[272752] improve interaction with Java change events

1 files changed, 97 insertions, 1 deletions

diff --git a/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/JptUiPlugin.java b/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/JptUiPlugin.java
index ebbfc821be..e24a78f905 100644
--- a/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/JptUiPlugin.java
+++ b/jpa/plugins/org.eclipse.jpt.ui/src/org/eclipse/jpt/ui/JptUiPlugin.java
@@ -13,10 +13,17 @@ import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.jpt.core.JpaPlatform;
+import org.eclipse.jpt.core.internal.JpaModelManager;
 import org.eclipse.jpt.ui.internal.platform.JpaPlatformUiRegistry;
 import org.eclipse.jpt.ui.navigator.JpaNavigatorProvider;
+import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Event;
+import org.eclipse.swt.widgets.Listener;
 import org.eclipse.ui.plugin.AbstractUIPlugin;
+import org.osgi.framework.BundleContext;
 
 /**
  *
@@ -30,13 +37,18 @@ import org.eclipse.ui.plugin.AbstractUIPlugin;
 @SuppressWarnings("nls")
 public class JptUiPlugin extends AbstractUIPlugin
 {
+	private final Listener focusListener;
+
 	private static JptUiPlugin INSTANCE;
 
 	/**
 	 * The plug-in identifier of JPA UI support
 	 * (value <code>"org.eclipse.jpt.ui"</code>).
 	 */
-	public final static String PLUGIN_ID = "org.eclipse.jpt.ui";  //$NON-NLS-1$
+	public static final String PLUGIN_ID = "org.eclipse.jpt.ui";  //$NON-NLS-1$
+
+	private static final String FOCUS_DATA_KEY = PLUGIN_ID + ".focus";
+	private static final Object FOCUS_DATA = new Object();
 
 	/**
 	 * Returns the singleton JPT UI plug-in.
@@ -86,9 +98,68 @@ public class JptUiPlugin extends AbstractUIPlugin
 
 	public JptUiPlugin() {
 		super();
+		this.focusListener = this.buildFocusListener();
 		INSTANCE = this;
 	}
 
+	private Listener buildFocusListener() {
+		return new Listener() {
+			public void handleEvent(Event event) {
+				JptUiPlugin.this.focusIn((Control) event.widget);
+			}
+		};
+	}
+
+	/**
+	 * This method is called whenever a "focus in" event is generated.
+	 * If the control gaining focus is part of one of our composites (typically
+	 * a JPA Details View), we stop listening to Java change events
+	 * (and assume all changes to the Java model are generated by us).
+	 * If the control gaining focus is *not* part of one of our composites,
+	 * we start listening to the Java change events again.
+	 */
+	void focusIn(Control control) {
+		while (control != null) {
+			if (control.getData(FOCUS_DATA_KEY) == FOCUS_DATA) {
+				this.focusIn();
+				return;
+			}
+			control = control.getParent();
+		}
+		this.focusOut();
+	}
+
+	/**
+	 * This method is called whenever a Dali UI control that affects Java
+	 * source code gains the UI focus. When this happens we deactivate
+	 * the Dali Java change listener so we ignore any changes to the Java
+	 * source code that probably originated from Dali. This means we will miss
+	 * any changes to the Java source code that is caused by non-UI activity;
+	 * but, we hope, these changes are unrelated to JPA annotations etc.
+	 * @see #focusOut()
+	 */
+	private void focusIn() {
+		JpaModelManager.instance().setJavaElementChangeListenerIsActive(false);
+	}
+
+	/**
+	 * This method is called whenever a non-Dali UI control gains the UI focus.
+	 * When this happens we activate the Dali Java change listener so that we
+	 * begin to keep the Dali model synchronized with the Java source code.
+	 * @see #focusIn()
+	 */
+	private void focusOut() {
+		JpaModelManager.instance().setJavaElementChangeListenerIsActive(true);
+	}
+
+	/**
+	 * Tag the specified control so that whenever it (or any of its children,
+	 * grandchildren, etc.) has the focus, the Dali model ignores any Java
+	 * change events.
+	 */
+	public void controlAffectsJavaSource(Control control) {
+		control.setData(FOCUS_DATA_KEY, FOCUS_DATA);
+	}
 
 	/**
 	 * Return the JPA platform UI corresponding to the given JPA platform
@@ -102,4 +173,29 @@ public class JptUiPlugin extends AbstractUIPlugin
 		return platform == null ? null : platform.getNavigatorProvider();
 	}
 
+
+	// ********** plug-in implementation **********
+
+	/**
+	 * Register our SWT listener with the display so we receive notification
+	 * of every "focus in" event.
+	 */
+	@Override
+	public void start(BundleContext context) throws Exception {
+		super.start(context);
+		Display.getDefault().addFilter(SWT.FocusIn, this.focusListener);
+	}
+
+	/**
+	 * Unregister our SWT listener with the display.
+	 */
+	@Override
+	public void stop(BundleContext context) throws Exception {
+		try {
+			Display.getDefault().removeFilter(SWT.FocusIn, this.focusListener);
+		} finally {
+			super.stop(context);
+		}
+	}
+
 }