From: "Tony O'Bryan" <aho450s AT nic DOT smsu DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Saving BITMAP in allegro
Date: Sun, 07 Dec 1997 16:12:38 -0600
Organization: Southwest Missouri State University
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Jean-Sebastien Payette wrote:

> typedef struct BITMAP
> {
>    int w, h;               - size of the bitmap in pixels
>    int clip;               - non-zero if clipping is turned on
>    int cl, cr, ct, cb;     - clip rectangle left, right, top, and bottom
>    int seg;                - segment for use with the line pointers
>    unsigned char *line[ ];  - pointers to the start of each line
> } BITMAP;

int w,h are the width and height of the bitmap.
unsigned char *line[] point to the start of each scanline.  void *dat
points to the start of the image data (line[], dat are two different
ways of expressing essentially the same thing).

> 
> The author say that there is some other stuff in the struct but don't tell
> what??

The sources come with Allegro.  The rest of the bitmap structure isn't
documented because it's not really useful to the programmer.  Look in
allegro.h to see for yourself.
 
> I know about the Datafile but I don't want to use it, it won't fit in what
> i'm trying to do...

I imagine that the datafile will better fit what you're trying trying to
do than ripping apart the bitmap structure.