Date   : Fri, 14 May 1993 22:17:23 +1000 (EST)
From   : Andrew Leahy <A.Leahy@...>
Subject: Re: GIF viewer

>The gif viewer was written by Andrew Leahy <A.Leahy@...>. He  
>mailed me a copy about 6 months ago following a mention of it on the list. It  
>runs on a UNIX box, and uses PBMtools to convert the gif into a simple ppm  
>image. It then converts the image into VDU codes which can then be transfered,  
>and very simply displayed (they're pretty compact too - little worse than raw  
>bitmap).

Hey, that's me!
I ended up writing two versions of the program.

One converted the PPM files into VDU codes directly for display using a comms
program that supported BBC VDU sequences (I use Termulator for this - does
Tequilacomm support VDU codes?)

The other converted the PPM files to an intermediate format for d/load to
the Beeb. I then had a program to display these files on the Beeb. The
"intermediate" format wasn't compressed (20K Mode 1, 15K Mode 2 depending
on the dimensions of the image). But it meant I could save the image to disc, 
display, then SVPIC it.

This "format" also allowed me to d/load (what I called) BIG images, ie.
larger then what will fit on the screen, eg. 320x160+ in Mode 2.
I had a display program that allowed me to scroll up and down over the image
(pretty slowly...but it worked).
I have about 10 or so DFS discs full of "images" (of varied content :)

>The version he sent me had a few problems (I don't know why as it had worked  
>for him), and I made quite a few mods. The main problem which I never tracked  
>down is that it core dumps imediatly prior to terminating! However the images  
>can still be used.

Well it used to work for me, but ever since we got a new terminal server (about
a year ago) for the modems I get garbage...arggh. I haven't really had the
time to figure it out (specially when I've got to pay the phone bill!).
It never core dumped on me.
 
>The original version supported modes 1 and 2. I added mode 0. I'll put what  
>code I've got on shiraz (assuming Andrew doesnt object), with a demo file  
>(gravity.vdu).

Don't suppose you could mail it to me!
shiraz is very temperamental from here!

(PS: I keep mentioning this but no-one seems interested. I've patched the
XV program (X11 image display program) to load SVPIC'd images. Not that
I use it very much...it was just an interesting exercise!)
__________________________________________________________________________
Andrew "Alf" Leahy                         email: alf@...
University of Western Sydney - Nepean.            A.Leahy@...
Sydney, Australia.                         phone: (047) 360622 (work)