org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/internal/editpolicies/LabelSnapBackEditPolicy.java

/******************************************************************************
 * Copyright (c) 2004, 2007 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.diagram.ui.internal.editpolicies;

import org.eclipse.draw2d.geometry.Point;
import org.eclipse.emf.transaction.TransactionalEditingDomain;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.Request;
import org.eclipse.gef.commands.Command;
import org.eclipse.gmf.runtime.common.core.command.ICommand;
import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
import org.eclipse.gmf.runtime.diagram.ui.commands.SetBoundsCommand;
import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
import org.eclipse.gmf.runtime.diagram.ui.editparts.LabelEditPart;
import org.eclipse.gmf.runtime.diagram.ui.editpolicies.GraphicalNodeEditPolicy;
import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
import org.eclipse.gmf.runtime.emf.core.util.EObjectAdapter;
import org.eclipse.gmf.runtime.notation.View;


/**
 * EditPolicy which support the RequestConstants.REQ_SNAP_BACK request type.
 * 
 * Returns a command to position a label's offset to it default set at creation.
 * 
 * @author jcorchis
 */
public class LabelSnapBackEditPolicy
	extends GraphicalNodeEditPolicy {


	/**
	 * Understands RequestConstants.REQ_SNAP_BACK request types
	 * @param request
	 * @return boolean
	 */
	public boolean understandsRequest(Request request) {
		return RequestConstants.REQ_SNAP_BACK.equals(request.getType());
	}
	
	/**
	 * Returns a <code>Command</code> which sets the label's offset to its
	 * original position.
	 * 
	 * @param request the request
	 * @return the command
	 */
	public Command getCommand(Request request) {
		if (RequestConstants.REQ_SNAP_BACK.equals(request.getType())) {
			View view = (View)getHost().getModel();
			String hint = view.getType();
			Point offset = LabelEditPart.getSnapBackPosition(hint);
			if (offset == null)
				return null;
            
            TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
                .getEditingDomain();
            
	 		ICommand moveCommand = 
	 			new SetBoundsCommand(editingDomain,
	 				DiagramUIMessages.SetLocationCommand_Label_Resize,
	 				new EObjectAdapter(view),
					offset); 
			return new ICommandProxy(moveCommand);
		}
		return null;
	}

	public EditPart getTargetEditPart(Request request) {
		if (understandsRequest(request))
			return getHost();
		return super.getTargetEditPart(request);
	}
}