al_convert_mask_to_alpha - Allegro 5 API

       Convert  the  given mask color to an alpha channel in the bitmap.  Can be used to convert older 4.2-style
       bitmaps with magic pink to alpha-ready bitmaps.

       al_convert_mask_to_alpha - Allegro 5 API

ALLEGRO_COLOR(3alleg5)

Allegro reference manual                                                       al_convert_mask_to_alpha(3alleg5)

              #include <allegro5/allegro.h>

              void al_convert_mask_to_alpha(ALLEGRO_BITMAP *bitmap, ALLEGRO_COLOR mask_color)