public class DrawBox extends JPanel implements MouseListener, MouseMotionListener {
    /* RawPattern is exactly the same as HashSet<Point> */
    /* Point is a class with two ints, x and y, and setters/getters */

    private RawPattern pattern = new RawPattern();

    public DrawBox() {
        super();

        addMouseListener(this);
        addMouseMotionListener(this);
    }

    public void paintComponent(Graphics g)
    {
        g.clearRect(0, 0, getWidth(), getHeight());

        for(Point p : pattern)
        {
            g.fillOval(p.getX() - 2, p.getY() - 2, 5, 5);
        }
    }

    @Override
    public void mouseClicked(MouseEvent arg0) {
    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
    }

    @Override
    public void mouseExited(MouseEvent arg0) {
    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        Point p = new Point(arg0.getX(), arg0.getY());
        pattern.add(p);
        repaint();
    }

    @Override
    public void mouseReleased(MouseEvent arg0) {
        pattern.clear();
        repaint();
    }

    @Override
    public void mouseDragged(MouseEvent arg0) {
        Point p = new Point(arg0.getX(), arg0.getY());
        pattern.add(p);
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent arg0) {

    }
}