How to draw double buffered in C# or Java using GDI+

You draw something on a form using GDI+ or any other graphics library and try to update it with a timer. The problem is that the resulting display is flicking due to the lack of double buffering. Here is the solution. You have to draw on an image and then draw this image once using your Graphics object. This way you can obtain smooth display. Here is a simple code:

Graphics displayGraphics = e.Graphics;
Random r = new Random();
Image i = new Bitmap(ClientRectangle.Width, ClientRectangle.Height);
Graphics g = Graphics.FromImage(i);
g.FillRectangle(Brushes.White, ClientRectangle);
for (int x = 0; x < ClientRectangle.Width; x++)
{
    for (int y = 0; y < ClientRectangle.Height; y += 10)
    {
        Color c = Color.FromArgb(r.Next(25), r.Next(55), r.Next(5));
        Pen p = new Pen(c, 1);
        g.DrawLine(p, new Point(ClientRectangle.Width/2, ClientRectangle.Height/2), new Point(x, y));
        p.Dispose();
    }
}
displayGraphics.DrawImage(i, ClientRectangle);
i.Dispose();