PreferenceNode


1   /*******************************************************************************
2    * Copyright (c) 2000, 2007 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.jface.preference;
12  
13  import java.util.ArrayList  ;
14  import java.util.List  ;
15  
16  import org.eclipse.jface.resource.ImageDescriptor;
17  import org.eclipse.core.runtime.Assert;
18  import org.eclipse.swt.graphics.Image;
19  
20  /**
21   * A concrete implementation of a node in a preference dialog tree. This class
22   * also supports lazy creation of the node's preference page.
23   */
24  public class PreferenceNode implements IPreferenceNode {
25      /**
26       * Preference page, or <code>null</code> if not yet loaded.
27       */
28      private IPreferencePage page;
29  
30      /**
31       * The list of subnodes (immediate children) of this node (element type:
32       * <code>IPreferenceNode</code>).
33       */
34      private List   subNodes;
35  
36      /**
37       * Name of a class that implements <code>IPreferencePage</code>, or
38       * <code>null</code> if none.
39       */
40      private String   classname;
41  
42      /**
43       * The id of this node.
44       */
45      private String   id;
46  
47      /**
48       * Text label for this node. Note that this field is only used prior to the
49       * creation of the preference page.
50       */
51      private String   label;
52  
53      /**
54       * Image descriptor for this node, or <code>null</code> if none.
55       */
56      private ImageDescriptor imageDescriptor;
57  
58      /**
59       * Cached image, or <code>null</code> if none.
60       */
61      private Image image;
62  
63      /**
64       * Creates a new preference node with the given id. The new node has no
65       * subnodes.
66       * 
67       * @param id
68       *            the node id
69       */
70      public PreferenceNode(String   id) {
71          Assert.isNotNull(id);
72          this.id = id;
73      }
74  
75      /**
76       * Creates a preference node with the given id, label, and image, and
77       * lazily-loaded preference page. The preference node assumes (sole)
78       * responsibility for disposing of the image; this will happen when the node
79       * is disposed.
80       * 
81       * @param id
82       *            the node id
83       * @param label
84       *            the label used to display the node in the preference dialog's
85       *            tree
86       * @param image
87       *            the image displayed left of the label in the preference
88       *            dialog's tree, or <code>null</code> if none
89       * @param className
90       *            the class name of the preference page; this class must
91       *            implement <code>IPreferencePage</code>
92       */
93      public PreferenceNode(String   id, String   label, ImageDescriptor image,
94              String   className) {
95          this(id);
96          this.imageDescriptor = image;
97          Assert.isNotNull(label);
98          this.label = label;
99          this.classname = className;
100     }
101 
102     /**
103      * Creates a preference node with the given id and preference page. The
104      * title of the preference page is used for the node label. The node will
105      * not have an image.
106      * 
107      * @param id
108      *            the node id
109      * @param preferencePage
110      *            the preference page
111      */
112     public PreferenceNode(String   id, IPreferencePage preferencePage) {
113         this(id);
114         Assert.isNotNull(preferencePage);
115         page = preferencePage;
116     }
117 
118     /*
119      * (non-Javadoc) Method declared on IPreferenceNode.
120      */
121     public void add(IPreferenceNode node) {
122         if (subNodes == null) {
123             subNodes = new ArrayList  ();
124         }
125         subNodes.add(node);
126     }
127 
128     /**
129      * Creates a new instance of the given class <code>className</code>.
130      * 
131      * @param className
132      * @return new Object or <code>null</code> in case of failures.
133      */
134     private Object   createObject(String   className) {
135         Assert.isNotNull(className);
136         try {
137             Class   cl = Class.forName(className);
138             if (cl != null) {
139                 return cl.newInstance();
140             }
141         } catch (ClassNotFoundException   e) {
142             return null;
143         } catch (InstantiationException   e) {
144             return null;
145         } catch (IllegalAccessException   e) {
146             return null;
147         } catch (NoSuchMethodError   e) {
148             return null;
149         }
150         return null;
151     }
152 
153     /*
154      * (non-Javadoc) Method declared on IPreferenceNode.
155      */
156     public void createPage() {
157         page = (IPreferencePage) createObject(classname);
158         if (getLabelImage() != null) {
159             page.setImageDescriptor(imageDescriptor);
160         }
161         page.setTitle(label);
162     }
163 
164     /**
165      * (non-Javadoc) Method declared on IPreferenceNode.
166      */
167     public void disposeResources() {
168         if (image != null) {
169             image.dispose();
170             image = null;
171         }
172         if (page != null) {
173             page.dispose();
174             page = null;
175         }
176     }
177 
178     /*
179      * (non-Javadoc) Method declared on IContributionNode.
180      */
181     public IPreferenceNode findSubNode(String   id) {
182         Assert.isNotNull(id);
183         Assert.isTrue(id.length() > 0);
184         if (subNodes == null) {
185             return null;
186         }
187         int size = subNodes.size();
188         for (int i = 0; i < size; i++) {
189             IPreferenceNode node = (IPreferenceNode) subNodes.get(i);
190             if (id.equals(node.getId())) {
191                 return node;
192             }
193         }
194         return null;
195     }
196 
197     /*
198      * (non-Javadoc) Method declared on IPreferenceNode.
199      */
200     public String   getId() {
201         return this.id;
202     }
203 
204     /**
205      * Returns the image descriptor for this node.
206      * 
207      * @return the image descriptor
208      */
209     protected ImageDescriptor getImageDescriptor() {
210         return imageDescriptor;
211     }
212 
213     /*
214      * (non-Javadoc) Method declared on IPreferenceNode.
215      */
216     public Image getLabelImage() {
217         if (image == null && imageDescriptor != null) {
218             image = imageDescriptor.createImage();
219         }
220         return image;
221     }
222 
223     /*
224      * (non-Javadoc) Method declared on IPreferenceNode.
225      */
226     public String   getLabelText() {
227         if (page != null) {
228             return page.getTitle();
229         }
230         return label;
231     }
232 
233     /*
234      * (non-Javadoc) Method declared on IPreferenceNode.
235      */
236     public IPreferencePage getPage() {
237         return page;
238     }
239 
240     /*
241      * (non-Javadoc) Method declared on IPreferenceNode.
242      */
243     public IPreferenceNode[] getSubNodes() {
244         if (subNodes == null) {
245             return new IPreferenceNode[0];
246         }
247         return (IPreferenceNode[]) subNodes
248                 .toArray(new IPreferenceNode[subNodes.size()]);
249     }
250 
251     /*
252      * (non-Javadoc) Method declared on IPreferenceNode.
253      */
254     public IPreferenceNode remove(String   id) {
255         IPreferenceNode node = findSubNode(id);
256         if (node != null) {
257             remove(node);
258         }
259         return node;
260     }
261 
262     /*
263      * (non-Javadoc) Method declared on IPreferenceNode.
264      */
265     public boolean remove(IPreferenceNode node) {
266         if (subNodes == null) {
267             return false;
268         }
269         return subNodes.remove(node);
270     }
271 
272     /**
273      * Set the current page to be newPage.
274      * 
275      * @param newPage
276      */
277     public void setPage(IPreferencePage newPage) {
278         page = newPage;
279     }
280 }
281
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags