def METHOD_NAME(self, sx, sy, size):
    from kivy.core.window import Window as W
    WIDTH, HEIGHT = size
    xratio = WIDTH / W.width
    yratio = HEIGHT / W.height
    xoffset = - W.left / W.width
    yoffset = - (HEIGHT - W.top - W.height) / W.height
    sx = sx * xratio + xoffset
    sy = sy * yratio + yoffset
    return sx, sy