001 /* Button.java -- AWT button widget
002 Copyright (C) 1999, 2002, 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import java.awt.event.ActionEvent;
042 import java.awt.event.ActionListener;
043 import java.awt.peer.ButtonPeer;
044 import java.lang.reflect.Array;
045 import java.util.EventListener;
046
047 import javax.accessibility.Accessible;
048 import javax.accessibility.AccessibleAction;
049 import javax.accessibility.AccessibleContext;
050 import javax.accessibility.AccessibleRole;
051 import javax.accessibility.AccessibleValue;
052
053 /**
054 * This class provides a button widget for the AWT.
055 *
056 * @author Aaron M. Renn (arenn@urbanophile.com)
057 * @author Tom Tromey (tromey@cygnus.com)
058 */
059 public class Button extends Component
060 implements java.io.Serializable, Accessible
061 {
062
063 /*
064 * Static Variables
065 */
066
067 // FIXME: Need readObject/writeObject for serialization
068
069 // Serialization version constant
070 private static final long serialVersionUID = -8774683716313001058L;
071
072 /*************************************************************************/
073
074 /*
075 * Instance Variables
076 */
077
078 /**
079 * @serial The action command name for this button.
080 * This is package-private to avoid an accessor method.
081 */
082 String actionCommand;
083
084 /**
085 * @serial The label for this button.
086 * This is package-private to avoid an accessor method.
087 */
088 String label;
089
090 // List of ActionListeners for this class.
091 private transient ActionListener action_listeners;
092
093 /*
094 * The number used to generate the name returned by getName.
095 */
096 private static transient long next_button_number;
097
098 protected class AccessibleAWTButton extends AccessibleAWTComponent
099 implements AccessibleAction, AccessibleValue
100 {
101 private static final long serialVersionUID = -5932203980244017102L;
102
103 protected AccessibleAWTButton()
104 {
105 // Do nothing here.
106 }
107
108 /* (non-Javadoc)
109 * @see javax.accessibility.AccessibleAction#getAccessibleActionCount()
110 */
111 public int getAccessibleActionCount()
112 {
113 // Only 1 action possible
114 return 1;
115 }
116
117 /* (non-Javadoc)
118 * @see javax.accessibility.AccessibleAction#getAccessibleActionDescription(int)
119 */
120 public String getAccessibleActionDescription(int i)
121 {
122 // JDK 1.4.2 returns the string "click" for action 0. However, the API
123 // docs don't say what the string to be returned is, beyond being a
124 // description of the action. So we return the same thing for
125 // compatibility with 1.4.2.
126 if (i == 0)
127 return "click";
128 return null;
129 }
130
131 /* (non-Javadoc)
132 * @see javax.accessibility.AccessibleAction#doAccessibleAction(int)
133 */
134 public boolean doAccessibleAction(int i)
135 {
136 if (i != 0)
137 return false;
138 processActionEvent(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, actionCommand));
139 return true;
140 }
141
142 public String getAccessibleName()
143 {
144 return label;
145 }
146
147 public AccessibleAction getAccessibleAction()
148 {
149 return this;
150 }
151
152 public AccessibleValue getAccessibleValue()
153 {
154 return this;
155 }
156
157 /* (non-Javadoc)
158 * @see javax.accessibility.AccessibleValue#getCurrentAccessibleValue()
159 */
160 public Number getCurrentAccessibleValue()
161 {
162 // Docs say return 1 if selected, but buttons can't be selected, right?
163 return new Integer(0);
164 }
165
166 /* (non-Javadoc)
167 * @see javax.accessibility.AccessibleValue#setCurrentAccessibleValue(java.lang.Number)
168 */
169 public boolean setCurrentAccessibleValue(Number number)
170 {
171 // Since there's no selection with buttons, we're ignoring this.
172 // TODO someone who knows shoulw check this.
173 return false;
174 }
175
176 /* (non-Javadoc)
177 * @see javax.accessibility.AccessibleValue#getMinimumAccessibleValue()
178 */
179 public Number getMinimumAccessibleValue()
180 {
181 return new Integer(0);
182 }
183
184 /* (non-Javadoc)
185 * @see javax.accessibility.AccessibleValue#getMaximumAccessibleValue()
186 */
187 public Number getMaximumAccessibleValue()
188 {
189 return new Integer(0);
190 }
191
192 public AccessibleRole getAccessibleRole()
193 {
194 return AccessibleRole.PUSH_BUTTON;
195 }
196 }
197
198 /*************************************************************************/
199
200 /*
201 * Constructors
202 */
203
204 /**
205 * Initializes a new instance of <code>Button</code> with no label.
206 *
207 * @exception HeadlessException If GraphicsEnvironment.isHeadless()
208 * returns true
209 */
210 public
211 Button()
212 {
213 this("");
214 }
215
216 /*************************************************************************/
217
218 /**
219 * Initializes a new instance of <code>Button</code> with the specified
220 * label. The action command name is also initialized to this value.
221 *
222 * @param label The label to display on the button.
223 *
224 * @exception HeadlessException If GraphicsEnvironment.isHeadless()
225 * returns true
226 */
227 public
228 Button(String label)
229 {
230 this.label = label;
231 actionCommand = label;
232
233 if (GraphicsEnvironment.isHeadless ())
234 throw new HeadlessException ();
235 }
236
237 /*************************************************************************/
238
239 /*
240 * Instance Variables
241 */
242
243 /**
244 * Returns the label for this button.
245 *
246 * @return The label for this button.
