canvas.go
func ClipRect() (x int, y int, w int, h int) {
	return canvas.clipX, canvas.clipY, canvas.clipW, canvas.clipH
}
func ClipRect() (x int, y int, w int, h int) {
	return canvas.clipX, canvas.clipY, canvas.clipW, canvas.clipH
}
// ClipRect returns the current clipping rectangle