CompoundPopulateRanks.java

/*******************************************************************************
 * Copyright (c) 2003, 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.graph;

import java.util.Iterator;

/**
 * Places nodes into ranks for a compound directed graph.  If a subgraph spans a rank
 * without any nodes which belong to that rank, a bridge node is inserted to prevent nodes
 * from violating the subgraph boundary.
 * @author Randy Hudson
 * @since 2.1.2
 */
class CompoundPopulateRanks extends PopulateRanks {

public void visit(DirectedGraph g) {
	CompoundDirectedGraph graph = (CompoundDirectedGraph)g;
	
	/**
	 * Remove long containment edges at this point so they don't affect MinCross.
	 */
	Iterator containment = graph.containment.iterator();
	while (containment.hasNext()) {
		Edge e = (Edge)containment.next();
		if (e.getSlack() > 0) {
			graph.removeEdge(e);
			containment.remove();
		}
	}

	super.visit(g);
	NodeList subgraphs = graph.subgraphs;
	for (int i = 0; i < subgraphs.size(); i++) {
		Subgraph subgraph = (Subgraph)subgraphs.get(i);
		bridgeSubgraph(subgraph, graph);
	}
}

/**
 * @param subgraph
 */
private void bridgeSubgraph(Subgraph subgraph, CompoundDirectedGraph g) {
	int offset = subgraph.head.rank;
	boolean occupied[] = new boolean[subgraph.tail.rank - subgraph.head.rank + 1];
	Node bridge[] = new Node[occupied.length];
	
	for (int i = 0; i < subgraph.members.size(); i++) {
		Node n = (Node)subgraph.members.get(i);
		if (n instanceof Subgraph) {
			Subgraph s = (Subgraph)n;
			for (int r = s.head.rank; r <= s.tail.rank; r++)
				occupied[r - offset] = true;
		} else
			occupied[n.rank - offset] = true;
	}
	
	for (int i = 0; i < bridge.length; i++) {
		if (!occupied[i]) {
			Node br = bridge[i] = new Node("bridge", subgraph); //$NON-NLS-1$
			br.rank = i + offset;
			br.height = br.width = 0;
			br.nestingIndex = subgraph.nestingIndex;
			g.ranks.getRank(br.rank).add(br);
			g.nodes.add(br);
		}
	}
}

}