al_get_pixel - Allegro 5 API

       Get  a  pixel’s  color  value  from  the specified bitmap.  This operation is slow on non-memory bitmaps.
       Consider locking the bitmap if you are going to use this function multiple times on the same bitmap.

       al_get_pixel - Allegro 5 API

ALLEGRO_COLOR(3alleg5), al_put_pixel(3alleg5), al_lock_bitmap(3alleg5)

Allegro reference manual                                                                   al_get_pixel(3alleg5)

              #include <allegro5/allegro.h>

              ALLEGRO_COLOR al_get_pixel(ALLEGRO_BITMAP *bitmap, int x, int y)