一個座標點圍繞任意中心點旋轉–C#實現

            假設對圖片上任意點(x,y)，繞一個座標點(rx0,ry0)逆時針旋轉RotaryAngle角度後的新的座標設為(x', y')，有公式：

    x'= (x - rx0)*cos(RotaryAngle) + (y - ry0)*sin(RotaryAngle) + rx0 ;
    y'=-(x - rx0)*sin(RotaryAngle) + (y - ry0)*cos(RotaryAngle) + ry0 ;

/// <summary>        /// 對一個座標點按照一個中心進行旋轉        /// </summary>        /// <param name="center">中心點</param>        /// <param name="p1">要旋轉的點</param>        /// <param name="angle">旋轉角度，笛卡爾直角座標</param>        /// <returns></returns>        private  Point PointRotate(Point center, Point p1, double angle)        {            Point tmp = new Point();            double angleHude = angle * Math.PI / 180;/*角度變成弧度*/            double x1 = (p1.X - center.X) * Math.Cos(angleHude) + (p1.Y - center.Y ) * Math.Sin(angleHude) + center .X;            double y1 = -(p1.X - center.X) * Math.Sin(angleHude) + (p1.Y - center.Y) * Math.Cos(angleHude) + center.Y;            tmp.X = (int)x1;            tmp.Y = (int)y1;            return tmp;        }