Dynamic plot

//
// This simple control plot a (random) graph changing every 200 milliseconds
//
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace TestForm
{
    public class Plot : Control
    {
        static Random rand = new Random(123);

        Queue<double> values;
        Timer timer;

        const int pointsNum = 50;

        public Plot()
            : this(200)
        {
        }

        public Plot(int milliseconds)
        {
            timer = new Timer();
            timer.Interval = milliseconds;

            timer.Tick += new EventHandler(timer_Tick);

            values = new Queue<double>(10);

            // initial values
            for (int i = 0; i < pointsNum; i++)
                values.Enqueue(GetNewRandomValue());

            timer.Start();

        }

        void timer_Tick(object sender, EventArgs e)
        {
            values.Dequeue();
            values.Enqueue(GetNewRandomValue());

            this.Invalidate();
        }

        private double GetNewRandomValue()
        {
            return (int)(rand.NextDouble() * 100) / 200.0;
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            var dx0 = (int)(e.ClipRectangle.Width / 10.0);
            var dy0 = (int)(e.ClipRectangle.Height / 10.0);

            // draw border
            e.Graphics.FillRectangle(Brushes.White, e.ClipRectangle);

            // draw X axis
            e.Graphics.DrawLine(new Pen(Color.Black), dx0, e.ClipRectangle.Height - dy0, e.ClipRectangle.Width - dx0, e.ClipRectangle.Height - dy0);

            // draw Y axis
            e.Graphics.DrawLine(new Pen(Color.Black), dx0, dy0, dx0, e.ClipRectangle.Height - dy0);

            // draw the points
            Point[] points = new Point[values.Count];
            int i = 0;
            foreach (var value in values)
            {
                int x = (int)((e.ClipRectangle.Width - 2 * dx0) * (double)i / values.Count) + dx0;
                int y = (int)((e.ClipRectangle.Height - 2 * dy0) * value) + dy0;

                points[i] = new Point(x, y);

                i++;
            }

            e.Graphics.DrawLines(new Pen(Color.Red), points);

            base.OnPaint(e);
        }

    }
}