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1   /*
2    * Copyright 2002 - 2007 JEuclid, http://jeuclid.sf.net
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  /* $Id: AbstractElementWithDelegates.java,v bc1d5fde7b73 2009/06/01 14:40:54 maxberger $ */
18  
19  package net.sourceforge.jeuclid.elements;
20  
21  import java.util.List;
22  
23  import net.sourceforge.jeuclid.elements.presentation.AbstractContainer;
24  import net.sourceforge.jeuclid.layout.LayoutableNode;
25  
26  import org.apache.batik.dom.AbstractDocument;
27  
28  /**
29   * Generic class for all mathobjects that can be represented using other Math
30   * objects. These math objects use a delegates for the actual display and
31   * calculations.
32   * <p>
33   * To use this class, overwrite {@link #createDelegates()} to create the
34   * delegate objects.
35   * 
36   * @version $Revision: bc1d5fde7b73 $
37   */
38  public abstract class AbstractElementWithDelegates extends AbstractContainer {
39  
40      // TODO: Re-Enable resetting delegates on changeHook!
41      private List<LayoutableNode> delegates;
42  
43      /**
44       * Default constructor. Sets MathML Namespace.
45       * 
46       * @param qname
47       *            Qualified name.
48       * @param odoc
49       *            Owner Document.
50       */
51      public AbstractElementWithDelegates(final String qname,
52              final AbstractDocument odoc) {
53          super(qname, odoc);
54      }
55  
56      /**
57       * Overwrite this function in your implementation.
58       * 
59       * @return a MathObject representing the real contents.
60       */
61      protected abstract List<LayoutableNode> createDelegates();
62  
63      private void prepareDelegates() {
64          if (this.delegates == null) {
65              this.delegates = this.createDelegates();
66              for (final LayoutableNode element : this.delegates) {
67                  ((JEuclidElement) element).setFakeParent(this);
68              }
69          }
70      }
71  
72      /** {@inheritDoc} */
73      @Override
74      public List<LayoutableNode> getChildrenToLayout() {
75          this.prepareDelegates();
76          return this.delegates;
77      }
78  
79      /** {@inheritDoc} */
80      @Override
81      public List<LayoutableNode> getChildrenToDraw() {
82          this.prepareDelegates();
83          return this.delegates;
84      }
85  
86  }