/*
* Copyright 2010-2011 Research In Motion Limited.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package blackberry.core;
import java.util.Enumeration;
import net.rim.device.api.util.IntMultiMap;
/**
* Service that propagates events to subscribers.
*/
public final class EventService {
private static EventService _instance;
private IntMultiMap _callbackLookup;
public static EventService getInstance() {
if( _instance == null ) {
_instance = new EventService();
}
return _instance;
}
/**
* Constructor
*/
public EventService() {
_callbackLookup = new IntMultiMap();
}
/**
* Triggers an event to all subscribers.
*
* @param eventID
* the event id to trigger to all subscribers.
* @param args
* the arguments to pass to each subscribers.
* @param isConsumable
* indicates if the event fired can be consumed so that default handling is ignored
*
* @return true if default handling of the event fired should be ignored; false otherwise, if isConsumable is false, return
* value is ignored
*/
public boolean fireEvent( int eventID, Object[] args, boolean isConsumable ) {
boolean result = false;
for( Enumeration e = _callbackLookup.elements( eventID ); e.hasMoreElements(); ) {
ApplicationEventHandler ae = (ApplicationEventHandler) e.nextElement();
if( isConsumable ) {
result = result || ae.handlePreEvent( eventID, args );
} else {
ae.handleEvent( eventID, args );
}
}
return result;
}
/**
* Subscribes to the specified event, with the given callback.
*
* @param eventID
* The event id of the events to subscribe to.
* @param callback
* The callback to invoke when this event is triggered.
*
*/
public void addHandler( int eventID, ApplicationEventHandler callback ) {
_callbackLookup.add( eventID, callback );
}
/**
* Unsubscribes the callback object for only the event ID the callback is subscribed to
*
* @param callback
* the callback object to unsubscribe
*
*/
public void removeHandler( int eventID, ApplicationEventHandler callback ) {
_callbackLookup.removeValue( eventID, callback );
}
/**
* Unsubscribes the callback object for all events it subscribed to.
*
* @param callback
* the callback object to unsubscribe
*
*/
public void removeHandler( ApplicationEventHandler callback ) {
_callbackLookup.removeValue( callback );
}
}