c#圆角窗体

 public void SetWindowRegion()
        {
            System.Drawing.Drawing2D.GraphicsPath FormPath;
            FormPath = new System.Drawing.Drawing2D.GraphicsPath();
            Rectangle rect = new Rectangle(0, 0, this.Width, this.Height);
            FormPath = WinGetRoundedRectPath(rect, 15);
            this.Region = new Region(FormPath);
        }
        private GraphicsPath WinGetRoundedRectPath(Rectangle rect, int radius)
        {
            int diameter = radius;
            Rectangle arcRect = new Rectangle(rect.Location, new Size(diameter, diameter));
            GraphicsPath path = new GraphicsPath();
            //   左上角   
            path.AddArc(arcRect, 180, 90);
            //   右上角   
            arcRect.X = rect.Right - diameter;
            path.AddArc(arcRect, 270, 90);
            //   右下角   
            arcRect.Y = rect.Bottom - diameter;
            path.AddArc(arcRect, 0, 90);
            //   左下角   
            arcRect.X = rect.Left;
            path.AddArc(arcRect, 90, 90);
            path.CloseFigure();
            return path;
        }