dotspanel.java

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//********************************************************************
//  DotsPanel.java       Author: Lewis/Loftus
//
//  Represents the primary panel for the Dots program on which the
//  dots are drawn.
//********************************************************************

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

public class DotsPanel extends JPanel
{
   private final int WIDTH = 300, HEIGHT = 200;
   private final int RADIUS = 6;

   private ArrayList pointList;
   private int count;

   //-----------------------------------------------------------------
   //  Sets up this panel to listen for mouse events.
   //-----------------------------------------------------------------
   public DotsPanel()
   {
      pointList = new ArrayList();
      count = 0;

      addMouseListener (new DotsListener());

      setBackground (Color.black);
      setPreferredSize (new Dimension(WIDTH, HEIGHT));
   }

   //-----------------------------------------------------------------
   //  Draws all of the dots stored in the list.
   //-----------------------------------------------------------------
   public void paintComponent (Graphics page)
   {
      super.paintComponent(page);

      page.setColor (Color.green);

      // Retrieve an iterator for the ArrayList of points
      Iterator pointIterator = pointList.iterator();

      while (pointIterator.hasNext())
      {
         Point drawPoint = (Point) pointIterator.next();
         page.fillOval (drawPoint.x - RADIUS, drawPoint.y - RADIUS,
                        RADIUS * 2, RADIUS * 2);
      }

      page.drawString ("Count: " + count, 5, 15);
   }

   //*****************************************************************
   //  Represents the listener for mouse events.
   //*****************************************************************
   private class DotsListener implements MouseListener
   {
      //--------------------------------------------------------------
      //  Adds the current point to the list of points and redraws
      //  whenever the mouse button is pressed.
      //--------------------------------------------------------------
      public void mousePressed (MouseEvent event)
      {
         pointList.add (event.getPoint());
         count++;
         repaint();
      }

      //-----------------------------------------------------------------
      //  Provide empty definitions for unused event methods.
      //-----------------------------------------------------------------
      public void mouseClicked (MouseEvent event) {}
      public void mouseReleased (MouseEvent event) {}
      public void mouseEntered (MouseEvent event) {}
      public void mouseExited (MouseEvent event) {}
   }
}