SimplePointInAreaLocator.java
/*
* 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 2.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jts.algorithm.locate;
import java.util.Iterator;
import org.locationtech.jts.algorithm.PointLocation;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryCollection;
import org.locationtech.jts.geom.GeometryCollectionIterator;
import org.locationtech.jts.geom.LinearRing;
import org.locationtech.jts.geom.Location;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.geom.Polygonal;
/**
* Computes the location of points
* relative to a {@link Polygonal} {@link Geometry},
* using a simple <tt>O(n)</tt> algorithm.
* <p>
* The algorithm used reports
* if a point lies in the interior, exterior,
* or exactly on the boundary of the Geometry.
* <p>
* Instance methods are provided to implement
* the interface {@link SimplePointInAreaLocator}.
* However, they provide no performance
* advantage over the class methods.
* <p>
* This algorithm is suitable for use in cases where
* only a few points will be tested.
* If many points will be tested,
* {@link IndexedPointInAreaLocator} may provide better performance.
*
* @version 1.7
*/
public class SimplePointInAreaLocator
implements PointOnGeometryLocator
{
/**
* Determines the {@link Location} of a point in an areal {@link Geometry}.
* The return value is one of:
* <ul>
* <li>{@link Location#INTERIOR} if the point is in the geometry interior
* <li>{@link Location#BOUNDARY} if the point lies exactly on the boundary
* <li>{@link Location#EXTERIOR} if the point is outside the geometry
* </ul>
*
* @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;
/**
* Do a fast check against the geometry envelope first
*/
if (! geom.getEnvelopeInternal().intersects(p))
return Location.EXTERIOR;
return locateInGeometry(p, geom);
}
/**
* Determines whether a point is contained in a {@link Geometry},
* or lies on its boundary.
* This is a convenience method for
* <pre>
* Location.EXTERIOR != locate(p, geom)
* </pre>
*
* @param p the point to test
* @param geom the geometry to test
* @return true if the point lies in or on the geometry
*/
public static boolean isContained(Coordinate p, Geometry geom) {
return Location.EXTERIOR != locate(p, geom);
}
private static int locateInGeometry(Coordinate p, Geometry geom)
{
if (geom instanceof Polygon) {
return locatePointInPolygon(p, (Polygon) geom);
}
if (geom instanceof GeometryCollection) {
Iterator geomi = new GeometryCollectionIterator((GeometryCollection) geom);
while (geomi.hasNext()) {
Geometry g2 = (Geometry) geomi.next();
if (g2 != geom) {
int loc = locateInGeometry(p, g2);
if (loc != Location.EXTERIOR) return loc;
}
}
}
return Location.EXTERIOR;
}
/**
* Determines the {@link Location} of a point in a {@link Polygon}.
* The return value is one of:
* <ul>
* <li>{@link Location#INTERIOR} if the point is in the geometry interior
* <li>{@link Location#BOUNDARY} if the point lies exactly on the boundary
* <li>{@link Location#EXTERIOR} if the point is outside the geometry
* </ul>
*
* This method is provided for backwards compatibility only.
* Use {@link #locate(Coordinate, Geometry)} instead.
*
* @param p the point to test
* @param poly the geometry to test
* @return the Location of the point in the polygon
*
*/
public static int locatePointInPolygon(Coordinate p, Polygon poly)
{
if (poly.isEmpty()) return Location.EXTERIOR;
LinearRing shell = poly.getExteriorRing();
int shellLoc = locatePointInRing(p, shell);
if (shellLoc != Location.INTERIOR) return shellLoc;
// now test if the point lies in or on the holes
for (int i = 0; i < poly.getNumInteriorRing(); i++) {
LinearRing hole = poly.getInteriorRingN(i);
int holeLoc = locatePointInRing(p, hole);
if (holeLoc == Location.BOUNDARY) return Location.BOUNDARY;
if (holeLoc == Location.INTERIOR) return Location.EXTERIOR;
// if in EXTERIOR of this hole keep checking the other ones
}
// If not in any hole must be inside polygon
return Location.INTERIOR;
}
/**
* Determines whether a point lies in a {@link Polygon}.
* If the point lies on the polygon boundary it is
* considered to be inside.
*
* @param p the point to test
* @param poly the geometry to test
* @return true if the point lies in or on the polygon
*/
public static boolean containsPointInPolygon(Coordinate p, Polygon poly) {
return Location.EXTERIOR != locatePointInPolygon(p, poly);
}
/**
* 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 int locatePointInRing(Coordinate p, LinearRing ring)
{
// short-circuit if point is not in ring envelope
if (! ring.getEnvelopeInternal().intersects(p))
return Location.EXTERIOR;
return PointLocation.locateInRing(p, ring.getCoordinates());
}
private Geometry geom;
/**
* Create an instance of a point-in-area locator,
* using the provided areal geometry.
*
* @param geom the areal geometry to locate in
*/
public SimplePointInAreaLocator(Geometry geom) {
this.geom = geom;
}
/**
* Determines the {@link Location} of a point in an areal {@link Geometry}.
* The return value is one of:
* <ul>
* <li>{@link Location#INTERIOR} if the point is in the geometry interior
* <li>{@link Location#BOUNDARY} if the point lies exactly on the boundary
* <li>{@link Location#EXTERIOR} if the point is outside the geometry
* </ul>
*
* @param p the point to test
* @return the Location of the point in the geometry
*/
public int locate(Coordinate p) {
return SimplePointInAreaLocator.locate(p, geom);
}
}