al_create_sub_bitmap
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 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.
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.
See also: al_create_bitmap
Examples: ex_clip, ex_logo, ex_subbitmap, ex_transform
Most helpful discussions:
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