getpixel

getpixel(3alleg4)                Allegro manual                getpixel(3alleg4)



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)



Allegro                           version 4.4.3                getpixel(3alleg4)