def _quadPoints(size, disp1, disp2):
        """Return points for QUAD transformation."""
        w, h = size
        x1, y1 = disp1
        x2, y2 = disp2

        return (
            x1,    -y1,
            -x1,    h + y2,
            w + x2, h - y2,
            w - x2, y1
        )
Return points for QUAD transformation.