com.vividsolutions.jts.algorithm.locate.SimplePointInAreaLocator Maven / Gradle / Ivy
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/*
* 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.algorithm.locate;
import java.util.Iterator;
import com.vividsolutions.jts.algorithm.CGAlgorithms;
import com.vividsolutions.jts.geom.*;
/**
* Computes the location of points
* relative to a {@link Polygonal} {@link Geometry},
* using a simple O(n) algorithm.
* This algorithm is suitable for use in cases where
* only one or a few points will be tested against a given area.
*
* The algorithm used is only guaranteed to return correct results
* for points which are not on the boundary of the Geometry.
*
* @version 1.7
*/
public class SimplePointInAreaLocator
implements PointOnGeometryLocator
{
/**
* Determines the {@link Location} of a point in an areal {@link Geometry}.
* Currently this will never return a value of BOUNDARY.
*
* @param p the point to test
* @param geom the areal geometry to test
* @return the Location of the point in the geometry
*/
public static int locate(Coordinate p, Geometry geom)
{
if (geom.isEmpty()) return Location.EXTERIOR;
if (containsPoint(p, geom))
return Location.INTERIOR;
return Location.EXTERIOR;
}
private static boolean containsPoint(Coordinate p, Geometry geom)
{
if (geom instanceof Polygon) {
return containsPointInPolygon(p, (Polygon) geom);
}
else if (geom instanceof GeometryCollection) {
Iterator geomi = new GeometryCollectionIterator((GeometryCollection) geom);
while (geomi.hasNext()) {
Geometry g2 = (Geometry) geomi.next();
if (g2 != geom)
if (containsPoint(p, g2))
return true;
}
}
return false;
}
public static boolean containsPointInPolygon(Coordinate p, Polygon poly)
{
if (poly.isEmpty()) return false;
LinearRing shell = (LinearRing) poly.getExteriorRing();
if (! isPointInRing(p, shell)) return false;
// now test if the point lies in or on the holes
for (int i = 0; i < poly.getNumInteriorRing(); i++) {
LinearRing hole = (LinearRing) poly.getInteriorRingN(i);
if (isPointInRing(p, hole)) return false;
}
return true;
}
/**
* Determines whether a point lies in a LinearRing,
* using the ring envelope to short-circuit if possible.
*
* @param p the point to test
* @param ring a linear ring
* @return true if the point lies inside the ring
*/
private static boolean isPointInRing(Coordinate p, LinearRing ring)
{
// short-circuit if point is not in ring envelope
if (! ring.getEnvelopeInternal().intersects(p))
return false;
return CGAlgorithms.isPointInRing(p, ring.getCoordinates());
}
private Geometry geom;
public SimplePointInAreaLocator(Geometry geom) {
this.geom = geom;
}
public int locate(Coordinate p) {
return SimplePointInAreaLocator.locate(p, geom);
}
}