RetargetTextEditorAction


1   /*******************************************************************************
2    * Copyright (c) 2000, 2005 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  
12  
13  package org.eclipse.ui.texteditor;
14  
15  
16  import java.util.ResourceBundle  ;
17  
18  import org.eclipse.swt.events.HelpEvent;
19  import org.eclipse.swt.events.HelpListener;
20  
21  import org.eclipse.jface.action.IAction;
22  import org.eclipse.jface.util.IPropertyChangeListener;
23  import org.eclipse.jface.util.PropertyChangeEvent;
24  
25  
26  /**
27   * Action used by an editor action bar contributor to establish placeholders in
28   * menus or action bars which can be retargeted to dynamically changing actions,
29   * for example, those which come from the active editor. This action assumes that
30   * the "wrapped" action sends out property change events in response to state
31   * changes. It uses these change notifications to adapt its enabling state and
32   * its visual presentation.
33   */
34  public final class RetargetTextEditorAction extends ResourceAction {
35  
36      /** The target action. */
37      private IAction fAction;
38      /** The default label if there is no target action. */
39      private String   fDefaultText;
40      /**
41       * The local help listener
42       * @since 2.1
43       */
44      private HelpListener fLocalHelpListener;
45      /** The listener to pick up changes of the target action. */
46      private IPropertyChangeListener fListener= new IPropertyChangeListener() {
47          public void propertyChange(PropertyChangeEvent event) {
48              update(event);
49          }
50      };
51  
52      /**
53       * Creates a new action. The action configures its initial visual
54       * representation from the given resource bundle. If this action's
55       * wrapped action is set to <code>null</code> it also uses the
56       * information in the resource bundle.
57       *
58       * @param bundle the resource bundle
59       * @param prefix a prefix to be prepended to the various resource keys
60       *   (described in <code>ResourceAction</code> constructor), or
61       *   <code>null</code> if none
62       * @param   style one of <code>IAction.AS_PUSH_BUTTON</code>, <code>IAction.AS_CHECK_BOX</code>,
63       *          and <code>IAction.AS_RADIO_BUTTON</code>.
64       *
65       * @see ResourceAction#ResourceAction(ResourceBundle, String, int)
66       * @see IAction#AS_CHECK_BOX
67       * @see IAction#AS_DROP_DOWN_MENU
68       * @see IAction#AS_PUSH_BUTTON
69       * @see IAction#AS_RADIO_BUTTON
70       * @since 2.1
71       */
72      public RetargetTextEditorAction(ResourceBundle   bundle, String   prefix, int style) {
73          super(bundle, prefix, style);
74          fDefaultText= getText();
75          installHelpListener();
76      }
77  
78      /**
79       * Creates a new action. The action configures its initial visual
80       * representation from the given resource bundle. If this action's
81       * wrapped action is set to <code>null</code> it also uses the
82       * information in the resource bundle.
83       *
84       * @param bundle the resource bundle
85       * @param prefix a prefix to be prepended to the various resource keys
86       *   (described in <code>ResourceAction</code> constructor), or
87       *   <code>null</code> if none
88       * @see ResourceAction#ResourceAction(ResourceBundle, String)
89       */
90      public RetargetTextEditorAction(ResourceBundle   bundle, String   prefix) {
91          super(bundle, prefix);
92          fDefaultText= getText();
93          installHelpListener();
94      }
95  
96      /**
97       * Creates a new action. The action configures its initial visual
98       * representation from the given resource bundle. If this action's
99       * wrapped action is set to <code>null</code> it also uses the
100      * information in the resource bundle. The action gets the given
101      * action id.
102      *
103      * @param bundle the resource bundle
104      * @param prefix a prefix to be prepended to the various resource keys
105      *   (described in <code>ResourceAction</code> constructor), or <code>null</code> if none
106      * @param actionId the action id
107      * @param   style one of <code>IAction.AS_PUSH_BUTTON</code>, <code>IAction.AS_CHECK_BOX</code>,
108      *          and <code>IAction.AS_RADIO_BUTTON</code>.
