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From: hallinan@metatron.harvard.edu (Peter Hallinan)
Newsgroups: comp.windows.x
Subject: standard colormap utility
Message-ID: <4153@husc6.harvard.edu>
Date: 12 Sep 90 15:19:37 GMT
Sender: news@husc6.harvard.edu
Reply-To: hallinan@metatron.UUCP (Peter Hallinan)
Distribution: usa
Organization: Robotics Group - Harvard University Division of Applied Science
Lines: 66


I am trying to write a utility to change the standard colormap RGB_DEFAULT_MAP.
My reason for doing this is simply that one colormap can accomodate
all my applications if it is set up correctly, allowing all applications
to display correct colors simultaneously.  My intention is to call the utility
immediately after logging in on DecStations running DECWindows, and immediately
after starting X on Sun Workstations, i.e. before starting any X applications
such as xterm.

I would like RGB_DEFAULT_MAP to have the following structure:
192 read-only   color cells - my choice
 64 unallocated color cells - for various applications, eg xterm

The Xlib guide suggests using XSetStandardColormap(), but the code
sequence it describes does not clearly explain how to set RGB_DEFAULT_MAP
(it seems to be a special case), nor does it indicate exactly when
XSetStandardColormap() should be called. So now I am stuck.
A sketch of my (incorrect) code for this utility follows.
I would very much appreciate any comments and/or corrections.

Thanks in advance,
Peter Hallinan
hallinan@gramian.harvard.edu

/****************************************************************************/
main()
	{
	int i, scr, depth;
	Display *dsp;
	Window root;
	XVisualInfo vinfo;
	XColor cdef;
	Colormap cmap;
	XStandardColormap stdcmap;

	dsp = XOpenDisplay (getenv("DISPLAY"));
	scr = DefaultScreen (dsp);
	root = DefaultRootWindow(dsp);
	depth = DisplayPlanes (dsp, scr);

	/* create new color map w/ 192 read-only cells */
	XMatchVisualInfo (dsp, scr, depth, PseudoColor, &vinfo);
	cmap = XCreateColormap (dsp,root,vinfo.visual,AllocNone);

	/* allocate the new read-only default colors */
	for (i = 0; i < 192; i++)
		{
		cdef.pixel = i; cdef.red = xxx; etc
		XAllocColor (dsp, cmap, &cdef);
		}

	/* fill in XStandardColormap structure */
	stdcmap.colormap = cmap; etc

	/* somehow replace the old RGB_DEFAULT_MAP */
	XGrabServer (dsp);
	XChangeProperty (dsp, root, XA_RGB_DEFAULT_MAP, XA_RGB_COLOR_MAP,
		32, PropModeReplace, (char *)&stdcmap, 9);
	XSetStandardColormap (dsp, root, &stdcmap, XA_RGB_DEFAULT_MAP);
	XSetCloseDownMode (dsp, RetainPermanent);
	XUngrabServer (dsp);
	}

Peter W. Hallinan			Aiken 229
hallinan@gramian.harvard.edu		Harvard University
					Cambridge, MA  02138