gcc/libjava/javax/swing/DefaultButtonModel.java

/* DefaultButtonModel.java -- 
   Copyright (C) 2002, 2004 Free Software Foundation, Inc.

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)
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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.

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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
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package javax.swing;

import java.awt.AWTEvent;
import java.awt.AWTEventMulticaster;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.Serializable;
import java.util.EventListener;
import java.util.Vector;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;

/**
 * The purpose of this class is to model the dynamic state of an abstract
 * button. The concrete button type holding this state may be a a "toggle"
 * button (checkbox, radio button) or a "push" button (menu button, button).
 * 
 * Any change to the model's properties will trigger the firing of a
 * ChangeEvent.
 *
 * Any change to the "pressed" property will trigger the firing of an
 * ItemEvent in addition to ChangeEvent.
 *
 * Any change which causes the enabled, armed and pressed properties to
 * simultaneously become <code>true</code> will trigger the firing of an
 * ActionEvent in addition to the ChangeEvent.
 *
 * @author Graydon Hoare (graydon&064;redhat.com)
 */
public class DefaultButtonModel implements ButtonModel, Serializable
{
  static final long serialVersionUID = -5342609566534980231L;

  /** Indicates that the button is <em>partially</em> committed to being
   pressed, but not entirely. This usually happens when a user has pressed
   but not yet released the mouse button. */
  static int ARMED = 1;

  /** State constant indicating that the button is enabled. Buttons cannot
   be pressed or selected unless they are enabled. */
  static int ENABLED = 2;

  /** State constant indicating that the button has been fully
   pressed. This usually happens when a user has released the mouse over a
   previously "armed" button. */
  static int PRESSED = 4;

  /** State constant indicating that the mouse is currently positioned over
      the button. */
  static int ROLLOVER = 8;

  /** State constant indicating that the button is selected. This constant
      is only meaningful for toggle-type buttons (radio buttons,
      checkboxes). */
  static int SELECTED = 16;

  /** Represents the "state properties" (armed, enabled, pressed, rollover
      and selected) by a bitwise combination of integer constants. */
  int stateMask;

  /** List of ItemListeners, ChangeListeners, and ActionListeners
      registered on this model. */
  EventListenerList listenerList;

  /** The single ChangeEvent this model (re)uses to call its
      ChangeListeners. */
  ChangeEvent changeEvent;

  /** The group this model belongs to. Only one button in a group may be
      selected at any given time. */
    ButtonGroup group;

  /** The key code (one of {@link java.awt.event.KeyEvent} VK_*) used to
      press this button via a keyboard interface. */
  int mnemonic;

  /** The string used as the "command" property of any ActionEvent this
      model sends. */
  String actionCommand;

  public DefaultButtonModel()
  {
    stateMask = 0;
    listenerList = new EventListenerList();    
    changeEvent = new ChangeEvent(this);
  }

  /**
   * Return <code>null</code>. Use {@link AbstractButton} if you wish to
   * interface with a button via an {@link ItemSelectable} interface.
   *
   * @return <code>null</code>
   */
    public Object[] getSelectedObjects()
    {
	return null;
    }

  /**
   * Add an ActionListener to the model. Usually only called to subscribe
   * an AbstractButton's listener to the model.
   *
   * @param l The listener to add
   */
  public void addActionListener(ActionListener l)
	    {
    listenerList.add(ActionListener.class, l);
    }

  /**
   * Remove an ActionListener to the model. Usually only called to
   * unsubscribe an AbstractButton's listener to the model.
   *
   * @param l The listener to remove
   */
  public void removeActionListener(ActionListener l)
  {
    listenerList.remove(ActionListener.class, l);
  }

  /**
   * Add an ItemListener to the model. Usually only called to subscribe
   * an AbstractButton's listener to the model.
   *
   * @param l The listener to add
   */
  public void addItemListener(ItemListener l)
  {
    listenerList.add(ItemListener.class, l);
  }

  /**
   * Remove an ItemListener to the model. Usually only called to
   * unsubscribe an AbstractButton's listener to the model.
   *
   * @param l The listener to remove
   */
  public void removeItemListener(ItemListener l)
  {
    listenerList.remove(ItemListener.class, l);
  }

  /**
   * Add a ChangeListener to the model. Usually only called to subscribe
   * an AbstractButton's listener to the model.
   *
   * @param l The listener to add
   */
  public void addChangeListener(ChangeListener l)
  {
    listenerList.add(ChangeListener.class, l);
  }

  /**
   * Remove a ChangeListener to the model. Usually only called to
   * unsubscribe an AbstractButton's listener to the model.
   *
   * @param l The listener to remove
   */
  public void removeChangeListener(ChangeListener l)
  {
    listenerList.remove(ChangeListener.class, l);
  }

  /**
   * Inform each ItemListener in the {@link listenerList} that an ItemEvent
   * has occurred. This happens in response to any change to the {@link
   * stateMask} field.
   *
   * @param e The ItemEvent to fire
   */
  public void fireItemStateChanged(ItemEvent e)
  {
    EventListener[] ll = listenerList.getListeners(ItemListener.class);
    for (int i = 0; i < ll.length; i++)
      ((ItemListener)ll[i]).itemStateChanged(e);
  }

