org.eclipse.gmf.runtime.common.ui.services.dnd/src/org/eclipse/gmf/runtime/common/ui/services/dnd/drag/DelegatingDragSourceAdapter.java - gmf-runtime/org.eclipse.gmf-runtime - Git at Google

 /******************************************************************************
  * Copyright (c) 2002, 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.gmf.runtime.common.ui.services.dnd.drag;

 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.Hashtable;
 import java.util.Iterator;

 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.dialogs.ErrorDialog;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.swt.dnd.DragSource;
 import org.eclipse.swt.dnd.DragSourceEvent;
 import org.eclipse.swt.dnd.DragSourceListener;
 import org.eclipse.swt.dnd.Transfer;
 import org.eclipse.swt.dnd.TransferData;

 import org.eclipse.gmf.runtime.common.core.util.Log;
 import org.eclipse.gmf.runtime.common.core.util.Trace;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.core.DragDropListenerService;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.core.IListenerContext;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.core.TransferAdapterService;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDDebugOptions;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDPlugin;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDStatusCodes;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.core.DragListenerContext;
 import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.l10n.CommonUIServicesDNDMessages;

 /**
  * This class delegates all the drag source events to the transfer drag source
  * adapters. The transfer adapters delegate to the registered listeners
  *
  * @author Vishy Ramaswamy
  */
 public final class DelegatingDragSourceAdapter
 	implements DragSourceListener {

 	/**
 	 * Attribute for the all transfer drag source adapters mapped to their
 	 * transfer id.
 	 */
 	private final Hashtable allAdapters;

 	/**
 	 * Attribute for the current transfer drag source adapters.
 	 */
 	private ITransferDragSourceListener[] currentAdapters = null;

 	/**
 	 * Attribute for the chosen transfer drag source adapter.
 	 */
 	private ITransferDragSourceListener chosenAdapter = null;

 	/**
 	 * Attribute for the drag source context.
 	 */
 	private final DragSourceContext context;

 	/**
 	 * Constructor for DelegatingDragSourceAdapter.
 	 *
 	 * @param aContext
 	 *            the drag source context
 	 */
 	public DelegatingDragSourceAdapter(DragSourceContext aContext) {
 		super();

 		assert null != aContext : "aContext cannot be null"; //$NON-NLS-1$
 		this.context = aContext;

 		/* Set the adapters */
 		allAdapters = getAllTransferAdapters();
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.swt.dnd.DragSourceListener#dragStart(org.eclipse.swt.dnd.DragSourceEvent)
 	 */
 	public void dragStart(DragSourceEvent event) {
 		try {
 			if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
 				CommonUIServicesDNDDebugOptions.DND)) {
 				Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
 					CommonUIServicesDNDDebugOptions.DND, "dragStart entered"); //$NON-NLS-1$
 			}

 			/* Save the provided event information */
 			boolean saveDoit = event.doit;
 			Object saveData = event.data;

 			/* Clear the previous collection of adapters */
 			setCurrentAdapters(null);

 			/* Clear the previous chosen adapter */
 			setChosenAdapter(null);

 			/* Set the adapters */
 			setCurrentAdapters(getAdapters(getListeners()));

 			/* Iterate through the adapters */
 			boolean doIt = false;
 			ArrayList listOfActiveAdapters = new ArrayList();
 			ArrayList listOfActiveTransferAgents = new ArrayList();
 			if (getCurrentAdapters() != null && getCurrentAdapters().length > 0) {
 				for (int i = 0; i < getCurrentAdapters().length; i++) {
 					/* Set the do it flag */
 					event.doit = saveDoit;

 					/* Invoke the drag start */
 					getCurrentAdapters()[i].dragStart(event);

 					/* If ok to drag add the transfer to the list */
 					if (event.doit) {
 						listOfActiveAdapters.add(getCurrentAdapters()[i]);
 						listOfActiveTransferAgents.add(getCurrentAdapters()[i]
 							.getTransferAgent().getTransfer());
 					}

 					/* Ok to drag if anyone is ready to handle */
 					doIt = doIt || event.doit;
 				}

 				/* Set the transfers and the updated adapters */
 				if (doIt) {
 					/* Set the transfers */
 					((DragSource) event.widget)
 						.setTransfer((Transfer[]) listOfActiveTransferAgents
 							.toArray(new Transfer[listOfActiveTransferAgents
 								.size()]));

