FanRouter.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 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;
}

}