case-study/jdt-before/ui/org/eclipse/jdt/internal/ui/dnd/JdtViewerDragAdapter.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2011 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.jdt.internal.ui.dnd;
  12
  13 import org.eclipse.swt.dnd.DragSourceEvent;
  14
  15 import org.eclipse.core.runtime.Assert;
  16
  17 import org.eclipse.jface.util.DelegatingDragAdapter;
  18 import org.eclipse.jface.viewers.IStructuredSelection;
  19 import org.eclipse.jface.viewers.StructuredViewer;
  20
  21 public class JdtViewerDragAdapter extends DelegatingDragAdapter {
  22
  23         private StructuredViewer fViewer;
  24
  25         public JdtViewerDragAdapter(StructuredViewer viewer) {
  26                 super();
  27                 Assert.isNotNull(viewer);
  28                 fViewer= viewer;
  29         }
  30
  31         @Override
  32         public void dragStart(DragSourceEvent event) {
  33                 IStructuredSelection selection= (IStructuredSelection)fViewer.getSelection();
  34                 if (selection.isEmpty()) {
  35                         event.doit= false;
  36                         return;
  37                 }
  38                 super.dragStart(event);
  39         }
  40 }