svn-gvsig-desktop / trunk / libraries / libFMap / src / com / vividsolutions / jts / operation / overlay / SnapPolygonBuilder.java @ 9178
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/*
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* Created on 09-oct-2006
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*
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* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana
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*
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* Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,USA.
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*
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* For more information, contact:
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*
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* Generalitat Valenciana
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* Conselleria d'Infraestructures i Transport
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* Av. Blasco Ib??ez, 50
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* 46010 VALENCIA
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* SPAIN
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*
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* +34 963862235
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* gvsig@gva.es
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* www.gvsig.gva.es
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*
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* or
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*
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* IVER T.I. S.A
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* Salamanca 50
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* 46005 Valencia
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* Spain
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*
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* +34 963163400
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* dac@iver.es
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*/
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/* CVS MESSAGES:
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*
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* $Id: SnapPolygonBuilder.java 9178 2006-12-04 19:30:23Z azabala $
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* $Log$
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* Revision 1.1 2006-12-04 19:30:23 azabala
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* *** empty log message ***
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*
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* Revision 1.2 2006/10/17 18:25:53 azabala
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* *** empty log message ***
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*
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* Revision 1.1 2006/10/09 19:10:56 azabala
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* First version in CVS
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*
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*
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*/
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package com.vividsolutions.jts.operation.overlay; |
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import java.util.ArrayList; |
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import java.util.Collection; |
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import java.util.Iterator; |
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import java.util.List; |
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import com.vividsolutions.jts.algorithm.CGAlgorithms; |
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import com.vividsolutions.jts.geom.Coordinate; |
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import com.vividsolutions.jts.geom.Envelope; |
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import com.vividsolutions.jts.geom.GeometryFactory; |
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import com.vividsolutions.jts.geom.LinearRing; |
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import com.vividsolutions.jts.geom.Polygon; |
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import com.vividsolutions.jts.geomgraph.DirectedEdge; |
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import com.vividsolutions.jts.geomgraph.EdgeRing; |
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import com.vividsolutions.jts.geomgraph.SnappingPlanarGraph; |
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import com.vividsolutions.jts.operation.overlay.MaximalEdgeRing; |
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import com.vividsolutions.jts.operation.overlay.PolygonBuilder; |
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import com.vividsolutions.jts.util.Assert; |
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public class SnapPolygonBuilder extends PolygonBuilder { |
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private GeometryFactory geometryFactory;
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private CGAlgorithms cga;
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//private List dirEdgeList;
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//private NodeMap nodes;
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private List shellList = new ArrayList(); |
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public SnapPolygonBuilder(GeometryFactory geometryFactory,
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CGAlgorithms cga) |
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{ |
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super(geometryFactory, cga);
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this.geometryFactory = geometryFactory;
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this.cga = cga;
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} |
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/**
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* Add a complete graph.
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* The graph is assumed to contain one or more polygons,
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* possibly with holes.
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*/
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public void add(SnappingPlanarGraph graph) |
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{ |
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add(graph.getEdgeEnds(), graph.getNodes()); |
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} |
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/**
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* Add a set of edges and nodes, which form a graph.
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* The graph is assumed to contain one or more polygons,
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* possibly with holes.
