| /******************************************************************************* |
| * Copyright (c) 2007, 2009 Matthew Hall 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: |
| * Matthew Hall - initial API and implementation (bug 180746) |
| * Boris Bokowski, IBM - initial API and implementation |
| * Matthew Hall - bugs 212223, 208332, 245647 |
| * Will Horn - bug 215297 |
| ******************************************************************************/ |
| |
| package org.eclipse.core.internal.databinding.observable; |
| |
| import org.eclipse.core.databinding.observable.Diffs; |
| import org.eclipse.core.databinding.observable.IStaleListener; |
| import org.eclipse.core.databinding.observable.ObservableTracker; |
| import org.eclipse.core.databinding.observable.StaleEvent; |
| import org.eclipse.core.databinding.observable.value.AbstractObservableValue; |
| import org.eclipse.core.databinding.observable.value.IObservableValue; |
| import org.eclipse.core.databinding.observable.value.IValueChangeListener; |
| import org.eclipse.core.databinding.observable.value.IVetoableValue; |
| import org.eclipse.core.databinding.observable.value.ValueChangeEvent; |
| import org.eclipse.core.databinding.observable.value.ValueChangingEvent; |
| import org.eclipse.core.databinding.observable.value.ValueDiff; |
| |
| /** |
| * {@link IObservableValue} implementation that wraps an |
| * {@link IObservableValue} and delays notification of value change events from |
| * the wrapped observable value until a certain time has passed since the last |
| * change event. This class helps to boost performance in bindings (both in |
| * validation and in event firing) when the observed value is rapidly changing. |
| * A common use of this class is to delay validation until the user stops typing |
| * in an UI field. To notify about pending changes, a DelayedObservableValue |
| * fires a stale event when the wrapped observable value fires a change event, |
| * and remains stale as long as a value change is pending. |
| * |
| * Note that this class will not forward {@link ValueChangingEvent} events from |
| * a wrapped {@link IVetoableValue}. |
| * |
| * @since 1.2 |
| */ |
| public class DelayedObservableValue extends AbstractObservableValue implements |
| IStaleListener, IValueChangeListener { |
| class ValueUpdater implements Runnable { |
| private final Object oldValue; |
| |
| boolean cancel = false; |
| boolean running = false; |
| |
| ValueUpdater(Object oldValue) { |
| this.oldValue = oldValue; |
| } |
| |
| void cancel() { |
| cancel = true; |
| } |
| |
| public void run() { |
| if (!cancel) |
| try { |
| running = true; |
| internalFireValueChange(oldValue); |
| } finally { |
| running = false; |
| } |
| } |
| } |
| |
| private final int delay; |
| private IObservableValue observable; |
| |
| private boolean dirty = true; |
| private Object cachedValue = null; |
| |
| private boolean updating = false; |
| |
| private ValueUpdater updater = null; |
| |
| /** |
| * Constructs a new instance bound to the given |
| * <code>ISWTObservableValue</code> and configured to fire change events |
| * once there have been no value changes in the observable for |
| * <code>delay</code> milliseconds. |
| * |
| * @param delayMillis |
| * @param observable |
| * @throws IllegalArgumentException |
| * if <code>updateEventType</code> is an incorrect type. |
| */ |
| public DelayedObservableValue(int delayMillis, IObservableValue observable) { |
| super(observable.getRealm()); |
| this.delay = delayMillis; |
| this.observable = observable; |
| |
| observable.addValueChangeListener(this); |
| observable.addStaleListener(this); |
| |
| cachedValue = doGetValue(); |
| } |
| |
| public void handleValueChange(ValueChangeEvent event) { |
| if (!updating) |
| makeDirty(); |
| } |
| |
| public void handleStale(StaleEvent staleEvent) { |
| if (!updating) |
| fireStale(); |
| } |
| |
| protected Object doGetValue() { |
| if (dirty) { |
| cachedValue = observable.getValue(); |
| dirty = false; |
| |
| if (updater != null && !updater.running) { |
| fireValueChange(Diffs.createValueDiff(updater.oldValue, |
| cachedValue)); |
| cancelScheduledUpdate(); |
| } |
| } |
| return cachedValue; |
| } |
| |
| protected void doSetValue(Object value) { |
| updating = true; |
| try { |
| // Principle of least surprise: setValue overrides any pending |
| // update from observable. |
| dirty = false; |
| cancelScheduledUpdate(); |
| |
| Object oldValue = cachedValue; |
| observable.setValue(value); |
| // Bug 215297 - target observable could veto or override value |
| // passed to setValue(). Make sure we cache whatever is set. |
| cachedValue = observable.getValue(); |
| |
| if (!Util.equals(oldValue, cachedValue)) |
| fireValueChange(Diffs.createValueDiff(oldValue, cachedValue)); |
| } finally { |
| updating = false; |
| } |
| } |
| |
| public boolean isStale() { |
| ObservableTracker.getterCalled(this); |
| return (dirty && updater != null) || observable.isStale(); |
| } |
| |
| /** |
| * Returns the type of the value from {@link #doGetValue()}, i.e. |
| * String.class |
| * |
| * @see org.eclipse.core.databinding.observable.value.IObservableValue#getValueType() |
| */ |
| public Object getValueType() { |
| return observable.getValueType(); |
| } |
| |
| public synchronized void dispose() { |
| cancelScheduledUpdate(); |
| if (observable != null) { |
| observable.dispose(); |
| observable = null; |
| } |
| super.dispose(); |
| } |
| |
| private void makeDirty() { |
| if (!dirty) { |
| dirty = true; |
| fireStale(); |
| } |
| cancelScheduledUpdate(); // if any |
| scheduleUpdate(); |
| } |
| |
| private void cancelScheduledUpdate() { |
| if (updater != null) { |
| updater.cancel(); |
| updater = null; |
| } |
| } |
| |
| private void scheduleUpdate() { |
| updater = new ValueUpdater(cachedValue); |
| getRealm().timerExec(delay, updater); |
| } |
| |
| private void internalFireValueChange(final Object oldValue) { |
| cancelScheduledUpdate(); |
| fireValueChange(new ValueDiff() { |
| public Object getOldValue() { |
| return oldValue; |
| } |
| |
| public Object getNewValue() { |
| return getValue(); |
| } |
| }); |
| } |
| } |