Class DistanceToPointFinder

1	/*
2	* Copyright (c) 2016 Vivid Solutions.
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	package org.locationtech.jts.operation.buffer.validate;
13
14	import org.locationtech.jts.geom.Coordinate;
15	import org.locationtech.jts.geom.Geometry;
16	import org.locationtech.jts.geom.GeometryCollection;
17	import org.locationtech.jts.geom.LineSegment;
18	import org.locationtech.jts.geom.LineString;
19	import org.locationtech.jts.geom.Polygon;
20
21	/**
22	* Computes the Euclidean distance (L2 metric) from a Point to a Geometry.
23	* Also computes two points which are separated by the distance.
24	*/
25	public class DistanceToPointFinder {
26
27	public DistanceToPointFinder() {
28	}
29
30	public static void computeDistance(Geometry geom, Coordinate pt, PointPairDistance ptDist)
31	{
32	if (geom instanceof LineString) {
33	computeDistance((LineString) geom, pt, ptDist);
34	}
35	else if (geom instanceof Polygon) {
36	computeDistance((Polygon) geom, pt, ptDist);
37	}
38	else if (geom instanceof GeometryCollection) {
39	GeometryCollection gc = (GeometryCollection) geom;
40	for (int i = 0; i < gc.getNumGeometries(); i++) {
41	Geometry g = gc.getGeometryN(i);
42	computeDistance(g, pt, ptDist);
43	}
44	}
45	else { // assume geom is Point
46	ptDist.setMinimum(geom.getCoordinate(), pt);
47	}
48	}
49	public static void computeDistance(LineString line, Coordinate pt, PointPairDistance ptDist)
50	{
51	Coordinate[] coords = line.getCoordinates();
52	LineSegment tempSegment = new LineSegment();
53	for (int i = 0; i < coords.length - 1; i++) {
54	tempSegment.setCoordinates(coords[i], coords[i + 1]);
55	// this is somewhat inefficient - could do better
56	Coordinate closestPt = tempSegment.closestPoint(pt);
57	ptDist.setMinimum(closestPt, pt);
58	}
59	}
60
61	public static void computeDistance(LineSegment segment, Coordinate pt, PointPairDistance ptDist)
62	{
63	Coordinate closestPt = segment.closestPoint(pt);
64	ptDist.setMinimum(closestPt, pt);
65	}
66
67	public static void computeDistance(Polygon poly, Coordinate pt, PointPairDistance ptDist)
68	{
69	computeDistance(poly.getExteriorRing(), pt, ptDist);
70	for (int i = 0; i < poly.getNumInteriorRing(); i++) {
71	computeDistance(poly.getInteriorRingN(i), pt, ptDist);
72	}
73	}
74	}
75