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*/
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public void add(Collection dirEdges, Collection nodes) |
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{ |
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SnappingPlanarGraph.linkResultDirectedEdges(nodes); |
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List maxEdgeRings = buildMaximalEdgeRings(dirEdges);
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List freeHoleList = new ArrayList(); |
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List edgeRings = buildMinimalEdgeRings(maxEdgeRings, shellList, freeHoleList);
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sortShellsAndHoles(edgeRings, shellList, freeHoleList); |
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placeFreeHoles(shellList, freeHoleList); |
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} |
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public List getPolygons() |
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{ |
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List resultPolyList = computePolygons(shellList);
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return resultPolyList;
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} |
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/**
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* for all DirectedEdges in result, form them into MaximalEdgeRings
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*/
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private List buildMaximalEdgeRings(Collection dirEdges) |
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{ |
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List maxEdgeRings = new ArrayList(); |
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for (Iterator it = dirEdges.iterator(); it.hasNext(); ) { |
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DirectedEdge de = (DirectedEdge) it.next(); |
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if (de.isInResult() && de.getLabel().isArea() ) {
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// if this edge has not yet been processed
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if (de.getEdgeRing() == null) { |
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MaximalEdgeRing er = new MaximalEdgeRing(de, geometryFactory, cga);
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maxEdgeRings.add(er); |
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er.setInResult(); |
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// System.out.println("max node degree = " + er.getMaxDegree());
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} |
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} |
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} |
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return maxEdgeRings;
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} |
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private List buildMinimalEdgeRings(List maxEdgeRings, List shellList, List freeHoleList) |
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{ |
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List edgeRings = new ArrayList(); |
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for (Iterator it = maxEdgeRings.iterator(); it.hasNext(); ) { |
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MaximalEdgeRing er = (MaximalEdgeRing) it.next(); |
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if (er.getMaxNodeDegree() > 2) { |
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er.linkDirectedEdgesForMinimalEdgeRings(); |
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List minEdgeRings = er.buildMinimalRings();
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// at this point we can go ahead and attempt to place holes, if this EdgeRing is a polygon
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EdgeRing shell = findShell(minEdgeRings); |
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if (shell != null) { |
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placePolygonHoles(shell, minEdgeRings); |
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shellList.add(shell); |
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} |
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else {
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freeHoleList.addAll(minEdgeRings); |
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} |
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} |
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else {
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edgeRings.add(er); |
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} |
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} |
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return edgeRings;
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} |
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/**
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* This method takes a list of MinimalEdgeRings derived from a MaximalEdgeRing,
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* and tests whether they form a Polygon. This is the case if there is a single shell
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* in the list. In this case the shell is returned.
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* The other possibility is that they are a series of connected holes, in which case
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* no shell is returned.
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*
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* @return the shell EdgeRing, if there is one
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* @return null, if all the rings are holes
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*/
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private EdgeRing findShell(List minEdgeRings) |
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{ |
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int shellCount = 0; |
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EdgeRing shell = null;
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for (Iterator it = minEdgeRings.iterator(); it.hasNext(); ) { |
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EdgeRing er = (MinimalEdgeRing) it.next(); |
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if (! er.isHole()) {
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shell = er; |
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shellCount++; |
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} |
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} |
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Assert.isTrue(shellCount <= 1, "found two shells in MinimalEdgeRing list"); |
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return shell;
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} |
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/**
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* This method assigns the holes for a Polygon (formed from a list of
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* MinimalEdgeRings) to its shell.
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* Determining the holes for a MinimalEdgeRing polygon serves two purposes:
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* <ul>
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* <li>it is faster than using a point-in-polygon check later on.
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* <li>it ensures correctness, since if the PIP test was used the point
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* chosen might lie on the shell, which might return an incorrect result from the
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* PIP test
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* </ul>
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*/
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private void placePolygonHoles(EdgeRing shell, List minEdgeRings) |
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{ |
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for (Iterator it = minEdgeRings.iterator(); it.hasNext(); ) { |
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MinimalEdgeRing er = (MinimalEdgeRing) it.next(); |
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if (er.isHole()) {
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er.setShell(shell); |
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} |
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} |
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} |
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/**
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* For all rings in the input list,
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* determine whether the ring is a shell or a hole
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* and add it to the appropriate list.
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* Due to the way the DirectedEdges were linked,
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* a ring is a shell if it is oriented CW, a hole otherwise.
