001/* JToggleButton.java -- 
002   Copyright (C) 2002, 2004, 2005, 2006,  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.swing;
040
041import java.awt.event.ActionEvent;
042import java.awt.event.ItemEvent;
043import java.awt.event.ItemListener;
044
045import javax.accessibility.Accessible;
046import javax.accessibility.AccessibleContext;
047import javax.accessibility.AccessibleRole;
048import javax.accessibility.AccessibleState;
049import javax.swing.plaf.ButtonUI;
050
051/**
052 * The <code>JToggleButton</code> component provides a stateful button,
053 * which can be either selected or unselected.  This provides the basis
054 * for the implementations of radio buttons (<code>JRadioButton</code>)
055 * and check boxes (<code>JCheckBox</code>).
056 *
057 * @author Michael Koch  (konqueror@gmx.de)
058 * @author Graydon Hoare  (graydon@redhat.com)
059 * @author Andrew John Hughes  (gnu_andrew@member.fsf.org)
060 * @see JRadioButton
061 * @see JCheckBox
062 * @since 1.2
063 */
064public class JToggleButton extends AbstractButton implements Accessible
065{
066  /**
067   * This class provides accessibility support for the toggle button.
068   */
069  protected class AccessibleJToggleButton
070    extends AccessibleAbstractButton
071    implements ItemListener
072  {
073    private static final long serialVersionUID = -8652952712161229225L;
074
075    /**
076     * Constructor for the accessible toggle button.
077     */
078    public AccessibleJToggleButton()
079    {
080      super();
081      /* Register the accessible toggle button as a listener for item events */
082      addItemListener(this);
083    }
084
085    /**
086     * Returns the accessible role for the toggle button.
087     *
088     * @return An instance of <code>AccessibleRole</code>, describing
089     *         the role of the toggle button.
090     */
091    public AccessibleRole getAccessibleRole()
092    {
093      return AccessibleRole.TOGGLE_BUTTON;
094    }
095    
096    /**
097     * Monitors the toggle button for state changes and fires accessible
098     * property change events when they occur.
099     *
100     * @param event the event that occurred.
101     */
102    public void itemStateChanged(ItemEvent event)
103    {
104        /* Fire a state property change event as the button's state has changed */
105        if (event.getStateChange() == ItemEvent.SELECTED)
106          {
107            /* State has changed from unselected (null) to selected */
108            firePropertyChange(ACCESSIBLE_STATE_PROPERTY, null, AccessibleState.SELECTED);
109          } 
110        else
111          {
112            /* State has changed from selected to unselected (null) */
113            firePropertyChange(ACCESSIBLE_STATE_PROPERTY, AccessibleState.ENABLED, null);
114          }
115    }
116    
117  }
118
119  /**
120   * The model handles the storage and maintenance of the state of
121   * the toggle button.  This follows the same paradigm (the MVC
122   * or Model-View-Controller design pattern) employed by
123   * other Swing components, where the data associated with a component
124   * is stored separately from the display aspects.
125   */
126  public static class ToggleButtonModel extends DefaultButtonModel
127  {
128    /**
129     * Compatible with Sun's JDK.
130     */
131    private static final long serialVersionUID = -1589950750899943974L;
132    
133    /**
134     * Sets the pressed state of the button.  The selected state
135     * of the button also changes follwing the button being pressed.
136     *
137     * @param p true if the button is pressed down.
138     */
139    public void setPressed(boolean p)  
140    {
141      // cannot change PRESSED state unless button is enabled
142      if (! isEnabled())
143        return;
144      
145      // if this call does not represent a CHANGE in state, then return
146      if ((p && isPressed()) || (!p && !isPressed()))
147        return;
148
149      // The JDK first fires events in the following order:
150      // 1. ChangeEvent for selected
151      // 2. ChangeEvent for pressed
152      // 3. ActionEvent
153      // So do we.
154
155      // setPressed(false) == mouse release on us,
156      // if we were armed, we flip the selected state.
157      if (!p && isArmed())
158        {
159          setSelected(! isSelected());
160        }
161
162      // make the change
163      if (p)
164        stateMask = stateMask | PRESSED;
165      else
166        stateMask = stateMask & (~PRESSED);
167      
168      // notify interested ChangeListeners
169      fireStateChanged();
170
171      if (!p && isArmed())
172        {
173          fireActionPerformed(new ActionEvent(this,
174                                              ActionEvent.ACTION_PERFORMED,
175                                              actionCommand));
176        }
177    }
178      
179      /**
180       * Checks if the button is selected.