247 */
248 public String
249 getLabel()
250 {
251 return(label);
252 }
253
254 /*************************************************************************/
255
256 /**
257 * Sets the label for this button to the specified value.
258 *
259 * @param label The new label for this button.
260 */
261 public synchronized void
262 setLabel(String label)
263 {
264 this.label = label;
265 actionCommand = label;
266 if (peer != null)
267 {
268 ButtonPeer bp = (ButtonPeer) peer;
269 bp.setLabel (label);
270 }
271 }
272
273 /*************************************************************************/
274
275 /**
276 * Returns the action command name for this button.
277 *
278 * @return The action command name for this button.
279 */
280 public String
281 getActionCommand()
282 {
283 return(actionCommand);
284 }
285
286 /*************************************************************************/
287
288 /**
289 * Sets the action command name for this button to the specified value.
290 *
291 * @param actionCommand The new action command name.
292 */
293 public void
294 setActionCommand(String actionCommand)
295 {
296 this.actionCommand = actionCommand == null ? label : actionCommand;
297 }
298
299 /*************************************************************************/
300
301 /**
302 * Adds a new entry to the list of listeners that will receive
303 * action events from this button.
304 *
305 * @param listener The listener to add.
306 */
307 public synchronized void
308 addActionListener(ActionListener listener)
309 {
310 action_listeners = AWTEventMulticaster.add(action_listeners, listener);
311 }
312
313 /*************************************************************************/
314
315 /**
316 * Removes the specified listener from the list of listeners that will
317 * receive action events from this button.
318 *
319 * @param listener The listener to remove.
320 */
321 public synchronized void
322 removeActionListener(ActionListener listener)
323 {
324 action_listeners = AWTEventMulticaster.remove(action_listeners, listener);
325 }
326
327 /**
328 * Returns all added <code>ActionListener</code> objects.
329 *
330 * @return an array of listeners
331 *
332 * @since 1.4
333 */
334 public synchronized ActionListener[] getActionListeners()
335 {
336 return (ActionListener[])
337 AWTEventMulticaster.getListeners(action_listeners,
338 ActionListener.class);
339 }
340
341 /**
342 * Returns all registered EventListers of the given listenerType.
343 * listenerType must be a subclass of EventListener, or a
344 * ClassClassException is thrown.
345 *
346 * @param listenerType the listener type to return
347 *
348 * @return an array of listeners
349 *
350 * @exception ClassCastException If listenerType doesn't specify a class or
351 * interface that implements @see java.util.EventListener.
352 *
353 * @since 1.3
354 */
355 public <T extends EventListener> T[] getListeners(Class<T> listenerType)
356 {
357 if (listenerType == ActionListener.class)
358 return (T[]) getActionListeners();
359 return (T[]) Array.newInstance(listenerType, 0);
360 }
361
362 /*************************************************************************/
363
364 /**
365 * Notifies this button that it should create its native peer object.
366 */
367 public void
368 addNotify()
369 {
370 if (peer == null)
371 peer = getToolkit ().createButton (this);
372 super.addNotify();
373 }
374
375 /*************************************************************************/
376
377 /**
378 * Processes an event for this button. If the specified event is an
379 * instance of <code>ActionEvent</code>, then the
380 * <code>processActionEvent()</code> method is called to dispatch it
381 * to any registered listeners. Otherwise, the superclass method
382 * will be invoked. Note that this method will not be called at all
383 * unless <code>ActionEvent</code>'s are enabled. This will be done
384 * implicitly if any listeners are added.
385 *
386 * @param event The event to process.
387 */
388 protected void
389 processEvent(AWTEvent event)
390 {
391 if (event instanceof ActionEvent)
392 processActionEvent((ActionEvent)event);
393 else
394 super.processEvent(event);
395 }
396
397 /*************************************************************************/
398
399 /**
400 * This method dispatches an action event for this button to any
401 * registered listeners.
402 *
403 * @param event The event to process.
404 */
405 protected void
406 processActionEvent(ActionEvent event)
407 {
408 if (action_listeners != null)
409 action_listeners.actionPerformed(event);
410 }
411
412 void
413 dispatchEventImpl(AWTEvent e)
414 {
415 if (e.id <= ActionEvent.ACTION_LAST
416 && e.id >= ActionEvent.ACTION_FIRST
417 && (action_listeners != null
418 || (eventMask & AWTEvent.ACTION_EVENT_MASK) != 0))
419 processEvent(e);
420 else
421 super.dispatchEventImpl(e);
422 }
423
424 /*************************************************************************/
425
426 /**
427 * Returns a debugging string for this button.
428 *
429 * @return A debugging string for this button.
430 */
431 protected String
432 paramString()
433 {
434 return getName () + "," + getX () + "," + getY () + ","
435 + getWidth () + "x" + getHeight () + ",label=" + getLabel ();
436 }
437
438 /**
439 * Gets the AccessibleContext associated with this <code>Button</code>.
440 * The context is created, if necessary.
441 *
442 * @return the associated context
443 */
444 public AccessibleContext getAccessibleContext()
445 {
446 /* Create the context if this is the first request */
447 if (accessibleContext == null)
448 accessibleContext = new AccessibleAWTButton();
449 return accessibleContext;
450 }
451
452 /**
453 * Generate a unique name for this button.
454 *
455 * @return A unique name for this button.
456 */
457 String generateName ()
458 {
459 return "button" + getUniqueLong ();
460 }
461
462 private static synchronized long getUniqueLong ()
463 {
464 return next_button_number++;
465 }
466
467 } // class Button