1 files changed, 118 insertions, 19 deletions

diff --git a/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/edit/parts/TimeElementEditPartHelper.java b/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/edit/parts/TimeElementEditPartHelper.java
index f950853d680..c427bbf30c0 100644
--- a/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/edit/parts/TimeElementEditPartHelper.java
+++ b/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/edit/parts/TimeElementEditPartHelper.java
@@ -15,29 +15,39 @@
 
 package org.eclipse.papyrus.uml.diagram.sequence.edit.parts;
 
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
 import java.util.Optional;
+import java.util.concurrent.Executor;
 import java.util.function.Supplier;
 
 import org.eclipse.draw2d.Connection;
 import org.eclipse.draw2d.ConnectionAnchor;
 import org.eclipse.draw2d.geometry.Dimension;
 import org.eclipse.draw2d.geometry.Point;
+import org.eclipse.draw2d.geometry.PointList;
 import org.eclipse.draw2d.geometry.Rectangle;
 import org.eclipse.gef.ConnectionEditPart;
-import org.eclipse.gef.EditPart;
+import org.eclipse.gef.Disposable;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.figures.IBorderItemLocator;
 import org.eclipse.gmf.runtime.notation.NotationPackage;
+import org.eclipse.papyrus.infra.core.utils.OneShotExecutor;
+import org.eclipse.papyrus.infra.gmfdiag.common.helper.DiagramHelper;
 import org.eclipse.papyrus.infra.gmfdiag.common.utils.DiagramEditPartsUtil;
+import org.eclipse.papyrus.infra.ui.util.TransactionUIHelper;
 import org.eclipse.uml2.uml.MessageEnd;
 
 /**
  * Common behaviour that time-element edit-parts can delegate.
  */
 class TimeElementEditPartHelper {
+	private static final MessageTracker NONE = new MessageTracker();
 
 	private final IGraphicalEditPart owner;
 	private final Supplier<? extends Optional<MessageEnd>> messageEndSupplier;
+	private final Executor executor;
+	private MessageTracker messageTracker = NONE;
 
 	/**
 	 * Initializes me with the edit-part that I help.
@@ -54,14 +64,16 @@ class TimeElementEditPartHelper {
 
 		this.owner = owner;
 		this.messageEndSupplier = messageEndSupplier;
+
+		// Don't post redundant refreshes
+		this.executor = new OneShotExecutor(TransactionUIHelper.getExecutor(owner.getEditingDomain()));
 	}
 
 	boolean refreshBounds(IBorderItemLocator locator) {
 		boolean result = false;
 
 		if (locator != null) {
-			Optional<Point> messageEndLoc = getMessageEnd().map(this::getLocation);
-
+			Optional<Point> messageEndLoc = Optional.ofNullable(getLocation());
 			if (messageEndLoc.isPresent()) {
 				// We are fixed by a message end, then
 				Dimension size = new Dimension(
@@ -76,6 +88,11 @@ class TimeElementEditPartHelper {
 		return result;
 	}
 
+	// Asynchronously post a refresh of my owner edit-part
+	private void postRefresh() {
+		executor.execute(() -> DiagramHelper.refresh(owner, true));
+	}
+
 	/**
 	 * Obtain the message end that is my observedor constrained event, if any.
 	 *
@@ -93,25 +110,107 @@ class TimeElementEditPartHelper {
 	 * @return the location of that end relative to my parent, or {@code null} if it cannot
 	 *         be determined
 	 */
-	Point getLocation(MessageEnd messageEnd) {
-		Point result = null;
-
-		if (messageEnd != null) {
-			EditPart messageEP = DiagramEditPartsUtil.getChildByEObject(messageEnd.getMessage(),
-					(IGraphicalEditPart) owner.getRoot().getContents(), true);
-			if (messageEP instanceof ConnectionEditPart) {
-				Connection connection = (Connection) ((ConnectionEditPart) messageEP).getFigure();
-				ConnectionAnchor anchor = messageEnd.isSend()
-						? connection.getSourceAnchor()
-						: connection.getTargetAnchor();
-				if (anchor != null) {
-					result = anchor.getReferencePoint().getCopy();
-					owner.getFigure().getParent().translateToRelative(result);
-				}
+	Point getLocation() {
+		return getMessage().getLocation();
+	}
+
+	private MessageTracker getMessage() {
+		if (!messageTracker.isValid()) {
+			messageTracker.dispose();
+
+			// Refresh our idea of what the message is
+			messageTracker = messageEndSupplier.get()
+					.map(end -> new MessageTracker(this, end))
+					.filter(MessageTracker::isValid)
+					.orElse(NONE);
+		}
+
+		return messageTracker;
+	}
+
+	//
+	// Nested types
+	//
+
+	/**
+	 * A helper for tracking the message, if any, the end of which is linked to a time
+	 * element to cause that time element to follow (track) the movement of the message
+	 * end.
+	 */
+	private static final class MessageTracker implements Supplier<ConnectionEditPart>, Disposable {
+		private final PropertyChangeListener connectionListener = this::connectionMoved;
+		private final TimeElementEditPartHelper owner;
+		private final ConnectionEditPart connectionEP;
+		private final Connection connection;
+		private final boolean source;
+		private final Point anchor = new Point();
+
+		MessageTracker() {
+			super();
+
+			this.owner = null;
+			connectionEP = null;
+			connection = null;
+			source = false;
+		}
+
+		MessageTracker(TimeElementEditPartHelper owner, MessageEnd end) {
+			super();
+
+			this.owner = owner;
+
+			IGraphicalEditPart ep = DiagramEditPartsUtil.getChildByEObject(end.getMessage(),
+					(IGraphicalEditPart) owner.owner.getRoot().getContents(), true);
+			if ((ep instanceof ConnectionEditPart) && ep.isActive()) {
+				connectionEP = (ConnectionEditPart) ep;
+				connection = (Connection) connectionEP.getFigure();
+				connection.addPropertyChangeListener(Connection.PROPERTY_POINTS, connectionListener);
+				source = end.isSend();
+				anchor.setLocation(source ? connection.getPoints().getFirstPoint() : connection.getPoints().getLastPoint());
+			} else {
+				connectionEP = null;
+				connection = null;
+				source = false;
 			}
 		}
 
-		return result;
+		@Override
+		public void dispose() {
+			if (connection != null) {
+				connection.removePropertyChangeListener(Connection.PROPERTY_POINTS, connectionListener);
+			}
+		}
+
+		@Override
+		public ConnectionEditPart get() {
+			return isValid() ? connectionEP : null;
+		}
+
+		public Point getLocation() {
+			Point result = null;
+
+			if (isValid()) {
+				// If we were ever valid, we have a connection
+				ConnectionAnchor anchor = source ? connection.getSourceAnchor() : connection.getTargetAnchor();
+				result = anchor.getReferencePoint().getCopy();
+				owner.owner.getFigure().getParent().translateToRelative(result);
+			}
+
+			return result;
+		}
+
+		boolean isValid() {
+			return (connectionEP != null) && connectionEP.isActive();
+		}
+
+		private void connectionMoved(PropertyChangeEvent event) {
+			PointList points = (PointList) event.getNewValue();
+			Point newAnchor = source ? points.getFirstPoint() : points.getLastPoint();
+			if (!anchor.equals(newAnchor)) {
+				anchor.setLocation(newAnchor);
+				owner.postRefresh();
+			}
+		}
 	}
 
 }