 					/* Set the adapters */
 					setCurrentAdapters((org.eclipse.gmf.runtime.common.ui.services.dnd.drag.ITransferDragSourceListener[]) listOfActiveAdapters
 						.toArray(new ITransferDragSourceListener[listOfActiveAdapters
 							.size()]));
 				}

 				if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
 					CommonUIServicesDNDDebugOptions.DND)) {
 					String result = doIt ? "true" : "false"; //$NON-NLS-1$ //$NON-NLS-2$
 					Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
 						CommonUIServicesDNDDebugOptions.DND,
 						"DragStart::Event do it flag is " + result); //$NON-NLS-1$

 					/* Write the transfer adapters */
 					for (int i = 0; i < getCurrentAdapters().length; i++) {
 						Trace
 							.trace(
 								CommonUIServicesDNDPlugin.getDefault(),
 								CommonUIServicesDNDDebugOptions.DND,
 								"DragStart::Transfer Adapter is " + getCurrentAdapters()[i].getClass().getName()); //$NON-NLS-1$
 					}
 				}

 				/* Set the event information */
 				event.data = saveData;
 				event.doit = doIt;
 			} else {
 				/* Delegate to the drag source */
 				getContext().dragStart(event);
 			}
 		} catch (Throwable e) {
 			event.doit = false;
 			handle(e, false);
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.swt.dnd.DragSourceListener#dragSetData(org.eclipse.swt.dnd.DragSourceEvent)
 	 */
 	public void dragSetData(DragSourceEvent event) {
 		try {
 			/* Get the corresponding chosen adapter */
 			setChosenAdapter(getAdapter(event.dataType));

 			if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
 				CommonUIServicesDNDDebugOptions.DND)) {
 				String adapterChosen = getChosenAdapter() != null ? getChosenAdapter()
 					.getClass().getName()
 					: "No Adapter Chosen"; //$NON-NLS-1$
 				Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
 					CommonUIServicesDNDDebugOptions.DND,
 					"DragSetData::Chosen Adapter is " + adapterChosen); //$NON-NLS-1$
 			}

 			if (getChosenAdapter() != null) {
 				getChosenAdapter().dragSetData(event);
 			} else {
 				/* Delegate to the drag source */
 				getContext().dragSetData(event);
 			}
 		} catch (Throwable e) {
 			event.data = null;
 			handle(e, false);
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.swt.dnd.DragSourceListener#dragFinished(org.eclipse.swt.dnd.DragSourceEvent)
 	 */
 	public void dragFinished(DragSourceEvent event) {
 		try {
 			if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
 				CommonUIServicesDNDDebugOptions.DND)) {
 				String adapterChosen = getChosenAdapter() != null ? getChosenAdapter()
 					.getClass().getName()
 					: "No Adapter Chosen"; //$NON-NLS-1$
 				Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
 					CommonUIServicesDNDDebugOptions.DND,
 					"DragFinished::Chosen Adapter is " + adapterChosen); //$NON-NLS-1$
 			}

 			/* Get the corresponding chosen adapter */
 			if (getChosenAdapter() != null) {
 				getChosenAdapter().dragFinished(event);
 			} else {
 				setChosenAdapter(getAdapter(event.dataType));
 				if (getChosenAdapter() != null) {
 					getChosenAdapter().dragFinished(event);
 				} else {
 					/* Delegate to the drag source */
 					getContext().dragFinished(event);
 				}
 			}
 		} catch (Throwable e) {
 			handle(e, false);
 		} finally {
 			setChosenAdapter(null);
 			setCurrentAdapters(null);
 		}
 	}

 	/**
 	 * Returns the current adapters.
 	 *
 	 * @return ITransferDragSourceListener[]
 	 */
 	private ITransferDragSourceListener[] getCurrentAdapters() {
 		return currentAdapters;
 	}

 	/**
 	 * Returns the drag source context.
 	 *
 	 * @return DragSourceContext
 	 */
 	private DragSourceContext getContext() {
 		return context;
 	}

 	/**
 	 * Returns the set of registered listeners. The listeners are acquired
 	 * through the <code>DragDropListenerService</code>.
 	 *
 	 * @return IDragSourceListener[] an array of listeners
 	 */
 	private IDragSourceListener[] getListeners() {
 		/* Get the structured selection */
 		ISelection selection = getContext().getSelection();

