C#中画的图为什么在最小化后会消失？

Question

     private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            Graphics paper;
            paper = pictureBox1.CreateGraphics();
            Pen pen=new Pen(Color.Red);
            Bitmap pic = new Bitmap(@"D:\201138155254591.jpg");
            paper.DrawImage(pic, 250, 50, 700, 600);
        }

Answer 1

private void pictureBox1_Paint(object sender, PaintEventArgs e)
  {
  e.graphics.DrawImage(pic, 250, 50, 700, 600);
  }

Answer 2

这个问题我遇到过 !好像要refresh（）一下的！最小化之后要重绘的！