【求助】C# 如何在picturebox中截取多边形

Question

        private void button2_Click(object sender, EventArgs e)
        {
            Bitmap _Bit = (Bitmap)Image.FromFile(@"C:\1.bmp");
            Point[] _Point = new Point[3];
            _Point[0] = new Point(0, 0);
            _Point[1] = new Point(0, 100);
            _Point[2] = new Point(100, 100);  //定义了一个三角
            this.BackgroundImage = GetBitmap(_Bit, _Point);
        }        public static Bitmap GetBitmap(Bitmap p_Bitmap, Point[] p_Point)
        {
            System.Drawing.Drawing2D.GraphicsPath _Path = new System.Drawing.Drawing2D.GraphicsPath();
            _Path.AddPolygon(p_Point);
            Region _Region = new Region(new RectangleF(0, 0, p_Bitmap.Width, p_Bitmap.Height));
            _Region.Xor(_Path);
            Bitmap _New = (Bitmap)p_Bitmap.Clone();
            Graphics _Graphics = Graphics.FromImage(_New);
           _Graphics.FillRegion(Brushes.White,_Region);  
            _Graphics.Dispose();
            return _New;
            
        }这样看看.