Name: clC74495 Date: 08/26/99


Below is a Example that creates a few lightweight buttons
and draws them in an applet. This applet runs 6 times
slower on JDK 1.1.8 compared to JDK 1.1.7

When debugging this problem it was noticed that
JDK 1.1.8 creates far too many paint messages for
the light weight components compared to JDK 1.1.7.

This applet merely creates an applet Frame and then draws
an image into the background. It then creates 3 leight
weight buttons and draws them on top of the background.
I put a println statement in the paint method of the buttons and
found that under 1.1.8 the buttons are constantly redrawn again
and again (209 times) while the background is drawn.
It seems like redrawing the background
causes the buttons to be repainted, causing a "Feedback" effect.


To run this applet, compile ExampleApplet.java, OpenlookButton.java
and then run appletviewer example.html

----- Below is ExampleApplet.java ------
/*
 * @(#)ExampleApplet.java 1.2 97/01/14 Jeff Dinkins
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc. All Rights Reserved.
 *
 */

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

/**
 * ExampleApplet: Applet that demonstrates
 * OpenlookButtons.
 *
 * The applet creates a window that has a pretty background
 * picture, and adds an OpenlookButton.
 *
 * Notice how the lightweight Openlook Button component has "transparent"
 * corners and you can see the image behind them! Cool!
 */
public class ExampleApplet extends Applet {

  Image background;

  public void init() {
      setLayout(new FlowLayout());
      loadBackgroundImage();

      // *** Create buttons
      OpenlookButton button1 = new OpenlookButton("Motif sucks");
      add(button1);

      OpenlookButton button2 = new OpenlookButton("I miss Openlook!");
      add(button2);

      OpenlookButton button3 = new OpenlookButton("Java is Cool!");
      add(button3);

      // *** Create button listener
      ExampleActionListener listener = new ExampleActionListener();
      button1.addActionListener(listener);
      button2.addActionListener(listener);
      button3.addActionListener(listener);
  }

  public void loadBackgroundImage() {
      background = getImage(getCodeBase(), "images/scott.jpg");
  }

  /**
   * override update to *not* erase the background before painting
   */
  public void update(Graphics g) {
      paint(g);
  }

  /**
   * paint the background picture, then call super.paint which
   * will paint all contained components
   *
   * NOTE: You MUST call super.paint(g) or the lightweight
   * component(s) won't get painted.
   */
  public void paint(Graphics g) {
      g.drawImage(background, 0, 0, getSize().width, getSize().height,
                  getBackground(), this);
      super.paint(g);
  }

}

class ExampleActionListener implements ActionListener {
 
    public ExampleActionListener() {
    }
 
    public void actionPerformed(ActionEvent e) {
        System.out.println("Button Pressed: " + e.getActionCommand());
    }
}




------------- Below is OpenlookButton.java ------
/*
 * @(#)OpenlookButton.java 1.2 97/01/14 Jeff Dinkins
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc. All Rights Reserved.
 *
 */

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

/**
 * OpenlookButton - a class that produces a lightweight button.
 *
 * Lightweight components can have "transparent" areas, meaning that
 * you can see the background of the container behind them.
 *
 */
public class OpenlookButton extends Component {

  static int capWidth = 20; // The width of the Button's endcap
  String label; // The Button's text
  protected boolean pressed = false; // true if the button is detented.
  ActionListener actionListener; // Post action events to listeners
  
  
  /**
   * Constructs an OpenlookButton with no label.
   */
  public OpenlookButton() {
      this("");
  }

  /**
   * Constructs an OpenlookButton with the specified label.
   * @param label the label of the button
   */
  public OpenlookButton(String label) {
      this.label = label;
      enableEvents(AWTEvent.MOUSE_EVENT_MASK);
  }

  /**
   * gets the label
   * @see setLabel
   */
  public String getLabel() {
      return label;
  }
  
  /**
   * sets the label
   * @see getLabel
   */
  public void setLabel(String label) {
      this.label = label;
      invalidate();
      repaint();
  }
  
  /**
   * paints the button
   */
  public void paint(Graphics g) {
      int width = getSize().width - 1;
      int height = getSize().height - 1;

      Color interior;
      Color highlight1;
      Color highlight2;
      
      System.out.println("Start\n");
      
      interior = getBackground();

      // ***** determine what colors to use
      if(pressed) {
highlight1 = interior.darker();
highlight2 = interior.brighter();
      } else {
highlight1 = interior.brighter();
highlight2 = interior.darker();
      }

      // ***** paint the interior of the button
      g.setColor(interior);
      // left cap
      g.fillArc(0, 0, // start
capWidth, height, // size
90, 180); // angle

      // right cap
      g.fillArc(width - capWidth, 0, // start
capWidth, height, // size
270, 180); // angle

