Class GeometryItemDistance

1	/*
2	* Copyright (c) 2016 Martin Davis.
3	*
4	* All rights reserved. This program and the accompanying materials
5	* are made available under the terms of the Eclipse Public License 2.0
6	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
7	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
8	* and the Eclipse Distribution License is available at
9	*
10	* http://www.eclipse.org/org/documents/edl-v10.php.
11	*/
12
13	package org.locationtech.jts.index.strtree;
14
15	import org.locationtech.jts.geom.Geometry;
16
17	/**
18	* An {@link ItemDistance} function for
19	* items which are {@link Geometry}s,
20	* using the {@link Geometry#distance(Geometry)} method.
21	* <p>
22	* To make this distance function suitable for
23	* using to query a single index tree,
24	* the distance metric is <i>anti-reflexive</i>.
25	* That is, if the two arguments are the same Geometry object,
26	* the distance returned is {@link Double.MAX_VALUE}.
27	*
28	* @author Martin Davis
29	*
30	*/
31	public class GeometryItemDistance
32	implements ItemDistance
33	{
34	/**
35	* Computes the distance between two {@link Geometry} items,
36	* using the {@link Geometry#distance(Geometry)} method.
37	*
38	* @param item1 an item which is a Geometry
39	* @param item2 an item which is a Geometry
40	* @return the distance between the geometries
41	* @throws ClassCastException if either item is not a Geometry
42	*/
43	public double distance(ItemBoundable item1, ItemBoundable item2) {
44	if (item1 == item2) return Double.MAX_VALUE;
45	Geometry g1 = (Geometry) item1.getItem();
46	Geometry g2 = (Geometry) item2.getItem();
47	return g1.distance(g2);
48	}
49	}
50
51