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EnigmA Amiga Run 1996 February
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EnigmA AMIGA RUN 04 (1996)(G.R. Edizioni)(IT)[!][issue 1996-02][Skylink CD III].iso
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gfdttp39.lha
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readme
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1993-02-02
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How to use your GIF datatype. This version is 39.3.
In this archive, you will find 2 files: Gif.datatype, and GIF (with an icon).
(Yes I know, strictly speaking, that's three).
This program can ONLY be used under WB3 (or above, I presume).
The Gif.datatype file must be copied into the directory:
SYS:Classes/Datatypes
The GIF and GIF.info files can be copied into one of two places:
SYS:Storage/Datatypes
If you just want to have the datatype available. You will have to double-
click on the GIF icon, or use AddDataType to actually use it. OR
SYS:Devs/Datatypes
If you want the datatype permanently installed. Doing this means that the
datatype is automatically added to the system every time you boot. This
means that the very first time you install it, you will have to double-click
on it or reboot to use it.
Once the GIF datatype has been installed, any datatype aware program can be
used to read GIF files as if they were IFF. For example, MultiView will
display them, and you can use them as screen/window backdrops. MultiView
will display the images on the workbench, and will remap the colours to
whatever workbench you have selected. If you run a 4 colour WB, you will get
a best effort in four colours. Actually, MultiView does quite a good job of
this. Normally, you will want to use a 256 colour workbench, in which case,
you will get all the colours. Due to the pen sharing in WB3, you can have
several pictures open simultaneously, and still get a good colour match.
By selecting the appropriate tooltypes, MultiView can also display pictures
on their own screen. Consult the MultiView documentation for more details.
The datatype was written to handle 87a and 89a type GIFs, although I haven't
been able to test the 89a ones. It will only read the first image in a file
containing multiple images, although I haven't been able to test this either.
A datatype is a library, and so naturally is fully re-entrant. This version
has also been tested on a 68000.
This version of the the datatype is a performance-enhanced version of the
second release, 39.2. A number of enhancements were made:
1) Following a suggestion made to me by Matthias Scheler, (grateful
thanks to him - my email doesn't seem to get through?) I replaced calls
to WritePixel with WritePixelLine8. This significantly speeds up the
decoding.
2) Other small optimisations to the decoder, inlining code at the expense
of executable size.
I was delaying release of this pending a further change, but have been
persuaded to let this signifcantly sped-up version out. The further change
being planned is to allow the datatype to write GIF files. Since I don't
think many datatype-aware programs support this yet, this shouldn't cause
too much trouble.
There are no restrictions on the distribution of this archive. The datatype
copes successfully with the modest collection of GIFs I have access to, but
testing has been somewhat less than rigorous. If you have any problems, I
can be contacted on sgoddy@cix.compulink.co.uk or 100014,674 on CIS.
The Graphics Interchange Format (c) is the Copyright property of CompuServe
Incorporated. GIF (sm) is a Service Mark property of Compuserve Incorporated.
Steve the G. 02/02/93.