Class Node

1
2
3
4	/*
5	* Copyright (c) 2016 Vivid Solutions.
6	*
7	* All rights reserved. This program and the accompanying materials
8	* are made available under the terms of the Eclipse Public License 2.0
9	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
10	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
11	* and the Eclipse Distribution License is available at
12	*
13	* http://www.eclipse.org/org/documents/edl-v10.php.
14	*/
15	package org.locationtech.jts.geomgraph;
16
17	import java.io.PrintStream;
18	import java.util.Iterator;
19
20	import org.locationtech.jts.geom.Coordinate;
21	import org.locationtech.jts.geom.IntersectionMatrix;
22	import org.locationtech.jts.geom.Location;
23
24
25	/**
26	* @version 1.7
27	*/
28	public class Node
29	extends GraphComponent
30	{
31	protected Coordinate coord; // only non-null if this node is precise
32	protected EdgeEndStar edges;
33
34	public Node(Coordinate coord, EdgeEndStar edges)
35	{
36	this.coord = coord;
37	this.edges = edges;
38	label = new Label(0, Location.NONE);
39	}
40
41	public Coordinate getCoordinate() { return coord; }
42	public EdgeEndStar getEdges() { return edges; }
43
44	/**
45	* Tests whether any incident edge is flagged as
46	* being in the result.
47	* This test can be used to determine if the node is in the result,
48	* since if any incident edge is in the result, the node must be in the result as well.
49	*
50	* @return <code>true</code> if any incident edge in the in the result
51	*/
52	public boolean isIncidentEdgeInResult()
53	{
54	for (Iterator it = getEdges().getEdges().iterator(); it.hasNext(); ) {
55	DirectedEdge de = (DirectedEdge) it.next();
56	if (de.getEdge().isInResult())
57	return true;
58	}
59	return false;
60	}
61
62	public boolean isIsolated()
63	{
64	return (label.getGeometryCount() == 1);
65	}
66	/**
67	* Basic nodes do not compute IMs
68	*/
69	protected void computeIM(IntersectionMatrix im) {}
70	/**
71	* Add the edge to the list of edges at this node
72	*/
73	public void add(EdgeEnd e)
74	{
75	// Assert: start pt of e is equal to node point
76	edges.insert(e);
77	e.setNode(this);
78	}
79
80	public void mergeLabel(Node n)
81	{
82	mergeLabel(n.label);
83	}
84
85	/**
86	* To merge labels for two nodes,
87	* the merged location for each LabelElement is computed.
88	* The location for the corresponding node LabelElement is set to the result,
89	* as long as the location is non-null.
90	*/
91
92	public void mergeLabel(Label label2)
93	{
94	for (int i = 0; i < 2; i++) {
95	int loc = computeMergedLocation(label2, i);
96	int thisLoc = label.getLocation(i);
97	if (thisLoc == Location.NONE) label.setLocation(i, loc);
98	}
99	}
100
101	public void setLabel(int argIndex, int onLocation)
102	{
103	if (label == null) {
104	label = new Label(argIndex, onLocation);
105	}
106	else
107	label.setLocation(argIndex, onLocation);
108	}
109
110	/**
111	* Updates the label of a node to BOUNDARY,
112	* obeying the mod-2 boundaryDetermination rule.
113	*/
114	public void setLabelBoundary(int argIndex)
115	{
116	if (label == null) return;
117
118	// determine the current location for the point (if any)
119	int loc = Location.NONE;
120	if (label != null)
121	loc = label.getLocation(argIndex);
122	// flip the loc
123	int newLoc;
124	switch (loc) {
125	case Location.BOUNDARY: newLoc = Location.INTERIOR; break;
126	case Location.INTERIOR: newLoc = Location.BOUNDARY; break;
127	default: newLoc = Location.BOUNDARY; break;
128	}
129	label.setLocation(argIndex, newLoc);
130	}
131
132	/**
133	* The location for a given eltIndex for a node will be one
134	* of { null, INTERIOR, BOUNDARY }.
135	* A node may be on both the boundary and the interior of a geometry;
136	* in this case, the rule is that the node is considered to be in the boundary.
137	* The merged location is the maximum of the two input values.
138	*/
139	int computeMergedLocation(Label label2, int eltIndex)
140	{
141	int loc = Location.NONE;
142	loc = label.getLocation(eltIndex);
143	if (! label2.isNull(eltIndex)) {
144	int nLoc = label2.getLocation(eltIndex);
145	if (loc != Location.BOUNDARY) loc = nLoc;
146	}
147	return loc;
148	}
149
150	public void print(PrintStream out)
151	{
152	out.println("node " + coord + " lbl: " + label);
153	}
154	}
155