  /**
   * Inform each ActionListener in the {@link listenerList} that an
   * ActionEvent has occurred. This happens in response to the any change
   * to the {@link stateMask} field which makes the enabled, armed and
   * pressed properties all simultaneously <code>true</code>.
   *
   * @param e The ActionEvent to fire
   */
  public void fireActionPerformed(ActionEvent e)
  {
    EventListener[] ll = listenerList.getListeners(ActionListener.class);
    for (int i = 0; i < ll.length; i++)
      ((ActionListener)ll[i]).actionPerformed(e);
  }

  /**
   * Inform each ChangeListener in the {@link listenerList} that a
   * ChangeEvent has occurred. This happens in response to the any change
   * to a property of the model.
   *
   * @param event The ChangeEvent to fire
   */
  public void fireStateChanged(ChangeEvent e)
  {
    EventListener[] ll = listenerList.getListeners(ChangeListener.class);
    for (int i = 0; i < ll.length; i++)
      ((ChangeListener)ll[i]).stateChanged(e);
  }

  /**
   * Helper method to fire a ChangeEvent with the model as the event's
   * source.
   */
  protected void changeState(int stateflag, boolean b)
    {
    int oldstate = stateMask;
    int newstate;

    if (b)
      newstate = oldstate | stateflag;
    else
      newstate = oldstate & ~stateflag;

    if (oldstate == newstate)
      return;

    stateMask = newstate;

    fireStateChanged(changeEvent);

    if ((newstate & ENABLED) == 0)
      return;

    if ((oldstate & SELECTED) == 0
        && (newstate & SELECTED) == SELECTED)
      fireItemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED, 
                                         null, ItemEvent.SELECTED));

    else if ((oldstate & SELECTED) == SELECTED
             && (newstate & SELECTED) == 0)
      fireItemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED, 
                                         null, ItemEvent.DESELECTED));

    else if ((newstate & ARMED) == ARMED
             && (newstate & PRESSED) == PRESSED)
	    {
        fireActionPerformed(new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
                                            actionCommand));
        stateMask = stateMask & ~(PRESSED | ARMED);
	    }
    
    }

  /**
   * Get the value of the model's "armed" property.
   * 
   * @return The current "armed" property 
   */
  public boolean isArmed()
	    {
    return (stateMask & ARMED) == ARMED;
    }

  /**
   * Set the value of the model's "armed" property.
   *
   * @param a The new "armed" property
   */
  public void setArmed(boolean a)
  {
    changeState(ARMED, a);
  }

  /**
   * Get the value of the model's "enabled" property.
   *
   * @return The current "enabled" property.
   */
  public boolean isEnabled()
    {
    return (stateMask & ENABLED) == ENABLED;
    }

  /**
   * Set the value of the model's "enabled" property.
   *
   * @param e The new "enabled" property
   */
  public void setEnabled(boolean e)
  {
    changeState(ENABLED, e);
  }

  /**
   * Set the value of the model's "pressed" property.
   *
   * @param p The new "pressed" property
   */
  public void setPressed(boolean p)
    {	
    changeState(PRESSED, p);
    }

  /**
   * Get the value of the model's "pressed" property.
   *
   * @return The current "pressed" property
   */
  public boolean isPressed()
  {
    return (stateMask & PRESSED) == PRESSED;
  }

  /**
   * Set the value of the model's "rollover" property.
   *
   * @param r The new "rollover" property
   */
  public void setRollover(boolean r)
  {
    changeState(ROLLOVER, r);
  }


  /**
   * Set the value of the model's "selected" property.
   *
   * @param s The new "selected" property
   */
  public void setSelected(boolean s)
  {
    changeState(SELECTED, s);
  }

  /**
   * Get the value of the model's "selected" property.
   *
   * @return The current "selected" property
   */
  public boolean isSelected()
  {
    return (stateMask & SELECTED) == SELECTED;
  }

  /**
   * Get the value of the model's "rollover" property.
   *
   * @return The current "rollover" property
   */
  public boolean isRollover()
    {
    return (stateMask & ROLLOVER) == ROLLOVER;
    }

  /**
   * Get the value of the model's "mnemonic" property.
   *
   * @return The current "mnemonic" property
   */
  public int getMnemonic()
    { 
    return mnemonic;
  }

  /**
   * Set the value of the model's "mnemonic" property.
   *
   * @param key The new "mnemonic" property
   */
  public void setMnemonic(int key)
	    {
    if (mnemonic != key)
		    {
        mnemonic = key;
        fireStateChanged(changeEvent);
		    }
  }

  /**
   * Set the value of the model's "actionCommand" property. This property
   * is used as the "command" property of the {@link ActionEvent} fired
   * from the model.
   *
   * @param s The new "actionCommand" property.
   */
  public void setActionCommand(String s)
		    {
    if (actionCommand != s)
      {
        actionCommand = s;
        fireStateChanged(changeEvent);
		    }
	    } 

  /**
   * Set the value of the model's "actionCommand" property. This property
   * is used as the "command" property of the {@link ActionEvent} fired
   * from the model.
   *
   * @return The current "actionCommand" property
   */
  public String getActionCommand()
	    {
    return actionCommand;
  }

  /**
   * Set the value of the model's "group" property. The model is said to be
   * a member of the {@link ButtonGroup} held in its "group" property, and
   * only one models in a given group can have their "selected" property be
   * <code>true</code> at a time.
   *
   * @param g The new "group" property
   */
  public void setGroup(ButtonGroup g)
  {
    if (group != g)
      {
        group = g;
        fireStateChanged(changeEvent);
	    }
    }
}