private void Form1_Paint(object sender, PaintEventArgs e)
        {
            // Bounding (Clipping Rectangle)
            Rectangle rcBnd = new Rectangle(45, 31, 757, 757);

            // Draw Clipping rectangle
            e.Graphics.DrawRectangle(Pens.Purple, rcBnd);

            // Set Clipping area
            e.Graphics.SetClip(rcBnd, CombineMode.Replace);

            // Draw a line between p1 & p2
            Point p1 = new Point(457, 421);
            Point p2 = new Point(458, 1038);
            e.Graphics.DrawLine(Pens.Blue, p1, p2);

            // Reset clipping
            e.Graphics.ResetClip();
        }