| /******************************************************************************* |
| * 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.ui.internal.listeners; |
| |
| import org.eclipse.jpt.utility.model.event.StateChangeEvent; |
| import org.eclipse.jpt.utility.model.listener.StateChangeListener; |
| import org.eclipse.swt.widgets.Display; |
| |
| /** |
| * Wrap another state 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. |
| */ |
| public class SWTStateChangeListenerWrapper |
| implements StateChangeListener |
| { |
| private final StateChangeListener listener; |
| |
| public SWTStateChangeListenerWrapper(StateChangeListener listener) { |
| super(); |
| if (listener == null) { |
| throw new NullPointerException(); |
| } |
| this.listener = listener; |
| } |
| |
| public void stateChanged(StateChangeEvent event) { |
| if (this.isExecutingOnUIThread()) { |
| this.stateChanged_(event); |
| } else { |
| this.executeOnUIThread(this.buildStateChangedRunnable(event)); |
| } |
| } |
| |
| private Runnable buildStateChangedRunnable(final StateChangeEvent event) { |
| return new Runnable() { |
| public void run() { |
| SWTStateChangeListenerWrapper.this.stateChanged_(event); |
| } |
| }; |
| } |
| |
| 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 stateChanged_(StateChangeEvent event) { |
| this.listener.stateChanged(event); |
| } |
| |
| @Override |
| public String toString() { |
| return "SWT(" + this.listener.toString() + ')'; //$NON-NLS-1$ |
| } |
| |
| } |