canvas.py 文件源码

def getAngle(self, center, p1, p2):
        dx1 = p1.x() - center.x();
        dy1 = p1.y() - center.y();

        dx2 = p2.x() - center.x();
        dy2 = p2.y() - center.y();

        c = math.sqrt(dx1*dx1 + dy1*dy1) * math.sqrt(dx2*dx2 + dy2*dy2)
        if c == 0: return 0
        y = (dx1*dx2+dy1*dy2)/c
        if y>1: return 0
        angle = math.acos(y)

        if (dx1*dy2-dx2*dy1)>0:   
            return angle
        else:
            return -angle