yet still be kind to other applications
that may be running. Many thanks in advance for any and all aid.

--Bruce

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Bruce M. Cameron                                 bmc@mayo.edu
Biotechnology Computing Resource                 (507) 284-3288
Medical Sciences 1-14                            
Mayo Foundation
Rochester, MN 55960                              WD9CKW
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