Path: utzoo!attcan!uunet!ginosko!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!bloom-beacon!POPEYE.NOSC.MIL!glasgow
From: glasgow@POPEYE.NOSC.MIL (Michael Glasgow)
Newsgroups: comp.windows.x
Subject: Storing colors in the DefaultColormap
Message-ID: <8912302146.AA03921@popeye.nosc.mil.sun.com>
Date: 30 Dec 89 21:46:48 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 27


     I have an application that displays a digital image in a window.
The image is stored as a bunch of eight bit values that are indexes
into a predefined color map.  Each image uses only the last 216 colors
of the colormap, leaving the first 40 colors to be used by the rest of
the system.

     I can create an entire colormap, and store these colors in the
colormap at the given locations with XStoreColors(), and then
use XInstallColormap() to get the colormap to change.  This will
cause any windows which have used XAllocColor() to change colors.
I don't want this to happen.

     Another way I could get the colors that I need is to use
XAllocColor on all 216 colors, and do a translation as I read in the
data to its proper pixel value.  The problem with this is that it is
slow for a 1500x1500 or larger image.

     Is there a way to store a given color cell definition in a 
specific location in the colormap?   Also, is there a way to Query
the colormap, so that I can find out how many colormap cells are
available?

Any response would be greatly appreciated.

Michael Glasgow
glasgow@popeye.nosc.mil