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 bitmaps 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(3alleg4),
_getpixel(3alleg4),
is_inside_bitmap(3alleg4),
getr(3alleg4),
getg(3alleg4),
getb(3alleg4),
geta(3alleg4),
ex12bit(3alleg4),
exalpha(3alleg4),
exflame(3alleg4),
exlights(3alleg4)