放大镜

using (Graphics g = pictureBox1.CreateGraphics())
                {//画板
                    Rectangle sourceRec = new Rectangle(e.X - 10, e.Y - 10, 10, 10);//选择放大区域
                    Rectangle destRec = new Rectangle(e.X - 40, e.Y - 40, 80, 80);//方法的区域
                    g.DrawImage(image, 0, 0, image.Width, image.Height);
                    g.DrawImage(image, destRec, sourceRec, GraphicsUnit.Pixel);//重新绘制，放大
                }