giflib for fc5

Toshio Kuratomi toshio at tiki-lounge.com
Mon Sep 19 23:14:32 UTC 2005


On Mon, 2005-09-19 at 10:50 -1000, Warren Togami wrote:
> Michael A. Peters wrote:
> > Can we replace libungif with giflib in fc5?
> > 
> > The LZW patent is dead, Unisys specifically says so on their website.
> > 
> > The current version of gd shipping with Fedora now supports gif.
> > The cvs version of gnuplot now supports the gif terminal type again
> > using the gd library.
> > The libtiff library in fc4 now has lzw patched back in.
> > 
> > I've been using giflib on my system since fc3 (removing libungif and
> > installing giflib in its place, with the shared library symlinks going
> > the other way) and there are absolutely no issues.
> > 
> > I'll file a bugzilla on libungif for it, I think I might have already in
> > the past - but are there any other reasons anyone can think of for not
> > going with giflib?
> > 
> > giflib is available from same sourceforge location as libungif and being
> > maintained in parallel with libungif. I'm guessing it is only a matter
> > of time before libungif disappears.
> > 
> 
> http://sourceforge.net/projects/libungif
> "A library for reading and writing gif images. The save functionality 
> uses an uncompressed gif algorithm to avoid the Unisys LZW patent. This 
> library is based on Eric Raymond's giflib and implements a superset of 
> that library's API. "
> 
> This and other hits on Google indicate that libungif has some exported 
> functions that giflib lacks.  Are you sure this is a perfectly safe 
> drop-in replacement?  There are not a whole lot of details on this website.

The history of libungif and giflib is that GNOME 1 (via imlib) began to
use giflib for its GIF support.  Red Hat and other distributions
realized this would cause problems due to the Unisys LZW patent.  I
found a posting that showed how to create uncompressed gifs that
wouldn't invoke the patent (Unisys patented the encoder and combined
decoder+encoder... Not a standalone decoder) and created libungif as a
drop in replacement for giflib to circumvent the patent issues.

As time went on, bugfixes and a desire for new features led to a need
for API/ABI changes.  I sent fixes and enhancements to Eric Raymond to
coordinate a release so we could continue to have compatible libraries.
He wasn't interested in maintaining giflib any more so I took over
maintenence of that.  The sourceforge page reflects that libungif is a
superset of esr's giflib but not the present sourceforge hosted giflib.

I'll go carify the web page now.

-Toshio
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