Provided by: allegro4-doc_4.4.2-4_all
getpixel - Reads a pixel from a bitmap. Allegro game programming library.
#include <allegro.h> int getpixel(BITMAP *bmp, int x, int y);
Reads a pixel from point (x, y) in the bitmap.
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.