'Return vector with the length and width of one view pixel in scene coordinates'

def pixelSize(self):

    p0 = Point(0, 0)
    p1 = Point(1, 1)
    tr = self.transform().inverted()[0]
    p01 = tr.map(p0)
    p11 = tr.map(p1)
    return Point((p11 - p01))
