MickeyMouse.cs

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        // The previous mouse location.
        private Point OldMousePos = new Point(-1, -1);

        // See if the mouse has moved.

        private void MyTimer_Tick(object sender, EventArgs e)
        {
            // See if the cursor has moved.
            Point new_pos = Control.MousePosition;
            if (new_pos.Equals(OldMousePos)) return;
            OldMousePos = new_pos;

            // Redraw.
            this.Invalidate();
        }

        // Draw the eyes.
        private void DrawEyes(Graphics gr)
        {
            // Convert the cursor position into form units.
            Point local_pos = this.PointToClient(OldMousePos);

            // Calculate the size of the eye.
            int hgt = (int)(this.ClientSize.Height * 0.2);
            int wid = (int)(this.ClientSize.Width * 0.1);

            // Find the positions of the eyes.
            int y = (int) ((this.ClientSize.Height - hgt) / 1.9);
            int x1 = (int)((this.ClientSize.Width) / 2.5);
            int x2 = wid + 1 * x1;

            // Create a Bitmap on which to draw.
            gr.SmoothingMode = SmoothingMode.AntiAlias;

            // Draw the eyes.
            DrawEye(gr, local_pos, x1, y, wid, hgt);
            DrawEye(gr, local_pos, x2, y, wid, hgt);
        }

        // Draw an eye here.
        private void DrawEye(Graphics gr, Point local_pos, int x1, int y1, int wid, int hgt)
        {
            // Draw the outside.
            gr.FillEllipse(Brushes.White, x1, y1, wid, hgt);
            gr.DrawEllipse(Pens.Black, x1, y1, wid, hgt);

            // Find the center of the eye.
            int cx = x1 + wid / 2;
            int cy = y1 + hgt / 2;

            // Get the unit vector pointing towards the mouse position.
            double dx = local_pos.X - cx;
            double dy = local_pos.Y - cy;
            double dist = Math.Sqrt(dx * dx + dy * dy);
            dx /= dist;
            dy /= dist;

            // This point is 1/4 of the way
            // from the center to the edge of the eye.
            double px = cx + dx * wid / 4;
            double py = cy + dy * hgt / 4;

            // Draw an ellipse 1/2 the size of the eye
            // centered at (px, py).
            gr.FillEllipse(Brushes.Black, (int)(px - wid / 4),
                (int)(py - hgt / 4), wid / 2, hgt / 2);
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            DrawEyes(e.Graphics);
        }
    }