'nother XLib Question

[Douglas Linder <linderd@ses.curtin.edu.au>]

Greets. : )

I have a tiny X lib question I'm justing dying to have some kind sole
who knows a lot about X windows answer for me. It's just for the good
old XCreateImage and XPutImage routines.

Very simple, I create an XYPixmap, and  I draw it and get a seg fault. I
can't figure out why. The bitmap pad is 32, and the bytes-per-line is
set to (Image Width), which every color being represented by 8-bits in
the data. The data array is allocated and three times as big as it needs
to be (there are 3 frames in the image data, after each other (the data
gets loaded that way). I -was- going to just moving the pointer up and
pass the next chunk to the next call of XCreateImage, but I never got
that far).

I'm certain the rest of the program is fine; My drawing routines with
the GC and the basic stuff like drawing lines and boxes and arcs works
perfectly.

For reference, if it helps: The display depth its working on is 16 bbp.
Am I severely misunderstanding this? I played with Ximages before, a
while ago, but I got to this point then as well and decided it was too
tricky; but I -really- want to get this working this time.

Let's get back to the very basics. The bitmap pad is the size used in
the x server memory to hold the color information, right? It's 32 bit
because the X-server uses that internally (which is why you can plug
direct color straight into X server memory if that's what you want to
do). I actually get the 32 from BitmapPad (display), but it doesn't
really matter.

An XY Pixmap consists of 3 color planes, R/B/G. Each color plane is the
set of pixal values for that color plane for a particular pixel. The
scan line is STILL only (image width) bytes wide, becuase the r/g/b data
is in 8-bit values.

Am I wrong? If this were a ZPixmap, the scan line would be (3*Image
Width) bytes wide, because the rgb are consecutive in a single plane. Or
so I think. Nb. I'm using an XYPixmap because the image format makes it
easier (& quicker) to load in planes rather than rgb clumped.

Well, thanks to anyone who can help! I know the ximage stuff is slightly
arcane, so many thanks to anyone who actually knows enough to help!

Ciao!
Doug.


---------------------------------------------------------------------
To unsubscribe, e-mail: linuxgames-unsubscribe@sunsite.dk
For additional commands, e-mail: linuxgames-help@sunsite.dk