al_create_sub_bitmap - Man Page

#include <allegro5/allegro.h>

ALLEGRO_BITMAP *al_create_sub_bitmap(ALLEGRO_BITMAP *parent,
   int x, int y, int w, int h)

Creates a sub-bitmap of the parent, at the specified coordinates and of the specified size. A sub-bitmap is a bitmap that shares drawing memory with a pre-existing (parent) bitmap, but possibly with a different size and clipping settings.

The sub-bitmap may originate off or extend past the parent bitmap.

See the discussion in al_get_backbuffer(3) about using sub-bitmaps of the backbuffer.

The parent bitmap’s clipping rectangles are ignored.

If a sub-bitmap was not or cannot be created then NULL is returned.

When you are done with using the sub-bitmap you must call al_destroy_bitmap(3) on it to free any resources allocated for it.

Note that destroying parents of sub-bitmaps will not destroy the sub-bitmaps; instead the sub-bitmaps become invalid and should no longer be used for drawing - they still must be destroyed with al_destroy_bitmap(3) however. It does not matter whether you destroy a sub-bitmap before or after its parent otherwise.

al_create_bitmap(3)

al_create_bitmap(3), al_get_bitmap_x(3), al_get_bitmap_y(3), al_get_parent_bitmap(3), al_is_sub_bitmap(3), al_reparent_bitmap(3).