1 files changed, 86 insertions, 0 deletions
diff --git a/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/model/listener/awt/AWTStateChangeListenerWrapper.java b/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/model/listener/awt/AWTStateChangeListenerWrapper.java
new file mode 100644
index 0000000000..c1ecf2b2ee
--- /dev/null
+++ b/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/model/listener/awt/AWTStateChangeListenerWrapper.java
@@ -0,0 +1,86 @@
+/*******************************************************************************
+ * 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.utility.internal.model.listener.awt;
+
+import java.awt.EventQueue;
+
+import org.eclipse.jpt.common.utility.model.event.StateChangeEvent;
+import org.eclipse.jpt.common.utility.model.listener.StateChangeListener;
+
+/**
+ * Wrap another state change listener and forward events to it on the AWT
+ * event queue, 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 final class AWTStateChangeListenerWrapper
+	implements StateChangeListener
+{
+	private final StateChangeListener listener;
+
+	public AWTStateChangeListenerWrapper(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.executeOnEventQueue(this.buildStateChangedRunnable(event));
+		}
+	}
+
+	private Runnable buildStateChangedRunnable(final StateChangeEvent event) {
+		return new Runnable() {
+			public void run() {
+				AWTStateChangeListenerWrapper.this.stateChanged_(event);
+			}
+			@Override
+			public String toString() {
+				return "state changed runnable"; //$NON-NLS-1$
+			}
+		};
+	}
+
+	private boolean isExecutingOnUIThread() {
+		return EventQueue.isDispatchThread();
+	}
+
+	/**
+	 * {@link EventQueue#invokeLater(Runnable)} seems to work OK;
+	 * but using {@link EventQueue#invokeAndWait(Runnable)} can sometimes make
+	 * things more predictable when debugging, at the risk of deadlocks.
+	 */
+	private void executeOnEventQueue(Runnable r) {
+		EventQueue.invokeLater(r);
+//		try {
+//			EventQueue.invokeAndWait(r);
+//		} catch (InterruptedException ex) {
+//			throw new RuntimeException(ex);
+//		} catch (java.lang.reflect.InvocationTargetException ex) {
+//			throw new RuntimeException(ex);
+//		}
+	}
+
+	void stateChanged_(StateChangeEvent event) {
+		this.listener.stateChanged(event);
+	}
+
+	@Override
+	public String toString() {
+		return "AWT(" + this.listener.toString() + ')'; //$NON-NLS-1$
+	}
+
+}