Re: NSImageRGBColorTable crash
Re: NSImageRGBColorTable crash
- Subject: Re: NSImageRGBColorTable crash
- From: Glenn Andreas <email@hidden>
- Date: Tue, 20 Apr 2004 09:17:45 -0500
At 5:50 AM +0200 4/20/04, David Remahl wrote:
On 20 apr 2004, at 05.26, Glenn Andreas wrote:
So I tried changing it to skip the CLUT, and take the NSData it
produces, and recreate the image and dump the clut from there.
Turns out it appears that "packed RGB" is actually suppose to mean
"packed ARGB" (or maybe RGBA), because if I do:
python -c 'f=open("/tmp/clut","w");
f.write("\xff\xff\xff\xff"*256); f.close()'
it seems to work.
Oh, interresting...
I was pretty certain the file should be RGB, 8 bit / component,
because I found an old release note with the following text:
http://www.geminisolutions.com/WebObjects_4.5/Documentation/Developer/YellowBox/ReleaseNotes/AppKit.html
"NSImageRGBColorTable: -- For GIF input and output. It consists of
a 768 byte NSData object that contains a packed RGB table with each
component being 8 bits."
Especially since that's matches how an 8 bit color table is specified
on a GIF file.
Using a 1024 byte color table, I avoid the crash, but the image
creation failes and I get the following on the console:
2004-04-20 05:41:58.734 App[12837] Unknown GIF label (0x00)
2004-04-20 05:41:58.736 App[12837] Inconsistent set of values to
create NSBitmapImageRep
Sigh...
I guess make a GIF without the explicit color table, extract it,
write it to a file, and use that file as the source for the explicit
color table the second time through. If you can't "round trip" the
color table, then it is definitely a bug. I'd say that at the very
least there's a bug in the documentation.
It might be interesting to see what sort of GIF file it actually
produces with the 1024 byte explicit clut as well (for example, can
you open it with photoshop?)
--
Glenn Andreas email@hidden
mondo blobbo, Cythera, Theldrow, oh my!
Mad, Bad, and Dangerous to Know
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