/* * 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. * <p> * It is <b>not</b> 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. * <p> * 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); } } }