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*/
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private void sortShellsAndHoles(List edgeRings, List shellList, List freeHoleList) |
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{ |
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for (Iterator it = edgeRings.iterator(); it.hasNext(); ) { |
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EdgeRing er = (EdgeRing) it.next(); |
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// er.setInResult();
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if (er.isHole() ) {
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freeHoleList.add(er); |
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} |
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else {
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shellList.add(er); |
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} |
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} |
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} |
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/**
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* This method determines finds a containing shell for all holes
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* which have not yet been assigned to a shell.
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* These "free" holes should
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* all be <b>properly</b> contained in their parent shells, so it is safe to use the
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* <code>findEdgeRingContaining</code> method.
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* (This is the case because any holes which are NOT
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* properly contained (i.e. are connected to their
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* parent shell) would have formed part of a MaximalEdgeRing
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* and been handled in a previous step).
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*/
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private void placeFreeHoles(List shellList, List freeHoleList) |
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{ |
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for (Iterator it = freeHoleList.iterator(); it.hasNext(); ) { |
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EdgeRing hole = (EdgeRing) it.next(); |
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// only place this hole if it doesn't yet have a shell
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if (hole.getShell() == null) { |
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EdgeRing shell = findEdgeRingContaining(hole, shellList); |
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Assert.isTrue(shell != null, "unable to assign hole to a shell"); |
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hole.setShell(shell); |
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} |
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} |
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} |
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/**
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* Find the innermost enclosing shell EdgeRing containing the argument EdgeRing, if any.
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* The innermost enclosing ring is the <i>smallest</i> enclosing ring.
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* The algorithm used depends on the fact that:
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* <br>
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* ring A contains ring B iff envelope(ring A) contains envelope(ring B)
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* <br>
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* This routine is only safe to use if the chosen point of the hole
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* is known to be properly contained in a shell
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* (which is guaranteed to be the case if the hole does not touch its shell)
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*
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* @return containing EdgeRing, if there is one
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* @return null if no containing EdgeRing is found
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*/
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//TODO Estudiar como meter el snapping
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private EdgeRing findEdgeRingContaining(EdgeRing testEr, List shellList) |
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{ |
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LinearRing testRing = testEr.getLinearRing(); |
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Envelope testEnv = testRing.getEnvelopeInternal(); |
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Coordinate testPt = testRing.getCoordinateN(0);
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EdgeRing minShell = null;
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Envelope minEnv = null;
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for (Iterator it = shellList.iterator(); it.hasNext(); ) { |
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EdgeRing tryShell = (EdgeRing) it.next(); |
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LinearRing tryRing = tryShell.getLinearRing(); |
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Envelope tryEnv = tryRing.getEnvelopeInternal(); |
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if (minShell != null) minEnv = minShell.getLinearRing().getEnvelopeInternal(); |
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boolean isContained = false; |
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if (tryEnv.contains(testEnv)
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&& CGAlgorithms.isPointInRing(testPt, tryRing.getCoordinates()) ) |
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isContained = true;
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// check if this new containing ring is smaller than the current minimum ring
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if (isContained) {
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if (minShell == null |
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|| minEnv.contains(tryEnv)) { |
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minShell = tryShell; |
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} |
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} |
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} |
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return minShell;
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} |
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private List computePolygons(List shellList) |
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{ |
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List resultPolyList = new ArrayList(); |
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// add Polygons for all shells
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for (Iterator it = shellList.iterator(); it.hasNext(); ) { |
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EdgeRing er = (EdgeRing) it.next(); |
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Polygon poly = er.toPolygon(geometryFactory);
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resultPolyList.add(poly); |
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} |
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return resultPolyList;
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} |
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/**
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* Checks the current set of shells (with their associated holes) to
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* see if any of them contain the point.
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*/
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//TODO METER SNAPPING
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public boolean containsPoint(Coordinate p) |
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{ |
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for (Iterator it = shellList.iterator(); it.hasNext(); ) { |
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EdgeRing er = (EdgeRing) it.next(); |
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if (er.containsPoint(p))
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return true; |
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} |
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return false; |
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} |
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} |
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