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List:       kde-core-devel
Subject:    Re: KHTML developers: Animated GIF playing
From:       Mosfet <dan.duley () verizon ! net>
Date:       2003-05-13 12:57:26
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Well, dithering shouldn't be a problem... GIF color tables can only have 256 
colors ;-) You can have a global color table and local ones, but each image 
frame will use only one colormap with 256 colors. Here's what the spec says:

    7 6 5 4 3 2 1 0        Field Name                    Type
     +===============+
  0  |               |       Red 0                         Byte
     +-             -+
  1  |               |       Green 0                       Byte
     +-             -+
  2  |               |       Blue 0                        Byte
     +-             -+
  3  |               |       Red 1                         Byte
     +-             -+
     |               |       Green 1                       Byte
     +-             -+
 up  |               |
     +-   . . . .   -+       ...
to  |               |
     +-             -+
     |               |       Green 255                     Byte
     +-             -+
767  |               |       Blue 255                      Byte


On Tuesday 13 May 2003 01:45 am, Stephan Kulow wrote:
> On Monday 12 May 2003 16:36, Mosfet wrote:
> > I've been kindof annoyed at animated GIF playing using QMovie for some
> > time. It used to take a lot of resources, now it sometimes takes all the
> > CPU and makes the GUI crawl. Because of this I wrote my own animated GIF
> > player based on libungif. Qt's version manually parses each byte of the
> > GIF ;-)
> >
> > My libungif version seems to work much smoother to me, esp. with large
> > GIF animations. I didn't code it using QImageConsumer but I can do so if
> > you all are interested in using it. Drop me a line and I can convert it
> > and provide the code to you.
>
> It can't get much worse I'd say. Just make sure your code handles color
> maps and dithering correctly. I don't know what libungif gives you, but
> with the Qt GIF reader this was the biggest problem. I'd be happy to test
> your code. Unfortunatly my own collection of test GIF images is lost, but I
> find some :)
>
> Greetings, Stephan
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