Provided by: allegro5-doc_5.2.5.0-2_all bug


       al_lock_bitmap_region - Allegro 5 API


              #include <allegro5/allegro.h>

              ALLEGRO_LOCKED_REGION *al_lock_bitmap_region(ALLEGRO_BITMAP *bitmap,
                 int x, int y, int width, int height, int format, int flags)


       Like al_lock_bitmap(3alleg5), but only locks a specific area of the bitmap.  If the bitmap
       is a video bitmap, only that area of the texture will be  updated  when  it  is  unlocked.
       Locking only the region you indend to modify will be faster than locking the whole bitmap.

              Note:  Using  the  ALLEGRO_LOCK_WRITEONLY with a blocked pixel format (i.e. formats
              for which al_get_pixel_block_width(3alleg5)  or  al_get_pixel_block_height(3alleg5)
              do  not return 1) requires you to have the region be aligned to the block width for
              optimal performance.  If it is not, then the function will have to lock the  region
              with  the  ALLEGRO_LOCK_READWRITE  instead  in  order to pad this region with valid


       ALLEGRO_LOCKED_REGION(3alleg5), ALLEGRO_PIXEL_FORMAT(3alleg5), al_unlock_bitmap(3alleg5)