Class LinearRing

1
2
3	/*
4	* Copyright (c) 2016 Vivid Solutions.
5	*
6	* All rights reserved. This program and the accompanying materials
7	* are made available under the terms of the Eclipse Public License 2.0
8	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
9	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
10	* and the Eclipse Distribution License is available at
11	*
12	* http://www.eclipse.org/org/documents/edl-v10.php.
13	*/
14	package org.locationtech.jts.geom;
15
16	/**
17	* Models an OGC SFS <code>LinearRing</code>.
18	* A <code>LinearRing</code> is a {@link LineString} which is both closed and simple.
19	* In other words,
20	* the first and last coordinate in the ring must be equal,
21	* and the interior of the ring must not self-intersect.
22	* Either orientation of the ring is allowed.
23	* <p>
24	* A ring must have either 0 or 4 or more points.
25	* The first and last points must be equal (in 2D).
26	* If these conditions are not met, the constructors throw
27	* an {@link IllegalArgumentException}
28	*
29	* @version 1.7
30	*/
31	public class LinearRing extends LineString
32	{
33	/**
34	* The minimum number of vertices allowed in a valid non-empty ring (= 4).
35	* Empty rings with 0 vertices are also valid.
36	*/
37	public static final int MINIMUM_VALID_SIZE = 4;
38
39	private static final long serialVersionUID = -4261142084085851829L;
40
41	/**
42	* Constructs a <code>LinearRing</code> with the given points.
43	*
44	*@param points points forming a closed and simple linestring, or
45	* <code>null</code> or an empty array to create the empty geometry.
46	* This array must not contain <code>null</code> elements.
47	*
48	*@param precisionModel the specification of the grid of allowable points
49	* for this <code>LinearRing</code>
50	*@param SRID the ID of the Spatial Reference System used by this
51	* <code>LinearRing</code>
52	* @throws IllegalArgumentException if the ring is not closed, or has too few points
53	*
54	* @deprecated Use GeometryFactory instead
55	*/
56	public LinearRing(Coordinate points[], PrecisionModel precisionModel,
57	int SRID) {
58	this(points, new GeometryFactory(precisionModel, SRID));
59	validateConstruction();
60	}
61
62	/**
63	* This method is ONLY used to avoid deprecation warnings.
64	* @param points
65	* @param factory
66	* @throws IllegalArgumentException if the ring is not closed, or has too few points
67	*/
68	private LinearRing(Coordinate points[], GeometryFactory factory) {
69	this(factory.getCoordinateSequenceFactory().create(points), factory);
70	}
71
72
73	/**
74	* Constructs a <code>LinearRing</code> with the vertices
75	* specified by the given {@link CoordinateSequence}.
76	*
77	*@param points a sequence points forming a closed and simple linestring, or
78	* <code>null</code> to create the empty geometry.
79	*
80	* @throws IllegalArgumentException if the ring is not closed, or has too few points
81	*
82	*/
83	public LinearRing(CoordinateSequence points, GeometryFactory factory) {
84	super(points, factory);
85	validateConstruction();
86	}
87
88	private void validateConstruction() {
89	if (!isEmpty() && ! super.isClosed()) {
90	throw new IllegalArgumentException("Points of LinearRing do not form a closed linestring");
91	}
92	if (getCoordinateSequence().size() >= 1 && getCoordinateSequence().size() < MINIMUM_VALID_SIZE) {
93	throw new IllegalArgumentException("Invalid number of points in LinearRing (found "
94	+ getCoordinateSequence().size() + " - must be 0 or >= 4)");
95	}
96	}
97
98	/**
99	* Returns <code>Dimension.FALSE</code>, since by definition LinearRings do
100	* not have a boundary.
101	*
102	* @return Dimension.FALSE
103	*/
104	public int getBoundaryDimension() {
105	return Dimension.FALSE;
106	}
107
108	/**
109	* Tests whether this ring is closed.
110	* Empty rings are closed by definition.
111	*
112	* @return true if this ring is closed
113	*/
114	public boolean isClosed() {
115	if (isEmpty()) {
116	// empty LinearRings are closed by definition
117	return true;
118	}
119	return super.isClosed();
120	}
121
122
123	public String getGeometryType() {
124	return Geometry.TYPENAME_LINEARRING;
125	}
126
127	protected int getTypeCode() {
128	return Geometry.TYPECODE_LINEARRING;
129	}
130
131	protected LinearRing copyInternal() {
132	return new LinearRing(points.copy(), factory);
133	}
134
135	public LinearRing reverse()
136	{
137	return (LinearRing) super.reverse();
138	}
139
140	public LinearRing reverseInternal() {
141	CoordinateSequence seq = points.copy();
142	CoordinateSequences.reverse(seq);
143	return getFactory().createLinearRing(seq);
144	}
145	}
146