Ptidej-v5.2-master/POM Tests/data/ArgoUML_0.28/src/org/argouml/uml/diagram/DiagramUtils.java
// $Id: DiagramUtils.java 16125 2008-11-22 06:19:18Z tfmorris $
// Copyright (c) 2008 The Regents of the University of California. All
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// software and its documentation without fee, and without a written
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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;
    }
}
