/*
* 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.HashMap;
import java.util.Map;
import org.geotools.graph.build.GraphBuilder;
import org.geotools.graph.build.GraphGenerator;
import org.geotools.graph.build.basic.BasicGraphBuilder;
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 com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.LineSegment;
/**
* An implementation of GraphGenerator used to generate a 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 BasicEdge and contain an object
* of type LineSegment.<BR>
* Nodes created by the generator are of type BasicXYNode and contain an object
* of type Coordinate.
*
* @see org.geotools.graph.structure.line.BasicXYNode
* @see org.geotools.graph.structure.basic.BasicEdge
* @see com.vividsolutions.jts.geom.LineSegment
* @see com.vividsolutions.jts.geom.Coordinate
*
* @author Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net
*
*
* @source $URL$
*/
public class BasicLineGraphGenerator implements LineGraphGenerator {
/** coordinate to node map **/
private HashMap m_coord2node;
/** underlying builder **/
private GraphBuilder m_builder;
/**
* Constructs a new BasicLineGraphGenerator.
*/
public BasicLineGraphGenerator () {
m_coord2node = new HashMap();
setGraphBuilder(new BasicGraphBuilder());
}
/**
* Adds a line to the graph.
*
* @param obj An instance of LineSegment.
*
* @return A BasicEdge.
*
* @see LineSegment
* @see GraphGenerator#add(Object)
*/
public Graphable add(Object obj) {
LineSegment line = (LineSegment)obj;
Coordinate c;
Node n1, n2;
//check first coordinate
c = line.p0;
if ((n1 = (Node)m_coord2node.get(c)) == null) {
//first time coordinate seen, create node for it
n1 = getGraphBuilder().buildNode();
//set underlying object to coordinate
//n1.setObject(c);
setObject(n1, c);
getGraphBuilder().addNode(n1);
m_coord2node.put(c,n1);
}
//check second coordinate
c = line.p1;
if ((n2 = (Node)m_coord2node.get(c)) == null) {
//first time coordinate seen, create node for it
n2 = getGraphBuilder().buildNode();
//set underlying object to coordiante
//n2.setObject(c);
setObject(n2,c);
getGraphBuilder().addNode(n2);
m_coord2node.put(c,n2);
}
//build the edge setting underlying object to line
Edge e = getGraphBuilder().buildEdge(n1,n2);
//e.setObject(line);
setObject(e, line);
getGraphBuilder().addEdge(e);
//return the created edge
return(e);
}
/**
* Returns the edge which represents a line. 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;
//get nodes representing coordinate
Node n1 = (Node)m_coord2node.get(line.p0);
Node n2 = (Node)m_coord2node.get(line.p1);
if (n1 == null || n2 == null) return(null);
//return edge shared between them
return(n1.getEdge(n2));
//note: if there are identical lines in the graph then it is undefined
//which of them will be returned
}
/**
* Removes the edge from the graph that represents a line.
*
* @return Edge that represents the line.
*
* @see GraphGenerator#remove(Object)
*/
public Graphable remove(Object obj) {
LineSegment line = (LineSegment)obj;
Node n1 = (Node)m_coord2node.get(line.p0);
Node n2 = (Node)m_coord2node.get(line.p1);
if (n1 == null || n2 == null) return(null);
Edge e = (Edge)n1.getEdge(n2);
getGraphBuilder().removeEdge(e);
return(e);
}
/**
* @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(getGraphBuilder().getGraph());
}
/**
* Returns the coordinate to node map used to build nodes representing line
* endpoint coordinates.
*
* @return coordinate to ndoe map.
*/
public Map getNodeMap() {
return(m_coord2node);
}
//TODO COMMENT ME!
public Node getNode(Coordinate c) {
return((Node)m_coord2node.get(c));
}
public Edge getEdge(Coordinate c1, Coordinate c2) {
Node n1 = (Node)m_coord2node.get(c1);
Node n2 = (Node)m_coord2node.get(c2);
return(n1.getEdge(n2));
}
protected void setObject(Edge e, Object obj) {
e.setObject(obj);
}
protected void setObject(Node n, Object obj) {
n.setObject(obj);
}
}