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comparison org.eclipse.jface.examples.databinding/src/org/eclipse/jface/examples/databinding/snippets/Snippet008ComputedValue.d @ 90:6086085e153d

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Added databinding snippets. unmodified java sources.
author Frank Benoit <benoit@tionex.de>
date Sun, 19 Apr 2009 11:33:55 +0200
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children 5d5bd660917f
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89:0ca1aee7decf 90:6086085e153d
1 /*******************************************************************************
2 * Copyright (c) 2006 Brad Reynolds 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 * Brad Reynolds - initial API and implementation
10 * Matthew Hall - bug 260329
11 ******************************************************************************/
12
13 package org.eclipse.jface.examples.databinding.snippets;
14
15 import org.eclipse.core.databinding.DataBindingContext;
16 import org.eclipse.core.databinding.UpdateValueStrategy;
17 import org.eclipse.core.databinding.observable.ObservableTracker;
18 import org.eclipse.core.databinding.observable.Realm;
19 import org.eclipse.core.databinding.observable.value.ComputedValue;
20 import org.eclipse.core.databinding.observable.value.IObservableValue;
21 import org.eclipse.core.databinding.observable.value.WritableValue;
22 import org.eclipse.jface.databinding.swt.SWTObservables;
23 import org.eclipse.jface.layout.GridDataFactory;
24 import org.eclipse.jface.layout.GridLayoutFactory;
25 import org.eclipse.swt.SWT;
26 import org.eclipse.swt.layout.FillLayout;
27 import org.eclipse.swt.widgets.Composite;
28 import org.eclipse.swt.widgets.Display;
29 import org.eclipse.swt.widgets.Label;
30 import org.eclipse.swt.widgets.Shell;
31 import org.eclipse.swt.widgets.Text;
32
33 /**
34 * Snippet that demostrates a simple use case using ComputedValue to format a
35 * name as the user enters first and last name.
36 *
37 * @since 3.2
38 */
39 public class Snippet008ComputedValue {
40 /**
41 * @param args
42 */
43 public static void main(String[] args) {
44 final Display display = new Display();
45 Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable() {
46 public void run() {
47 Shell shell = new Shell(display);
48 shell.setLayout(new FillLayout());
49
50 final UI ui = new UI(shell);
51 final Data data = new Data();
52
53 // Bind the UI to the Data.
54 DataBindingContext dbc = new DataBindingContext();
55 dbc.bindValue(SWTObservables.observeText(ui.firstName,
56 SWT.Modify), data.firstName);
57 dbc.bindValue(SWTObservables.observeText(ui.lastName,
58 SWT.Modify), data.lastName);
59
60 // Construct the formatted name observable.
61 FormattedName formattedName = new FormattedName(data.firstName,
62 data.lastName);
63
64 // Bind the formatted name Text to the formatted name
65 // observable.
66 dbc.bindValue(SWTObservables.observeText(ui.formattedName,
67 SWT.None), formattedName, new UpdateValueStrategy(false, UpdateValueStrategy.POLICY_NEVER), null);
68
69 shell.pack();
70 shell.open();
71 while (!shell.isDisposed()) {
72 if (!display.readAndDispatch())
73 display.sleep();
74 }
75 }
76 });
77 display.dispose();
78 }
79
80 /**
81 * Creates the formatted name on change of the first or last name
82 * observables.
83 * <p>
84 * The key to understanding ComputedValue is understanding that it knows of
85 * the observables that are queried without being told. This is done with
86 * {@link ObservableTracker} voodoo. When calculate() is invoked
87 * <code>ObservableTracker</code> records the observables that are
88 * queried. It then exposes those observables and <code>ComputedValue</code>
89 * can listen to changes in those objects and react accordingly.
90 * </p>
91 *
92 * @since 3.2
93 */
94 static class FormattedName extends ComputedValue {
95 private IObservableValue firstName;
96
97 private IObservableValue lastName;
98
99 FormattedName(IObservableValue firstName, IObservableValue lastName) {
100 this.firstName = firstName;
101 this.lastName = lastName;
102 }
103
104 protected Object calculate() {
105 String lastName = (String) this.lastName.getValue();
106 String firstName = (String) this.firstName.getValue();
107 lastName = (lastName != null && lastName.length() > 0) ? lastName
108 : "[Last Name]";
109 firstName = (firstName != null && firstName.length() > 0) ? firstName
110 : "[First Name]";
111
112 StringBuffer buffer = new StringBuffer();
113 buffer.append(lastName).append(", ").append(firstName);
114
115 return buffer.toString();
116 }
117 }
118
119 static class Data {
120 final WritableValue firstName;
121
122 final WritableValue lastName;
123
124 Data() {
125 firstName = new WritableValue("", String.class);
126 lastName = new WritableValue("", String.class);
127 }
128 }
129
130 /**
131 * Composite that creates the UI.
132 *
133 * @since 3.2
134 */
135 static class UI extends Composite {
136 final Text firstName;
137
138 final Text lastName;
139
140 final Text formattedName;
141
142 UI(Composite parent) {
143 super(parent, SWT.NONE);
144
145 GridLayoutFactory.swtDefaults().numColumns(2).applyTo(this);
146
147 new Label(this, SWT.NONE).setText("First Name:");
148 new Label(this, SWT.NONE).setText("Last Name");
149
150 GridDataFactory gdf = GridDataFactory.swtDefaults().align(SWT.FILL,
151 SWT.FILL).grab(true, false);
152 firstName = new Text(this, SWT.BORDER);
153 gdf.applyTo(firstName);
154
155 lastName = new Text(this, SWT.BORDER);
156 gdf.applyTo(lastName);
157
158 gdf = GridDataFactory.swtDefaults().span(2, 1).grab(true, false)
159 .align(SWT.FILL, SWT.BEGINNING);
160 Label label = new Label(this, SWT.NONE);
161 label.setText("Formatted Name:");
162 gdf.applyTo(label);
163
164 formattedName = new Text(this, SWT.BORDER);
165 formattedName.setEditable(false);
166 gdf.applyTo(formattedName);
167 }
168 }
169 }