 		/* Check the selection */
 		if (selection == null || selection.isEmpty()
 			|| !(selection instanceof IStructuredSelection)) {
 			return null;
 		}

 		/* Get the selection as an object array */
 		Object[] array = ((IStructuredSelection) selection).toArray();

 		/* Create a unique list of element types */
 		ArrayList listOfElementTypes = new ArrayList();
 		for (int i = 0; i < array.length; i++) {
 			if (!listOfElementTypes.contains(array[i].getClass())) {
 				listOfElementTypes.add(array[i].getClass());
 			}
 		}

 		/* Get the drag source listeners */
 		ArrayList listOfListeners = new ArrayList();
 		Iterator iterator = listOfElementTypes.iterator();
 		while (iterator.hasNext()) {
 			/* Get the element type */
 			Class clazz = (Class) iterator.next();

 			/* Create a drag listener context */
 			DragListenerContext aContext = new DragListenerContext(getContext()
 				.getActivePart(), clazz, IListenerContext.ALL_TRANSFERS, false);

 			/* Get the drag source listeners */
 			IDragSourceListener[] listeners = DragDropListenerService
 				.getInstance().getDragSourceListeners(aContext);

 			/* Get a compatible one if no listener is found for a direct match */
 			if (listeners == null || listeners.length == 0) {
 				/* Create a drag listener context */
 				aContext = new DragListenerContext(
 					getContext().getActivePart(), clazz,
 					IListenerContext.ALL_TRANSFERS, true);

 				/* Get the drag source listener */
 				listeners = DragDropListenerService.getInstance()
 					.getDragSourceListeners(aContext);
 			}

 			/* Add to the list */
 			if (listeners != null && listeners.length != 0) {
 				for (int i = 0; i < listeners.length; i++) {
 					if (!listOfListeners.contains(listeners[i])) {
 						listOfListeners.add(listeners[i]);
 					}
 				}
 			}
 		}

 		/* Combine all the listeners into one array */
 		return !listOfListeners.isEmpty() ? (IDragSourceListener[]) listOfListeners
 			.toArray(new IDragSourceListener[listOfListeners.size()])
 			: null;
 	}

 	/**
 	 * Returns the set of transfer drag source adapters. The adapters are
 	 * created based on the transfers supported by the listeners
 	 *
 	 * @param listeners
 	 *            The registered list of <code>IDragSourceListener</code>
 	 * @return ITransferDragSourceListener[] an array of transfer adapters
 	 */
 	private ITransferDragSourceListener[] getAdapters(
 			IDragSourceListener[] listeners) {
 		/* Return if no listeners or no selection */
 		if (listeners == null || listeners.length == 0) {
 			return null;
 		}

 		/* Create placeholder for active listeners */
 		Hashtable listOfUniqueTransferIds = new Hashtable();

 		/* Check if the listeners can handle the drag */
 		for (int i = 0; i < listeners.length; i++) {
 			/* Check if the selection is draggable */
 			if (!listeners[i].isDraggable(getContext())) {
 				continue;
 			}

 			/* Get the transfer ids */
 			String[] transferIds = listeners[i].getSupportingTransferIds();
 			if (transferIds == null || transferIds.length == 0) {
 				continue;
 			}

 			/* Iterate through the ids */
 			for (int y = 0; y < transferIds.length; y++) {
 				/* Placeholder for listeners */
 				ArrayList listOfListeners = null;

 				if (!listOfUniqueTransferIds.containsKey(transferIds[y])) {
 					/* Create a new list */
 					listOfListeners = new ArrayList();
 				} else {
 					/* Get the list of listeners and add to it */
 					listOfListeners = (ArrayList) listOfUniqueTransferIds
 						.get(transferIds[y]);
 				}

 				/* Update the list */
 				if (listOfListeners != null) {
 					listOfListeners.add(listeners[i]);
 					listOfUniqueTransferIds
 						.put(transferIds[y], listOfListeners);
 				}
 			}
 		}

 		/* Return if no active transfer agents */
 		if (listOfUniqueTransferIds.isEmpty()) {
 			return null;
 		}

 		/* Get the adapters */
 		ArrayList listOfAdapters = new ArrayList();
 		Enumeration enumeration = listOfUniqueTransferIds.keys();
 		while (enumeration.hasMoreElements()) {
 			/* Get the next id */
 			String transferId = (String) enumeration.nextElement();

 			/* Get the listeners */
 			ArrayList supportingListeners = (ArrayList) listOfUniqueTransferIds
 				.get(transferId);

