SingleSelectionObservableValue


1   /*******************************************************************************
2    * Copyright (c) 2005, 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   *     Brad Reynolds - bug 164653
11   *******************************************************************************/
12  package org.eclipse.jface.internal.databinding.internal.swt;
13  
14  import org.eclipse.core.databinding.observable.Diffs;
15  import org.eclipse.jface.internal.databinding.provisional.swt.AbstractSWTObservableValue;
16  import org.eclipse.swt.widgets.Control;
17  
18  /**
19   * @since 1.0
20   * 
21   */
22  abstract public class SingleSelectionObservableValue extends
23          AbstractSWTObservableValue {
24  
25      private boolean updating = false;
26  
27      private int currentSelection;
28  
29      /**
30       * @param control
31       *            the control
32       */
33      public SingleSelectionObservableValue(Control control) {
34          super(control);
35  
36          currentSelection = doGetSelectionIndex();
37          doAddSelectionListener(new Runnable  (){
38              public void run() {
39                  if (!updating) {
40                      int newSelection = doGetSelectionIndex();
41                      fireValueChange(Diffs.createValueDiff(new Integer  (
42                              currentSelection), new Integer  (newSelection)));
43                      currentSelection = newSelection;
44                  }
45              }
46          });
47      }
48  
49      /**
50       * @param runnable
51       */
52      protected abstract void doAddSelectionListener(Runnable   runnable);
53  
54      public void doSetValue(Object   value) {
55          try {
56              updating = true;
57              int intValue = ((Integer  ) value).intValue();
58              doSetSelectionIndex(intValue);
59              currentSelection = intValue;
60          } finally {
61              updating = false;
62          }
63      }
64  
65      /**
66       * @param intValue
67       *            the selection index
68       */
69      protected abstract void doSetSelectionIndex(int intValue);
70  
71      public Object   doGetValue() {
72          return new Integer  (doGetSelectionIndex());
73      }
74  
75      /**
76       * @return the selection index
77       */
78      protected abstract int doGetSelectionIndex();
79  
80      public Object   getValueType() {
81          return Integer.TYPE;
82      }
83  
84  }
85
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