bundles/org.eclipse.rap.draw2d/src/org/eclipse/draw2d/FanRouter.java

/*******************************************************************************
 * Copyright (c) 2000, 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.draw2d;

import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PointList;
import org.eclipse.draw2d.geometry.Ray;

/**
 * Automatic router that spreads its {@link Connection Connections} in a
 * fan-like fashion upon collision.
 */
public class FanRouter extends AutomaticRouter {

	private int separation = 10;

	/**
	 * Returns the separation in pixels between fanned connections.
	 * 
	 * @return the separation
	 * @since 2.0
	 */
	public int getSeparation() {
		return separation;
	}

	/**
	 * Modifies a given PointList that collides with some other PointList. The
	 * given <i>index</i> indicates that this it the i<sup>th</sup> PointList in
	 * a group of colliding points.
	 * 
	 * @param points
	 *            the colliding points
	 * @param index
	 *            the index
	 */
	protected void handleCollision(PointList points, int index) {
		Point start = points.getFirstPoint();
		Point end = points.getLastPoint();

		if (start.equals(end))
			return;

		Point midPoint = new Point((end.x + start.x) / 2, (end.y + start.y) / 2);
		int position = end.getPosition(start);
		Ray ray;
		if (position == PositionConstants.SOUTH
				|| position == PositionConstants.EAST)
			ray = new Ray(start, end);
		else
			ray = new Ray(end, start);
		double length = ray.length();

		double xSeparation = separation * ray.x / length;
		double ySeparation = separation * ray.y / length;

		Point bendPoint;

		if (index % 2 == 0) {
			bendPoint = new Point(
					midPoint.x + (index / 2) * (-1 * ySeparation), midPoint.y
							+ (index / 2) * xSeparation);
		} else {
			bendPoint = new Point(midPoint.x + (index / 2) * ySeparation,
					midPoint.y + (index / 2) * (-1 * xSeparation));
		}
		if (!bendPoint.equals(midPoint))
			points.insertPoint(bendPoint, 1);
	}

	/**
	 * Sets the colliding {@link Connection Connection's} separation in pixels.
	 * 
	 * @param value
	 *            the separation
	 * @since 2.0
	 */
	public void setSeparation(int value) {
		separation = value;
	}

}