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From: evensen@husc9.Harvard.EDU (Erik Evensen)
Newsgroups: comp.windows.x
Subject: getting standard colormaps
Message-ID: <1991May3.160944.824@husc3.harvard.edu>
Date: 3 May 91 20:09:42 GMT
Sender: evensen@husc9 (Erik Evensen)
Organization: Harvard University Science Center
Lines: 44
Nntp-Posting-Host: husc9.harvard.edu

I'm working on an application where it would be very desireable
to use the XA_RGB_BEST_MAP standard colormap.  My problem is that
I can't seem to get this Colormap.  I read and tried out the
pertinent sections in both Oliver Jones's book and Scheifler
& Gettys's opus but nothing seems to work; i.e., XGetStandardColormap
and XGetRGBColormaps return 0 for status.  The code I've tried
looks something like this:
Display                 *gVfbDisplay;   /* display we are attached to */
XStandardColormap       gVfbBestRGB;    /* the best rgb color map */
        if ((gVfbDisplay = XOpenDisplay("")) == NULL)
                return VFBFAIL;
        if (XGetStandardColormap(gVfbDisplay, 
	    DefaultRootWindow(gVfbDisplay),
            &gVfbBestRGB, XA_RGB_BEST_MAP) == 0) {
                printf("failed to get standard colormap...goodbye\n");
                exit(-1);
        }

or

XStandardColormap	*gVfbBestRGB;
int			nMaps;
	if (XGetRGBColormaps(gVfbDisplay,
	    DefaultRootWindow(gVfbDisplay),
	    &gVfbBestRGB, &nMaps, XA_RGB_BEST_MAP) == 0) {
		printf("failed to get standard colormap...goodbye\n");
		exit(-1);
	}

I read faq #117 "Why can't my program get a standard colormap?"
but this didn't really shed any light on the topic.

I'm using X11R4 on various machines (Sparcs and DecStations)
using both the console and (primarily) an NCD color X-terminal
for display.  I'm using the twm window manager.

Actually, I guess the only thing I haven't tried is the 
prescription in appendix D of Scheifler & Gettys.  But I think
this looks like an awfully messy and unfriendly thing to do
-- looks like it should be reserved for window managers...

Thanks in advance for any help or pointers...

--Erik (evensen@husc9.harvard.edu)