org.apache.fop.events.EventBroadcaster Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/* $Id: EventBroadcaster.java 1734671 2016-03-12 05:39:53Z gadams $ */
package org.apache.fop.events;
/**
* The EventBroadcaster is the central relay point for events. It receives events from various
* parts of the application and forwards them to any registered EventListener.
*/
public interface EventBroadcaster {
/**
* Adds an event listener to the broadcaster. It is appended to the list of previously
* registered listeners (the order of registration defines the calling order).
* @param listener the listener to be added
*/
void addEventListener(EventListener listener);
/**
* Removes an event listener from the broadcaster. If the event listener is not registered,
* nothing happens.
* @param listener the listener to be removed
*/
void removeEventListener(EventListener listener);
/**
* Indicates whether any listeners have been registered with the broadcaster.
* @return true if listeners are present, false otherwise
*/
boolean hasEventListeners();
/**
* Broadcasts an event. This method is usually called from within the observed component.
* @param event the event to be broadcast
*/
void broadcastEvent(Event event);
/**
* Returns an event producer instance for the given interface class.
* @param clazz the Class object identifying an {@link EventProducer} interface
* @return the event producer instance
*/
T getEventProducerFor(Class clazz);
}