private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawLine(
new Pen(Color.Red,2f),
new Point(0,0),
new Point(pictureBox1.Size.Width, pictureBox1.Size.Height ));
e.Graphics.DrawEllipse(
new Pen(Color.Red, 2f),
0,0, pictureBox1.Size.Width, pictureBox1.Size.Height );
}