ResourceTransferDragAdapter


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.search.internal.ui.text;
12  
13  import java.util.ArrayList  ;
14  import java.util.Collections  ;
15  import java.util.Iterator  ;
16  import java.util.List  ;
17  
18  import org.eclipse.core.runtime.Assert;
19  
20  import org.eclipse.core.resources.IResource;
21  
22  import org.eclipse.swt.dnd.DragSourceAdapter;
23  import org.eclipse.swt.dnd.DragSourceEvent;
24  import org.eclipse.swt.dnd.Transfer;
25  
26  import org.eclipse.jface.util.TransferDragSourceListener;
27  import org.eclipse.jface.viewers.ISelection;
28  import org.eclipse.jface.viewers.ISelectionProvider;
29  import org.eclipse.jface.viewers.IStructuredSelection;
30  
31  import org.eclipse.ui.part.ResourceTransfer;
32  
33  /**
34   * A drag adapter that transfers the current selection as </code>
35   * IResource</code>. Only those elements in the selection are part 
36   * of the transfer which can be converted into an <code>IResource
37   * </code>.
38   */
39  public class ResourceTransferDragAdapter extends DragSourceAdapter implements TransferDragSourceListener {
40  
41      private ISelectionProvider fProvider;
42  
43      /**
44       * Creates a new ResourceTransferDragAdapter for the given selection
45       * provider.
46       * 
47       * @param provider the selection provider to access the viewer's selection
48       */
49      public ResourceTransferDragAdapter(ISelectionProvider provider) {
50          fProvider= provider;
51          Assert.isNotNull(fProvider);
52      }
53      
54      public Transfer getTransfer() {
55          return ResourceTransfer.getInstance();
56      }
57      
58      public void dragStart(DragSourceEvent event) {
59          event.doit= convertSelection().size() > 0;
60      }
61      
62      public void dragSetData(DragSourceEvent event) {
63          List   resources= convertSelection();
64          event.data= resources.toArray(new IResource[resources.size()]);
65      }
66      
67      public void dragFinished(DragSourceEvent event) {
68          if (!event.doit)
69              return;
70      }
71      
72      private List   convertSelection() {
73          ISelection s= fProvider.getSelection();
74          if (!(s instanceof IStructuredSelection))
75              return Collections.EMPTY_LIST;
76          IStructuredSelection selection= (IStructuredSelection) s;
77          List   result= new ArrayList  (selection.size());
78          for (Iterator   iter= selection.iterator(); iter.hasNext();) {
79              Object   element= iter.next();
80              if (element instanceof IResource) {
81                  result.add(element);
82              }
83          }
84          return result;
85      }
86  }
87  
88
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