bundles/org.eclipse.gef/src/org/eclipse/gef/CompoundSnapToHelper.java

/*******************************************************************************
 * Copyright (c) 2003, 2010 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.gef;

import org.eclipse.core.runtime.Assert;

import org.eclipse.draw2d.geometry.PrecisionRectangle;

/**
 * Combines multiple SnapToHelpers into one compound helper. The compound helper
 * deletages to multiple other helpers.
 * 
 * @author Pratik Shah
 */
public class CompoundSnapToHelper extends SnapToHelper {

	private SnapToHelper[] delegates;

	/**
	 * Constructs a compound snap to helper which will delegate to the provided
	 * array of helpers. The first helper in the array has highest priority and
	 * will be given the first opportunity to perform snapping.
	 * 
	 * @since 3.0
	 * @param delegates
	 *            an array of helpers
	 */
	public CompoundSnapToHelper(SnapToHelper delegates[]) {
		Assert.isTrue(delegates.length != 0);
		this.delegates = delegates;
	}

	/**
	 * Gets the array of helpers.
	 * 
	 * @return the array of helpers.
	 * @since 3.4
	 */
	protected SnapToHelper[] getDelegates() {
		return delegates;
	}

	/**
	 * @see SnapToHelper#snapRectangle(Request, int, PrecisionRectangle,
	 *      PrecisionRectangle)
	 */
	public int snapRectangle(Request request, int snapOrientation,
			PrecisionRectangle baseRect, PrecisionRectangle result) {
		for (int i = 0; i < getDelegates().length && snapOrientation != NONE; i++)
			snapOrientation = getDelegates()[i].snapRectangle(request,
					snapOrientation, baseRect, result);
		return snapOrientation;
	}

}