how to make diagram fit with in panel?

[gopal0430]

hey i am trying to build a windows application in .net,i have to draw factorial image inside the panel

     private void Canvas_Paint(object sender, PaintEventArgs e)
            {
                start_x = Canvas.Width / 2;
                start_Y = Canvas.Height / 2;
                for (int i = 0; i < 400; i++)
                    draw_T();
 
            }
 
     public void draw_T()
            {
                mypen = new Pen(Color.Green, 2F);
                my_angle = my_angle + (45);
                my_length = 100 + (1);
 
                end_x = (int)(start_x + Math.Cos(my_angle * .0174539676) * my_length);
 
                end_Y = (int)(start_Y + Math.Sin(my_angle * .0174539676) * my_length);
 
                Point[] points =
                {
                    new Point (start_x,start_Y),
                    new Point (end_x,end_Y)
                                };
                Point[] points1 =
                {
                    new Point ((end_x+start_x)/2,(end_Y+start_Y)/2),
                     new Point (end_x+50,end_Y-100)
                                };
                start_x = end_x;
                start_Y = end_Y;
                Graphics g = Canvas.CreateGraphics();
                g.DrawLines(mypen, points);
                g.DrawLines(mypen, points1);
            }

drawing T shape line,then i start to draw another T shape from last end points .But problem is diagram is going outside of the panel.How do i fix drawing inside the panel