org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/internal/commands/SnapCommand.java

/******************************************************************************
 * Copyright (c) 2007, 2008 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.commands;

import java.util.Iterator;
import java.util.List;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.PositionConstants;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PrecisionPoint;
import org.eclipse.draw2d.geometry.PrecisionRectangle;

import org.eclipse.emf.transaction.TransactionalEditingDomain;

import org.eclipse.gef.SnapToHelper;
import org.eclipse.gef.commands.CompoundCommand;
import org.eclipse.gef.handles.HandleBounds;
import org.eclipse.gef.requests.ChangeBoundsRequest;
import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
import org.eclipse.gmf.runtime.common.core.command.CommandResult;
import org.eclipse.gmf.runtime.diagram.ui.editparts.DiagramRootEditPart;
import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
import org.eclipse.gmf.runtime.draw2d.ui.mapmode.IMapMode;
import org.eclipse.gmf.runtime.emf.commands.core.command.AbstractTransactionalCommand;
import org.eclipse.gmf.runtime.notation.Bounds;
import org.eclipse.gmf.runtime.notation.LayoutConstraint;
import org.eclipse.gmf.runtime.notation.Node;
import org.eclipse.gmf.runtime.notation.View;

/**
 * This command is used to snap edit parts on a diagram, where the edit parts are
 * passed in as the parameter.
 * 
 * @author carson_li
 */
public class SnapCommand extends AbstractTransactionalCommand {

	/** the edit parts requested to be snapped to grid */
	protected List editparts;

	/**
	 * Constructor for <code>SnapCommand</code>.
	 * 
	 * @param editingDomain
	 *            the editing domain through which model changes are made
	 * @param editparts
	 *            the list containing the edit parts that need to be snapped
	 */
	public SnapCommand(TransactionalEditingDomain editingDomain, List editparts) {

		super(editingDomain, DiagramUIMessages.SnapToGrid_textLabel, null);
		this.editparts = editparts;

	}

	/*
	 * @see org.eclipse.gmf.runtime.emf.commands.core.command.AbstractTransactionalCommand#getAffectedFiles()
	 */
	public List getAffectedFiles() {
		if (editparts != null) {
			// we only need the first child since all the edit parts being
			// snapped originate from the same diagram
			IGraphicalEditPart parent = (IGraphicalEditPart) editparts.get(0);
			View view = (View) parent.getParent().getModel();
			return getWorkspaceFiles(view);
		}
		return super.getAffectedFiles();
	}

	/**
	 * Executes a snap command for all the desired edit parts.
	 * 
	 */
	protected CommandResult doExecuteWithResult(
			IProgressMonitor progressMonitor, IAdaptable info)
			throws ExecutionException {

		CompoundCommand snapCommand = new CompoundCommand();

		for (Iterator iter = editparts.iterator(); iter.hasNext();) {
			IGraphicalEditPart newEditPart = (IGraphicalEditPart) iter.next();
			IMapMode mapMode = ((DiagramRootEditPart) newEditPart.getRoot()).getMapMode();

			if (newEditPart.getModel() instanceof Node) {

				LayoutConstraint constraint = ((Node) newEditPart.getModel()).getLayoutConstraint();
				if (constraint instanceof Bounds) {
					
					Bounds bounds = (Bounds) constraint;
					ChangeBoundsRequest request = new ChangeBoundsRequest(RequestConstants.REQ_MOVE);
					request.setEditParts(newEditPart);

					// translate all coordinates to device units as a standard if necessary
					// this is done since moveDelta uses device units
					
					PrecisionPoint moveDelta = new PrecisionPoint(bounds.getX()
                        - newEditPart.getFigure().getBounds().x, bounds.getY()
                        - newEditPart.getFigure().getBounds().y);
					mapMode.LPtoDP(moveDelta);

					// In the case that the figure bounds and model's layout constant are the same,
					// xDiff and yDiff will evaluate to zero, but snapToHelper will still locate the closest
					// NorthWest snap locations. In the case that they're not, we assume the figure's bounds
					// have not been updated, so the moveDelta value will simulate a drag to the new location
					// In both situations we base the resulting snap location off the figure's bounds

					// snapToGrid logic taken from DragEditPartsTracker.java
					request.getExtendedData().clear();
					request.setMoveDelta(moveDelta);

					PrecisionRectangle figureBounds = null;
					IFigure figure = newEditPart.getFigure();
					if (figure instanceof HandleBounds) {
						figureBounds = new PrecisionRectangle(
								((HandleBounds) figure).getHandleBounds());
					} else {
						figureBounds = new PrecisionRectangle(figure.getBounds());
					}

					figure.translateToAbsolute(figureBounds);
				
					SnapToHelper snapToHelper = (SnapToHelper) newEditPart.getAdapter(SnapToHelper.class);
					PrecisionRectangle baseRect = new PrecisionRectangle(figureBounds);
					baseRect.translate(moveDelta);

					if (snapToHelper != null) {
						snapToHelper.snapPoint(request,
								PositionConstants.HORIZONTAL | PositionConstants.VERTICAL,
								new PrecisionRectangle[] { baseRect },	moveDelta);
						request.setMoveDelta(moveDelta);
					}

					snapCommand.add(newEditPart.getCommand(request));
				}
			}
		}

		if (snapCommand != null && snapCommand.canExecute()) {
			snapCommand.execute();
		}
		return CommandResult.newOKCommandResult();
	}
}