Patch to fix transparent GIF89 bug in XMosaic 2.1

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To: www-talk@www0.cern.ch
Cc: phillips@cs.ubc.ca, dolesa@smtp-gw.spawar.navy.mil
Subject: Patch to fix transparent GIF89 bug in XMosaic 2.1
Date: Sat, 08 Jan 1994 13:49:22 -0800
From: "Roy T. Fielding" <fielding@simplon.ICS.UCI.EDU>
Message-id: <9401081349.aa07138@paris.ics.uci.edu>
Content-Length: 1465

Hello all,

Well, the third round of testing finally identified (and fixed)
the problem I was having with some of my GIFs going blank.

The problem was that the global variables used to determine whether a
GIF is transparent are only initialized once.  Therefore, after the
first transparent GIF is read, Mosaic for X 2.1 treats all later 2-color
GIFs as if they too are transparent.

To test your system to see if it is affected by the Gif89 bug, look
at <http://www.ics.uci.edu/Test/Gif89-test.html>.  I have no idea 
whether or not the same bug affects the other Mosaic platforms.

What follows is the patch to fix the initialization bug in
Mosaic-2.1/src/gifread.c which causes 2-color inlined GIFs to appear
faded/blank after a transparent GIF89 has been read.

PLEASE NOTE that this is NOT AN OFFICIAL PATCH, but it works
and it is so small and harmless that it justifies a general post.
Be sure to be in the Mosaic-2.1/src before doing the patch.

....Roy Fielding   ICS Grad Student, University of California, Irvine  USA
                   (fielding@ics.uci.edu)

-------------------------- cut here ----------------------------------
*** save/gifread.c	Sat Jan  8 11:36:09 1994
--- gifread.c	Sat Jan  8 11:43:37 1994
***************
*** 91,96 ****
--- 91,101 ----
  	verbose = FALSE;
  	showComment = FALSE;
  
+ 	Gif89.transparent = -1;
+ 	Gif89.delayTime = -1;
+ 	Gif89.inputFlag = -1;
+ 	Gif89.disposal = 0;
+ 
  	if (! ReadOK(fd,buf,6))
  	{
  #if 0