DualGraphFaceLabeller.java

/*
 * This file is part of the Trickl Open Source Libraries.
 *
 * Trickl Open Source Libraries - http://open.trickl.com/
 *
 * Copyright (C) 2011 Tim Gee.
 *
 * Trickl Open Source Libraries are free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Trickl Open Source Libraries are distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this project.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.trickl.graph.planar;

import com.trickl.graph.Labeller;
import com.trickl.graph.edges.DirectedEdge;
import com.trickl.graph.edges.IntegerEdgeFactory;
import com.trickl.graph.vertices.IntegerVertexFactory;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 *
 * @author tgee
 */
public class DualGraphFaceLabeller<V, E> implements Labeller<DirectedEdge<V>> {
   
   private Map<Integer, Set<DirectedEdge<V>>> labelFaces = new HashMap<Integer, Set<DirectedEdge<V>>>();
   private Map<DirectedEdge<V>, Integer> faceLabels = new HashMap<DirectedEdge<V>, Integer>();
      
   public DualGraphFaceLabeller(PlanarGraph<V, E> graph) {
      generateLabels(graph);
   }

   @Override
   public int getLabelCount() {      
      return labelFaces.size();
   }

   @Override
   public int getLabel(DirectedEdge<V> face) {      
      return faceLabels.get(face);
   }

   @Override
   public Set<DirectedEdge<V>> getMembers(int label) {      
      return labelFaces.get(label);
   }   
   
   private void generateLabels(PlanarGraph<V, E> graph) {      
      DoublyConnectedEdgeList<Integer, Integer, Object> dualGraph = new DoublyConnectedEdgeList<Integer, Integer, Object>(new IntegerEdgeFactory<Integer>(), Object.class);
      
      DualGraphVisitor<V, E, Integer, Integer> dualGraphVisitor = new DualGraphVisitor(graph, dualGraph, new IntegerVertexFactory());
      PlanarFaceTraversal<V, E> planarFaceTraversal = new CanonicalPlanarFaceTraversal<V, E>(graph);
      planarFaceTraversal.traverse(dualGraphVisitor);
      
      Labeller<Integer> dualVertexLabeller = new SixColorVertexLabeller(dualGraph);
      
      Map<Integer, Set<DirectedEdge<V>>> vertexToFaceMap = dualGraphVisitor.getVertexToFaceMap();
      labelFaces.clear();
      faceLabels.clear();
      for (Integer dualVertex : dualGraph.vertexSet()) {
         int label = dualVertexLabeller.getLabel(dualVertex);         
         if (!labelFaces.containsKey(label)) {
            labelFaces.put(label, new HashSet<DirectedEdge<V>>());
         }
         
         for (DirectedEdge<V> edge : vertexToFaceMap.get(dualVertex)) {
            labelFaces.get(label).add(edge);
            faceLabels.put(edge, label);
         }
      }
   }
}