 			/* Get the adapter */
 			ITransferDragSourceListener adapter = (ITransferDragSourceListener) getAllAdapters()
 				.get(Integer.valueOf(transferId.hashCode()));
 			if (adapter != null) {
 				/* Initialize the adapter */
 				adapter.init(
 					(IDragSourceListener[]) supportingListeners
 						.toArray(new IDragSourceListener[supportingListeners
 							.size()]), getContext());

 				/* Add to the list */
 				listOfAdapters.add(adapter);
 			}
 		}

 		/* Return the list of adapters */
 		return !listOfAdapters.isEmpty() ? (ITransferDragSourceListener[]) listOfAdapters
 			.toArray(new ITransferDragSourceListener[listOfAdapters.size()])
 			: null;
 	}

 	/**
 	 * Sets the current adapters.
 	 *
 	 * @param currentAdapterArray
 	 *            The adapters to set
 	 */
 	private void setCurrentAdapters(
 			ITransferDragSourceListener[] currentAdapterArray) {
 		this.currentAdapters = currentAdapterArray;
 	}

 	/**
 	 * Returns the chosen adapter
 	 *
 	 * @param type
 	 *            The transfer data type
 	 * @return The transfer drag source adapter chosen
 	 */
 	private ITransferDragSourceListener getAdapter(TransferData type) {
 		if (type != null) {
 			for (int i = 0; i < getCurrentAdapters().length; i++) {
 				if (getCurrentAdapters()[i].getTransferAgent().getTransfer()
 					.isSupportedType(type)) {
 					return getCurrentAdapters()[i];
 				}
 			}
 		}

 		return null;
 	}

 	/**
 	 * Returns the chosenAdapter.
 	 *
 	 * @return ITransferDragSourceListener
 	 */
 	private ITransferDragSourceListener getChosenAdapter() {
 		return chosenAdapter;
 	}

 	/**
 	 * Sets the chosenAdapter.
 	 *
 	 * @param aChosenAdapter
 	 *            The chosenAdapter to set
 	 */
 	private void setChosenAdapter(ITransferDragSourceListener aChosenAdapter) {
 		this.chosenAdapter = aChosenAdapter;
 	}

 	/**
 	 * Returns the set of transfer drag source adapters. The adapters are
 	 * created based on the provided transfer ids determined from the drag and
 	 * drop service.
 	 *
 	 * @return Hashtable a table of transfer adapters
 	 */
 	private Hashtable getAllTransferAdapters() {
 		/* Create placeholder for possible adapters */
 		Hashtable listOfSupportedAdapters = new Hashtable();

 		/* Get the ids from the drag and drop service */
 		String[] transferIds = DragDropListenerService.getInstance()
 			.getAllTransferIds(getContext().getActivePart().getSite().getId(),
 				IListenerContext.DRAG);

 		/* Iterate through the ids */
 		if (transferIds == null || transferIds.length == 0) {
 			return null;
 		}

 		/* Create the adapters */
 		for (int i = 0; i < transferIds.length; i++) {
 			ITransferDragSourceListener adapter = TransferAdapterService
 				.getInstance().getTransferDragSourceAdapter(transferIds[i]);

 			if (adapter != null) {
 				listOfSupportedAdapters.put(Integer.valueOf(transferIds[i]
 					.hashCode()), adapter);
 			}
 		}

 		/* Return the adapters */
 		return listOfSupportedAdapters;
 	}

 	/**
 	 * Handles the specified exception.
 	 *
 	 * @param exception
 	 *            The exception to be handled.
 	 * @param displayDialog
 	 *            boolean to indicate whether to display dialog
 	 */
 	private void handle(Throwable exception, boolean displayDialog) {
 		if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
 			CommonUIServicesDNDDebugOptions.EXCEPTIONS_CATCHING)) {
 			Trace.catching(CommonUIServicesDNDPlugin.getDefault(),
 				CommonUIServicesDNDDebugOptions.EXCEPTIONS_CATCHING,
 				getClass(), "handle", exception); //$NON-NLS-1$
 		}

 		IStatus status = new Status(IStatus.ERROR, CommonUIServicesDNDPlugin
 			.getPluginId(), CommonUIServicesDNDStatusCodes.DRAG_ACTION_FAILURE,
 			CommonUIServicesDNDMessages.DelegatingDragSourceAdapter__ERROR__errorMessage, exception);

