Texture Brush

bool cl = false;
        int x1, y1 = 0;
        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            cl = true;
            x1 = e.X;
            y1 = e.Y;
        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            cl = false;
        }
        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            if (cl == true)
            {
                Bitmap b = new Bitmap(5, 5);
                Rectangle r1 = new Rectangle(0, 0, 5, 5);
                Graphics g = Graphics.FromImage(b);
                g.SmoothingMode = SmoothingMode.AntiAlias;
                LinearGradientBrush lgb = new LinearGradientBrush(r1,
                    Color.Yellow, Color.Green , LinearGradientMode.ForwardDiagonal);
                g.FillRectangle(lgb, r1);
               
                Rectangle r = new Rectangle(x1, y1, (e.X - x1) + 1, (e.Y - y1) + 1);
                Bitmap b1 = new Bitmap(Width, Height);
                Graphics g1 = Graphics.FromImage(b1);
                g1.SmoothingMode = SmoothingMode.AntiAlias;
                TextureBrush tb = new TextureBrush(b);
                g1.FillRectangle(tb, r);
                g1.DrawRectangle(new Pen(Brushes.Black), r);
                this.BackgroundImage = b1;

            }
        }