com.vividsolutions.jts.operation.relate.RelateNodeGraph 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.operation.relate;
/**
* @version 1.7
*/
import java.util.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.util.*;
import com.vividsolutions.jts.geomgraph.*;
/**
* Implements the simple graph of Nodes and EdgeEnd which is all that is
* required to determine topological relationships between Geometries.
* Also supports building a topological graph of a single Geometry, to
* allow verification of valid topology.
*
* It is not necessary to create a fully linked
* PlanarGraph to determine relationships, since it is sufficient
* to know how the Geometries interact locally around the nodes.
* In fact, this is not even feasible, since it is not possible to compute
* exact intersection points, and hence the topology around those nodes
* cannot be computed robustly.
* The only Nodes that are created are for improper intersections;
* that is, nodes which occur at existing vertices of the Geometries.
* Proper intersections (e.g. ones which occur between the interior of line segments)
* have their topology determined implicitly, without creating a Node object
* to represent them.
*
* @version 1.7
*/
public class RelateNodeGraph {
private NodeMap nodes = new NodeMap(new RelateNodeFactory());
public RelateNodeGraph() {
}
public Iterator getNodeIterator() { return nodes.iterator(); }
public void build(GeometryGraph geomGraph)
{
// compute nodes for intersections between previously noded edges
computeIntersectionNodes(geomGraph, 0);
/**
* Copy the labelling for the nodes in the parent Geometry. These override
* any labels determined by intersections.
*/
copyNodesAndLabels(geomGraph, 0);
/**
* Build EdgeEnds for all intersections.
*/
EdgeEndBuilder eeBuilder = new EdgeEndBuilder();
List eeList = eeBuilder.computeEdgeEnds(geomGraph.getEdgeIterator());
insertEdgeEnds(eeList);
//Debug.println("==== NodeList ===");
//Debug.print(nodes);
}
/**
* Insert nodes for all intersections on the edges of a Geometry.
* Label the created nodes the same as the edge label if they do not already have a label.
* This allows nodes created by either self-intersections or
* mutual intersections to be labelled.
* Endpoint nodes will already be labelled from when they were inserted.
*
* Precondition: edge intersections have been computed.
*/
public void computeIntersectionNodes(GeometryGraph geomGraph, int argIndex)
{
for (Iterator edgeIt = geomGraph.getEdgeIterator(); edgeIt.hasNext(); ) {
Edge e = (Edge) edgeIt.next();
int eLoc = e.getLabel().getLocation(argIndex);
for (Iterator eiIt = e.getEdgeIntersectionList().iterator(); eiIt.hasNext(); ) {
EdgeIntersection ei = (EdgeIntersection) eiIt.next();
RelateNode n = (RelateNode) nodes.addNode(ei.coord);
if (eLoc == Location.BOUNDARY)
n.setLabelBoundary(argIndex);
else {
if (n.getLabel().isNull(argIndex))
n.setLabel(argIndex, Location.INTERIOR);
}
//Debug.println(n);
}
}
}
/**
* Copy all nodes from an arg geometry into this graph.
* The node label in the arg geometry overrides any previously computed
* label for that argIndex.
* (E.g. a node may be an intersection node with
* a computed label of BOUNDARY,
* but in the original arg Geometry it is actually
* in the interior due to the Boundary Determination Rule)
*/
public void copyNodesAndLabels(GeometryGraph geomGraph, int argIndex)
{
for (Iterator nodeIt = geomGraph.getNodeIterator(); nodeIt.hasNext(); ) {
Node graphNode = (Node) nodeIt.next();
Node newNode = nodes.addNode(graphNode.getCoordinate());
newNode.setLabel(argIndex, graphNode.getLabel().getLocation(argIndex));
//node.print(System.out);
}
}
public void insertEdgeEnds(List ee)
{
for (Iterator i = ee.iterator(); i.hasNext(); ) {
EdgeEnd e = (EdgeEnd) i.next();
nodes.add(e);
}
}
}