/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is 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
* Lesser General Public License for more details.
*/
package org.geotools.graph.build.line;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.geotools.graph.build.GraphBuilder;
import org.geotools.graph.build.GraphGenerator;
import org.geotools.graph.structure.Edge;
import org.geotools.graph.structure.Graph;
import org.geotools.graph.structure.Graphable;
import org.geotools.graph.structure.Node;
import org.geotools.graph.structure.line.OptXYNode;
import org.geotools.graph.structure.opt.OptEdge;
import org.geotools.graph.structure.opt.OptNode;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.LineSegment;
/**
* An implementation of GraphGenerator used to generate an optimized graph
* representing a line network. Graphs are generated by supplying the generator
* with objects of type LineSegment via the add(Object) method. <BR>
* <BR>
* For each line segment added, an edge in the graph is created. The builder
* records the end coordinates of each line added, and maintains a map of
* coordinates to nodes, creating nodes when neccessary.<BR>
* <BR>
* Edges created by the generator are of type OptBasicEdge.<BR>
* Nodes created by the generator are of type OptXYNode. <BR>
* <BR>
* Since building optimized graphs requires knowing the degree of nodes before
* creating them, the physical construction of the graph is delayed until a call
* to generate() is made. No component is created with a call to add(Object),
* only information about the object is recorded.
*
* @see org.geotools.graph.structure.opt.OptEdge
* @see org.geotools.graph.structure.line.OptXYNode
*
* @author Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net
*
*
*
* @source $URL$
*/
public class OptLineGraphGenerator implements LineGraphGenerator {
/** coordinate to node / count **/
private HashMap m_coord2count;
/** lines added to the network **/
private ArrayList m_lines;
/** underlying builder **/
private GraphBuilder m_builder;
/**
* Constructs a new OptLineGraphGenerator.
*/
public OptLineGraphGenerator() {
m_coord2count = new HashMap();
m_lines = new ArrayList();
setGraphBuilder(new OptLineGraphBuilder());
}
/**
* Adds a line to the graph. Note that this method returns null since actual
* building of the graph components is delayed until generate() is called.
*
* @param obj A LineSegment object.
*
* @return null because the actual building of the graph components is delayed
* until generate() is called.
*/
public Graphable add(Object obj) {
LineSegment line = (LineSegment)obj;
Integer count;
//update count of first coordinate
if ((count = (Integer)m_coord2count.get(line.p0)) == null) {
m_coord2count.put(line.p0, new Integer(1));
}
else m_coord2count.put(line.p0, new Integer(count.intValue()+1));
//update count of second coordinate
if ((count = (Integer)m_coord2count.get(line.p1)) == null) {
m_coord2count.put(line.p1, new Integer(1));
}
else m_coord2count.put(line.p1, new Integer(count.intValue()+1));
//hold onto a reference to the line
m_lines.add(line);
//return null, no componenets created
return(null);
}
/**
* Returns the edge which represents a line. This method must be called
* after the call to generate(). Note that if the exact same line
* has been added to the graph multiple times, then only one of the edges
* that represents it will be returned. It is undefined which edge will be
* returned.
*
* @param obj An instance of LineSegment.
*
* @return Edge that represents the line.
*
* @see GraphGenerator#get(Object)
*/
public Graphable get(Object obj) {
LineSegment line = (LineSegment)obj;
Node n1 = (Node)m_coord2count.get(line.p0);
Node n2 = (Node)m_coord2count.get(line.p0);
return(n1.getEdge(n2));
//note: if there are identical lines in the graph then it is undefined
//which of them will be returned
}
/**
* Unsupported operation.
*
* @throws UnsupportedOperationException
*/
public Graphable remove(Object obj) {
throw new UnsupportedOperationException(
getClass().getName() + "#remove(Object)"
);
}
/**
* @see GraphGenerator#setGraphBuilder(GraphBuilder)
*/
public void setGraphBuilder(GraphBuilder builder) {
m_builder = builder;
}
/**
* @see GraphGenerator#getGraphBuilder()
*/
public GraphBuilder getGraphBuilder() {
return(m_builder);
}
/**
* @see GraphGenerator#getGraph()
*/
public Graph getGraph() {
return(m_builder.getGraph());
}
/**
* Performs the actual generation of the graph.
*/
public void generate() {
generateNodes();
generateEdges();
}
/**
* Returns the coordinate to node map. Note that before the call to generate
* the map does not contain any nodes.
*
* @return Coordinate to node map.
*/
public Map getNodeMap() {
return(m_coord2count);
}
/**
* Returns the lines added to the graph.
*
* @return A list of LineSegment objects.
*/
protected List getLines() {
return(m_lines);
}
protected void generateNodes() {
//create nodes from coordiante counts
for (Iterator itr = m_coord2count.entrySet().iterator(); itr.hasNext();) {
Map.Entry entry = (Map.Entry)itr.next();
Coordinate coord = (Coordinate)entry.getKey();
Integer count = (Integer)entry.getValue();
OptXYNode node = (OptXYNode)m_builder.buildNode();
node.setDegree(count.intValue());
node.setCoordinate(coord);
m_builder.addNode(node);
entry.setValue(node);
}
}
protected void generateEdges() {
//relate nodes
for (Iterator itr = m_lines.iterator(); itr.hasNext();) {
LineSegment line = (LineSegment)itr.next();
generateEdge(line);
}
}
protected Edge generateEdge(LineSegment line) {
OptNode n1 = (OptNode)m_coord2count.get(line.p0);
OptNode n2 = (OptNode)m_coord2count.get(line.p1);
OptEdge edge = (OptEdge)m_builder.buildEdge(n1,n2);
m_builder.addEdge(edge);
return(edge);
}
//TODO DOCUMENT ME!
public Node getNode(Coordinate c) {
return((Node)m_coord2count.get(c));
}
public Edge getEdge(Coordinate c1, Coordinate c2) {
Node n1 = (Node)m_coord2count.get(c1);
Node n2 = (Node)m_coord2count.get(c2);
return(n1.getEdge(n2));
}
}