C#

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(255), r.Next(255),
						r.Next(255));
Pen p = new Pen(c, 1);
g.DrawLine(p, new Point(0, 0), new Point(x, y));
p.Dispose();
}
}
displayGraphics.DrawImage(i, ClientRectangle);
i.Dispose();