Class FuzzyPointLocator

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
13	package org.locationtech.jts.operation.overlay.validate;
14
15	import java.util.ArrayList;
16	import java.util.List;
17
18	import org.locationtech.jts.algorithm.PointLocator;
19	import org.locationtech.jts.geom.Coordinate;
20	import org.locationtech.jts.geom.CoordinateSequence;
21	import org.locationtech.jts.geom.Geometry;
22	import org.locationtech.jts.geom.GeometryFactory;
23	import org.locationtech.jts.geom.GeometryFilter;
24	import org.locationtech.jts.geom.LineSegment;
25	import org.locationtech.jts.geom.LineString;
26	import org.locationtech.jts.geom.Location;
27	import org.locationtech.jts.geom.MultiLineString;
28	import org.locationtech.jts.geom.Polygon;
29
30	/**
31	* Finds the most likely {@link Location} of a point relative to
32	* the polygonal components of a geometry, using a tolerance value.
33	* If a point is not clearly in the Interior or Exterior,
34	* it is considered to be on the Boundary.
35	* In other words, if the point is within the tolerance of the Boundary,
36	* it is considered to be on the Boundary; otherwise,
37	* whether it is Interior or Exterior is determined directly.
38	*
39	* @author Martin Davis
40	* @version 1.7
41	*/
42	public class FuzzyPointLocator
43	{
44	private Geometry g;
45	private double boundaryDistanceTolerance;
46	private MultiLineString linework;
47	private PointLocator ptLocator = new PointLocator();
48	private LineSegment seg = new LineSegment();
49
50	public FuzzyPointLocator(Geometry g, double boundaryDistanceTolerance)
51	{
52	this.g = g;
53	this.boundaryDistanceTolerance = boundaryDistanceTolerance;
54	linework = extractLinework(g);
55	}
56
57	public int getLocation(Coordinate pt)
58	{
59	if (isWithinToleranceOfBoundary(pt))
60	return Location.BOUNDARY;
61	/*
62	double dist = linework.distance(point);
63
64	// if point is close to boundary, it is considered to be on the boundary
65	if (dist < tolerance)
66	return Location.BOUNDARY;
67	*/
68
69	// now we know point must be clearly inside or outside geometry, so return actual location value
70	return ptLocator.locate(pt, g);
71	}
72
73	/**
74	* Extracts linework for polygonal components.
75	*
76	* @param g the geometry from which to extract
77	* @return a lineal geometry containing the extracted linework
78	*/
79	private MultiLineString extractLinework(Geometry g)
80	{
81	PolygonalLineworkExtracter extracter = new PolygonalLineworkExtracter();
82	g.apply(extracter);
83	List linework = extracter.getLinework();
84	LineString[] lines = GeometryFactory.toLineStringArray(linework);
85	return g.getFactory().createMultiLineString(lines);
86	}
87
88	private boolean isWithinToleranceOfBoundary(Coordinate pt)
89	{
90	for (int i = 0; i < linework.getNumGeometries(); i++) {
91	LineString line = (LineString) linework.getGeometryN(i);
92	CoordinateSequence seq = line.getCoordinateSequence();
93	for (int j = 0; j < seq.size() - 1; j++) {
94	seq.getCoordinate(j, seg.p0);
95	seq.getCoordinate(j + 1, seg.p1);
96	double dist = seg.distance(pt);
97	if (dist <= boundaryDistanceTolerance)
98	return true;
99	}
100	}
101	return false;
102	}
103	}
104
105	/**
106	* Extracts the LineStrings in the boundaries
107	* of all the polygonal elements in the target {@link Geometry}.
108	*
109	* @author Martin Davis
110	*/
111	class PolygonalLineworkExtracter
112	implements GeometryFilter
113	{
114	private List linework;
115
116	public PolygonalLineworkExtracter()
117	{
118	linework = new ArrayList();
119	}
120
121	/**
122	* Filters out all linework for polygonal elements
123	*/
124	public void filter(Geometry g)
125	{
126	if (g instanceof Polygon) {
127	Polygon poly = (Polygon) g;
128	linework.add(poly.getExteriorRing());
129	for (int i = 0; i < poly.getNumInteriorRing(); i++) {
130	linework.add(poly.getInteriorRingN(i));
131	}
132	}
133	}
134
135	/**
136	* Gets the list of polygonal linework.
137	*
138	* @return a List of LineStrings
139	*/
140	public List getLinework() { return linework; }
141	}
142