/*******************************************************************************
* Copyright (c) 2007 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Boris Bokowski, IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jface.internal.databinding.provisional.swt;
import org.eclipse.core.databinding.observable.ChangeEvent;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.IObservable;
import org.eclipse.core.databinding.observable.ObservableTracker;
import org.eclipse.core.databinding.observable.list.IListChangeListener;
import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.list.ListChangeEvent;
import org.eclipse.core.databinding.observable.list.ListDiffEntry;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Widget;
/**
* NON-API - This class can be used to update a composite with automatic dependency tracking.
* @since 1.1
*
*/
public abstract class CompositeUpdater {
private class UpdateRunnable implements Runnable, IChangeListener {
private Widget widget;
Object element;
private boolean dirty = true;
private IObservable[] dependencies = new IObservable[0];
UpdateRunnable(Widget widget, Object element) {
this.widget = widget;
this.element = element;
}
// Runnable implementation. This method runs at most once per repaint
// whenever the
// value gets marked as dirty.
public void run() {
if (theComposite != null && !theComposite.isDisposed()
&& widget != null && !widget.isDisposed()) {
updateIfNecessary();
}
}
private void updateIfNecessary() {
if (dirty) {
dependencies = ObservableTracker.runAndMonitor(new Runnable() {
public void run() {
updateWidget(widget, element);
}
}, this, null);
dirty = false;
}
}
// IChangeListener implementation (listening to any dependency)
public void handleChange(ChangeEvent event) {
// Whenever this updator becomes dirty, schedule the run() method
makeDirty();
}
protected final void makeDirty() {
if (!dirty) {
dirty = true;
stopListening();
if (!theComposite.isDisposed()) {
SWTUtil.runOnce(theComposite.getDisplay(), this);
}
}
}
private void stopListening() {
// Stop listening for dependency changes
for (int i = 0; i < dependencies.length; i++) {
IObservable observable = dependencies[i];
observable.removeChangeListener(this);
}
}
}
private class PrivateInterface implements DisposeListener,
IListChangeListener {
// DisposeListener implementation
public void widgetDisposed(DisposeEvent e) {
CompositeUpdater.this.dispose();
}
public void handleListChange(ListChangeEvent event) {
ListDiffEntry[] diffs = event.diff.getDifferences();
for (int i = 0; i < diffs.length; i++) {
ListDiffEntry listDiffEntry = diffs[i];
if (listDiffEntry.isAddition()) {
Widget newChild = createWidget(listDiffEntry.getPosition());
final UpdateRunnable updateRunnable = new UpdateRunnable(newChild, listDiffEntry
.getElement());
newChild.setData(updateRunnable);
updateRunnable.updateIfNecessary();
} else {
theComposite.getChildren()[listDiffEntry.getPosition()]
.dispose();
}
}
theComposite.layout();
}
}
private PrivateInterface privateInterface = new PrivateInterface();
private Composite theComposite;
private IObservableList model;
/**
* Creates an updater for the given control and list. For each element of
* the list, a child widget of the composite will be created using
* {@link #createWidget(int)}.
*
* @param toUpdate
* composite to update
* @param model
* an observable list to track
*/
public CompositeUpdater(Composite toUpdate, IObservableList model) {
this.theComposite = toUpdate;
this.model = model;
model.addListChangeListener(privateInterface);
theComposite.addDisposeListener(privateInterface);
}
/**
* This is called automatically when the control is disposed. It may also be
* called explicitly to remove this updator from the control. Subclasses
* will normally extend this method to detach any listeners they attached in
* their constructor.
*/
public void dispose() {
theComposite.removeDisposeListener(privateInterface);
model.removeListChangeListener(privateInterface);
}
/**
* Creates a new child widget for the target composite at the given index.
*
* <p>
* Subclasses should implement this method to provide the code that creates
* a child widget at a specific index. Note that
* {@link #updateWidget(Widget, Object)} will be called after this method
* returns. Only those properties of the widget that don't change over time
* should be set in this method.
* </p>
*
* @param index
* the at which to create the widget
* @return the widget
*/
protected abstract Widget createWidget(int index);
/**
* Updates the given widget based on the element found in the model list.
* This method will be invoked once after the widget is created, and once
* before any repaint during which the control is visible and dirty.
*
* <p>
* Subclasses should implement this method to provide any code that changes
* the appearance of the widget.
* </p>
*
* @param widget
* the widget to update
* @param element
* the element associated with the widget
*/
protected abstract void updateWidget(Widget widget, Object element);
}