ServerTreeRenderer


1   /* 
2    * Copyright (C) 2006 Methodhead Software LLC.  All rights reserved.
3    * 
4    * This file is part of TransferCM.
5    * 
6    * TransferCM is free software; you can redistribute it and/or modify it under the
7    * terms of the GNU General Public License as published by the Free Software
8    * Foundation; either version 2 of the License, or (at your option) any later
9    * version.
10   * 
11   * TransferCM is distributed in the hope that it will be useful, but WITHOUT ANY
12   * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13   * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
14   * details.
15   * 
16   * You should have received a copy of the GNU General Public License along with
17   * TransferCM; if not, write to the Free Software Foundation, Inc., 51 Franklin St,
18   * Fifth Floor, Boston, MA  02110-1301  USA
19   */
20  
21  package com.methodhead.tree;
22  
23  import java.util.ArrayList  ;
24  import java.util.Iterator  ;
25  import java.util.List  ;
26  import java.util.Map  ;
27  
28  import javax.swing.tree.TreeNode  ;
29  
30  /**
31   * <p>
32   *   A <tt>TreeRenderer</tt> for trees whose state is maintained on the server.
33   *   The renderer only renders those nodes that are visible, and a request must
34   *   be made to open or close a node.  A mechanism must exist on the server
35   *   side to handle those requests.  While more elaborate to implement, this
36   *   approach makes it possible maintain a tree's state across requests.
37   * </p>
38   */
39  public class ServerTreeRenderer
40  extends TreeRenderer {
41  
42    // constructors /////////////////////////////////////////////////////////////
43  
44    // constants ////////////////////////////////////////////////////////////////
45  
46    // classes //////////////////////////////////////////////////////////////////
47  
48    // methods //////////////////////////////////////////////////////////////////
49  
50    /**
51     *
52     */
53    public String   renderTree(
54      FoldingTreeNode root )
55    throws
56      TreeException {
57  
58      if ( openUrl_ == null )
59        throw new TreeException( "openUrl has not been set." );
60  
61      if ( closeUrl_ == null )
62        throw new TreeException( "closeUrl has not been set." );
63  
64      //
65      // set defaults
66      //
67      if ( getClosedHandleImage() == null )
68        closedHandleImageHtml_ = "+";
69      else
70        closedHandleImageHtml_ =
71          "<img border=\"0\" SRC=\"" + getClosedHandleImage() + "\">";
72  
73      if ( getOpenedHandleImage() == null )
74        openedHandleImageHtml_ = "-";
75      else
76        openedHandleImageHtml_ =
77          "<img border=\"0\" SRC=\"" + getOpenedHandleImage() + "\">";
78  
79      //
80      // get visible nodes
81      //
82      List   nodes = new ArrayList  ();
83      getVisibleNodes( nodes, root );
84  
85      //
86      // get maximum visible level
87      //
88      int maxVisibleLevel = getMaxLevel( nodes );
89  
90      //
91      // render the tree
92      //
93      StringBuffer   buf = new StringBuffer  ();
94      renderHeader( buf );
95      
96      for ( Iterator   iter = nodes.iterator(); iter.hasNext(); ) {
97        FoldingTreeNode node = ( FoldingTreeNode )iter.next();
98        renderNode( buf, maxVisibleLevel, node );
99      }
100 
101     renderFooter( buf );
102 
103     //
104     // return the html
105     //
106     return buf.toString();
107   }
108 
109   /**
110    * Transforms the tree into a list of nodes that should be displayed.
111    */
112   protected void getVisibleNodes(
113     List   rows,
114     FoldingTreeNode node ) {
115 
116     if ( !node.isRoot() || !isRootHidden() )
117       rows.add( node );
118 
119     if ( !node.isLeaf() && node.getOpened() )
120       for ( int i = 0; i < node.getChildCount(); i++ )
121         getVisibleNodes( rows, ( FoldingTreeNode )node.getChildAt( i ) );
122   }
123 
124   /**
125    * Returns the level of the deepest level node in <tt>nodes</tt>.
126    */
127   protected int getMaxLevel(
128     List   nodes ) {
129 
130     int level = 0;
131     for ( Iterator   iter = nodes.iterator(); iter.hasNext(); ) {
132       FoldingTreeNode node = ( FoldingTreeNode )iter.next();
133 
134       int tmp = node.getLevel();
135 
136       if ( tmp > level )
137         level = tmp;
138     }
139 
140     return level;
141   }
142 
143   /**
144    * Renders the header of the tree: a <tt>table</tt> tag.
