// CS7 -
// RandomPaint allows the user to click & drag the mouse drawing lines 
// along the way.  A click of the button will change the color of the lines
// randomly.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.applet.*;

public class RandomPaint extends JApplet {

   // class variables (to hold mouse coordinates)
   private int last_x = 0, last_y = 0;
   private int now_x = 0, now_y = 0;

   // the graphics context
   private Graphics g;

   public void init() {
      // colors
      final Color [] someColors = { Color.black, Color.red,
         Color.green, Color.blue, Color.magenta };

      // get access to the applet's top-level container
      Container pane = getContentPane();

      // load the graphics context
      g = getGraphics();

      // create components
      final JButton flipButton = new JButton("Change Color");

      // add the button
      pane.setLayout(new FlowLayout());	// java fits things in for you
      pane.add(flipButton);

      // when the button is pressed, pick a new color randomly
      flipButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            // randomly pick a color from the array
            g.setColor(someColors[(int)(Math.random()*10) % someColors.length]);
         }
      });

      // This mouse listener just waits for mouse click events ("down").
      // When it happens, we simply remember where the mouse is now.
      addMouseListener(new MouseAdapter() {
         public void mousePressed(MouseEvent e) {
            last_x = e.getX();
            last_y = e.getY();
         }
      });

      // This listener detects a drag event. 
      // By calling repaint(), our paint() method is called, therefore drawing
      // a bunch of small lines.  It appears pretty smooth for the user.
      addMouseMotionListener(new MouseMotionAdapter() {
         public void mouseDragged(MouseEvent e) {
            now_x = e.getX();
            now_y = e.getY();
            g.drawLine(last_x, last_y, now_x, now_y);
            last_x = now_x;  // we now have "new" old locations
            last_y = now_y;
         }
      });
	  
   }  // end init()
}  // end of class