| /******************************************************************************* |
| * Copyright (c) 2007, 2010 Oracle. 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: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.ui.internal.listeners; |
| |
| import org.eclipse.jpt.common.utility.model.event.PropertyChangeEvent; |
| import org.eclipse.jpt.common.utility.model.listener.PropertyChangeListener; |
| import org.eclipse.swt.widgets.Display; |
| |
| /** |
| * Wrap another property change listener and forward events to it on the SWT |
| * UI thread, asynchronously if necessary. If the event arrived on the UI |
| * thread that is probably because it was initiated by a UI widget; as a |
| * result, we want to loop back synchronously so the events can be |
| * short-circuited. (Typically, the adapter(s) between a <em>property</em> and |
| * its corresponding UI widget are read-write; as opposed to the adapter(s) |
| * between a <em>collection</em> (or <em>list</em>) and its UI widget, which |
| * is read-only.) |
| */ |
| public class SWTPropertyChangeListenerWrapper |
| implements PropertyChangeListener |
| { |
| private final PropertyChangeListener listener; |
| |
| public SWTPropertyChangeListenerWrapper(PropertyChangeListener listener) { |
| super(); |
| if (listener == null) { |
| throw new NullPointerException(); |
| } |
| this.listener = listener; |
| } |
| |
| public void propertyChanged(PropertyChangeEvent event) { |
| if (this.isExecutingOnUIThread()) { |
| this.propertyChanged_(event); |
| } else { |
| this.executeOnUIThread(this.buildPropertyChangedRunnable(event)); |
| } |
| } |
| |
| private Runnable buildPropertyChangedRunnable(final PropertyChangeEvent event) { |
| return new Runnable() { |
| public void run() { |
| SWTPropertyChangeListenerWrapper.this.propertyChanged_(event); |
| } |
| @Override |
| public String toString() { |
| return "property changed runnable"; //$NON-NLS-1$ |
| } |
| }; |
| } |
| |
| private boolean isExecutingOnUIThread() { |
| return Display.getCurrent() != null; |
| } |
| |
| /** |
| * {@link Display#asyncExec(Runnable)} seems to work OK; |
| * but using {@link Display#syncExec(Runnable)} can somtimes make things |
| * more predictable when debugging, at the risk of deadlocks. |
| */ |
| private void executeOnUIThread(Runnable r) { |
| Display.getDefault().asyncExec(r); |
| // Display.getDefault().syncExec(r); |
| } |
| |
| void propertyChanged_(PropertyChangeEvent event) { |
| this.listener.propertyChanged(event); |
| } |
| |
| @Override |
| public String toString() { |
| return "SWT(" + this.listener.toString() + ')'; //$NON-NLS-1$ |
| } |
| |
| } |