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From: tyager@maxx.UUCP (Tom Yager)
Newsgroups: comp.windows.x,comp.windows.x.motif
Subject: Re: Colormaps
Message-ID: <59@maxx.UUCP>
Date: 16 Jul 90 02:58:42 GMT
References: <1990Jul13.183517.23734@media.uucp>
Organization: MAXX: Tom Yager's UNIX lab, Amherst, NH.
Lines: 44

In article <1990Jul13.183517.23734@media.uucp>, arthur@media.uucp (Art Poley) writes:
> Does anyone know how to preserve the colors used by the motif window manager
> within my 256 element colormap? Basically, I would like to create a (256 - N) 
> element colormap.  Where N would be the number of colors needed to preserve 
> the 3D-look, menus, etc. used by the mwm.  Due to the dynamic nature of the
> imaging colormap, sharing of colormaps does not seem like a good approach.  
> I'd really just assume that N out of my 256 are reserved for the window manager.
> Hopefully N won't be to large (16 or less?).
> 
> If anyone has any suggestions, references, etc., I'd really appreciate it.
> Art Poley - Media Cybernetics		Phone: (301)495-3305
> Internet: arthur%media@uunet.uu.net 	UUCP: {uunet,hqda-ai}!media!arthur

If you use XSetWindowColormap() to install the colormap, and mwm's
colormapFocusPolicy resource is set to "keyboard," then that window's map
should be active whenever it has input focus. When you shift focus away from
that window, the default colormap (and, therefore, mwm's shading) should be
restored. Is that not sufficient?

Writing your application to set aside a fixed number of colors for external
use is possible, but limiting. I'm a little shaky on this; one of the others
may want to correct or clarify: You can replace the system's default colormap,
allocating all but 16 cells for your own use. Then, programs which run after
this change wouldn't touch your colors. I'd say that's "breaking the rules,"
however, since you're making serious assumptions about what other applications
the user will want to run alongside your own. This approach also requires that
you restart the window manager and other applications after you've reset the
map. That's a pain, too.

The best-behaved thing to do, I think, is either to install a window-bound
colormap, or just use the default map. Keep allocating colors until you run
out, and apply your color transforms based on the number of colors you get.
The Motif-based Mandelbrot generator I've written uses that policy, and that
helps it to run well on anything from monochrome to 8-plane. I give the user
the option (at run time) whether to use a private colormap.

Good luck.
(ty)

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