// DrawMask aligns r.Min in dst with sp in src and mp in mask and then
// replaces the rectangle r in dst with the result of a Porter-Duff
// composition. A nil mask is treated as opaque.
func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
draw.DrawMask(dst, r, src, sp, mask, mp, draw.Op(op))
}
// Draw implements the Drawer interface by calling the Draw function with
// this Op.
func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
(draw.Op(op)).Draw(dst, r, src, sp)
}
// Draw calls DrawMask with a nil mask.
func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op) {
draw.Draw(dst, r, src, sp, draw.Op(op))
}