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.ISelection;
  import org.eclipse.jface.viewers.ISelectionProvider;
  import org.eclipse.swt.dnd.DND;
  import org.eclipse.swt.dnd.DragSourceAdapter;
  import org.eclipse.swt.dnd.DragSourceEvent;
  import org.eclipse.swt.dnd.Transfer;
  import org.eclipse.ui.views.navigator.LocalSelectionTransfer;
  
  public class BasicSelectionTransferDragAdapter extends DragSourceAdapter implements TransferDragSourceListener {
  	
  	private ISelectionProvider fProvider;
  	
  	public BasicSelectionTransferDragAdapter(ISelectionProvider provider) {
  		Assert.isNotNull(provider);
  		fProvider= provider;
  	}
  
  	/**
  	 * @see TransferDragSourceListener#getTransfer
  	 */
  	public Transfer getTransfer() {
  		return LocalSelectionTransfer.getInstance();
  	}
  	
  	/* non Java-doc
  	 * @see org.eclipse.swt.dnd.DragSourceListener#dragStart
  	 */
  	public void dragStart(DragSourceEvent event) {
  		ISelection selection= fProvider.getSelection();
  		LocalSelectionTransfer.getInstance().setSelection(selection);
  		LocalSelectionTransfer.getInstance().setSelectionSetTime(event.time & 0xFFFFFFFFL);
  		event.doit= isDragable(selection);
  	}
  	
  	/**
  	 * Checks if the elements contained in the given selection can
  	 * be dragged.
  	 * <p>
  	 * Subclasses may override.
  	 * 
  	 * @param selection containing the elements to be dragged
  	 */
  	protected boolean isDragable(ISelection selection) {
  		return true;
  	}
  
  
  	/* non Java-doc
  	 * @see org.eclipse.swt.dnd.DragSourceListener#dragSetData
  	 */		
  	public void dragSetData(DragSourceEvent event) {
  		// For consistency set the data to the selection even though
  		// the selection is provided by the LocalSelectionTransfer
  		// to the drop target adapter.
  		event.data= LocalSelectionTransfer.getInstance().getSelection();
  	}
  
  
  	/* non Java-doc
  	 * @see org.eclipse.swt.dnd.DragSourceListener#dragFinished
  	 */	
  	public void dragFinished(DragSourceEvent event) {
  		// Make sure we don't have to do any remaining work
  		Assert.isTrue(event.detail != DND.DROP_MOVE);
  		LocalSelectionTransfer.getInstance().setSelection(null);
  		LocalSelectionTransfer.getInstance().setSelectionSetTime(0);
  	}	
  }
  