/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jtslab.clean;
import java.util.ArrayList;
import java.util.List;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.LinearRing;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.geom.prep.PreparedGeometry;
import org.locationtech.jts.geom.prep.PreparedGeometryFactory;
import org.locationtech.jts.geom.util.GeometryMapper;
import org.locationtech.jts.geom.util.GeometryMapper.MapOp;
/**
* Removes holes which are invalid due to not being wholly covered by the parent shell.
* <p>
* Notes:
* <ul>
* <li>Does not remove holes which are invalid due to touching other rings at more than one point
* <li>Does not remove holes which are nested inside another hole
* </ul>
*
* @author Martin Davis
*
*/
public class InvalidHoleRemover {
/**
* Removes invalid holes from the polygons in a geometry.
*
* @param geom the geometry to clean
* @return the geometry with invalid holes removed
*/
public static Geometry clean(Geometry geom) {
InvalidHoleRemover pihr = new InvalidHoleRemover(geom);
return pihr.getResult();
}
private Geometry geom;
/**
* Creates a new invalid hole remover instance.
*
* @param geom the geometry to process
*/
public InvalidHoleRemover(Geometry geom) {
this.geom = geom;
}
/**
* Gets the cleaned geometry.
*
* @return the geometry with invalid holes removed.
*/
public Geometry getResult()
{
return GeometryMapper.map(geom, new InvalidHoleRemoverMapOp());
}
private static class InvalidHoleRemoverMapOp implements MapOp {
public Geometry map(Geometry geom) {
if (geom instanceof Polygon)
return PolygonInvalidHoleRemover.clean((Polygon) geom);
return geom;
}
}
private static class PolygonInvalidHoleRemover {
public static Polygon clean(Polygon poly) {
PolygonInvalidHoleRemover pihr = new PolygonInvalidHoleRemover(poly);
return pihr.getResult();
}
private Polygon poly;
public PolygonInvalidHoleRemover(Polygon poly) {
this.poly = poly;
}
public Polygon getResult()
{
GeometryFactory gf = poly.getFactory();
Polygon shell = gf.createPolygon((LinearRing) poly.getExteriorRing());
PreparedGeometry shellPrep = PreparedGeometryFactory.prepare(shell);
List holes = new ArrayList();
for (int i = 0; i < poly.getNumInteriorRing(); i++) {
LinearRing hole = (LinearRing) poly.getInteriorRingN(i);
if (shellPrep.covers(hole)) {
holes.add(hole);
}
}
// all holes valid, so return original
if (holes.size() == poly.getNumInteriorRing())
return poly;
// return new polygon with covered holes only
Polygon result = gf.createPolygon((LinearRing) poly.getExteriorRing(),
GeometryFactory.toLinearRingArray(holes));
return result;
}
}
}