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Zut! A graphical back-end

Time and time again I've needed a quick and dirty way to visualize some data interactively and simply, a quick 30 minute hack. X is intricate enough to make this hard. Zut attempts to solve this problem. You can put RGB picture on the screen by feeding it the RGB values, 8 bits for each of R, G and B (total 24 bits). It can also put PMB pictures on the screen.

If you wish to animate something, you can just keep feeding it new pixels.

Zut is french for something like "dang!" It's not pronounced "zoot"; unfortunately, the french "u" sound does not exist in english. So until you meet a french speaking person you can ask, just say it however you want.

License

This is GPL stuff. See gpl.txt.

Building

./configure
make

Testing

Try these. Hint: ctrl-c at the command-line of the shell that you're using should kill zut if you need it.

zut -l
mandel | zut -v
mandel 300 300 | zut 300 300 -v
boing | zut -vfb
boing 400 300 100 | zut 400 300 -fbv

Installing

If you want you can put the zut binary in your /usr/local/bin by typing

make install

Documentation

This is it baby. Look at mandel.c for an example.

To put a picture on the screen:

for(i=0;i<height;i++)
for(j=0;j<width;j++)
{ putchar(red[i][j]); putchar(green[i][j]); putchar(blue[i][j]); }

pipe that into zut. You need to tell zut the size of the picture. If width=30 and height=93 then you do

zut 30 93

For a list of command-line options for zut, type

zut -h

FAQ and Troubleshooting

Q: Can't compile!
A:
uh...

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Q: It's not working at all!
Q: How do I disable MIT-SHM?
A:
Try with the -n or -x options if something funny is going on. WARNING: -x is VERY slow. MIT-SHM can cause problems sometimes. I don't know if it's because I can't code or if it's because MIT-SHM can be weird, in any case, the -n option will disable it. This will make things a bit slower, but in many cases that's not a problem.

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Q: It display random colors!
A:
Make certain you are outputting the right stuff. For example if you do boing 250 250 | zut 300 300 -fbv, that will be pretty random. The problem is that boing is outputting in the wrong resolution. Make certain that you start zut in the proper resolution.

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Q: How do I tell Zut what size window to open? A:
If you want your program to be able to tell zut what size window to open, you could try giving the -p option to zut and writing an appropriate header to stdout (see zut -h to see what I'm talking about). Otherwise, you can give the width and height as a parameter to zut. See zut -h for a full list of options.

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Q: Zut is giving me a cryptic error message; something about shmget or shmctl.
A:
If you think you're having problems because you're running out of shared memory resources, try looking at the man page for ipcs(8) and ipcrm(8). Zut 1.1 would not free its shared memory resources at termination, perhaps some other programs have the same problem.

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Q: It's slow!
A:
For a double-buffered kind of feeling, try -b. It won't draw the scanlines as it receives them, only after a screenful has been received. This way you won't get any partially drawn picture on the screen.

If it's still too slow, make sure you're running locally and if possible using MIT-SHM. To make zut output more information, use the -v option (verbose). Zut can also print a frames-per-second count with the -f option. I can get 11fps in 500x500 on my machine and that's a crappy machine.

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Q: Why are my programs slower than boing.c? A:
First off boing is very simple so that helps being fast. Second, if you actually put all your data to stdout using putchar(), that's slow. That's because each putchar generates a kernel trip. If instead you put all your data in a buffer and then blast it to the pipe with fwrite or write, it will be much faster. That's what boing does.

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Q: Contact?
A:
Sebastien Loisel
http://www.math.mcgill.ca/~loisel/zut/zut.html loisel@math.mcgill.ca