/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* For further information about Alkacon Software GmbH, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.opencms.gwt.client.util;
import java.util.HashMap;
import java.util.Map;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.Timer;
/**
* Takes care of the burst of the same event, by skipping the first ones and executing only the last one.<p>
*
* Usage example:
*
* <pre>
* Window.addResizeHandler(new ResizeHandler() {
* public void onResize(ResizeEvent event) {
* CmsBurstEventManager.get().schedule("resize-window", new Command() {
* public void execute() {
* // resize
* }
* }, 200);
* }
* });
* </pre>
*
* @since 8.0.0
*
* @see <a href="http://ui-programming.blogspot.com/2010/02/gwt-how-to-implement-delayedtask-in.html">Original implementation</a>
*/
public final class CmsBurstEventManager {
/**
* The class is model of one 'burst' event that is added to the manager.<p>
*/
private static class BurstEvent {
/** The timer. */
private final Timer m_timer;
/**
* Constructor of the 'burst' event.<p>
*
* @param name the unique name, which identifies the event
* @param command command to execute when the timer expires
*/
public BurstEvent(final String name, final Command command) {
m_timer = new Timer() {
/**
* @see com.google.gwt.user.client.Timer#run()
*/
@Override
public void run() {
if (command != null) {
command.execute();
}
CmsBurstEventManager.get().cancel(name);
}
};
}
/**
* Returns the timer.<p>
*
* @return the timer
*/
public Timer getTimer() {
return m_timer;
}
}
/** The singleton instance. */
private static CmsBurstEventManager INSTANCE;
/** The internal memory. */
private Map<String, BurstEvent> m_memory = new HashMap<String, BurstEvent>();
/**
* Hidden constructor.<p>
*/
private CmsBurstEventManager() {
// emtpy
}
/**
* Returns the singleton instance.<p>
*
* @return the singleton instance
*/
protected static CmsBurstEventManager get() {
if (INSTANCE == null) {
INSTANCE = new CmsBurstEventManager();
}
return INSTANCE;
}
/**
* Adds an 'burst' event to the manager.<p>
*
* @param name the unique name, which identifies the event
* @param command command to execute when the timer expires
* @param delayMsec the timer delay (it's reseted if multiple events are added)
*/
public void schedule(final String name, final Command command, final int delayMsec) {
BurstEvent e = m_memory.remove(name);
if (e != null) {
// disable the old event
e.getTimer().cancel();
}
// put the new event and schedule it
e = new BurstEvent(name, command);
m_memory.put(name, e);
e.getTimer().schedule(delayMsec);
}
/**
* Removes the event from the manager.<p>
*
* @param eventName the name of the event that we need to remove
*/
public void cancel(final String eventName) {
BurstEvent oe = m_memory.remove(eventName);
if (oe != null) {
// disable the old event.
oe.getTimer().cancel();
}
}
}