Class Label

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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 org.locationtech.jts.geom.Location;
18
19	/**
20	* A <code>Label</code> indicates the topological relationship of a component
21	* of a topology graph to a given <code>Geometry</code>.
22	* This class supports labels for relationships to two <code>Geometry</code>s,
23	* which is sufficient for algorithms for binary operations.
24	* <P>
25	* Topology graphs support the concept of labeling nodes and edges in the graph.
26	* The label of a node or edge specifies its topological relationship to one or
27	* more geometries. (In fact, since JTS operations have only two arguments labels
28	* are required for only two geometries). A label for a node or edge has one or
29	* two elements, depending on whether the node or edge occurs in one or both of the
30	* input <code>Geometry</code>s. Elements contain attributes which categorize the
31	* topological location of the node or edge relative to the parent
32	* <code>Geometry</code>; that is, whether the node or edge is in the interior,
33	* boundary or exterior of the <code>Geometry</code>. Attributes have a value
34	* from the set <code>{Interior, Boundary, Exterior}</code>. In a node each
35	* element has a single attribute <code><On></code>. For an edge each element has a
36	* triplet of attributes <code><Left, On, Right></code>.
37	* <P>
38	* It is up to the client code to associate the 0 and 1 <code>TopologyLocation</code>s
39	* with specific geometries.
40	* @version 1.7
41	*
42	*/
43	public class Label {
44
45	// converts a Label to a Line label (that is, one with no side Locations)
46	public static Label toLineLabel(Label label)
47	{
48	Label lineLabel = new Label(Location.NONE);
49	for (int i = 0; i < 2; i++) {
50	lineLabel.setLocation(i, label.getLocation(i));
51	}
52	return lineLabel;
53	}
54
55	TopologyLocation elt[] = new TopologyLocation[2];
56
57	/**
58	* Construct a Label with a single location for both Geometries.
59	* Initialize the locations to Null
60	*/
61	public Label(int onLoc)
62	{
63	elt[0] = new TopologyLocation(onLoc);
64	elt[1] = new TopologyLocation(onLoc);
65	}
66	/**
67	* Construct a Label with a single location for both Geometries.
68	* Initialize the location for the Geometry index.
69	*/
70	public Label(int geomIndex, int onLoc)
71	{
72	elt[0] = new TopologyLocation(Location.NONE);
73	elt[1] = new TopologyLocation(Location.NONE);
74	elt[geomIndex].setLocation(onLoc);
75	}
76	/**
77	* Construct a Label with On, Left and Right locations for both Geometries.
78	* Initialize the locations for both Geometries to the given values.
79	*/
80	public Label(int onLoc, int leftLoc, int rightLoc)
81	{
82	elt[0] = new TopologyLocation(onLoc, leftLoc, rightLoc);
83	elt[1] = new TopologyLocation(onLoc, leftLoc, rightLoc);
84	}
85	/**
86	* Construct a Label with On, Left and Right locations for both Geometries.
87	* Initialize the locations for the given Geometry index.
88	*/
89	public Label(int geomIndex, int onLoc, int leftLoc, int rightLoc)
90	{
91	elt[0] = new TopologyLocation(Location.NONE, Location.NONE, Location.NONE);
92	elt[1] = new TopologyLocation(Location.NONE, Location.NONE, Location.NONE);
93	elt[geomIndex].setLocations(onLoc, leftLoc, rightLoc);
94	}
95	/**
96	* Construct a Label with the same values as the argument Label.
97	*/
98	public Label(Label lbl)
99	{
100	elt[0] = new TopologyLocation(lbl.elt[0]);
101	elt[1] = new TopologyLocation(lbl.elt[1]);
102	}
103
104	public void flip()
105	{
106	elt[0].flip();
107	elt[1].flip();
108	}
109
110	public int getLocation(int geomIndex, int posIndex) { return elt[geomIndex].get(posIndex); }
111	public int getLocation(int geomIndex) { return elt[geomIndex].get(Position.ON); }
112	public void setLocation(int geomIndex, int posIndex, int location)
113	{
114	elt[geomIndex].setLocation(posIndex, location);
115	}
116	public void setLocation(int geomIndex, int location)
117	{
118	elt[geomIndex].setLocation(Position.ON, location);
119	}
120	public void setAllLocations(int geomIndex, int location)
121	{
122	elt[geomIndex].setAllLocations(location);
123	}
124	public void setAllLocationsIfNull(int geomIndex, int location)
125	{
126	elt[geomIndex].setAllLocationsIfNull(location);
127	}
128	public void setAllLocationsIfNull(int location)
129	{
130	setAllLocationsIfNull(0, location);
131	setAllLocationsIfNull(1, location);
132	}
133	/**
134	* Merge this label with another one.
135	* Merging updates any null attributes of this label with the attributes from lbl
136	*/
137	public void merge(Label lbl)
138	{
139	for (int i = 0; i < 2; i++) {
140	if (elt[i] == null && lbl.elt[i] != null) {
141	elt[i] = new TopologyLocation(lbl.elt[i]);
142	}
143	else {
144	elt[i].merge(lbl.elt[i]);
145	}
146	}
147	}
148	public int getGeometryCount()
149	{
150	int count = 0;
151	if (! elt[0].isNull()) count++;
152	if (! elt[1].isNull()) count++;
153	return count;
154	}
155	public boolean isNull(int geomIndex) { return elt[geomIndex].isNull(); }
156	public boolean isAnyNull(int geomIndex) { return elt[geomIndex].isAnyNull(); }
157
158	public boolean isArea() { return elt[0].isArea() \|\| elt[1].isArea(); }
159	public boolean isArea(int geomIndex)
160	{
161	/* Testing
162	if (elt[0].getLocations().length != elt[1].getLocations().length) {
163	System.out.println(this);
164	}
165	*/
166	return elt[geomIndex].isArea();
167	}
168	public boolean isLine(int geomIndex) { return elt[geomIndex].isLine(); }
169
170	public boolean isEqualOnSide(Label lbl, int side)
171	{
172	return
173	this.elt[0].isEqualOnSide(lbl.elt[0], side)
174	&& this.elt[1].isEqualOnSide(lbl.elt[1], side);
175	}
176	public boolean allPositionsEqual(int geomIndex, int loc)
177	{
178	return elt[geomIndex].allPositionsEqual(loc);
179	}
180	/**
181	* Converts one GeometryLocation to a Line location
182	*/
183	public void toLine(int geomIndex)
184	{
185	if (elt[geomIndex].isArea())
186	elt[geomIndex] = new TopologyLocation(elt[geomIndex].location[0]);
187	}
188	public String toString()
189	{
190	StringBuffer buf = new StringBuffer();
191	if (elt[0] != null) {
192	buf.append("A:");
193	buf.append(elt[0].toString());
194	}
195	if (elt[1] != null) {
196	buf.append(" B:");
197	buf.append(elt[1].toString());
198	}
199	return buf.toString();
200	}
201	}
202