bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDragAdapter.java

/*******************************************************************************
 * Copyright (c) 2003, 2006 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.ui.navigator;

import java.util.LinkedHashSet;
import java.util.Set;

import org.eclipse.jface.util.LocalSelectionTransfer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.widgets.Control;
import org.eclipse.ui.internal.navigator.NavigatorPlugin;
import org.eclipse.ui.internal.navigator.dnd.NavigatorPluginDropAction;
import org.eclipse.ui.part.PluginTransfer;

/**
 * 
 * Provides an implementation of {@link DragSourceAdapter} which uses the
 * extensions provided by the associated {@link INavigatorContentService}.
 * 
 * <p>
 * Clients should not need to create an instance of this class unless they are
 * creating their own custom viewer. Otherwise, {@link CommonViewer} configures
 * its drag adapter automatically.
 * </p> 
 * 
 * @see INavigatorDnDService
 * @see CommonDragAdapterAssistant
 * @see CommonDropAdapter
 * @see CommonDropAdapterAssistant
 * @see CommonViewer
 * @since 3.2
 * 
 */
public final class CommonDragAdapter extends DragSourceAdapter {

	private static final boolean DEBUG = false;

	private final INavigatorContentService contentService;

	private final ISelectionProvider provider;

	/**
	 * Create a DragAdapter that drives the configuration of the drag data.
	 * 
	 * @param aContentService
	 *            The content service this Drag Adapter is associated with
	 * @param aProvider
	 *            The provider that can give the current selection from the
	 *            appropriate viewer.
	 */
	public CommonDragAdapter(INavigatorContentService aContentService,
			ISelectionProvider aProvider) {
		super();
		contentService = aContentService;
		provider = aProvider;
	}

	/**
	 * 
	 * @return An array of supported Drag Transfer types. The list contains [
	 *         {@link LocalSelectionTransfer#getTransfer()},
	 *         {@link PluginTransfer#getInstance()}] in addition to any
	 *         supported types contributed by the
	 *         {@link CommonDragAdapterAssistant assistants}.
	 * @see CommonDragAdapterAssistant
	 * @see LocalSelectionTransfer
	 * @see PluginTransfer
	 */
	public Transfer[] getSupportedDragTransfers() {
		CommonDragAdapterAssistant[] assistants = contentService
				.getDnDService().getCommonDragAssistants();

		Set supportedTypes = new LinkedHashSet();
		supportedTypes.add(PluginTransfer.getInstance());
		supportedTypes.add(LocalSelectionTransfer.getTransfer());
		Transfer[] transferTypes = null;
		for (int i = 0; i < assistants.length; i++) {
			transferTypes = assistants[i].getSupportedTransferTypes();
			for (int j = 0; j < transferTypes.length; j++) {
				if (transferTypes[j] != null) {
					supportedTypes.add(transferTypes[j]);
				}
			}
		}
		
		Transfer[] transfers = (Transfer[]) supportedTypes
				.toArray(new Transfer[supportedTypes.size()]);
		return transfers;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.swt.dnd.DragSourceAdapter#dragStart(org.eclipse.swt.dnd.DragSourceEvent)
	 */
	public void dragStart(DragSourceEvent event) {
		if (DEBUG) {
			System.out.println("CommonDragAdapter.dragStart (begin): " + event); //$NON-NLS-1$
		}
		try {
			// Workaround for 1GEUS9V
			DragSource dragSource = (DragSource) event.widget;
			Control control = dragSource.getControl();
			if (control == control.getDisplay().getFocusControl()) {
				ISelection selection = provider.getSelection();
				if (!selection.isEmpty()) {
					LocalSelectionTransfer.getTransfer()
							.setSelection(selection);
					event.doit = true;
				} else {
					event.doit = false;
				}
			} else {
				event.doit = false;
			}
		} catch (RuntimeException e) {
			NavigatorPlugin.logError(0, e.getMessage(), e);
		}

		if (DEBUG) {
			System.out
					.println("CommonDragAdapter.dragStart (end): doit=" + event.doit); //$NON-NLS-1$
	}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.swt.dnd.DragSourceAdapter#dragSetData(org.eclipse.swt.dnd.DragSourceEvent)
	 */
	public void dragSetData(DragSourceEvent event) {

		ISelection selection = LocalSelectionTransfer.getTransfer()
				.getSelection();

		if (DEBUG) {
			System.out
					.println("CommonDragAdapter.dragSetData (begin): event" + event + " selection=" + selection); //$NON-NLS-1$ //$NON-NLS-2$
		}

		if (LocalSelectionTransfer.getTransfer()
				.isSupportedType(event.dataType)) {
			event.data = selection;

			if (DEBUG) {
				System.out
						.println("CommonDragAdapter.dragSetData set LocalSelectionTransfer"); //$NON-NLS-1$
			}
		} else if (PluginTransfer.getInstance().isSupportedType(event.dataType)) {
			event.data = NavigatorPluginDropAction
					.createTransferData(contentService);
			if (DEBUG) {
				System.out
						.println("CommonDragAdapter.dragSetData set PluginTransfer"); //$NON-NLS-1$
			}
		} else if (selection instanceof IStructuredSelection) {
			if (DEBUG) {
				System.out
						.println("CommonDragAdapter.dragSetData looking for assistants"); //$NON-NLS-1$
			}

			INavigatorDnDService dndService = contentService.getDnDService();
			CommonDragAdapterAssistant[] assistants = dndService
					.getCommonDragAssistants();
			for (int i = 0; i < assistants.length; i++) {

				Transfer[] supportedTransferTypes = assistants[i]
						.getSupportedTransferTypes();
				for (int j = 0; j < supportedTransferTypes.length; j++) {
					if (supportedTransferTypes[j]
							.isSupportedType(event.dataType)) {
						try {
							if (DEBUG) {
								System.out
										.println("CommonDragAdapter.dragSetData set assistant transfer type"); //$NON-NLS-1$
							}
							if(assistants[i].setDragData(event,
									(IStructuredSelection) selection)) {
								return;
							}
						} catch (RuntimeException re) {
							NavigatorPlugin.logError(0, re.getMessage(), re);
						}
					}

				}
			}

		} else {
			event.doit = false;
		}

		if (DEBUG) {
			System.out.println("CommonDragAdapter.dragSetData (end): " + event); //$NON-NLS-1$
		}
	}
	 
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.swt.dnd.DragSourceAdapter#dragFinished(org.eclipse.swt.dnd.DragSourceEvent)
	 */
	public void dragFinished(DragSourceEvent event) {

		if (DEBUG) {
			System.out.println("CommonDragAdapter.dragFinished()."); //$NON-NLS-1$
		}

		LocalSelectionTransfer.getTransfer().setSelection(null);

		// TODO Handle clean up if drop target was outside of workbench
		// if (event.doit != false) {
		//			
		// }
	}

}