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/* DefaultButtonModel.java --

   Copyright (C) 2002, 2004, 2006, 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

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02110-1301 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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independent module, the terms and conditions of the license of that

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this exception to your version of the library, but you are not

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package javax.swing;

import java.awt.ItemSelectable;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.ItemEvent;

import java.awt.event.ItemListener;

import java.awt.event.KeyEvent;

import java.io.Serializable;

import java.util.EventListener;

import javax.swing.event.ChangeEvent;

import javax.swing.event.ChangeListener;

import javax.swing.event.EventListenerList;

/**

 * The default implementation of {@link ButtonModel}.

 * 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).

 * If the model is disabled, only the "selected" property can be changed. An

 * attempt to change the "armed", "rollover" or "pressed" properties  while

 * the model is disabled will be blocked. Any successful (non-blocked) change

 * to the model's properties will trigger the firing of a ChangeEvent. Any

 * change to the "selected" property will trigger the firing of an ItemEvent

 * in addition to ChangeEvent. This is true whether the model is enabled or

 * not. One other state change is special: the transition from "enabled,

 * armed and pressed" to "enabled, armed and not-pressed". This is considered

 * the "trailing edge" of a successful mouse click, and therefore fires an

 * ActionEvent in addition to a ChangeEvent. In all other respects this class

 * is just a container of boolean flags.

 *

 * @author Graydon Hoare (graydon_at_redhat.com)

 */

public class DefaultButtonModel implements ButtonModel, Serializable

{

  /** DOCUMENT ME! */

  private 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.

   */

  public static final int ARMED = 1;

  /**

   * State constant indicating that the button is enabled. Buttons cannot be

   * pressed or selected unless they are enabled.

   */

  public static final int ENABLED = 8;

  /**

   * State constant indicating that the user is holding down the button. When

   * this transitions from true to false, an ActionEvent may be fired,

   * depending on the value of the "armed" property.

   */

  public static final int PRESSED = 4;

  /**

   * State constant indicating that the mouse is currently positioned over the

   * button.

   */

  public static final int ROLLOVER = 16;

  /**

   * State constant indicating that the button is selected. This constant is

   * only meaningful for toggle-type buttons (radio buttons, checkboxes).

   */

  public static final int SELECTED = 2;

  /**

   * Represents the "state properties" (armed, enabled, pressed, rollover and

   * selected) by a bitwise combination of integer constants.

   */

  protected int stateMask = ENABLED;

  /**

   * List of ItemListeners, ChangeListeners, and ActionListeners registered on

   * this model.

   */

  protected EventListenerList listenerList = new EventListenerList();

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

  protected ChangeEvent changeEvent = new ChangeEvent(this);

  /**

   * The group this model belongs to. Only one button in a group may be

   * selected at any given time.

   */

  protected ButtonGroup group;

  /**

   * The key code (one of {@link java.awt.event.KeyEvent} VK_) used to press

   * this button via a keyboard interface.

   */

  protected int mnemonic = KeyEvent.VK_UNDEFINED;

  /**

   * The string used as the "command" property of any ActionEvent this model

   * sends.

   */

  protected String actionCommand;

  /**

   * Creates a new DefaultButtonModel object.

   */

  public DefaultButtonModel()

  {

    // Nothing to do here.

  }

  /**

   * 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;

  }

  /**

   * Returns a specified class of listeners.

   *

   * @param listenerType the type of listener to return

   *

   * @return array of listeners

   */

  public <T extends EventListener> T[] getListeners(Class<T> listenerType)

  {

    return listenerList.getListeners(listenerType);

  }

  /**

   * 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);

  }

  /**

   * Returns all registered <code>ActionListener</code> objects.

   *

   * @return array of <code>ActionListener</code> objects

   */

  public ActionListener[] getActionListeners()

  {

    return (ActionListener[]) listenerList.getListeners(ActionListener.class);

  }

  /**

   * 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);

  }

  /**

   * Returns all registered <code>ItemListener</code> objects.

   *

   * @return array of <code>ItemListener</code> objects

   */

  public ItemListener[] getItemListeners()

  {

    return (ItemListener[]) listenerList.getListeners(ItemListener.class);

  }

  /**

   * 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);

  }

  /**

   * Returns all registered <code>ChangeListener</code> objects.