 		Log.log(CommonUIServicesDNDPlugin.getDefault(), status);

 		if (displayDialog) {

 			status = new Status(IStatus.ERROR, CommonUIServicesDNDPlugin
 				.getPluginId(),
 				CommonUIServicesDNDStatusCodes.DRAG_ACTION_FAILURE,
 				CommonUIServicesDNDMessages.DelegatingDragSourceAdapter__ERROR__errorMessage,
 				exception);

 			ErrorDialog.openError(getContext().getActivePart().getSite()
 				.getShell(), null, null, status);
 		}
 	}

 	/**
 	 * Returns the adapters.
 	 *
 	 * @return Hashtable
 	 */
 	private Hashtable getAllAdapters() {
 		return allAdapters;
 	}
 }
	/******************************************************************************
	* Copyright (c) 2002, 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.gmf.runtime.common.ui.services.dnd.drag;

	import java.util.ArrayList;
	import java.util.Enumeration;
	import java.util.Hashtable;
	import java.util.Iterator;

	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.jface.dialogs.ErrorDialog;
	import org.eclipse.jface.viewers.ISelection;
	import org.eclipse.jface.viewers.IStructuredSelection;
	import org.eclipse.swt.dnd.DragSource;
	import org.eclipse.swt.dnd.DragSourceEvent;
	import org.eclipse.swt.dnd.DragSourceListener;
	import org.eclipse.swt.dnd.Transfer;
	import org.eclipse.swt.dnd.TransferData;

	import org.eclipse.gmf.runtime.common.core.util.Log;
	import org.eclipse.gmf.runtime.common.core.util.Trace;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.core.DragDropListenerService;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.core.IListenerContext;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.core.TransferAdapterService;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDDebugOptions;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDPlugin;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.CommonUIServicesDNDStatusCodes;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.core.DragListenerContext;
	import org.eclipse.gmf.runtime.common.ui.services.dnd.internal.l10n.CommonUIServicesDNDMessages;

	/**
	* This class delegates all the drag source events to the transfer drag source
	* adapters. The transfer adapters delegate to the registered listeners
	*
	* @author Vishy Ramaswamy
	*/
	public final class DelegatingDragSourceAdapter
	implements DragSourceListener {

	/**
	* Attribute for the all transfer drag source adapters mapped to their
	* transfer id.
	*/
	private final Hashtable allAdapters;

	/**
	* Attribute for the current transfer drag source adapters.
	*/
	private ITransferDragSourceListener[] currentAdapters = null;

	/**
	* Attribute for the chosen transfer drag source adapter.
	*/
	private ITransferDragSourceListener chosenAdapter = null;

	/**
	* Attribute for the drag source context.
	*/
	private final DragSourceContext context;

	/**
	* Constructor for DelegatingDragSourceAdapter.
	*
	* @param aContext
	* the drag source context
	*/
	public DelegatingDragSourceAdapter(DragSourceContext aContext) {
	super();

	assert null != aContext : "aContext cannot be null"; //$NON-NLS-1$
	this.context = aContext;

	/* Set the adapters */
	allAdapters = getAllTransferAdapters();
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.swt.dnd.DragSourceListener#dragStart(org.eclipse.swt.dnd.DragSourceEvent)
	*/
	public void dragStart(DragSourceEvent event) {
	try {
	if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND)) {
	Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND, "dragStart entered"); //$NON-NLS-1$
	}

	/* Save the provided event information */
	boolean saveDoit = event.doit;
	Object saveData = event.data;

	/* Clear the previous collection of adapters */
	setCurrentAdapters(null);

	/* Clear the previous chosen adapter */
	setChosenAdapter(null);

	/* Set the adapters */
	setCurrentAdapters(getAdapters(getListeners()));

	/* Iterate through the adapters */
	boolean doIt = false;
	ArrayList listOfActiveAdapters = new ArrayList();
	ArrayList listOfActiveTransferAgents = new ArrayList();
	if (getCurrentAdapters() != null && getCurrentAdapters().length > 0) {
	for (int i = 0; i < getCurrentAdapters().length; i++) {
	/* Set the do it flag */
	event.doit = saveDoit;

	/* Invoke the drag start */
	getCurrentAdapters()[i].dragStart(event);

