Message-ID:	<332B58A4.60@pobox.oleane.com>
Date:	Sun, 16 Mar 1997 03:19:16 +0100
From:	Francois Charton <deef AT pobox DOT oleane DOT com>
Organization:	CCMSA
MIME-Version:	1.0
To:	Mark T Logan <fwec AT juno DOT com>
CC:	djgpp AT delorie DOT com
Subject:	Re: Problems using allegro
References:	<19970312 DOT 054752 DOT 7495 DOT 0 DOT fwec AT juno DOT com> <19970315 DOT 101544 DOT 7423 DOT 14 DOT fwec AT juno DOT com>

Mark T Logan wrote:
> 
> has targa support(as of 2.2).  I agree that GIF and JPG would be good,
> but I
> know nothing about these formats except that GIF uses LZH, or whatever
> that algorithm is called.  Same one as PKZIP uses.  

GIF uses LZW as its compression algorithm. PKZIP uses LZSS, which is not 
the same at all (though it was invented by the same two researchers, 
Lempel and Ziv, hence the name similarity).

> I suspect someone
> out there must have GIF reading code, and It would be a gracious gesture
> on their part to donate it to allegro.

Be careful with GIF: Unisys has a patent on LZW. In the past, they said 
they did not mean to enforce it for free/shareware packages, but I have 
heard that they recently changed their mind... So, adding GIF support to 
Allegro might put Allegro in trouble.

As for JPEG, the Independent Jpeg Group  has produced a Jpeg Library 
(LIBJPEG.a), which compiles fine with DJGPP (it is available on simtel, 
in directory graphics, as jpegsrcXXX.zip). It provides all the calls you 
need for implementing Jpeg codes/decoders. This should be an easy way to 
provide Jpeg support. (A similar library also exists for PNG).

Francois

- Raw text -