      // inner rectangle
      g.fillRect(capWidth/2, 0, width - capWidth, height);
      

      // ***** highlight the perimeter of the button
      // draw upper and lower highlight lines
      g.setColor(highlight1);
      g.drawLine(capWidth/2, 0, width - capWidth/2, 0);
      g.setColor(highlight2);
      g.drawLine(capWidth/2, height, width - capWidth/2, height);

      // upper arc left cap
      g.setColor(highlight1);
      g.drawArc(0, 0, // start
                capWidth, height, // size
                90, 180-40 // angle
      );
 
      // lower arc left cap
      g.setColor(highlight2);
      g.drawArc(0, 0, // start
                capWidth, height, // size
                270-40, 40 // angle
      );

      // upper arc right cap
      g.setColor(highlight1);
      g.drawArc(width - capWidth, 0, // start
                capWidth, height, // size
                90-40, 40 // angle
      );
 
      // lower arc right cap
      g.setColor(highlight2);
      g.drawArc(width - capWidth, 0, // start
                capWidth, height, // size
                270, 180-40 // angle
      );

      // ***** draw the label centered in the button
      Font f = getFont();
      if(f != null) {
FontMetrics fm = getFontMetrics(getFont());
g.setColor(getForeground());
g.drawString(label,
width/2 - fm.stringWidth(label)/2,
height/2 + fm.getHeight()/2 - fm.getMaxDescent()
);
      }
      
      System.out.println("End of paint\n");
  }
  
  /**
   * The preferred size of the button.
   */
  public Dimension getPreferredSize() {
      Font f = getFont();
      if(f != null) {
FontMetrics fm = getFontMetrics(getFont());
return new Dimension(fm.stringWidth(label) + capWidth*2,
fm.getHeight() + 10);
      } else {
return new Dimension(100, 50);
      }
  }
  
  /**
   * The minimum size of the button.
   */
  public Dimension getMinimumSize() {
      return new Dimension(100, 50);
  }

  /**
   * Adds the specified action listener to receive action events
   * from this button.
   * @param listener the action listener
   */
   public void addActionListener(ActionListener listener) {
       actionListener = AWTEventMulticaster.add(actionListener, listener);
       enableEvents(AWTEvent.MOUSE_EVENT_MASK);
   }
 
   /**
    * Removes the specified action listener so it no longer receives
    * action events from this button.
    * @param listener the action listener
    */
   public void removeActionListener(ActionListener listener) {
       actionListener = AWTEventMulticaster.remove(actionListener, listener);
   }
 
 
   /**
    * Paints the button and sends an action event to all listeners.
    */
   public void processMouseEvent(MouseEvent e) {
       Graphics g;
       switch(e.getID()) {
          case MouseEvent.MOUSE_PRESSED:
            // render myself inverted....
            pressed = true;

// Repaint might flicker a bit. To avoid this, you can use
// double buffering (see the Gauge example).
repaint();
            break;
          case MouseEvent.MOUSE_RELEASED:
            if(actionListener != null) {
               actionListener.actionPerformed(new ActionEvent(
                   this, ActionEvent.ACTION_PERFORMED, label));
            }
            // render myself normal again
            if(pressed == true) {
                pressed = false;

// Repaint might flicker a bit. To avoid this, you can use
// double buffering (see the Gauge example).
repaint();
            }
            break;
          case MouseEvent.MOUSE_ENTERED:
 
            break;
          case MouseEvent.MOUSE_EXITED:
            if(pressed == true) {
                // Cancel! Don't send action event.
                pressed = false;

// Repaint might flicker a bit. To avoid this, you can use
// double buffering (see the Gauge example).
repaint();

                // Note: for a more complete button implementation,
                // you wouldn't want to cancel at this point, but
                // rather detect when the mouse re-entered, and
                // re-highlight the button. There are a few state
                // issues that that you need to handle, which we leave
                // this an an excercise for the reader (I always
                // wanted to say that!)
            }
            break;
       }
       super.processMouseEvent(e);
   }


}


-------------- Below is example.html -----------------


<HTML>
<HEAD><TITLE>Openlook Button Example</TITLE></HEAD>

<body bgcolor="#ffffff">
<font size=-1>
<em>DRAFT.
Feedback to <a href=mailto:###@###.###>Kathy Walrath</a></em>.
<br>
<a href=../index.html>Back to How to Create Lightweight Components</a>
<hr>
</font>

<h1>Openlook Button Lightweight Component Example</h1>

<APPLET
Code=ExampleApplet.class
Width=400 Height=300>
</APPLET>

<hr>
<p>
Source Code:

<ul>
<li> <A HREF="OpenlookButton.java">OpenlookButton.java</A>
<li> <A HREF="ExampleApplet.java">ExampleApplet.java</A>
</ul>
(Review ID: 94405)
======================================================================