109      *
110      * @see ResourceAction#ResourceAction(ResourceBundle, String, int)
111      * @see IAction#AS_CHECK_BOX
112      * @see IAction#AS_DROP_DOWN_MENU
113      * @see IAction#AS_PUSH_BUTTON
114      * @see IAction#AS_RADIO_BUTTON
115      * @since 2.1
116      */
117     public RetargetTextEditorAction(ResourceBundle   bundle, String   prefix, String   actionId, int style) {
118         super(bundle, prefix, style);
119         fDefaultText= getText();
120         setId(actionId);
121         installHelpListener();
122     }
123 
124     /**
125      * Creates a new action. The action configures its initial visual
126      * representation from the given resource bundle. If this action's
127      * wrapped action is set to <code>null</code> it also uses the
128      * information in the resource bundle. The action gets the given
129      * action id.
130      *
131      * @param bundle the resource bundle
132      * @param prefix a prefix to be prepended to the various resource keys
133      *   (described in <code>ResourceAction</code> constructor), or <code>null</code> if none
134      * @param actionId the action id
135      * @see ResourceAction#ResourceAction(ResourceBundle, String)
136      * @since 2.0
137      */
138     public RetargetTextEditorAction(ResourceBundle   bundle, String   prefix, String   actionId) {
139         super(bundle, prefix);
140         fDefaultText= getText();
141         setId(actionId);
142         installHelpListener();
143     }
144 
145     /**
146      * Updates to the changes of the underlying action.
147      *
148      * @param event the change event describing the state change
149      */
150     private void update(PropertyChangeEvent event) {
151         if (ENABLED.equals(event.getProperty())) {
152             Boolean   bool= (Boolean  ) event.getNewValue();
153             setEnabled(bool.booleanValue());
154         } else if (TEXT.equals(event.getProperty()))
155             setText((String  ) event.getNewValue());
156         else if (TOOL_TIP_TEXT.equals(event.getProperty()))
157             setToolTipText((String  ) event.getNewValue());
158         else if (CHECKED.equals(event.getProperty())) {
159             Boolean   bool= (Boolean  ) event.getNewValue();
160             setChecked(bool.booleanValue());
161         }
162     }
163 
164     /**
165      * Sets the underlying action.
166      *
167      * @param action the underlying action
168      */
169     public void setAction(IAction action) {
170 
171         if (fAction != null) {
172             fAction.removePropertyChangeListener(fListener);
173             fAction= null;
174         }
175 
176         fAction= action;
177 
178         if (fAction == null) {
179 
180             setEnabled(false);
181             if (getStyle() == AS_CHECK_BOX || getStyle() == AS_RADIO_BUTTON)
182                setChecked(false);
183             setText(fDefaultText);
184             setToolTipText(""); //$NON-NLS-1$
185 
186         } else {
187 
188             setEnabled(fAction.isEnabled());
189             if (fAction.getStyle() == AS_CHECK_BOX || fAction.getStyle() ==  AS_RADIO_BUTTON)
190                super.setChecked(fAction.isChecked());
191             setText(fAction.getText());
192             setToolTipText(fAction.getToolTipText());
193             fAction.addPropertyChangeListener(fListener);
194         }
195     }
196 
197     /**
198      * Installs the help listener.
199      *
200      * @since 2.1
201      */
202     private void installHelpListener() {
203         super.setHelpListener(new HelpListener() {
204             public void helpRequested(HelpEvent e) {
205                 HelpListener listener= null;
206                 if (fAction != null) {
207                     // if we have a handler, see if it has a help listener
208                     listener= fAction.getHelpListener();
209                     if (listener == null)
210                         // use our own help listener
211                         listener= fLocalHelpListener;
212                 }
213                 if (listener != null)
214                     // pass on the event
215                     listener.helpRequested(e);
216             }
217         });
218     }
219 
220     /**
221      * The <code>RetargetTextEditorAction</code> implementation of this method declared on
222      * <code>IAction</code> stores the help listener in a local field. The
223      * supplied listener is only used if there is no handler.
224      *
225      * @param listener the help listener
226      * @since 2.1
227      */
228     public void setHelpListener(HelpListener listener) {
229         fLocalHelpListener= listener;
230     }
231 
232     /*
233      * @see IAction#run()
234      */
235     public void run() {
236         if (fAction != null)
237             fAction.run();
238     }
239 }
240
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