SelectAllHandler


1   /*******************************************************************************
2    * Copyright (c) 2004, 2006 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.ui.internal.handlers;
12  
13  import java.lang.reflect.InvocationTargetException  ;
14  import java.lang.reflect.Method  ;
15  
16  import org.eclipse.core.commands.ExecutionEvent;
17  import org.eclipse.core.commands.ExecutionException;
18  import org.eclipse.core.runtime.IConfigurationElement;
19  import org.eclipse.swt.SWT;
20  import org.eclipse.swt.graphics.Point;
21  import org.eclipse.swt.widgets.Composite;
22  import org.eclipse.swt.widgets.Control;
23  import org.eclipse.swt.widgets.Display;
24  import org.eclipse.ui.internal.ExceptionHandler;
25  
26  /**
27   * This handler is an adaptation of the widget method handler allowing select
28   * all to work even in some cases where the "selectAll" method does not exist.
29   * This handler attempts to use "getTextLimit" and "setSelection" to do select
30   * all. If this doesn't work, then it finally fails.
31   * 
32   * @since 3.0
33   */
34  public class SelectAllHandler extends WidgetMethodHandler {
35  
36      /**
37       * The parameters for a single point select all.
38       */
39      private static final Class  [] METHOD_PARAMETERS = { Point.class };
40  
41      public final Object   execute(final ExecutionEvent event)
42              throws ExecutionException {
43          final Method   methodToExecute = getMethodToExecute();
44          if (methodToExecute != null) {
45              try {
46                  final Control focusControl = Display.getCurrent()
47                          .getFocusControl();
48                  
49                  final int numParams = methodToExecute.getParameterTypes().length;
50  
51                  if ((focusControl instanceof Composite)
52                          && ((((Composite) focusControl).getStyle() & SWT.EMBEDDED) != 0)) {
53                      
54                      // we only support selectAll for swing components
55                      if (numParams != 0) {
56                          return null;
57                      }
58  
59                      /*
60                       * Okay. Have a seat. Relax a while. This is going to be a
61                       * bumpy ride. If it is an embedded widget, then it *might*
62                       * be a Swing widget. At the point where this handler is
63                       * executing, the key event is already bound to be
64                       * swallowed. If I don't do something, then the key will be
65                       * gone for good. So, I will try to forward the event to the
66                       * Swing widget. Unfortunately, we can't even count on the
67                       * Swing libraries existing, so I need to use reflection
68                       * everywhere. And, to top it off, I need to dispatch the
69                       * event on the Swing event queue, which means that it will
70                       * be carried out asynchronously to the SWT event queue.
71                       */
72                      try {
73                          final Object   focusComponent = getFocusComponent();
74                          if (focusComponent != null) {
75                              Runnable   methodRunnable = new Runnable  () {
76                                  public void run() {
77                                      try {
78                                          methodToExecute.invoke(focusComponent,
79                                                  null);
80                                          // and back to the UI thread :-)
81                                          focusControl.getDisplay().asyncExec(
82                                                  new Runnable  () {
83                                                      public void run() {
84                                                          if (!focusControl
85                                                                  .isDisposed()) {
86                                                              focusControl
87                                                                      .notifyListeners(
88                                                                              SWT.Selection,
89                                                                              null);
90                                                          }
91                                                      }
92                                                  });
93                                      } catch (final IllegalAccessException   e) {
94                                          // The method is protected, so do
95                                          // nothing.
96                                      } catch (final InvocationTargetException   e) {
97                                          /*
98                                           * I would like to log this exception --
99                                           * and possibly show a dialog to the
100                                          * user -- but I have to go back to the
101                                          * SWT event loop to do this. So, back
102                                          * we go....
103                                          */
104                                         focusControl.getDisplay().asyncExec(
105                                                 new Runnable  () {
106                                                     public void run() {
107                                                         ExceptionHandler
108                                                                 .getInstance()
109                                                                 .handleException(
110                                                                         new ExecutionException(
111                                                                                 "An exception occurred while executing " //$NON-NLS-1$
112                                                                                         + methodToExecute
113                                                                                                 .getName(),
114                                                                                 e
115                                                                                         .getTargetException()));
116                                                     }
117                                                 });
118                                     }
119                                 }
120                             };
121 
122                             swingInvokeLater(methodRunnable);
123                         }
124                     } catch (final ClassNotFoundException   e) {
125                         // There is no Swing support, so do nothing.
126 
127                     } catch (final NoSuchMethodException   e) {
128                         // The API has changed, which seems amazingly unlikely.
129                         throw new Error  ("Something is seriously wrong here"); //$NON-NLS-1$
130                     }
131                 } else if (numParams == 0) {
132                     // This is a no-argument selectAll method.
133                     methodToExecute.invoke(focusControl, null);
134                     focusControl.notifyListeners(SWT.Selection, null);
135 
136                 } else if (numParams == 1) {
137                     // This is a single-point selection method.
138                     final Method   textLimitAccessor = focusControl.getClass()
139                             .getMethod("getTextLimit", NO_PARAMETERS); //$NON-NLS-1$
140                     final Integer   textLimit = (Integer  ) textLimitAccessor
141                             .invoke(focusControl, null);
142                     final Object  [] parameters = { new Point(0, textLimit
143                             .intValue()) };
144                     methodToExecute.invoke(focusControl, parameters);
145                     focusControl.notifyListeners(SWT.Selection, null);
146 
147                 } else {
148                     /*
149                      * This means that getMethodToExecute() has been changed,
150                      * while this method hasn't.
151                      */
152                     throw new ExecutionException(
153                             "Too many parameters on select all", new Exception  ()); //$NON-NLS-1$
154 
155                 }
156 
157             } catch (IllegalAccessException   e) {
158                 // The method is protected, so do nothing.
159 
160             } catch (InvocationTargetException   e) {
161                 throw new ExecutionException(
162                         "An exception occurred while executing " //$NON-NLS-1$
163                                 + getMethodToExecute(), e.getTargetException());
164 
165             } catch (NoSuchMethodException   e) {
166                 // I can't get the text limit. Do nothing.
167 
168             }
169         }
170 
171         return null;
172     }
173 
174     /**
175      * Looks up the select all method on the given focus control.
176      * 
177      * @return The method on the focus control; <code>null</code> if none.
178      */
179     protected Method   getMethodToExecute() {
180         Method   method = super.getMethodToExecute();
181 
182         // Let's see if we have a control that supports point-based selection.
183         if (method == null) {
184             final Control focusControl = Display.getCurrent().getFocusControl();
185             if (focusControl != null) {
186                 try {
187                     method = focusControl.getClass().getMethod("setSelection", //$NON-NLS-1$
188                             METHOD_PARAMETERS);
189                 } catch (NoSuchMethodException   e) {
190                     // Do nothing.
191                 }
192             }
193         }
194 
195         return method;
196     }
197 
198     /**
199      * @see org.eclipse.core.runtime.IExecutableExtension#setInitializationData(org.eclipse.core.runtime.IConfigurationElement,
200      *      java.lang.String, java.lang.Object)
201      */
202     public void setInitializationData(IConfigurationElement config,
203             String   propertyName, Object   data) {
204         // The name is always "selectAll".
205         methodName = "selectAll"; //$NON-NLS-1$
206     }
207 }
208
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