001 /* Timer.java --
002 Copyright (C) 2002, 2004, 2005, 2006, 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 javax.swing;
040
041 import java.awt.event.ActionEvent;
042 import java.awt.event.ActionListener;
043 import java.io.Serializable;
044 import java.util.EventListener;
045
046 import javax.swing.event.EventListenerList;
047
048 /**
049 * Fires one or more action events after the specified delay. This is
050 * a specialised version of <code>java.util.Timer</code> just for
051 * firing <code>ActionEvent</code>s. All Timers share one (daemon)
052 * Thread (or java.util.Timer). All events are fired from the event
053 * queue.
054 *
055 * @author Ronald Veldema
056 * @author Audrius Meskauskas (audriusa@Bionformatics.org) - bug fixes
057 * and documentation comments
058 */
059 public class Timer
060 implements Serializable
061 {
062 /**
063 * Given to the shared java.util.Timer to (possibly repeatedly) call
064 * queueEvent().
065 */
066 private class Task extends java.util.TimerTask
067 {
068 public void run()
069 {
070 if (logTimers)
071 System.out.println("javax.swing.Timer -> queueEvent()");
072 queueEvent();
073
074 if (!repeats)
075 task = null;
076 }
077 }
078
079 /**
080 * Use serialVersionUID for interoperability.
081 */
082 private static final long serialVersionUID = -1116180831621385484L;
083
084 /**
085 * The encloding class, used with {@link SwingUtilities#invokeLater}
086 * to invoke the {@link #drainEvents()}.
087 */
088 private Runnable drainer = new Runnable()
089 {
090 public void run()
091 {
092 drainEvents();
093 }
094 };
095
096 /**
097 * The static java.util.Timer daemon which will be used to schedule
098 * all javax.swing.Timer.Task objects. The daemon will always be
099 * running, even if there's no task scheduled in it.
100 */
101 private static java.util.Timer timer = new java.util.Timer("swing.Timer",
102 true);
103
104 /**
105 * If <code>true</code>, the timer prints a message to
106 * {@link System#out} when firing each event.
107 */
108 static boolean logTimers;
109
110 /**
111 * A field to store all listeners who are listening to this timer.
112 */
113 protected EventListenerList listenerList = new EventListenerList();
114
115 /**
116 * <code>true</code> if the timer coalesces events.
117 */
118 boolean coalesce = true;
119
120 /**
121 * <code>true</code> if the timer is firing repetetive events.
122 */
123 boolean repeats = true;
124
125 /**
126 * The delay between subsequent repetetive events.
127 */
128 int delay;
129
130 /**
131 * The initial delay before the first event.
132 */
133 int initialDelay;
134
135 /**
136 * The number of events that have been already fired by this timer.
137 * This is used as a numeric identifier for the next event that would
138 * be fired.
139 */
140 int ticks;
141
142 /**
143 * The task that calls queueEvent(). When null this Timer is stopped.
144 * This is package private to avoid synthetic accessor method.
145 */
146 Task task;
147
148 /**
149 * This object manages a "queue" of virtual actionEvents, maintained as a
150 * simple long counter. When the timer expires, a new event is queued,
151 * and a dispatcher object is pushed into the system event queue. When
152 * the system thread runs the dispatcher, it will fire as many
153 * ActionEvents as have been queued, unless the timer is set to
154 * coalescing mode, in which case it will fire only one ActionEvent.
155 */
156 private long queue;
157
158 /**
159 * <code>synchronized(queueLock)</code> replaces
160 * <code>synchronized(queue)</code> that is not supported by this language.
161 */
162 private Object queueLock = new Object();
163
164 /**
165 * Creates a new Timer object.
166 *
167 * @param d the default value for both initial and between event delay, in
168 * milliseconds.
169 * @param listener the first action listener, can be <code>null</code>.
170 */
171 public Timer(int d, ActionListener listener)
172 {
173 delay = d;
174 initialDelay = d;
175
176 if (listener != null)
177 addActionListener(listener);
178 }
179
180 /**
181 * Get the array of action listeners.
182 *
183 * @return the array of action listeners that are listening for the events,
184 * fired by this timer
185 *
186 * @since 1.4
187 */
188 public ActionListener[] getActionListeners()
189 {
190 return (ActionListener[]) listenerList.getListeners(ActionListener.class);
191 }
192
193 /**
194 * Sets whether the Timer coalesces multiple pending event firings.
195 * If the coalescing is enabled, the multiple events that have not been
196 * fired on time are replaced by the single event. The events may not
197 * be fired on time if the application is busy.
198 *
199 * @param c <code>true</code> (default) to enable the event coalescing,
200 * <code>false</code> otherwise
201 */
202 public void setCoalesce(boolean c)
203 {
204 coalesce = c;
205 }
206
207 /**
208 * Checks if the Timer coalesces multiple pending event firings.
209 * If the coalescing is enabled, the multiple events that have not been
210 * fired on time are replaced by the single event. The events may not
211 * be fired on time if the application is busy.
212 *
213 * @return <code>true</code> if the coalescing is enabled,
214 * <code>false</code> otherwise
215 */
216 public boolean isCoalesce()
217 {
218 return coalesce;
219 }
220
221 /**
222 * Get the event listeners of the given type that are listening for the
223 * events, fired by this timer.
224 *
225 * @param listenerType the listener type (for example, ActionListener.class)
226 *
227 * @return the array of event listeners that are listening for the events,
228 * fired by this timer
229 * @since 1.3
230 */
231 public <T extends EventListener> T[] getListeners(Class<T> listenerType)
232 {
233 return listenerList.getListeners(listenerType);
234 }
235
236 /**
237 * Set the timer logging state. If it is set to <code>true</code>, the
238 * timer prints a message to {@link System#out} when firing each
239 * action event.
