1 files changed, 61 insertions, 0 deletions
diff --git a/fop-events/src/main/java/org/apache/fop/events/EventBroadcaster.java b/fop-events/src/main/java/org/apache/fop/events/EventBroadcaster.java
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index 000000000..57f30c9cf
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+++ b/fop-events/src/main/java/org/apache/fop/events/EventBroadcaster.java
@@ -0,0 +1,61 @@
+/*
+ * 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.
+ */
+
+/* $Id$ */
+
+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 extends EventProducer> T getEventProducerFor(Class<T> clazz);
+
+}