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getpixel man page on DragonFly

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getpixel(3)			Allegro manual			   getpixel(3)

NAME
       getpixel	 -  Reads  a  pixel  from  a  bitmap. Allegro game programming
       library.

SYNOPSIS
       #include <allegro.h>

       int getpixel(BITMAP *bmp, int x, int y);

DESCRIPTION
       Reads a pixel from point (x, y) in the bitmap.

RETURN VALUE
       Returns -1 if the point lies outside the bitmap (ignoring the  clipping
       rectangle), otherwise the value of the pixel in the color format of the
       bitmap.

       Warning: -1 is also a valid value for pixels contained in  32-bit  bit‐
       maps  with  alpha  channel  (when  R,G,B,A are all equal to 255) so you
       can't use the test against -1 as a predicate for such bitmaps. In  this
       cases, the only reliable predicate is is_inside_bitmap().

       To  extract  the individual color components, use the getr() / getg() /
       getb() / geta() family of functions.

SEE ALSO
       putpixel(3),  _getpixel(3),  is_inside_bitmap(3),   getr(3),   getg(3),
       getb(3), geta(3), ex12bit(3), exalpha(3), exflame(3), exlights(3)

Allegro				 version 4.4.2			   getpixel(3)

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