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comparison org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/provisional/swt/MenuUpdater.d @ 78:0a55d2d5a946

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Added file for databinding
author Frank Benoit <benoit@tionex.de>
date Tue, 14 Apr 2009 11:35:29 +0200
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76:f05e6e8b2f2d 78:0a55d2d5a946
1 /*******************************************************************************
2 * Copyright (c) 2006, 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 module org.eclipse.jface.internal.databinding.provisional.swt.MenuUpdater;
12
13 import java.lang.all;
14
15 import org.eclipse.core.databinding.observable.ChangeEvent;
16 import org.eclipse.core.databinding.observable.IChangeListener;
17 import org.eclipse.core.databinding.observable.IObservable;
18 import org.eclipse.core.databinding.observable.ObservableTracker;
19 import org.eclipse.swt.events.DisposeEvent;
20 import org.eclipse.swt.events.DisposeListener;
21 import org.eclipse.swt.events.MenuEvent;
22 import org.eclipse.swt.events.MenuListener;
23 import org.eclipse.swt.widgets.Menu;
24
25 /**
26 * NON-API - A MenuUpdater updates an SWT menu in response to changes in the model. By
27 * wrapping a block of code in a MenuUpdater, clients can rely on the fact that
28 * the block of code will be re-executed whenever anything changes in the model
29 * that might affect its behavior.
30 *
31 * <p>
32 * MenuUpdaters only execute once their menus are shown. If something changes in
33 * the model, the updater is flagged as dirty and it stops listening to the
34 * model until the next time the menu is shown. If the menu is visible while the
35 * model changes, it will be updated right away.
36 * </p>
37 *
38 * <p>
39 * Clients should subclass this when copying information from the model to a
40 * menu. Typical usage:
41 * </p>
42 *
43 * <ul>
44 * <li>Override updateMenu. It should do whatever is necessary to display the
45 * contents of the model in the menu.</li>
46 * <li>In the constructor, attach listeners to the model. The listeners should
47 * call markDirty whenever anything changes in the model that affects
48 * updateMenu. Note: this step can be omitted when calling any method tagged
49 * with "@TrackedGetter" since MenuUpdater will automatically attach a listener
50 * to any object if a "@TrackedGetter" method is called in updateMenu.</li>
51 * <li>(optional)Extend dispose() to remove any listeners attached in the
52 * constructor</li>
53 * </ul>
54 *
55 * @since 1.1
56 */
57 public abstract class MenuUpdater {
58
59 private class PrivateInterface : MenuListener,
60 DisposeListener, Runnable, IChangeListener {
61
62 // DisposeListener implementation
63 public void widgetDisposed(DisposeEvent e) {
64 this.outer.dispose();
65 }
66
67 // Runnable implementation. This method runs at most once per repaint whenever the
68 // value gets marked as dirty.
69 public void run() {
70 if (theMenu !is null && !theMenu.isDisposed() && theMenu.isVisible()) {
71 updateIfNecessary();
72 }
73 }
74
75 // IChangeListener implementation (listening to the ComputedValue)
76 public void handleChange(ChangeEvent event) {
77 // Whenever this updator becomes dirty, schedule the run() method
78 makeDirty();
79 }
80
81 public void menuHidden(MenuEvent e) {
82 // do nothing
83 }
84
85 public void menuShown(MenuEvent e) {
86 updateIfNecessary();
87 }
88
89 }
90
91 private Runnable updateRunnable = new class() Runnable {
92 public void run() {
93 updateMenu();
94 }
95 };
96
97 private PrivateInterface privateInterface = new PrivateInterface();
98 private Menu theMenu;
99 private IObservable[] dependencies = new IObservable[0];
100 private bool dirty = false;
101
102 /**
103 * Creates an updator for the given menu.
104 *
105 * @param toUpdate menu to update
106 */
107 public this(Menu toUpdate) {
108 theMenu = toUpdate;
109
110 theMenu.addDisposeListener(privateInterface);
111 theMenu.addMenuListener(privateInterface);
112 makeDirty();
113 }
114
115 private void updateIfNecessary() {
116 if (dirty) {
117 dependencies = ObservableTracker.runAndMonitor(updateRunnable, privateInterface, null);
118 dirty = false;
119 }
120 }
121
122 /**
123 * This is called automatically when the menu is disposed. It may also
124 * be called explicitly to remove this updator from the menu. Subclasses
125 * will normally extend this method to detach any listeners they attached
126 * in their constructor.
127 */
128 public void dispose() {
129 theMenu.removeDisposeListener(privateInterface);
130 theMenu.removeMenuListener(privateInterface);
131
132 stopListening();
133 }
134
135 private void stopListening() {
136 // Stop listening for dependency changes
137 for (int i = 0; i < dependencies.length; i++) {
138 IObservable observable = dependencies[i];
139
140 observable.removeChangeListener(privateInterface);
141 }
142 }
143
144 /**
145 * Updates the menu. This method will be invoked once after the
146 * updater is created, and once for any SWT.Show event if this
147 * updater is marked as dirty at that time.
148 *
149 * <p>
150 * Subclasses should overload this method to provide any code that
151 * udates the menu.
152 * </p>
153 */
154 protected abstract void updateMenu();
155
156 /**
157 * Marks this updator as dirty. Causes the updateControl method to
158 * be invoked before the next time the control is repainted.
159 */
160 protected final void makeDirty() {
161 if (!dirty) {
162 dirty = true;
163 stopListening();
164 SWTUtil.runOnce(theMenu.getDisplay(), privateInterface);
165 }
166 }
167
168 }