Message-ID:	<34B825B4.3079@compuserve.com>
Date:	Sat, 10 Jan 1998 20:51:48 -0500
From:	Laurent Turcotte <lturcott AT compuserve DOT com>
MIME-Version:	1.0
Subject:	Re: Extracting a pixel from an Allegro BITMAP
References:	<19980109085201 DOT DAA02949 AT ladder02 DOT news DOT aol DOT com>
Newsgroups:	comp.os.msdos.djgpp
Lines:	34
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hi

For a bitmap buffer

BITMAP  buffer;

pixel = buffer.line[y][x]
	
the line element of the BITMAP structure contain pointers
to start of lines (a lookup table)
So there are no multiplications involved .

Regards
Laurent Turcotte

> Hello everybody...
> 
>     in the past... my buffers have been char *
> 
>  I could simply do:
> 
>        a_pixel = double_buffer[(y<<8) + (y<<6) + (x>>2)];
> 
>      - or -
> 
>       double_buffer [(y<<8) + (y<<6) + (x>>2)] = a_pixel;
> 
>    - and even -
> 
>       a_pixel = image->buffer[(y<<8) + (y<<6) + (x>>2)];
> .. and the other way around....
> 
>    How can I do that with an Allegro BITMAP?
> ...

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