From: Ronald Landheer <ronald DOT landheer AT libertysurf DOT fr>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: BITMAP info
Date: Sat, 27 Jan 2001 19:31:47 -0100
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To: djgpp AT delorie DOT com
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23yrold3yrold schreef:
> Hello. I've been trying to find the BITMAP structure in Allegro's source
> code, is it in there somewhere? I'm interested in writing my own blitting
> routines (as well as writing my own graphics file format) but I can't find
> all the information I need in those source files; I've been using them to
> learn this stuff. Any help anyone?
In any case, it's documented in the documentation that comes with
Allegro, but here it is, from the allegro.h header file:

typedef struct BITMAP            /* a bitmap structure */
{
   int w, h;                     /* width and height in pixels */
   int clip;                     /* flag if clipping is turned on */
   int cl, cr, ct, cb;           /* clip left, right, top and bottom
values */
   GFX_VTABLE *vtable;           /* drawing functions */
   void (*write_bank)(void);     /* write bank selector, see bank.s */
   void (*read_bank)(void);      /* read bank selector, see bank.s */
   void *dat;                    /* the memory we allocated for the
bitmap */
   int bitmap_id;                /* for identifying sub-bitmaps */
   void *extra;                  /* points to a structure with more info
*/
   int x_ofs;                    /* horizontal offset (for sub-bitmaps)
*/
   int y_ofs;                    /* vertical offset (for sub-bitmaps) */
   int seg;                      /* bitmap segment */
   unsigned char *line[0];       /* pointers to the start of each line
*/
} BITMAP;

Ye might want to look in there for any other stuff you're looking for as
well - it was pretty easy to find..

Greetz!

Ronald