240 *
241 * @param lt <code>true</code> if logging is enabled, <code>false</code>
242 * (default value) otherwise
243 */
244 public static void setLogTimers(boolean lt)
245 {
246 logTimers = lt;
247 }
248
249 /**
250 * Return the logging state.
251 *
252 * @return <code>true</code> if the timer is printing a message to
253 * {@link System#out}
254 * when firing each action event
255 */
256 public static boolean getLogTimers()
257 {
258 return logTimers;
259 }
260
261 /**
262 * Set the delay between firing the subsequent events.
263 * This parameter does not change the value of the initial delay before
264 * firing the first event.
265 *
266 * @param d The time gap between the subsequent events, in milliseconds
267 *
268 * @throws IllegalArgumentException if <code>d</code> is less than zero.
269 */
270 public void setDelay(int d)
271 {
272 if (d < 0)
273 throw new IllegalArgumentException("Invalid delay: " + d);
274 delay = d;
275 }
276
277 /**
278 * Get the delay between firing the subsequent events.
279 *
280 * @return The delay between subsequent events, in milliseconds
281 */
282 public int getDelay()
283 {
284 return delay;
285 }
286
287 /**
288 * Set the intial delay before firing the first event since calling
289 * the {@link #start()} method. If the initial delay has not been
290 * set, it is assumed having the same value as the delay between the
291 * subsequent events.
292 *
293 * @param i the initial delay, in milliseconds
294 *
295 * @throws IllegalArgumentException if <code>i</code> is less than zero.
296 */
297 public void setInitialDelay(int i)
298 {
299 if (i < 0)
300 throw new IllegalArgumentException("Invalid initial delay: " + i);
301 initialDelay = i;
302 }
303
304 /**
305 * Get the intial delay before firing the first event since calling
306 * the {@link #start()} method. If the initial delay has not been
307 * set, returns the same value as {@link #getDelay()}.
308 *
309 * @return the initial delay before firing the first action event.
310 */
311 public int getInitialDelay()
312 {
313 return initialDelay;
314 }
315
316 /**
317 * Enable firing the repetetive events.
318 *
319 * @param r <code>true</code> (default value) to fire repetetive events.
320 * <code>false</code> to fire
321 * only one event after the initial delay
322 */
323 public void setRepeats(boolean r)
324 {
325 repeats = r;
326 }
327
328 /**
329 * Check is this timer fires repetetive events.
330 *
331 * @return <code>true</code> if the timer fires repetetive events,
332 * <code>false</code> if it fires
333 * only one event after the initial delay
334 */
335 public boolean isRepeats()
336 {
337 return repeats;
338 }
339
340 /**
341 * Get the timer state.
342 *
343 * @return <code>true</code> if the timer has been started and is firing
344 * the action events as scheduled. <code>false</code>
345 * if the timer is inactive.
346 */
347 public boolean isRunning()
348 {
349 return task != null;
350 }
351
352 /**
353 * Add the action listener
354 *
355 * @param listener the action listener to add
356 */
357 public void addActionListener(ActionListener listener)
358 {
359 listenerList.add(ActionListener.class, listener);
360 }
361
362 /**
363 * Remove the action listener.
364 *
365 * @param listener the action listener to remove
366 */
367 public void removeActionListener(ActionListener listener)
368 {
369 listenerList.remove(ActionListener.class, listener);
370 }
371
372 /**
373 * Cancel all pending tasks and fire the first event after the initial
374 * delay.
375 */
376 public void restart()
377 {
378 stop();
379 start();
380 }
381
382 /**
383 * Start firing the action events.
384 */
385 public void start()
386 {
387 Task t = task;
388 if (t == null)
389 {
390 t = new Task();
391 if (isRepeats())
392 timer.schedule(t, getInitialDelay(), getDelay());
393 else
394 timer.schedule(t, getInitialDelay());
395 task = t;
396 }
397 }
398
399 /**
400 * Stop firing the action events.
401 */
402 public void stop()
403 {
404 Task t = task;
405 if (t != null)
406 {
407 t.cancel();
408 task = null;
409 }
410 }
411
412 /**
413 * Fire the given action event to the action listeners.
414 *
415 * @param event the event to fire
416 */
417 protected void fireActionPerformed(ActionEvent event)
418 {
419 ActionListener[] listeners = getActionListeners();
420
421 for (int i = 0; i < listeners.length; i++)
422 listeners [ i ].actionPerformed(event);
423 }
424
425 /**
426 * Fire the action event, named "Timer" and having the numeric
427 * identifier, equal to the numer of events that have been
428 * already fired before.
429 */
430 void fireActionPerformed()
431 {
432 fireActionPerformed(new ActionEvent(this, ticks++, "Timer"));
433 }
434
435 /**
436 * Fire the queued action events.
437 * In the coalescing mode, a single event is fired as a replacement
438 * for all queued events. In non coalescing mode, a series of
439 * all queued events is fired.
440 * This is package-private to avoid an accessor method.
441 */
442 void drainEvents()
443 {
444 synchronized (queueLock)
445 {
446 if (isCoalesce())
447 {
448 if (queue > 0)
449 fireActionPerformed();
450 }
451 else
452 {
453 while (queue > 0)
454 {
455 fireActionPerformed();
456 queue--;
457 }
458 }
459 queue = 0;
460 }
461 }
462
463 /**
464 * Post a scheduled event to the event queue.
465 * Package-private to avoid an accessor method.
466 */
467 void queueEvent()
468 {
469 synchronized(queueLock)
470 {
471 queue++;
472 if (queue == 1)
473 SwingUtilities.invokeLater(drainer);
474 }
475 }
476 }