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

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 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
  14 import org.eclipse.swt.dnd.DND;
  15 import org.eclipse.swt.dnd.DropTargetEvent;
  16 import org.eclipse.swt.dnd.TransferData;
  17 import org.eclipse.swt.graphics.Point;
  18 import org.eclipse.swt.graphics.Rectangle;
  19 import org.eclipse.swt.widgets.Item;
  20
  21 import org.eclipse.jface.viewers.ISelection;
  22 import org.eclipse.jface.viewers.StructuredViewer;
  23
  24 import org.eclipse.jdt.internal.ui.packageview.SelectionTransferDropAdapter;
  25
  26 public abstract class ViewerInputDropAdapter extends SelectionTransferDropAdapter {
  27
  28         private static final int ITEM_MARGIN_LEFT= 40;
  29         private static final int ITEM_MARGIN_RIGTH= 10;
  30         private static final int OPERATION= DND.DROP_LINK;
  31
  32         public ViewerInputDropAdapter(StructuredViewer viewer) {
  33                 super(viewer);
  34         }
  35
  36         protected abstract Object getInputElement(ISelection selection);
  37
  38         protected abstract void doInputView(Object inputElement);
  39
  40         /**
  41          * {@inheritDoc}
  42          */
  43         @Override
  44         protected int determineOperation(Object target, int operation, TransferData transferType, int operations) {
  45
  46                 setSelectionFeedbackEnabled(true);
  47                 setExpandEnabled(true);
  48
  49                 initializeSelection();
  50
  51                 if (target != null) {
  52                         return super.determineOperation(target, operation, transferType, operations);
  53                 } else if (getInputElement(getSelection()) != null) {
  54                         setSelectionFeedbackEnabled(false);
  55                         setExpandEnabled(false);
  56                         return OPERATION;
  57                 } else {
  58                         return DND.DROP_NONE;
  59                 }
  60         }
  61
  62         /**
  63          * {@inheritDoc}
  64          */
  65         @Override
  66         public boolean performDrop(Object data) {
  67                 setSelectionFeedbackEnabled(true);
  68                 setExpandEnabled(true);
  69
  70                 if (getCurrentTarget() != null || getCurrentOperation() != OPERATION) {
  71                         return super.performDrop(data);
  72                 }
  73
  74                 Object input= getInputElement(getSelection());
  75                 if (input != null) {
  76                         doInputView(input);
  77                         return true;
  78                 }
  79
  80                 return false;
  81         }
  82
  83         /**
  84          * {@inheritDoc}
  85          */
  86         @Override
  87         public boolean isEnabled(DropTargetEvent event) {
  88                 return true;
  89         }
  90
  91         /**
  92          * {@inheritDoc}
  93          */
  94         @Override
  95         protected Object determineTarget(DropTargetEvent event) {
  96                 if (event.item == null)
  97                         return super.determineTarget(event);
  98
  99                 Point coordinates= getViewer().getControl().toControl(new Point(event.x, event.y));
 100                 Rectangle bounds= getBounds((Item) event.item);
 101                 if (coordinates.x < bounds.x - ITEM_MARGIN_LEFT || coordinates.x >= bounds.x + bounds.width + ITEM_MARGIN_RIGTH) {
 102                         event.item= null; // too far away
 103                         return null;
 104                 }
 105
 106                 return super.determineTarget(event);
 107         }
 108
 109 }