org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/views/breakpoints/BreakpointsDragAdapter.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 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.debug.internal.ui.views.breakpoints;

import org.eclipse.jface.util.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 BreakpointsDragAdapter extends DragSourceAdapter implements TransferDragSourceListener {
    
    private ISelectionProvider fProvider;
    private BreakpointsView fView;
    private BreakpointContainer[] fContainers;
    
    public BreakpointsDragAdapter(BreakpointsView view, ISelectionProvider provider) {
        Assert.isNotNull(provider);
        fProvider= provider;
        fView = view;
    }

    /**
     * @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) {
        if (fView.canMove(selection)) {
            fContainers = fView.getMovedFromContainers(selection);
            return true;
        }
        return false;
    }


    /* 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) {
        if (event.detail == DND.DROP_MOVE) {
            // remove from source on move operation
            fView.performRemove(fContainers, LocalSelectionTransfer.getInstance().getSelection());
        }
        LocalSelectionTransfer.getInstance().setSelection(null);
        LocalSelectionTransfer.getInstance().setSelectionSetTime(0);
    }   
}