1 /* Button.java -- AWT button widget
2 Copyright (C) 1999, 2002, 2004, 2005 Free Software Foundation, Inc.
3
4 This file is part of GNU Classpath.
5
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 USA.
20
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
37
38
39 package java.awt;
40
41 import java.awt.event.ActionEvent;
42 import java.awt.event.ActionListener;
43 import java.awt.peer.ButtonPeer;
44 import java.lang.reflect.Array;
45 import java.util.EventListener;
46
47 import javax.accessibility.Accessible;
48 import javax.accessibility.AccessibleAction;
49 import javax.accessibility.AccessibleContext;
50 import javax.accessibility.AccessibleRole;
51 import javax.accessibility.AccessibleValue;
52
53 /**
54 * This class provides a button widget for the AWT.
55 *
56 * @author Aaron M. Renn (arenn@urbanophile.com)
57 * @author Tom Tromey (tromey@cygnus.com)
58 */
59 public class Button extends Component
60 implements java.io.Serializable, Accessible
61 {
62
63 /*
64 * Static Variables
65 */
66
67 // FIXME: Need readObject/writeObject for serialization
68
69 // Serialization version constant
70 private static final long serialVersionUID = -8774683716313001058L;
71
72 /*************************************************************************/
73
74 /*
75 * Instance Variables
76 */
77
78 /**
79 * @serial The action command name for this button.
80 * This is package-private to avoid an accessor method.
81 */
82 String actionCommand;
83
84 /**
85 * @serial The label for this button.
86 * This is package-private to avoid an accessor method.
87 */
88 String label;
89
90 // List of ActionListeners for this class.
91 private transient ActionListener action_listeners;
92
93 /*
94 * The number used to generate the name returned by getName.
95 */
96 private static transient long next_button_number;
97
98 protected class AccessibleAWTButton extends AccessibleAWTComponent
99 implements AccessibleAction, AccessibleValue
100 {
101 private static final long serialVersionUID = -5932203980244017102L;
102
AccessibleAWTButton()103 protected AccessibleAWTButton()
104 {
105 // Do nothing here.
106 }
107
108 /* (non-Javadoc)
109 * @see javax.accessibility.AccessibleAction#getAccessibleActionCount()
110 */
getAccessibleActionCount()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 */
getAccessibleActionDescription(int i)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 */
doAccessibleAction(int i)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
getAccessibleName()142 public String getAccessibleName()
143 {
144 return label;
145 }
146
getAccessibleAction()147 public AccessibleAction getAccessibleAction()
148 {
149 return this;
150 }
151
getAccessibleValue()152 public AccessibleValue getAccessibleValue()
153 {
154 return this;
155 }
156
157 /* (non-Javadoc)
158 * @see javax.accessibility.AccessibleValue#getCurrentAccessibleValue()
159 */
getCurrentAccessibleValue()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 */
setCurrentAccessibleValue(Number number)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 */
getMinimumAccessibleValue()179 public Number getMinimumAccessibleValue()
180 {
181 return new Integer(0);
182 }
183
184 /* (non-Javadoc)
185 * @see javax.accessibility.AccessibleValue#getMaximumAccessibleValue()
186 */
getMaximumAccessibleValue()187 public Number getMaximumAccessibleValue()
188 {
189 return new Integer(0);
190 }
191
getAccessibleRole()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
Button()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
Button(String label)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
getLabel()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
setLabel(String label)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
getActionCommand()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
setActionCommand(String actionCommand)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
addActionListener(ActionListener listener)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
removeActionListener(ActionListener listener)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 */
getActionListeners()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 */
getListeners(Class<T> listenerType)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
addNotify()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
processEvent(AWTEvent event)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
processActionEvent(ActionEvent event)406 processActionEvent(ActionEvent event)
407 {
408 if (action_listeners != null)
409 action_listeners.actionPerformed(event);
410 }
411
412 void
dispatchEventImpl(AWTEvent e)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
paramString()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 */
getAccessibleContext()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 */
generateName()457 String generateName ()
458 {
459 return "button" + getUniqueLong ();
460 }
461
getUniqueLong()462 private static synchronized long getUniqueLong ()
463 {
464 return next_button_number++;
465 }
466
467 } // class Button
468