1al_get_backbuffer(3)       Library Functions Manual       al_get_backbuffer(3)
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NAME

6       al_get_backbuffer
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SYNOPSIS

9              #include <allegro5/allegro.h>
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11              ALLEGRO_BITMAP *al_get_backbuffer(ALLEGRO_DISPLAY *display)
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DESCRIPTION

14       Return a special bitmap representing the back-buffer of the display.
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16       Care should be taken when using the backbuffer bitmap (and its sub-bit‐
17       maps) as the source bitmap (e.g as the bitmap argument to  al_draw_bit‐
18       map(3)).  Only untransformed operations are hardware accelerated.  This
19       consists of al_draw_bitmap(3)  and  al_draw_bitmap_region(3)  when  the
20       current  transformation  is  the identity.  If the tranformation is not
21       the identity, or some other drawing operation is used, the call will be
22       routed through the memory bitmap routines, which are slow.  If you need
23       those operations to be accelerated, then first copy  a  region  of  the
24       backbuffer  into  a  temporary  bitmap  (via  the al_draw_bitmap(3) and
25       al_draw_bitmap_region(3)), and then use that temporary  bitmap  as  the
26       source bitmap.
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30Allegro reference manual                                  al_get_backbuffer(3)
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