Class LineStringExtracter

1
2	/*
3	* Copyright (c) 2016 Vivid Solutions.
4	*
5	* All rights reserved. This program and the accompanying materials
6	* are made available under the terms of the Eclipse Public License 2.0
7	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
8	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
9	* and the Eclipse Distribution License is available at
10	*
11	* http://www.eclipse.org/org/documents/edl-v10.php.
12	*/
13	package org.locationtech.jts.geom.util;
14
15	import java.util.ArrayList;
16	import java.util.List;
17
18	import org.locationtech.jts.geom.Geometry;
19	import org.locationtech.jts.geom.GeometryCollection;
20	import org.locationtech.jts.geom.GeometryFilter;
21	import org.locationtech.jts.geom.LineString;
22	import org.locationtech.jts.geom.MultiLineString;
23
24	/**
25	* Extracts all the {@link LineString} elements from a {@link Geometry}.
26	*
27	* @version 1.7
28	* @see GeometryExtracter
29	*/
30	public class LineStringExtracter
31	implements GeometryFilter
32	{
33	/**
34	* Extracts the {@link LineString} elements from a single {@link Geometry}
35	* and adds them to the provided {@link List}.
36	*
37	* @param geom the geometry from which to extract
38	* @param lines the list to add the extracted LineStrings to
39	* @return the list argument
40	*/
41	public static List getLines(Geometry geom, List lines)
42	{
43	if (geom instanceof LineString) {
44	lines.add(geom);
45	}
46	else if (geom instanceof GeometryCollection) {
47	geom.apply(new LineStringExtracter(lines));
48	}
49	// skip non-LineString elemental geometries
50
51	return lines;
52	}
53
54	/**
55	* Extracts the {@link LineString} elements from a single {@link Geometry}
56	* and returns them in a {@link List}.
57	*
58	* @param geom the geometry from which to extract
59	* @return a list containing the linear elements
60	*/
61	public static List getLines(Geometry geom)
62	{
63	return getLines(geom, new ArrayList());
64	}
65
66	/**
67	* Extracts the {@link LineString} elements from a single {@link Geometry}
68	* and returns them as either a {@link LineString} or {@link MultiLineString}.
69	*
70	* @param geom the geometry from which to extract
71	* @return a linear geometry
72	*/
73	public static Geometry getGeometry(Geometry geom)
74	{
75	return geom.getFactory().buildGeometry(getLines(geom));
76	}
77
78	private List comps;
79
80	/**
81	* Constructs a filter with a list in which to store the elements found.
82	*/
83	public LineStringExtracter(List comps)
84	{
85	this.comps = comps;
86	}
87
88	public void filter(Geometry geom)
89	{
90	if (geom instanceof LineString) comps.add(geom);
91	}
92
93	}
94