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/*
* Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
package javax.media.j3d;
import java.util.Hashtable;
/**
* The NodeReferenceTable object is used by a leaf node's
* <code>updateNodeReferences</code> method called by the
* <code>cloneTree</code> method.
* The NodeReferenceTable maps nodes from the original subgraph
* to the new nodes in the cloned subgraph. This information
* can then be used to update any cloned leaf node references
* to reference nodes in the cloned subgraph.
* <P>
* During a <code>cloneTree</code> call, after all nodes have been duplicated,
* each SceneGraphObject's <code>updateNodeReferences</code> method is called.
* This method takes a NodeReferenceTable object as a parameter. The
* SceneGraphObject's <code>updateNodeReferences</code> method can then use the
* <code>getNewObjectReference</code> method from this object to get updated
* references to objects that have been duplicated in the new cloneTree
* sub-graph. If a match is found, a
* reference to the corresponding SceneGraphObject in the newly cloned sub-graph
* is returned. If no corresponding reference is found, either a
* DanglingReferenceException is thrown by the <code>cloneTree</code>
* method or a reference to the original
* SceneGraphObject is returned depending on the value of the
* <code>allowDanglingReferences</code> parameter passed in the
* <code>cloneTree</code> call.
* @see SceneGraphObject#updateNodeReferences
* @see Node#cloneTree
* @see DanglingReferenceException
*/
public class NodeReferenceTable extends Object {
Hashtable objectHashtable;
boolean allowDanglingReferences;
/**
* Constructs an empty NodeReferenceTable.
* @since Java 3D 1.2
*/
public NodeReferenceTable() {
}
// Constructor - this is NOT public!
NodeReferenceTable(boolean allowDanglingReferences,
Hashtable objectHashtable) {
set(allowDanglingReferences, objectHashtable);
}
void set(boolean allowDanglingReferences,
Hashtable objectHashtable) {
this.objectHashtable = objectHashtable;
this.allowDanglingReferences = allowDanglingReferences;
}
/**
* This method is used in conjunction with the <code>cloneTree</code>
* method. It can be used by the <code>updateNodeReferences</code>
* method to see if a SceneGraphObject that is being referenced has been duplicated
* in the new cloneTree sub-graph.
* <P>
* A SceneGraphObject's <code>updateNodeReferences</code> method would use this
* method by calling it with the reference to the old (existed before
* the cloneTree operation) object. If the object has been duplicated
* in the cloneTree sub-graph, the corresponding object in the cloned
* sub-graph is returned. If no corresponding reference is found, either
* a DanglingReferenceException is thrown or a reference to the original
* SceneGraphObject is returned depending on the value of the
* <code>allowDanglingReferences</code> parameter passed in the
* <code>cloneTree</code> call.
*
* @param oldReference the reference to the object in
* the original sub-graph.
*
* @return A reference to the corresponding object in the cloned
* sub-graph. If no corresponding object exists, either a
* DanglingReferenceException will be generated by the
* <code>cloneTree</code> method or a reference to the original object
* is returned depending on the value of the
* <code>allowDanglingReferences</code> parameter passed in the
* <code>cloneTree</code> call.
*
* @see SceneGraphObject#updateNodeReferences
* @see Node#cloneTree
* @see DanglingReferenceException
*/
public final SceneGraphObject
getNewObjectReference(SceneGraphObject oldReference) {
// look up original SceneGraphObject in hash table
SceneGraphObject newObject =
(SceneGraphObject)objectHashtable.get(oldReference);
if (newObject != null) {
// found new reference
return newObject;
}
// dangling reference found!
if (allowDanglingReferences == true) {
return oldReference;
}
// dangling references not allowed
throw new DanglingReferenceException();
}
}
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