	/* If ok to drag add the transfer to the list */
	if (event.doit) {
	listOfActiveAdapters.add(getCurrentAdapters()[i]);
	listOfActiveTransferAgents.add(getCurrentAdapters()[i]
	.getTransferAgent().getTransfer());
	}

	/* Ok to drag if anyone is ready to handle */
	doIt = doIt \|\| event.doit;
	}

	/* Set the transfers and the updated adapters */
	if (doIt) {
	/* Set the transfers */
	((DragSource) event.widget)
	.setTransfer((Transfer[]) listOfActiveTransferAgents
	.toArray(new Transfer[listOfActiveTransferAgents
	.size()]));

	/* Set the adapters */
	setCurrentAdapters((org.eclipse.gmf.runtime.common.ui.services.dnd.drag.ITransferDragSourceListener[]) listOfActiveAdapters
	.toArray(new ITransferDragSourceListener[listOfActiveAdapters
	.size()]));
	}

	if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND)) {
	String result = doIt ? "true" : "false"; //$NON-NLS-1$ //$NON-NLS-2$
	Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND,
	"DragStart::Event do it flag is " + result); //$NON-NLS-1$

	/* Write the transfer adapters */
	for (int i = 0; i < getCurrentAdapters().length; i++) {
	Trace
	.trace(
	CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND,
	"DragStart::Transfer Adapter is " + getCurrentAdapters()[i].getClass().getName()); //$NON-NLS-1$
	}
	}

	/* Set the event information */
	event.data = saveData;
	event.doit = doIt;
	} else {
	/* Delegate to the drag source */
	getContext().dragStart(event);
	}
	} catch (Throwable e) {
	event.doit = false;
	handle(e, false);
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.swt.dnd.DragSourceListener#dragSetData(org.eclipse.swt.dnd.DragSourceEvent)
	*/
	public void dragSetData(DragSourceEvent event) {
	try {
	/* Get the corresponding chosen adapter */
	setChosenAdapter(getAdapter(event.dataType));

	if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND)) {
	String adapterChosen = getChosenAdapter() != null ? getChosenAdapter()
	.getClass().getName()
	: "No Adapter Chosen"; //$NON-NLS-1$
	Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND,
	"DragSetData::Chosen Adapter is " + adapterChosen); //$NON-NLS-1$
	}

	if (getChosenAdapter() != null) {
	getChosenAdapter().dragSetData(event);
	} else {
	/* Delegate to the drag source */
	getContext().dragSetData(event);
	}
	} catch (Throwable e) {
	event.data = null;
	handle(e, false);
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.swt.dnd.DragSourceListener#dragFinished(org.eclipse.swt.dnd.DragSourceEvent)
	*/
	public void dragFinished(DragSourceEvent event) {
	try {
	if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND)) {
	String adapterChosen = getChosenAdapter() != null ? getChosenAdapter()
	.getClass().getName()
	: "No Adapter Chosen"; //$NON-NLS-1$
	Trace.trace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.DND,
	"DragFinished::Chosen Adapter is " + adapterChosen); //$NON-NLS-1$
	}

	/* Get the corresponding chosen adapter */
	if (getChosenAdapter() != null) {
	getChosenAdapter().dragFinished(event);
	} else {
	setChosenAdapter(getAdapter(event.dataType));
	if (getChosenAdapter() != null) {
	getChosenAdapter().dragFinished(event);
	} else {
	/* Delegate to the drag source */
	getContext().dragFinished(event);
	}
	}
	} catch (Throwable e) {
	handle(e, false);
	} finally {
	setChosenAdapter(null);
	setCurrentAdapters(null);
	}
	}

	/**
	* Returns the current adapters.
	*
	* @return ITransferDragSourceListener[]
	*/
	private ITransferDragSourceListener[] getCurrentAdapters() {
	return currentAdapters;
	}

	/**
	* Returns the drag source context.
	*
	* @return DragSourceContext
	*/
	private DragSourceContext getContext() {
	return context;
	}

	/**
	* Returns the set of registered listeners. The listeners are acquired
	* through the <code>DragDropListenerService</code>.
	*
	* @return IDragSourceListener[] an array of listeners
	*/
	private IDragSourceListener[] getListeners() {
	/* Get the structured selection */
	ISelection selection = getContext().getSelection();

	/* Check the selection */
	if (selection == null \|\| selection.isEmpty()
	\|\| !(selection instanceof IStructuredSelection)) {
	return null;
	}

