Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!ncar!ico!attc!marbru
From: marbru@attc.UUCP (Martin Brunecky)
Newsgroups: comp.windows.x
Subject: Re: Colormap dilemma
Message-ID: <1239@attc.UUCP>
Date: 13 Mar 91 16:41:32 GMT
References: <1991Mar12.235227.28172@onecom>
Reply-To: marbru@auto-trol.com (Martin Brunecky)
Organization: Auto-trol Technology, Denver
Lines: 40

In article <1991Mar12.235227.28172@onecom> john@onecom.uucp (John Brinegar) writes:
>
>I have been having philosophical discussions concerning colormaps in X, and
>I am interested in receiving a dose of conventional wisdom on this topic.
>
  What about alternative:
  4) Creating a private, writeable (pseudo color visual) color map.
     Allocating all 256 colors (or 16 for 4 bitplane system).
     Reserving the top 128 (8) colors for your colors.
     Copying the low 128 (8) colors from the default colormap into
     your private colormap.
     This gives you color cells you want, and significantly reduces
     the "technicolor" effect. In fact, it works pretty well if you
     only preserve (copy) something  like 16-32 colors from the default map.

     Of course:
     - your private colors could go south if the focus moves out of
       your application. But at least your application would not
       destroy common controls (such as WM decorations) and the user
       will be able to navigate between applications.
       Also note that many servers do NOT change unallocated color cells
       when the colormap is swapped, so your "private" colors often 
       remain in effect even when the default map is reloaded.

     - you may periodically update the copy of the default colormap
       in your private colormap (to reflect changes due to other apps).

     - you may consider a server which does NOT allocate colors using
       the bottom-up approach (I haven't seen one yet, but ...). There
       are (clumsy) ways to find out which color cells ARE currently
       allocated in the default colormap (depending on it's visual),
       so you can figure out how the server does it's allocation and
       locate your "private" cells appropriately.


-- 
=*= Opinions presented here are solely of my own and not those of Auto-trol =*=
Martin Brunecky                           {...}sunpeaks!auto-trol!marbru
(303) 252-2499                        (sometimes also:  marbru@auto-trol.COM )
Auto-trol Technology Corp. 12500 North Washington St., Denver, CO 80241-2404