145    */
146   protected void renderHeader(
147     StringBuffer   buf )
148   throws
149     TreeException {
150 
151     buf.append( "<table>\n" );
152   }
153 
154   /**
155    * Renders the footer of the tree.
156    */
157   protected void renderFooter(
158     StringBuffer   buf )
159   throws
160     TreeException {
161 
162     buf.append( "</table>\n" );
163   }
164 
165   /**
166    * Renders a node.
167    */
168   protected void renderNode(
169     StringBuffer   buf,
170     int maxVisibleLevel,
171     FoldingTreeNode node ) {
172 
173     //
174     // if the root is hidden, it throws off most of these calculations by one;
175     // find this offset peppered through the code below
176     //
177     int hiddenRootOffset = 0;
178     if ( isRootHidden() )
179       hiddenRootOffset = 1;
180 
181     //
182     // scratch strings
183     //
184     String   s = null;
185     String   t = null;
186 
187     buf.append( "<tr>" );
188 
189     //
190     // insert an empty cell for each level deep the node is
191     //
192     for ( int i = hiddenRootOffset; i < node.getLevel(); i++ )
193       buf.append( "<td>&nbsp;</td>" );
194 
195     //
196     // render open/close link; leaf?
197     //
198     if ( node.isLeaf() ) {
199       buf.append(
200         "<td>&nbsp;</td>" );
201     }
202     else {
203       //
204       // opened?
205       //
206       if ( !node.getOpened() )
207         buf.append(
208           "<td><a HREF=\"" + openUrl_ + 
209           node.hashCode() + "\">" + closedHandleImageHtml_ + "</a></td>" );
210 
211       //
212       // closed
213       //
214       else
215         buf.append(
216           "<td><a HREF=\"" + closeUrl_ + 
217           node.hashCode() + "\">" + openedHandleImageHtml_ + "</a></td>" );
218     }
219 
220     //
221     // render icon
222     //
223     Map   iconImages = getIconImages();
224 
225     if ( iconImages != null ) {
226 
227       s = ( String   )iconImages.get( node.getIconHint() );
228 
229       if ( s == null )
230         s = ( String   )iconImages.get( DEFAULT_ICON );
231 
232       if ( s == null ) {
233         buf.append( "<td>&nbsp;</td>" );
234       }
235       else {
236         if ( node.getUrl() == null )
237           buf.append( "<td><img SRC=\"" + s + "\"></td>" );
238         else
239           buf.append(
240             "<td><a HREF=\"" + node.getUrl() + "\"><img border=\"0\" SRC=\"" +
241             s + "\"></a></td>" );
242       }
243     }
244 
245     //
246     // render label
247     //
248     if ( node.getUrl() == null )
249       buf.append(
250         "<td width=\"100%\" colspan=\"" +
251         ( maxVisibleLevel - node.getLevel() + 1 ) + "\">" +
252         node.getLabel() + "</td>" );
253     else
254       buf.append(
255         "<td width=\"100%\" colspan=\"" +
256         ( maxVisibleLevel - node.getLevel() + 1 ) +
257         "\"><a HREF=\"" + node.getUrl() + "\">" + node.getLabel() +
258         "</a></td>" );
259 
260     buf.append( "</tr>\n" );
261   }
262 
263   // properties ///////////////////////////////////////////////////////////////
264 
265   /**
266    * Sets the url to open a node; the hash code of the node to be opened will
267    * be appended to the end of this url.
268    */
269   public void setOpenUrl( String   openUrl ) {
270     openUrl_ = openUrl;
271   }
272 
273   /**
274    * Sets the url to close a node; the hash code of the node to be closed will
275    * be appended to the end of this url.
276    */
277   public void setCloseUrl( String   closeUrl ) {
278     closeUrl_ = closeUrl;
279   }
280 
281   // attributes ///////////////////////////////////////////////////////////////
282 
283   protected String   openUrl_ = null;
284   protected String   closeUrl_ = null;
285 
286   private String   openedHandleImageHtml_ = null;
287   private String   closedHandleImageHtml_ = null;
288 }
289
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags