Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!voder!nsc!amdahl!JUTS!duts!rla20
From: rla20@duts.ccc.amdahl.com (Roger L Allen)
Newsgroups: comp.sys.mac.programmer
Subject: Palette Manager Woes...HELP!
Message-ID: <3cR602lw02Cj01@JUTS.ccc.amdahl.com>
Date: 5 Sep 90 21:15:35 GMT
Sender: netnews@ccc.amdahl.com
Reply-To: rla20@DUTS.ccc.amdahl.com (Roger Allen)
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 44

Currently, I am working on my own Gif viewer.  Mostly it is for my own
personal enjoyment (agony) but if I can get this @#$%&* thing to work
maybe I will make it a shareware product in an already packed market.

ANYWAY, I am having a frustrating time with the palette manager and
getting the correct colors on the screen.  I've read the IM V PM Chapter,
I've read all the c.s.m.p items that seemed relevant and I'm still
confused.  Does Apple have a document written so mere humans can
understand the Palette Manager?

So, here is what the program is doing:

    1. Read in all the Gif header stuff and set up a Palette of all
       the colors that the image needs. (pmTolerant, 0 tolerance--I
       tried pmExplicit & pmAnimated to no avail)

    2. Open up a window that the image will go into, attach the Palette
       and activate it.

    3. Now, here is the tricky part...
       Read in the gif picture data and store it in an off-screen
       bitmap.  BUT, each gif data byte is really an index into
       its own CLUT (the palette I spoke of), it is not a RGB value.

So, Parts 1 & 2 went pretty well and I learned alot of interesting info
along the way.  But, Part 3 is causing me some grief.

What I have tried:

  I tried just putting the raw data into the bitmap via the baseAddr ptr.
  --no luck here, even when I did a Palette2CMap for the window.  The
  indexes seemed to change and the picture turned psychadelic(sp?)

  I also tried using PmSetForeColor(gifIndex) and then plotting the points
  as they are decoded--also no luck, I don't think the palette is loaded
  to this bitmap.

So, as you can see I need help.  Please email me and I will summarize
and re-post if the answers are helpful.

Thanks,

Roger Allen
rla20@DUTS.ccc.amdahl.com