/*

  * Copyright 2002 - 2007 JEuclid, http://jeuclid.sf.net

  * 

  * 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.

  */

 /* $Id: AbstractElementWithDelegates.java,v bc1d5fde7b73 2009/06/01 14:40:54 maxberger $ */

 package net.sourceforge.jeuclid.elements;

 import java.util.List;

 import net.sourceforge.jeuclid.elements.presentation.AbstractContainer;

 import net.sourceforge.jeuclid.layout.LayoutableNode;

 import org.apache.batik.dom.AbstractDocument;

 /**

  * Generic class for all mathobjects that can be represented using other Math

  * objects. These math objects use a delegates for the actual display and

  * calculations.

  * <p>

  * To use this class, overwrite {@link #createDelegates()} to create the

  * delegate objects.

  * 

  * @version $Revision: bc1d5fde7b73 $

  */

 public abstract class AbstractElementWithDelegates extends AbstractContainer {

     // TODO: Re-Enable resetting delegates on changeHook!

     private List<LayoutableNode> delegates;

     /**

      * Default constructor. Sets MathML Namespace.

      * 

      * @param qname

      *            Qualified name.

      * @param odoc

      *            Owner Document.

      */

     public AbstractElementWithDelegates(final String qname,

             final AbstractDocument odoc) {

         super(qname, odoc);

     }

     /**

      * Overwrite this function in your implementation.

      * 

      * @return a MathObject representing the real contents.

      */

     protected abstract List<LayoutableNode> createDelegates();

     private void prepareDelegates() {

         if (this.delegates == null) {

             this.delegates = this.createDelegates();

             for (final LayoutableNode element : this.delegates) {

                 ((JEuclidElement) element).setFakeParent(this);

             }

         }

     }

     /** {@inheritDoc} */

     @Override

     public List<LayoutableNode> getChildrenToLayout() {

         this.prepareDelegates();

         return this.delegates;

     }

     /** {@inheritDoc} */

     @Override

     public List<LayoutableNode> getChildrenToDraw() {

         this.prepareDelegates();

         return this.delegates;

     }

 }