/*
* 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.valid;
import java.util.*;
import com.vividsolutions.jts.algorithm.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geomgraph.*;
import com.vividsolutions.jts.geomgraph.index.SegmentIntersector;
import com.vividsolutions.jts.operation.relate.*;
import com.vividsolutions.jts.util.*;
/**
* Checks that a {@link GeometryGraph} representing an area
* (a {@link Polygon} or {@link MultiPolygon} )
* has consistent semantics for area geometries.
* This check is required for any reasonable polygonal model
* (including the OGC-SFS model, as well as models which allow ring self-intersection at single points)
* <p>
* Checks include:
* <ul>
* <li>test for rings which properly intersect
* (but not for ring self-intersection, or intersections at vertices)
* <li>test for consistent labelling at all node points
* (this detects vertex intersections with invalid topology,
* i.e. where the exterior side of an edge lies in the interior of the area)
* <li>test for duplicate rings
* </ul>
* If an inconsistency is found the location of the problem
* is recorded and is available to the caller.
*
* @version 1.7
*/
public class ConsistentAreaTester {
private final LineIntersector li = new RobustLineIntersector();
private GeometryGraph geomGraph;
private RelateNodeGraph nodeGraph = new RelateNodeGraph();
// the intersection point found (if any)
private Coordinate invalidPoint;
/**
* Creates a new tester for consistent areas.
*
* @param geomGraph the topology graph of the area geometry
*/
public ConsistentAreaTester(GeometryGraph geomGraph)
{
this.geomGraph = geomGraph;
}
/**
* @return the intersection point, or <code>null</code> if none was found
*/
public Coordinate getInvalidPoint() { return invalidPoint; }
/**
* Check all nodes to see if their labels are consistent with area topology.
*
* @return <code>true</code> if this area has a consistent node labelling
*/
public boolean isNodeConsistentArea()
{
/**
* To fully check validity, it is necessary to
* compute ALL intersections, including self-intersections within a single edge.
*/
SegmentIntersector intersector = geomGraph.computeSelfNodes(li, true);
if (intersector.hasProperIntersection()) {
invalidPoint = intersector.getProperIntersectionPoint();
return false;
}
nodeGraph.build(geomGraph);
return isNodeEdgeAreaLabelsConsistent();
}
/**
* Check all nodes to see if their labels are consistent.
* If any are not, return false
*
* @return <code>true</code> if the edge area labels are consistent at this node
*/
private boolean isNodeEdgeAreaLabelsConsistent()
{
for (Iterator nodeIt = nodeGraph.getNodeIterator(); nodeIt.hasNext(); ) {
RelateNode node = (RelateNode) nodeIt.next();
if (! node.getEdges().isAreaLabelsConsistent(geomGraph)) {
invalidPoint = (Coordinate) node.getCoordinate().clone();
return false;
}
}
return true;
}
/**
* Checks for two duplicate rings in an area.
* Duplicate rings are rings that are topologically equal
* (that is, which have the same sequence of points up to point order).
* If the area is topologically consistent (determined by calling the
* <code>isNodeConsistentArea</code>,
* duplicate rings can be found by checking for EdgeBundles which contain
* more than one EdgeEnd.
* (This is because topologically consistent areas cannot have two rings sharing
* the same line segment, unless the rings are equal).
* The start point of one of the equal rings will be placed in
* invalidPoint.
*
* @return true if this area Geometry is topologically consistent but has two duplicate rings
*/
public boolean hasDuplicateRings()
{
for (Iterator nodeIt = nodeGraph.getNodeIterator(); nodeIt.hasNext(); ) {
RelateNode node = (RelateNode) nodeIt.next();
for (Iterator i = node.getEdges().iterator(); i.hasNext(); ) {
EdgeEndBundle eeb = (EdgeEndBundle) i.next();
if (eeb.getEdgeEnds().size() > 1) {
invalidPoint = eeb.getEdge().getCoordinate(0);
return true;
}
}
}
return false;
}
}