import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.util.Random;

/**
 * This class draws random points in and around a circle.
 */
public class Monte5 extends Applet implements ActionListener
{
	private static Random randy;
	private int NUM_POINTS;
	private int SIZE;
	
	private Image offScreenImage;
	private Graphics offScreenGraphics;
	
	private Label insideLabel;
	private TextField insideField;
	private Label outsideLabel;
	private TextField outsideField;
	private Button dotButton;
	
	private int randomInRange(int low, int high)
	{
		return (Math.abs(randy.nextInt()) % (high-low+1)) + low;
	}
	
	private double distance(int x1, int y1, int x2, int y2)
	{
		return Math.sqrt(Math.pow(x1-x2, 2) + Math.pow(y1-y2, 2));	
	}
	
	public void init()
	{
		randy = new Random();
		NUM_POINTS = Integer.parseInt(getParameter("points"));
		Dimension dim = getSize();
		SIZE = dim.width;
		
        setLayout(new BorderLayout());
		
		dotButton = new Button("Click to generate dots");
		dotButton.addActionListener(this);
		
	    add(dotButton, BorderLayout.SOUTH);
		
		drawCircle();
	}
	
	public void drawCircle()
	{
		offScreenImage = createImage(SIZE, SIZE);
	    offScreenGraphics = offScreenImage.getGraphics();
		Graphics g = getGraphics();
		
		offScreenGraphics.clearRect(0,0,SIZE,SIZE);
		g.clearRect(0,0,SIZE,SIZE);
		
	    offScreenGraphics.setColor(Color.red);
        g.setColor(Color.red);
	    offScreenGraphics.fillOval(0, 0, SIZE, SIZE);
        g.fillOval(0, 0, SIZE, SIZE);
	}
	
	public void drawDots()
    {
        drawCircle();
		
		Graphics g = getGraphics();
        for (int i = 0; i < NUM_POINTS; i++) {
            int x = randomInRange(0, SIZE);
            int y = randomInRange(0, SIZE);
            if (distance(x, y, SIZE/2, SIZE/2) < SIZE/2) {
                offScreenGraphics.setColor(Color.white);
                g.setColor(Color.white);
            }
            else {
                offScreenGraphics.setColor(Color.black);
                g.setColor(Color.black);
            }
            offScreenGraphics.drawLine(x, y, x, y);
            g.drawLine(x, y, x, y);
		}
    }
	
	public void paint(Graphics g)
	{
		g.drawImage(offScreenImage, 0, 0, null);
	}
		
	public void actionPerformed(ActionEvent e)
	{
		if (e.getSource() == dotButton) {
			drawDots();
		}
	}
}