| /******************************************************************************* |
| * Copyright (c) 2007, 2008 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 |
| * Matthew Hall - bug 212468 |
| *******************************************************************************/ |
| package org.eclipse.core.internal.databinding.observable; |
| |
| import org.eclipse.core.databinding.observable.ChangeEvent; |
| import org.eclipse.core.databinding.observable.Diffs; |
| import org.eclipse.core.databinding.observable.IChangeListener; |
| import org.eclipse.core.databinding.observable.IObservable; |
| import org.eclipse.core.databinding.observable.IStaleListener; |
| import org.eclipse.core.databinding.observable.StaleEvent; |
| import org.eclipse.core.databinding.observable.value.AbstractObservableValue; |
| |
| /** |
| * An observable value that tracks the staleness of an {@link IObservable}. |
| * |
| * @since 1.1 |
| */ |
| public class StalenessObservableValue extends AbstractObservableValue { |
| |
| private class MyListener implements IChangeListener, IStaleListener { |
| public void handleChange(ChangeEvent event) { |
| if (stale && !event.getObservable().isStale()) { |
| stale = false; |
| fireValueChange(Diffs.createValueDiff(Boolean.TRUE, |
| Boolean.FALSE)); |
| } |
| } |
| |
| public void handleStale(StaleEvent staleEvent) { |
| if (!stale) { |
| stale = true; |
| fireValueChange(Diffs.createValueDiff(Boolean.FALSE, |
| Boolean.TRUE)); |
| } |
| } |
| } |
| |
| private IObservable tracked; |
| private boolean stale; |
| private MyListener listener = new MyListener(); |
| |
| /** |
| * Constructs a StalenessObservableValue that tracks the staleness of the |
| * given {@link IObservable}. |
| * |
| * @param observable |
| * the observable to track |
| */ |
| public StalenessObservableValue(IObservable observable) { |
| super(observable.getRealm()); |
| this.tracked = observable; |
| this.stale = observable.isStale(); |
| tracked.addChangeListener(listener); |
| tracked.addStaleListener(listener); |
| } |
| |
| protected Object doGetValue() { |
| return tracked.isStale() ? Boolean.TRUE : Boolean.FALSE; |
| } |
| |
| public Object getValueType() { |
| return Boolean.TYPE; |
| } |
| |
| public synchronized void dispose() { |
| if (tracked != null) { |
| tracked.removeChangeListener(listener); |
| tracked.removeStaleListener(listener); |
| tracked = null; |
| listener = null; |
| } |
| super.dispose(); |
| } |
| |
| } |