	/* Get the selection as an object array */
	Object[] array = ((IStructuredSelection) selection).toArray();

	/* Create a unique list of element types */
	ArrayList listOfElementTypes = new ArrayList();
	for (int i = 0; i < array.length; i++) {
	if (!listOfElementTypes.contains(array[i].getClass())) {
	listOfElementTypes.add(array[i].getClass());
	}
	}

	/* Get the drag source listeners */
	ArrayList listOfListeners = new ArrayList();
	Iterator iterator = listOfElementTypes.iterator();
	while (iterator.hasNext()) {
	/* Get the element type */
	Class clazz = (Class) iterator.next();

	/* Create a drag listener context */
	DragListenerContext aContext = new DragListenerContext(getContext()
	.getActivePart(), clazz, IListenerContext.ALL_TRANSFERS, false);

	/* Get the drag source listeners */
	IDragSourceListener[] listeners = DragDropListenerService
	.getInstance().getDragSourceListeners(aContext);

	/* Get a compatible one if no listener is found for a direct match */
	if (listeners == null \|\| listeners.length == 0) {
	/* Create a drag listener context */
	aContext = new DragListenerContext(
	getContext().getActivePart(), clazz,
	IListenerContext.ALL_TRANSFERS, true);

	/* Get the drag source listener */
	listeners = DragDropListenerService.getInstance()
	.getDragSourceListeners(aContext);
	}

	/* Add to the list */
	if (listeners != null && listeners.length != 0) {
	for (int i = 0; i < listeners.length; i++) {
	if (!listOfListeners.contains(listeners[i])) {
	listOfListeners.add(listeners[i]);
	}
	}
	}
	}

	/* Combine all the listeners into one array */
	return !listOfListeners.isEmpty() ? (IDragSourceListener[]) listOfListeners
	.toArray(new IDragSourceListener[listOfListeners.size()])
	: null;
	}

	/**
	* Returns the set of transfer drag source adapters. The adapters are
	* created based on the transfers supported by the listeners
	*
	* @param listeners
	* The registered list of <code>IDragSourceListener</code>
	* @return ITransferDragSourceListener[] an array of transfer adapters
	*/
	private ITransferDragSourceListener[] getAdapters(
	IDragSourceListener[] listeners) {
	/* Return if no listeners or no selection */
	if (listeners == null \|\| listeners.length == 0) {
	return null;
	}

	/* Create placeholder for active listeners */
	Hashtable listOfUniqueTransferIds = new Hashtable();

	/* Check if the listeners can handle the drag */
	for (int i = 0; i < listeners.length; i++) {
	/* Check if the selection is draggable */
	if (!listeners[i].isDraggable(getContext())) {
	continue;
	}

	/* Get the transfer ids */
	String[] transferIds = listeners[i].getSupportingTransferIds();
	if (transferIds == null \|\| transferIds.length == 0) {
	continue;
	}

	/* Iterate through the ids */
	for (int y = 0; y < transferIds.length; y++) {
	/* Placeholder for listeners */
	ArrayList listOfListeners = null;

	if (!listOfUniqueTransferIds.containsKey(transferIds[y])) {
	/* Create a new list */
	listOfListeners = new ArrayList();
	} else {
	/* Get the list of listeners and add to it */
	listOfListeners = (ArrayList) listOfUniqueTransferIds
	.get(transferIds[y]);
	}

	/* Update the list */
	if (listOfListeners != null) {
	listOfListeners.add(listeners[i]);
	listOfUniqueTransferIds
	.put(transferIds[y], listOfListeners);
	}
	}
	}

	/* Return if no active transfer agents */
	if (listOfUniqueTransferIds.isEmpty()) {
	return null;
	}

	/* Get the adapters */
	ArrayList listOfAdapters = new ArrayList();
	Enumeration enumeration = listOfUniqueTransferIds.keys();
	while (enumeration.hasMoreElements()) {
	/* Get the next id */
	String transferId = (String) enumeration.nextElement();

	/* Get the listeners */
	ArrayList supportingListeners = (ArrayList) listOfUniqueTransferIds
	.get(transferId);

	/* Get the adapter */
	ITransferDragSourceListener adapter = (ITransferDragSourceListener) getAllAdapters()
	.get(Integer.valueOf(transferId.hashCode()));
	if (adapter != null) {
	/* Initialize the adapter */
	adapter.init(
	(IDragSourceListener[]) supportingListeners
	.toArray(new IDragSourceListener[supportingListeners
	.size()]), getContext());

