func (r rectImage) Bounds() image.Rectangle { return image.Rectangle(r) }
func (r rectImage) At(x, y int) color.Color { if (image.Point{x, y}).In(image.Rectangle(r)) { return color.Opaque } return color.Transparent }
func (i *Image) Bounds() Rectangle { return image.Rectangle(i.O_x, i.O_y, i.O_x+Wid, i.O_y+Hgt) }