/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2006-2008, Open Source Geospatial Foundation (OSGeo)
*
* 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;
* version 2.1 of the License.
*
* 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.
*/
package org.geotools.resources.coverage;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryCollection;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.MultiPolygon;
import com.vividsolutions.jts.geom.Polygon;
import java.util.ArrayList;
import java.util.List;
import org.geotools.util.Utilities;
/**
* Performs some naive intersections on GeometryCollections, because JTS is not
* supporting them.
*
* @author Emanuele Tajariol (GeoSolutions)
*
*
* @source $URL$
*/
public class IntersectUtils {
/**
* Tests whether the two geometries intersect.
*
* <P>This method relies completely on {@link Geometry#intersects(Geometry)}
* but also tries to unroll <TT>GeometryCollection</TT>s.
*
* @param g1
* @param g2
* @return true if the two geometries intersect.
*/
public static boolean intersects(Geometry g1, Geometry g2) {
Utilities.ensureNonNull("g1", g1);
Utilities.ensureNonNull("g2", g2);
if(g1 instanceof GeometryCollection) {
if(g2 instanceof GeometryCollection) {
return intersects((GeometryCollection)g1, (GeometryCollection)g2);
} else {
return intersects((GeometryCollection)g1, g2);
}
} else {
if(g2 instanceof GeometryCollection) {
return intersects((GeometryCollection)g2, g1);
} else {
return g1.intersects(g2);
}
}
}
/**
* Helper method for {@link #intersects(Geometry, Geometry) intersects(Geometry, Geometry)}
*/
private static boolean intersects(GeometryCollection gc, Geometry g) {
final int size=gc.getNumGeometries();
for (int i = 0; i < size; i++) {
Geometry g1 = (Geometry)gc.getGeometryN(i);
if( g1.intersects(g) )
return true;
}
return false;
}
/**
* Helper method for {@link #intersects(Geometry, Geometry) intersects(Geometry, Geometry)}
*/
private static boolean intersects(GeometryCollection gc1, GeometryCollection gc2) {
final int size=gc1.getNumGeometries();
for (int i = 0; i < size; i++) {
Geometry g1 = (Geometry)gc1.getGeometryN(i);
if( intersects(gc2, g1) )
return true;
}
return false;
}
/**
* Return the intersection of two Geometries.
* <BR>This method relies completely on {@link Geometry#intersection(Geometry)}
* but also tries to unroll <TT>GeometryCollection</TT>s.
*
* @param g1
* @param g2
* @return true if the two geometries intersect.
*/
public static Geometry intersection(Geometry g1, Geometry g2) {
if(g1 instanceof GeometryCollection) {
if(g2 instanceof GeometryCollection) {
return intersection((GeometryCollection)g1, (GeometryCollection)g2);
} else {
List<Geometry> ret = intersection((GeometryCollection)g1, g2);
return g1.getFactory().createGeometryCollection(GeometryFactory.toGeometryArray(ret));
}
} else {
if(g2 instanceof GeometryCollection) {
List<Geometry> ret = intersection((GeometryCollection)g2, g1);
return g1.getFactory().createGeometryCollection(GeometryFactory.toGeometryArray(ret));
} else {
return g1.intersection(g2);
}
}
}
/**
* Helper method for {@link #intersection(Geometry, Geometry) intersection(Geometry, Geometry)}
*/
private static List<Geometry> intersection(GeometryCollection gc, Geometry g) {
List<Geometry> ret = new ArrayList<Geometry>();
final int size=gc.getNumGeometries();
for (int i = 0; i < size; i++) {
Geometry g1 = (Geometry)gc.getGeometryN(i);
collect(g1.intersection(g), ret);
}
return ret;
}
/**
* Helper method for {@link #intersection(Geometry, Geometry) intersection(Geometry, Geometry)}
*/
private static GeometryCollection intersection(GeometryCollection gc1, GeometryCollection gc2) {
List<Geometry> ret = new ArrayList<Geometry>();
final int size=gc1.getNumGeometries();
for (int i = 0; i < size; i++) {
Geometry g1 = (Geometry)gc1.getGeometryN(i);
List<Geometry> partial = intersection(gc2, g1);
ret.addAll(partial);
}
return gc1.getFactory().createGeometryCollection(GeometryFactory.toGeometryArray(ret));
}
/**
* Adds into the <TT>collector</TT> the Geometry <TT>g</TT>, or, if
* <TT>g</TT> is a GeometryCollection, every geometry in it.
*
* @param g the Geometry (or GeometryCollection to unroll)
* @param collector the Collection where the Geometries will be added into
*/
private static void collect(Geometry g, List<Geometry> collector) {
if(g instanceof GeometryCollection) {
GeometryCollection gc = (GeometryCollection)g;
for (int i = 0; i < gc.getNumGeometries(); i++) {
Geometry loop = gc.getGeometryN(i);
if(! loop.isEmpty())
collector.add(loop);
}
} else {
if(! g.isEmpty())
collector.add(g);
}
}
/**
* Flatten all first-level (i.e. non recursively) bundles
* (GeometryCollections and MultiPolygons) into a GeometryCollection.
* <BR>Valid structures:<UL>
* <LI>null -> null</LI>
* <LI>Polygon -> Polygon</LI>
* <LI>MultiPolygon -> GeometryCollection of Polygons</LI>
* <LI>GeometryCollection holding Polygons and MultiPolygons -> GeometryCollection of Polygons</LI>
* </UL>
* @throws IllegalArgumentException when encountering illegal Geometries; message is the Geometry class name.
* @param geometry
* @return
*/
public static Geometry unrollGeometries(Geometry geometry)
throws IllegalArgumentException {
if(geometry == null)
return null;
if(geometry instanceof com.vividsolutions.jts.geom.Polygon) {
return geometry;
} else if(geometry instanceof MultiPolygon) {
MultiPolygon mp = (MultiPolygon)geometry;
return geometry.getFactory().createGeometryCollection(unrollGeometries(mp).toArray(new Geometry[0]));
} else if(geometry instanceof GeometryCollection) {
List<com.vividsolutions.jts.geom.Polygon> ret = new ArrayList<Polygon>();
GeometryCollection gc = (GeometryCollection)geometry;
for (int i = 0; i < gc.getNumGeometries(); i++) {
Geometry g = gc.getGeometryN(i);
if(g instanceof com.vividsolutions.jts.geom.Polygon) {
ret.add((com.vividsolutions.jts.geom.Polygon) g );
} else if(g instanceof MultiPolygon) {
ret.addAll(unrollGeometries((MultiPolygon)g));
} else {
throw new IllegalArgumentException(g.getClass().toString());
}
}
return geometry.getFactory().createGeometryCollection(ret.toArray(new Geometry[0]));
} else {
throw new IllegalArgumentException(geometry.getClass().toString());
}
}
private static List<com.vividsolutions.jts.geom.Polygon> unrollGeometries(MultiPolygon mp) {
List<com.vividsolutions.jts.geom.Polygon> ret = new ArrayList<Polygon>();
for (int i = 0; i < mp.getNumGeometries(); i++) {
com.vividsolutions.jts.geom.Polygon g = (com.vividsolutions.jts.geom.Polygon)mp.getGeometryN(i);
ret.add(g);
}
return ret;
}
}