Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!ncar!ico!auto-trol!marbru
From: marbru@auto-trol.UUCP (Martin Brunecky)
Newsgroups: comp.windows.x
Subject: Keeping track of color allocation
Message-ID: <801@auto-trol.UUCP>
Date: 28 Aug 90 20:47:36 GMT
Reply-To: marbru@auto-trol.COM (Martin Brunecky, 303-252-2499)
Organization: Auto-trol Technology, Denver
Lines: 39


 Writing a modest X applications, I am running into problems with color
 map entries allocation. For known reasons, I am trying to use the
 default colormap. Since I need LOTS of colors, I have to FREE my
 colors once not needed (yes, displaying images...). 

 The problem is that using bunch of widgets (and may be even UIL/Mrm
 GOD forbid -), my application contains several "customers" issuing
 XAllocColor and other color cell allocation calls.

 When I allocate my color, I never know if the pixel returned to me
 is a "brand new one", or just a "clone" of a pixel already alocated
 from MY CLIENT by some widget (string-to-pixel converter) or something else.
 Thus, issuing XFreeColor on such a pixel, I am running a BIG risk that
 I will free a pixel that is still in use. 

 I can use writeable color cells - those will be unique to my allocation
 request. But with this approach I can lock-out other clients, leaving
 them with a very small palette of read-only color cells. I don't want
 to take this approach either.

 Looking at Xlib specifications and the X protocol specification suggests
 that I am out of luck, unless I overload Xlib color allocation functions.
 Difficult to do, especially when Xlib is a shareable image provided by
 DEC(DECkWindows-) or Sun (ClosedWindows-).

 Did anyone struggle with the same problem ? 
 Did I overlook something ?
 Any suggestions ? 
 Any plans to provide color allocation caching (similar to GC) in X11 R5 ?

 Please,  H E L P  !!!
 (I promise not to flame on UIL for at least one week !)

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