/* $Id: DiagramUtils.java 17850 2010-01-12 19:53:35Z linus $

  *****************************************************************************

  * Copyright (c) 2009 Contributors - see below

  * 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:

  *    tfmorris

  *****************************************************************************

  *

  * Some portions of this file was previously release using the BSD License:

  */

 // Copyright (c) 2008 The Regents of the University of California. All

 // Rights Reserved. Permission to use, copy, modify, and distribute this

 // software and its documentation without fee, and without a written

 // agreement is hereby granted, provided that the above copyright notice

 // and this paragraph appear in all copies. This software program and

 // documentation are copyrighted by The Regents of the University of

 // California. The software program and documentation are supplied "AS

 // IS", without any accompanying services from The Regents. The Regents

 // does not warrant that the operation of the program will be

 // uninterrupted or error-free. The end-user understands that the program

 // was developed for research purposes and is advised not to rely

 // exclusively on the program for any reason. IN NO EVENT SHALL THE

 // UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,

 // SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,

 // ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF

 // THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF

 // SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY

 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE

 // PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF

 // CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,

 // UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 package org.argouml.uml.diagram;

 import org.apache.log4j.Logger;

 import org.tigris.gef.base.Editor;

 import org.tigris.gef.base.Globals;

 import org.tigris.gef.base.Layer;

 import org.tigris.gef.base.LayerManager;

 import org.tigris.gef.base.LayerPerspective;

 /**

  * A utility class for diagrams (ArgoDiagrams).  It provides convenience 

  * methods which encapsulate and isolate access to GEF.

  * 

  * @author Tom Morris <tfmorris@gmail.com>

  */

 public class DiagramUtils {

     private static final Logger LOG = Logger.getLogger(DiagramUtils.class);

     /**

      * Instantiation not allowed.  Static methods only.

      */

     private DiagramUtils() {

         // not allowed

     }

     /**

      * @return the diagram containing the mouse (or which most recently

      *         contained the mouse).

      */

     public static ArgoDiagram getActiveDiagram() {

         LayerPerspective layer = getActiveLayer();

         if (layer != null) {

             return (ArgoDiagram) layer.getDiagram();

         }

         LOG.debug("No active diagram");

         return null;

     }

     /**

      * @return the active diagram layer. If the currently active layer is not a

      *         LayerPerspective, it can't be associated with a Diagram, so

      *         return null.

      */

     private static LayerPerspective getActiveLayer() {

         Editor editor = Globals.curEditor();

         if (editor != null) {

             LayerManager manager = editor.getLayerManager();

             if (manager != null) {

                 Layer layer = manager.getActiveLayer();

                 if (layer instanceof LayerPerspective) {

                     return (LayerPerspective) layer;

                 }

             }

         }

         return null;

     }

 }