   *

   * @return array of <code>ChangeListener</code> objects

   */

  public ChangeListener[] getChangeListeners()

  {

    return (ChangeListener[]) listenerList.getListeners(ChangeListener.class);

  }

  /**

   * 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

   */

  protected void fireItemStateChanged(ItemEvent e)

  {

    ItemListener[] ll = getItemListeners();

    for (int i = 0; i < ll.length; i++)

      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

   */

  protected void fireActionPerformed(ActionEvent e)

  {

    ActionListener[] ll = getActionListeners();

    for (int i = 0; i < ll.length; i++)

      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.

   */

  protected void fireStateChanged()

  {

    ChangeListener[] ll = getChangeListeners();

    for (int i = 0; i < ll.length; i++)

      ll[i].stateChanged(changeEvent);

  }

  /**

   * 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)

  {

    // if this call does not represent a CHANGE in state, then return

    if ((a && isArmed()) || (!a && !isArmed()))

      return;

    // cannot change ARMED state unless button is enabled

    if (!isEnabled())

      return;

    // make the change

    if (a)

      stateMask = stateMask | ARMED;

    else

      stateMask = stateMask & (~ARMED);

    // notify interested ChangeListeners

    fireStateChanged();

  }

  /**

   * 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)

  {

    // if this call does not represent a CHANGE in state, then return

    if ((e && isEnabled()) || (!e && !isEnabled()))

      return;

    // make the change

    if (e)

      stateMask = stateMask | ENABLED;

    else

      stateMask = stateMask & (~ENABLED) & (~ARMED) & (~PRESSED);

    // notify interested ChangeListeners

    fireStateChanged();

  }

  /**

   * Set the value of the model's "pressed" property.

   *

   * @param p The new "pressed" property

   */

  public void setPressed(boolean p)

  {

    // if this call does not represent a CHANGE in state, then return

    if ((p && isPressed()) || (!p && !isPressed()))

      return;

    // cannot changed PRESSED state unless button is enabled

    if (!isEnabled())

      return;

    // make the change

    if (p)

      stateMask = stateMask | PRESSED;

    else

      stateMask = stateMask & (~PRESSED);

    // if button is armed and was released, fire action event

    if (!p && isArmed())

      fireActionPerformed(new ActionEvent(this, ActionEvent.ACTION_PERFORMED,

                                          actionCommand));

    // notify interested ChangeListeners

    fireStateChanged();

  }

  /**

   * 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)

  {

    // if this call does not represent a CHANGE in state, then return

    if (r == isRollover())

      return;

    // cannot set ROLLOVER property unless button is enabled

    if (!isEnabled())

      return;

    // make the change

    if (r)

      stateMask = stateMask | ROLLOVER;

    else

      stateMask = stateMask & (~ROLLOVER);

    // notify interested ChangeListeners

    fireStateChanged();

  }

  /**

   * Set the value of the model's "selected" property.

   *

   * @param s The new "selected" property

   */

  public void setSelected(boolean s)

  {

    // if this call does not represent a CHANGE in state, then return

    if ((s && isSelected()) || (!s && !isSelected()))

      return;

    // make the change

    if (s)

      stateMask = stateMask | SELECTED;

    else

      stateMask = stateMask & (~SELECTED);

    // notify interested ChangeListeners

    fireStateChanged();

    // fire ItemStateChanged events

    if (s)

      {

        fireItemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED,

                                           this, ItemEvent.SELECTED));

        if (group != null)

          group.setSelected(this, true);

      }

    else

      {

        fireItemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED,

                                           this, ItemEvent.DESELECTED));

        if (group != null)

          group.setSelected(this, false);

      }

  }

  /**

   * 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();

      }

  }

  /**

   * 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();

      }

  }

  /**

   * Returns the current value of the model's "actionCommand" property.

   *

   * @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 model in a given group can have their "selected" property be

   * <code>true</code> at a time.

   *

   * @param g The new "group" property (<code>null</code> permitted).

   *

   * @see #getGroup()

   */

  public void setGroup(ButtonGroup g)

  {

    group = g;

  }

  /**

   * Returns the current value of the model's "group" property.

   *

   * @return The value of the "group" property

   *

   * @see #setGroup(ButtonGroup)

   */

  public ButtonGroup getGroup()

  {

    return group;

  }

}