/**
  * {@inheritDoc}
  *
  * @see org.eclipse.jface.viewers.ColumnLabelProvider#getImage(java.lang.Object)
  */
 @Override
 public Image getImage(Object element) {
   Image result = null;
   if (columnIndex == 0 && diagramPart != null) {
     final DiagramEditPart diaEditPart = diagramPart.getDiagramEditPart();
     final Object obj = diaEditPart.getModel();
     if (obj instanceof View) {
       final EObject designerElement = ((View) obj).getElement();
       if (designerElement instanceof DDiagram) {
         final List<Layer> activatedLayers = ((DDiagram) designerElement).getActivatedLayers();
         Image img = null;
         if (EqualityHelper.contains(activatedLayers, (EObject) element)) {
           img = DiagramUIPlugin.getPlugin().getBundledImage(DiagramImagesPath.ACTIVE_LAYER_ICON);
         } else {
           img =
               DiagramUIPlugin.getPlugin().getBundledImage(DiagramImagesPath.INACTIVE_LAYER_ICON);
         }
         result = img;
       }
     }
   } else if (columnIndex == 1) {
     if (element instanceof Layer) {
       Layer layer = (Layer) element;
       if (!StringUtil.isEmpty(layer.getIcon())) {
         result = ImageProvider.getImageFromPath(layer.getIcon());
       }
     }
   }
   return result;
 }
  private void computeMappings(final DDiagram diagram, final Layer layer) {
    final DiagramMappingsManager manager = diagramMappingsManagers.get(diagram);
    if (manager != null) {

      boolean needToRecomputeDescMappings = false;
      if (layer != null && layer.eContainer() instanceof DiagramExtensionDescription) {
        needToRecomputeDescMappings = true;
      }
      Session sess = SessionManager.INSTANCE.getSession(((DSemanticDiagram) diagram).getTarget());
      if (sess != null) {
        manager.computeMappings(sess.getSelectedViewpoints(false), needToRecomputeDescMappings);
      } else {
        manager.computeMappings(null, needToRecomputeDescMappings);
      }
    }
  }