set_clip_state (3) - Linux Manuals
set_clip_state: Turns on or off the clipping of a bitmap. Allegro game programming library.
set_clip_state - Turns on or off the clipping of a bitmap. Allegro game programming library.
void set_clip_state(BITMAP *bitmap, int state)
Turns on (if state is non-zero) or off (if state is zero) clipping for the
specified bitmap. Turning clipping off may slightly speed up some drawing
operations (usually a negligible difference, although every little helps)
but will result in your program dying a horrible death if you try to draw
beyond the edges of the bitmap.