/* * 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. * <p> * The algorithm used is only guaranteed to return correct results * for points which are <b>not</b> 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); } }