winforms printing all the contents of a panel in C#

public void PrepareImage()
 Graphics graphic = panel2.CreateGraphics();
            Size s = panel2.Size;
            memImage = new Bitmap(s.Width, s.Height, graphic);
            Graphics memGraphic = Graphics.FromImage(memImage);
            IntPtr dc1 = graphic.GetHdc();
            IntPtr dc2 = memGraphic.GetHdc();
            BitBlt(dc2, 0, 0, panel2.ClientRectangle.Width,
            panel2.ClientRectangle.Height, dc1, 0, 0, SRCCOPY);
            graphic.ReleaseHdc(dc1);
            memGraphic.ReleaseHdc(dc2);   
        }    
        private void btnprint_Click(object sender, EventArgs e)
        {
            PrepareImage();
            printDocument1.Print();
        }
        private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            Bitmap bmp=new Bitmap(panel2.Width, panel2.Height);
            panel2.DrawToBitmap(bmp, new Rectangle(0, 0, panel2.Width, panel2.Height));
            e.Graphics.DrawImage(bmp, 0, 0);
}