point1，point2为线段2端点 （计算结果转化为0~360）
private double Get_Angle(Point point1, Point point2)
{
double angle = 0;
angle = Math.Atan2((point2.Y - point1.Y), (point2.X - point1.X)) * 180 /Math.PI;
if (angle < 0)
{
angle += 360;
}
return angle;
}
