is_inside_bitmap
Tells if a point is inside a bitmap.
Description
Returns non-zero if point (x, y) lies inside the bitmap. If `clip' is
non-zero, the function compares the coordinates with the clipping
rectangle, that is it returns non-zero if the point lies inside the
clipping rectangle or if clipping is disabled for the bitmap. If `clip'
is zero, the function compares the coordinates with the actual dimensions
of the bitmap.
