Class MaximalEdgeRing

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.operation.overlay;
15
16	import java.util.ArrayList;
17	import java.util.List;
18
19	import org.locationtech.jts.geom.GeometryFactory;
20	import org.locationtech.jts.geomgraph.DirectedEdge;
21	import org.locationtech.jts.geomgraph.DirectedEdgeStar;
22	import org.locationtech.jts.geomgraph.EdgeRing;
23	import org.locationtech.jts.geomgraph.Node;
24
25	/**
26	* A ring of {@link DirectedEdge}s which may contain nodes of degree > 2.
27	* A <tt>MaximalEdgeRing</tt> may represent two different spatial entities:
28	* <ul>
29	* <li>a single polygon possibly containing inversions (if the ring is oriented CW)
30	* <li>a single hole possibly containing exversions (if the ring is oriented CCW)
31	* </ul>
32	* If the MaximalEdgeRing represents a polygon,
33	* the interior of the polygon is strongly connected.
34	* <p>
35	* These are the form of rings used to define polygons under some spatial data models.
36	* However, under the OGC SFS model, {@link MinimalEdgeRing}s are required.
37	* A MaximalEdgeRing can be converted to a list of MinimalEdgeRings using the
38	* {@link #buildMinimalRings() } method.
39	*
40	* @version 1.7
41	* @see org.locationtech.jts.operation.overlay.MinimalEdgeRing
42	*/
43	public class MaximalEdgeRing
44	extends EdgeRing
45	{
46
47	public MaximalEdgeRing(DirectedEdge start, GeometryFactory geometryFactory) {
48	super(start, geometryFactory);
49	}
50
51	public DirectedEdge getNext(DirectedEdge de)
52	{
53	return de.getNext();
54	}
55	public void setEdgeRing(DirectedEdge de, EdgeRing er)
56	{
57	de.setEdgeRing(er);
58	}
59
60	/**
61	* For all nodes in this EdgeRing,
62	* link the DirectedEdges at the node to form minimalEdgeRings
63	*/
64	public void linkDirectedEdgesForMinimalEdgeRings()
65	{
66	DirectedEdge de = startDe;
67	do {
68	Node node = de.getNode();
69	((DirectedEdgeStar) node.getEdges()).linkMinimalDirectedEdges(this);
70	de = de.getNext();
71	} while (de != startDe);
72	}
73
74	public List buildMinimalRings()
75	{
76	List minEdgeRings = new ArrayList();
77	DirectedEdge de = startDe;
78	do {
79	if (de.getMinEdgeRing() == null) {
80	EdgeRing minEr = new MinimalEdgeRing(de, geometryFactory);
81	minEdgeRings.add(minEr);
82	}
83	de = de.getNext();
84	} while (de != startDe);
85	return minEdgeRings;
86	}
87
88	}
89