NAME

       al_get_backbuffer - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro.h>

              ALLEGRO_BITMAP *al_get_backbuffer(ALLEGRO_DISPLAY *display)

DESCRIPTION

       Return a special bitmap representing the back-buffer of the display.

       Care  should be taken when using the backbuffer bitmap (and its sub-bitmaps) as the source bitmap (e.g as
       the bitmap argument to al_draw_bitmap(3alleg5)).  Only untransformed operations are hardware accelerated.
       These  consist  of  al_draw_bitmap(3alleg5)   and   al_draw_bitmap_region(3alleg5)   when   the   current
       transformation  is  the  identity.   If  the  transformation  is  not the identity, or some other drawing
       operation is used, the call will be routed through the memory bitmap routines, which are  slow.   If  you
       need  those  operations  to  be  accelerated, then first copy a region of the backbuffer into a temporary
       bitmap (via the al_draw_bitmap(3alleg5) and al_draw_bitmap_region(3alleg5)), and then use that  temporary
       bitmap as the source bitmap.

Allegro reference manual                                                              al_get_backbuffer(3alleg5)