content: /*******************************************************************************
   * Copyright (c) 2000, 2007 IBM Corporation 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
   * http://www.eclipse.org/legal/epl-v10.html
   *
   * Contributors:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.internal.ui.dnd;
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.jface.util.TransferDragSourceListener;
  import org.eclipse.jface.viewers.IStructuredSelection;
  import org.eclipse.jface.viewers.StructuredViewer;
  import org.eclipse.swt.dnd.DragSourceEvent;
  
  public class JdtViewerDragAdapter extends DelegatingDragAdapter {
  
  	private StructuredViewer fViewer;
  
  	public JdtViewerDragAdapter(StructuredViewer viewer, TransferDragSourceListener[] listeners) {
  		super(listeners);
  		Assert.isNotNull(viewer);
  		fViewer= viewer;
  	}
  	
  	public void dragStart(DragSourceEvent event) {
  		IStructuredSelection selection= (IStructuredSelection)fViewer.getSelection();
  		if (selection.isEmpty()) {
  			event.doit= false;
  			return; 
  		}
  		super.dragStart(event);
  	}
  }
  