org.eclipse.gmf.runtime.draw2d.ui/src/org/eclipse/gmf/runtime/draw2d/ui/internal/routers/FanRouter.java

/******************************************************************************
 * Copyright (c) 2002, 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.draw2d.ui.internal.routers;

import org.eclipse.draw2d.Connection;
import org.eclipse.draw2d.ConnectionRouter;
import org.eclipse.draw2d.PositionConstants;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PointList;
import org.eclipse.draw2d.geometry.Ray;
import org.eclipse.gmf.runtime.draw2d.ui.mapmode.MapModeUtil;

/**
 * This class exists only as a workaround to Bugzilla Bug 37342: 
 * FanRouter.handleCollision incorrect for PointList where start 
 * and end point are the same.
 * 
 * @author chmahone
 */
public class FanRouter extends org.eclipse.draw2d.FanRouter {

	static final int SEPARATION = 15;
	
	/* (non-Javadoc)
	 * @see org.eclipse.draw2d.ConnectionRouter#route(org.eclipse.draw2d.Connection)
	 */
	public void route(Connection conn) {
		routeBendpoints(conn);
	}
	
	/**
	 * routeBendpoints
	 * Method that performs the actual routing of the Connection.  Clients will override this instead
	 * of route which is final.
	 * 
	 * @param conn Connection to be routed.
	 */
	private void routeBendpoints(Connection conn) {
		if (!isFeedback(conn)) 
			setSeparation(MapModeUtil.getMapMode(conn).DPtoLP(SEPARATION));
		else
			setSeparation(SEPARATION);
		
		super.route(conn);
	}

	private boolean isFeedback(Connection conn) {
		Dimension dim = new Dimension(100, 100);
		Dimension dimCheck = dim.getCopy();
		conn.translateToRelative(dimCheck);
		return dim.equals(dimCheck);
	}
	
	/**
	 * This is a workaround to Bugzilla Bug 37342: 
 	 * FanRouter.handleCollision incorrect for PointList where start 
 	 * and end point are the same.  If there are only two points and 
 	 * they are both the same, then do nothing.
 	 * 
 	 * Also overridden to handle integer overflow issue with the Ray::Length method when
 	 * fed HiMetric values that are large.  Ray length has to be manually calculated
 	 * instead. 
	 * @see org.eclipse.draw2d.AutomaticRouter#handleCollision(org.eclipse.draw2d.geometry.PointList, int)
	 */
	protected void handleCollision(PointList points, int index) {
		if (points.size() == 2
			&& points.getFirstPoint().equals(points.getLastPoint())) {
			return;
		}
		
		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 = Math.sqrt(((double)ray.x * (double)ray.x) + ((double)ray.y * (double)ray.y));

		double xSeparation = getSeparation() * ray.x / length;
		double ySeparation = getSeparation() * 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);
	}


	/**
	 * @return Returns the connection router to which the routing is delegated. 
	 */
	public ConnectionRouter getRouter() {
		return next();
	}
}