[518439] Avoid ArithmeticException caused by a division by zero

Bug: 518439
Cherry-picked-from: 515553
Change-Id: I3bc37070e02658abdebd5acea58967e2b67b761b
Cherry-picks: I081c10def3fb5550ae8ca3b12682529eaf02aaba
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>

1 files changed, 6 insertions, 2 deletions

diff --git a/plugins/org.eclipse.sirius.diagram.ui/src-diag/org/eclipse/sirius/diagram/ui/internal/edit/parts/locator/EdgeLabelQuery.java b/plugins/org.eclipse.sirius.diagram.ui/src-diag/org/eclipse/sirius/diagram/ui/internal/edit/parts/locator/EdgeLabelQuery.java
index 3e0ee45f67..4e37efe7ff 100644
--- a/plugins/org.eclipse.sirius.diagram.ui/src-diag/org/eclipse/sirius/diagram/ui/internal/edit/parts/locator/EdgeLabelQuery.java
+++ b/plugins/org.eclipse.sirius.diagram.ui/src-diag/org/eclipse/sirius/diagram/ui/internal/edit/parts/locator/EdgeLabelQuery.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2015 THALES GLOBAL SERVICES.
+ * Copyright (c) 2015, 2017 THALES GLOBAL SERVICES and others
  * 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
@@ -411,7 +411,11 @@ public class EdgeLabelQuery {
             if (oldNearestSeg.isHorizontal() == newNearestSegment.isHorizontal()) {
                 Vector oldVector = new Vector(oldNearestSeg.getTerminus().x - oldNearestSeg.getOrigin().x, oldNearestSeg.getTerminus().y - oldNearestSeg.getOrigin().y);
                 Vector newVector = new Vector(newNearestSegment.getTerminus().x - newNearestSegment.getOrigin().x, newNearestSegment.getTerminus().y - newNearestSegment.getOrigin().y);
-                fromOldToNewCenterVector = applyOldRatioOnNewSegment(oldNearestSeg, oldNearestPoint, oldCenterLabel, newNearestSegment, oldVector.getAngle(newVector) == 180, false);
+                boolean oppositeDirection = false;
+                if (oldVector.getLength() != 0 && newVector.getLength() != 0) {
+                    oppositeDirection = oldVector.getAngle(newVector) == 180;
+                }
+                fromOldToNewCenterVector = applyOldRatioOnNewSegment(oldNearestSeg, oldNearestPoint, oldCenterLabel, newNearestSegment, oppositeDirection, false);
             }
         }
         return fromOldToNewCenterVector;