181       * 
182       * @return <code>true</code> if the button is selected.
183       */
184      public boolean isSelected()
185      {
186        return super.isSelected();
187      }
188      
189      /**
190       * Sets the selected state of the button.
191       * 
192       * @param b true if button is selected
193       */
194      public void setSelected(boolean b)
195      {
196        super.setSelected(b);
197      }  
198  }
199
200  /**
201   * Compatible with Sun's JDK.
202   */
203  private static final long serialVersionUID = -3128248873429850443L;
204    
205  /**
206   * Constructs an unselected toggle button with no text or icon.
207   */ 
208  public JToggleButton()
209  {
210    this(null, null, false);
211  }
212
213  /**
214   * Constructs a toggle button using the labelling, state
215   * and icon specified by the supplied action.
216   *
217   * @param a the action to use to define the properties of the button.
218   */
219  public JToggleButton(Action a)
220  {
221    this();
222    setAction(a);
223  }
224
225  /**
226   * Constructs an unselected toggle button with the supplied icon
227   * and no text.
228   *
229   * @param icon the icon to use.
230   */
231  public JToggleButton(Icon icon)
232  { 
233    this(null, icon, false);
234  }    
235  
236  /**
237   * Constructs a toggle button with the supplied icon and state.
238   *
239   * @param icon the icon to use.
240   * @param selected if true, the toggle button is initially in the
241   *        selected state.  Otherwise, the button is unselected.
242   */
243  public JToggleButton(Icon icon, boolean selected) 
244  {
245    this(null, icon, selected);
246  }
247  
248  /**
249   * Constructs an unselected toggle button using the supplied text
250   * and no icon.
251   *
252   * @param text the text to use.
253   */ 
254  public JToggleButton(String text)
255  {
256    this(text, null, false);
257  }
258      
259  /**
260   * Constructs a toggle button with the supplied text and state.
261   *
262   * @param text the text to use.
263   * @param selected if true, the toggle button is initially in the
264   *        selected state.  Otherwise, the button is unselected.
265   */
266  public JToggleButton(String text, boolean selected)
267  {
268    this(text, null, selected);
269  }
270
271  /**
272   * Constructs an unselected toggle button with the supplied text
273   * and icon.
274   *
275   * @param text the text to use.
276   * @param icon the icon to use.
277   */
278  public JToggleButton(String text, Icon icon)
279  {
280    this(text, icon, false);
281  }
282
283  /**
284   * Constructs a toggle button with the supplied text, icon and state.
285   *
286   * @param text the text to use.
287   * @param icon the icon to use.
288   * @param selected if true, the toggle button is initially in the
289   *        selected state.  Otherwise, the button is unselected.
290   */
291  public JToggleButton (String text, Icon icon, boolean selected) 
292  {
293    super();
294    setModel(new ToggleButtonModel());  
295    init(text, icon);
296    model.setSelected(selected);
297    setAlignmentX(LEFT_ALIGNMENT);
298  }
299
300  /**
301   * Gets the AccessibleContext associated with this <code>JToggleButton</code>.
302   * The context is created, if necessary.
303   *
304   * @return the associated context
305   */
306  public AccessibleContext getAccessibleContext()
307  {
308    /* Create the context if this is the first request */
309    if (accessibleContext == null)
310      {
311        /* Create the context */
312        accessibleContext = new AccessibleJToggleButton();
313      }
314    return accessibleContext;
315  }
316  
317  /**
318   * Returns a string that specifies the name of the Look and Feel
319   * class that renders this component.
320   *
321   * @return The Look and Feel UI class in <code>String</code> form.
322   */
323  public String getUIClassID()
324  {
325    return "ToggleButtonUI";
326  }
327  
328  /**
329   * Returns a textual representation of this component for debugging.
330   * Users should not depend on anything as regards the content or formatting
331   * of this string, except for the fact that the returned string may never be
332   * null (only empty).
333   *
334   * @return the component in <code>String</code> form for debugging.
335   */
336  protected  String paramString()
337  {
338    return super.paramString();
339  }
340  
341  /**
342   * This method resets the toggle button's UI delegate to the default UI for
343   * the current look and feel.
344   */
345  public void updateUI()
346  {     
347    setUI((ButtonUI)UIManager.getUI(this));
348  }
349
350}
351
352
353