	/* Add to the list */
	listOfAdapters.add(adapter);
	}
	}

	/* Return the list of adapters */
	return !listOfAdapters.isEmpty() ? (ITransferDragSourceListener[]) listOfAdapters
	.toArray(new ITransferDragSourceListener[listOfAdapters.size()])
	: null;
	}

	/**
	* Sets the current adapters.
	*
	* @param currentAdapterArray
	* The adapters to set
	*/
	private void setCurrentAdapters(
	ITransferDragSourceListener[] currentAdapterArray) {
	this.currentAdapters = currentAdapterArray;
	}

	/**
	* Returns the chosen adapter
	*
	* @param type
	* The transfer data type
	* @return The transfer drag source adapter chosen
	*/
	private ITransferDragSourceListener getAdapter(TransferData type) {
	if (type != null) {
	for (int i = 0; i < getCurrentAdapters().length; i++) {
	if (getCurrentAdapters()[i].getTransferAgent().getTransfer()
	.isSupportedType(type)) {
	return getCurrentAdapters()[i];
	}
	}
	}

	return null;
	}

	/**
	* Returns the chosenAdapter.
	*
	* @return ITransferDragSourceListener
	*/
	private ITransferDragSourceListener getChosenAdapter() {
	return chosenAdapter;
	}

	/**
	* Sets the chosenAdapter.
	*
	* @param aChosenAdapter
	* The chosenAdapter to set
	*/
	private void setChosenAdapter(ITransferDragSourceListener aChosenAdapter) {
	this.chosenAdapter = aChosenAdapter;
	}

	/**
	* Returns the set of transfer drag source adapters. The adapters are
	* created based on the provided transfer ids determined from the drag and
	* drop service.
	*
	* @return Hashtable a table of transfer adapters
	*/
	private Hashtable getAllTransferAdapters() {
	/* Create placeholder for possible adapters */
	Hashtable listOfSupportedAdapters = new Hashtable();

	/* Get the ids from the drag and drop service */
	String[] transferIds = DragDropListenerService.getInstance()
	.getAllTransferIds(getContext().getActivePart().getSite().getId(),
	IListenerContext.DRAG);

	/* Iterate through the ids */
	if (transferIds == null \|\| transferIds.length == 0) {
	return null;
	}

	/* Create the adapters */
	for (int i = 0; i < transferIds.length; i++) {
	ITransferDragSourceListener adapter = TransferAdapterService
	.getInstance().getTransferDragSourceAdapter(transferIds[i]);

	if (adapter != null) {
	listOfSupportedAdapters.put(Integer.valueOf(transferIds[i]
	.hashCode()), adapter);
	}
	}

	/* Return the adapters */
	return listOfSupportedAdapters;
	}

	/**
	* Handles the specified exception.
	*
	* @param exception
	* The exception to be handled.
	* @param displayDialog
	* boolean to indicate whether to display dialog
	*/
	private void handle(Throwable exception, boolean displayDialog) {
	if (Trace.shouldTrace(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.EXCEPTIONS_CATCHING)) {
	Trace.catching(CommonUIServicesDNDPlugin.getDefault(),
	CommonUIServicesDNDDebugOptions.EXCEPTIONS_CATCHING,
	getClass(), "handle", exception); //$NON-NLS-1$
	}

	IStatus status = new Status(IStatus.ERROR, CommonUIServicesDNDPlugin
	.getPluginId(), CommonUIServicesDNDStatusCodes.DRAG_ACTION_FAILURE,
	CommonUIServicesDNDMessages.DelegatingDragSourceAdapter__ERROR__errorMessage, exception);

	Log.log(CommonUIServicesDNDPlugin.getDefault(), status);

	if (displayDialog) {

	status = new Status(IStatus.ERROR, CommonUIServicesDNDPlugin
	.getPluginId(),
	CommonUIServicesDNDStatusCodes.DRAG_ACTION_FAILURE,
	CommonUIServicesDNDMessages.DelegatingDragSourceAdapter__ERROR__errorMessage,
	exception);

	ErrorDialog.openError(getContext().getActivePart().getSite()
	.getShell(), null, null, status);
	}
	}

	/**
	* Returns the adapters.
	*
	* @return Hashtable
	*/
	private Hashtable getAllAdapters() {
	return allAdapters;
	}
	}