com.vividsolutions.jts.geomgraph.PlanarGraph Maven / Gradle / Ivy
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/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* 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; either
* version 2.1 of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.geomgraph;
/**
* @version 1.7
*/
import java.io.PrintStream;
import java.util.*;
import com.vividsolutions.jts.util.*;
import com.vividsolutions.jts.algorithm.*;
import com.vividsolutions.jts.geom.*;
/**
* The computation of the IntersectionMatrix relies on the use of a structure
* called a "topology graph". The topology graph contains nodes and edges
* corresponding to the nodes and line segments of a Geometry. Each
* node and edge in the graph is labeled with its topological location relative to
* the source geometry.
*
* Note that there is no requirement that points of self-intersection be a vertex.
* Thus to obtain a correct topology graph, Geometrys must be
* self-noded before constructing their graphs.
*
* Two fundamental operations are supported by topology graphs:
*
* - Computing the intersections between all the edges and nodes of a single graph
*
- Computing the intersections between the edges and nodes of two different graphs
*
*
* @version 1.7
*/
public class PlanarGraph
{
/**
* For nodes in the Collection, link the DirectedEdges at the node that are in the result.
* This allows clients to link only a subset of nodes in the graph, for
* efficiency (because they know that only a subset is of interest).
*/
public static void linkResultDirectedEdges(Collection nodes)
{
for (Iterator nodeit = nodes.iterator(); nodeit.hasNext(); ) {
Node node = (Node) nodeit.next();
((DirectedEdgeStar) node.getEdges()).linkResultDirectedEdges();
}
}
protected List edges = new ArrayList();
protected NodeMap nodes;
protected List edgeEndList = new ArrayList();
public PlanarGraph(NodeFactory nodeFact) {
nodes = new NodeMap(nodeFact);
}
public PlanarGraph() {
nodes = new NodeMap(new NodeFactory());
}
public Iterator getEdgeIterator() { return edges.iterator(); }
public Collection getEdgeEnds() { return edgeEndList; }
public boolean isBoundaryNode(int geomIndex, Coordinate coord)
{
Node node = nodes.find(coord);
if (node == null) return false;
Label label = node.getLabel();
if (label != null && label.getLocation(geomIndex) == Location.BOUNDARY) return true;
return false;
}
protected void insertEdge(Edge e)
{
edges.add(e);
}
public void add(EdgeEnd e)
{
nodes.add(e);
edgeEndList.add(e);
}
public Iterator getNodeIterator() { return nodes.iterator(); }
public Collection getNodes() { return nodes.values(); }
public Node addNode(Node node) { return nodes.addNode(node); }
public Node addNode(Coordinate coord) { return nodes.addNode(coord); }
/**
* @return the node if found; null otherwise
*/
public Node find(Coordinate coord) { return nodes.find(coord); }
/**
* Add a set of edges to the graph. For each edge two DirectedEdges
* will be created. DirectedEdges are NOT linked by this method.
*/
public void addEdges(List edgesToAdd)
{
// create all the nodes for the edges
for (Iterator it = edgesToAdd.iterator(); it.hasNext(); ) {
Edge e = (Edge) it.next();
edges.add(e);
DirectedEdge de1 = new DirectedEdge(e, true);
DirectedEdge de2 = new DirectedEdge(e, false);
de1.setSym(de2);
de2.setSym(de1);
add(de1);
add(de2);
}
}
/**
* Link the DirectedEdges at the nodes of the graph.
* This allows clients to link only a subset of nodes in the graph, for
* efficiency (because they know that only a subset is of interest).
*/
public void linkResultDirectedEdges()
{
for (Iterator nodeit = nodes.iterator(); nodeit.hasNext(); ) {
Node node = (Node) nodeit.next();
((DirectedEdgeStar) node.getEdges()).linkResultDirectedEdges();
}
}
/**
* Link the DirectedEdges at the nodes of the graph.
* This allows clients to link only a subset of nodes in the graph, for
* efficiency (because they know that only a subset is of interest).
*/
public void linkAllDirectedEdges()
{
for (Iterator nodeit = nodes.iterator(); nodeit.hasNext(); ) {
Node node = (Node) nodeit.next();
((DirectedEdgeStar) node.getEdges()).linkAllDirectedEdges();
}
}
/**
* Returns the EdgeEnd which has edge e as its base edge
* (MD 18 Feb 2002 - this should return a pair of edges)
*
* @return the edge, if found
* null if the edge was not found
*/
public EdgeEnd findEdgeEnd(Edge e)
{
for (Iterator i = getEdgeEnds().iterator(); i.hasNext(); ) {
EdgeEnd ee = (EdgeEnd) i.next();
if (ee.getEdge() == e)
return ee;
}
return null;
}
/**
* Returns the edge whose first two coordinates are p0 and p1
*
* @return the edge, if found
* null if the edge was not found
*/
public Edge findEdge(Coordinate p0, Coordinate p1)
{
for (int i = 0; i < edges.size(); i++) {
Edge e = (Edge) edges.get(i);
Coordinate[] eCoord = e.getCoordinates();
if (p0.equals(eCoord[0]) && p1.equals(eCoord[1]) )
return e;
}
return null;
}
/**
* Returns the edge which starts at p0 and whose first segment is
* parallel to p1
*
* @return the edge, if found
* null if the edge was not found
*/
public Edge findEdgeInSameDirection(Coordinate p0, Coordinate p1)
{
for (int i = 0; i < edges.size(); i++) {
Edge e = (Edge) edges.get(i);
Coordinate[] eCoord = e.getCoordinates();
if (matchInSameDirection(p0, p1, eCoord[0], eCoord[1]) )
return e;
if (matchInSameDirection(p0, p1, eCoord[eCoord.length - 1], eCoord[eCoord.length - 2]) )
return e;
}
return null;
}
/**
* The coordinate pairs match if they define line segments lying in the same direction.
* E.g. the segments are parallel and in the same quadrant
* (as opposed to parallel and opposite!).
*/
private boolean matchInSameDirection(Coordinate p0, Coordinate p1, Coordinate ep0, Coordinate ep1)
{
if (! p0.equals(ep0))
return false;
if (CGAlgorithms.computeOrientation(p0, p1, ep1) == CGAlgorithms.COLLINEAR
&& Quadrant.quadrant(p0, p1) == Quadrant.quadrant(ep0, ep1) )
return true;
return false;
}
public void printEdges(PrintStream out)
{
out.println("Edges:");
for (int i = 0; i < edges.size(); i++) {
out.println("edge " + i + ":");
Edge e = (Edge) edges.get(i);
e.print(out);
e.eiList.print(out);
}
}
void debugPrint(Object o)
{
System.out.print(o);
}
void debugPrintln(Object o)
{
System.out.println(o);
}
}