// File DrawRect.java
//
// Author: Benjamin Lewis
// Date:   March 20, 1999
//
// This applet allows the user to draw a rectangle by dragging the
// mouse. The area of the rectangle will be shown in the status bar.
//
// Bugs: Some flicker while dragging the rectangle. Could be improved
// somewhat by double-buffering the graphics.

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

public class DrawRect extends Applet
{
  public final Color BACKGROUND_COLOR = Color.black;
  public final Color FOREGROUND_COLOR = Color.red;
  
  int x1 = 0;
  int x2 = 0;
  int y1 = 0;
  int y2 = 0;
  boolean rectangleSet = false;

  public void init()
  {
    // delegate the mouse listening to a new Mouse Listener
    RectMouseListener listener = new RectMouseListener(this);
    addMouseListener(listener);
    addMouseMotionListener(listener);
    
    // set up some pretty colors
    setBackground(BACKGROUND_COLOR);
    setForeground(FOREGROUND_COLOR);
  }

  public void drawRectangle()
  {
    // show the are of the rectangle on the status bar
    int area = Math.abs((x2-x1) * (y2-y1));
    showStatus("Area of rectangle is "+area+" pixels");
    
    rectangleSet = true; // a rectangle has been drawn
    
    repaint();
  }

  public void paint(Graphics g)
  {
    if (rectangleSet)
    {
      // We don't know which way the user dragged the mouse...
      int startx = Math.min(x1, x2);
      int starty = Math.min(y1, y2);
      int width  = Math.abs(x2 - x1);
      int height = Math.abs(y2 - y1);

      g.drawRect(startx, starty, width, height);
    }
  }
}

class RectMouseListener implements MouseListener, MouseMotionListener
{
  DrawRect applet;

  public RectMouseListener(DrawRect applet)
  {
    this.applet = applet;
  }

  public void mouseMoved(MouseEvent e)
  {
  }
  public void mouseDragged(MouseEvent e)
  {
    applet.x2 = e.getX();
    applet.y2 = e.getY();
    applet.drawRectangle();
  }
  
  public void mousePressed(MouseEvent e)
  {
    applet.x1 = e.getX();
    applet.y1 = e.getY();
  }
  public void mouseReleased(MouseEvent e)
  {
    applet.x2 = e.getX();
    applet.y2 = e.getY();
    applet.drawRectangle();
  }
  public void mouseClicked(MouseEvent e) {}
  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
}