awteventmulticaster.java

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/* AWTEventMulticaster.java -- allows multicast chaining of listeners
   Copyright (C) 1999, 2000, 2002 Free Software Foundation

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.awt;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.ContainerEvent;
import java.awt.event.ContainerListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.HierarchyBoundsListener;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.awt.event.InputMethodEvent;
import java.awt.event.InputMethodListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.event.TextEvent;
import java.awt.event.TextListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;
import java.awt.event.WindowListener;
import java.awt.event.WindowStateListener;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.EventListener;

/**
 * This class is used to implement a chain of event handlers.  Dispatching
 * using this class is thread safe.  Here is a quick example of how to
 * add and delete listeners using this class.  For this example, we will
 * assume are firing <code>AdjustmentEvent</code>'s.  However, this
 * same approach is useful for all events in the <code>java.awt.event</code>
 * package, and more if this class is subclassed.
 *
 * <p><code>
 * AdjustmentListener al;
 * public void addAdjustmentListener(AdjustmentListener listener)
 * {
 *   al = AWTEventMulticaster.add(al, listener);
 * }
 * public void removeAdjustmentListener(AdjustmentListener listener)
 * {
 *   al = AWTEventMulticaster.remove(al, listener);
 * }
 * </code>
 *
 * <p>When it come time to process an event, simply call <code>al</code>,
 * assuming it is not <code>null</code>, and all listeners in the chain will
 * be fired.
 *
 * <p>The first time <code>add</code> is called it is passed
 * <code>null</code> and <code>listener</code> as its arguments.  This
 * starts building the chain.  This class returns <code>listener</code>
 * which becomes the new <code>al</code>.  The next time, <code>add</code>
 * is called with <code>al</code> and <code>listener</code> and the
 * new listener is then chained to the old.
 *
 * @author Bryce McKinlay
 * @author Aaron M. Renn <[e-mail]>
 * @author Eric Blake <[e-mail]>
 * @since 1.1
 * @status updated to 1.4
 */
public class AWTEventMulticaster
  implements ComponentListener, ContainerListener, FocusListener, KeyListener,
             MouseListener, MouseMotionListener, WindowListener,
             WindowFocusListener, WindowStateListener, ActionListener,
             ItemListener, AdjustmentListener, TextListener,
             InputMethodListener, HierarchyListener, HierarchyBoundsListener,
             MouseWheelListener
{
  /**
   * A variable in the event chain.
   */
  protected final EventListener a;

  /**
   * A variable in the event chain.
   */
  protected final EventListener b;

  /**
   * Initializes a new instance of <code>AWTEventMulticaster</code> with
   * the specified event listener parameters. The parameters should not be
   * null, although it is not required to enforce this with a
   * NullPointerException.
   *
   * @param a the "a" listener object
   * @param b the "b" listener object
   */
  protected AWTEventMulticaster(EventListener a, EventListener b)
  {
    this.a = a;
    this.b = b;
  }

  /**
   * Removes one instance of the specified listener from this multicaster
   * chain. This descends recursively if either child is a multicaster, and
   * returns a multicaster chain with the old listener removed.
   *
   * @param oldl the object to remove from this multicaster
   * @return the resulting multicaster with the specified listener removed
   */
  protected EventListener remove(EventListener oldl)
  {
    // If oldl is an immediate child, return the other child.
    if (a == oldl)
      return b;
    if (b == oldl)
      return a;
    // If a and/or b are Multicaster's, search them recursively.
    if (a instanceof AWTEventMulticaster)
      {
        EventListener newa = ((AWTEventMulticaster) a).remove(oldl);
        if (newa != a)
          return new AWTEventMulticaster(newa, b);
      }
    if (b instanceof AWTEventMulticaster)
      {
        EventListener newb = ((AWTEventMulticaster) b).remove(oldl);
        if (newb != b)
          return new AWTEventMulticaster(a, newb);
      }
    // oldl was not found.
    return this;
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentResized(ComponentEvent e)
  {
    ((ComponentListener) a).componentResized(e);
    ((ComponentListener) b).componentResized(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentMoved(ComponentEvent e)
  {
    ((ComponentListener) a).componentMoved(e);
    ((ComponentListener) b).componentMoved(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentShown(ComponentEvent e)
  {
    ((ComponentListener) a).componentShown(e);
    ((ComponentListener) b).componentShown(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentHidden(ComponentEvent e)
  {
    ((ComponentListener) a).componentHidden(e);
    ((ComponentListener) b).componentHidden(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentAdded(ContainerEvent e)
  {
    ((ContainerListener) a).componentAdded(e);
    ((ContainerListener) b).componentAdded(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void componentRemoved(ContainerEvent e)
  {
    ((ContainerListener) a).componentRemoved(e);
    ((ContainerListener) b).componentRemoved(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void focusGained(FocusEvent e)
  {
    ((FocusListener) a).focusGained(e);
    ((FocusListener) b).focusGained(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void focusLost(FocusEvent e)
  {
    ((FocusListener) a).focusLost(e);
    ((FocusListener) b).focusLost(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void keyTyped(KeyEvent e)
  {
    ((KeyListener) a).keyTyped(e);
    ((KeyListener) b).keyTyped(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void keyPressed(KeyEvent e)
  {
    ((KeyListener) a).keyPressed(e);
    ((KeyListener) b).keyPressed(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void keyReleased(KeyEvent e)
  {
    ((KeyListener) a).keyReleased(e);
    ((KeyListener) b).keyReleased(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseClicked(MouseEvent e)
  {
    ((MouseListener) a).mouseClicked(e);
    ((MouseListener) b).mouseClicked(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mousePressed(MouseEvent e)
  {
    ((MouseListener) a).mousePressed(e);
    ((MouseListener) b).mousePressed(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseReleased(MouseEvent e)
  {
    ((MouseListener) a).mouseReleased(e);
    ((MouseListener) b).mouseReleased(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseEntered(MouseEvent e)
  {
    ((MouseListener) a).mouseEntered(e);
    ((MouseListener) b).mouseEntered(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseExited(MouseEvent e)
  {
    ((MouseListener) a).mouseExited(e);
    ((MouseListener) b).mouseExited(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseDragged(MouseEvent e)
  {
    ((MouseMotionListener) a).mouseDragged(e);
    ((MouseMotionListener) b).mouseDragged(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void mouseMoved(MouseEvent e)
  {
    ((MouseMotionListener) a).mouseMoved(e);
    ((MouseMotionListener) b).mouseMoved(e);
  }

  /**
   * Handles this event by dispatching it to the "a" and "b" listener
   * instances.
   *
   * @param event the event to handle
   */
  public void windowOpened(WindowEvent e)
  {
    ((WindowListener) a).windowOpened(e);