Class PolygonExtracter

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.Polygon;
22
23	/**
24	* Extracts all the {@link Polygon} elements from a {@link Geometry}.
25	*
26	* @version 1.7
27	* @see GeometryExtracter
28	*/
29	public class PolygonExtracter
30	implements GeometryFilter
31	{
32	/**
33	* Extracts the {@link Polygon} elements from a single {@link Geometry}
34	* and adds them to the provided {@link List}.
35	*
36	* @param geom the geometry from which to extract
37	* @param list the list to add the extracted elements to
38	*/
39	public static List getPolygons(Geometry geom, List list)
40	{
41	if (geom instanceof Polygon) {
42	list.add(geom);
43	}
44	else if (geom instanceof GeometryCollection) {
45	geom.apply(new PolygonExtracter(list));
46	}
47	// skip non-Polygonal elemental geometries
48
49	return list;
50	}
51
52	/**
53	* Extracts the {@link Polygon} elements from a single {@link Geometry}
54	* and returns them in a {@link List}.
55	*
56	* @param geom the geometry from which to extract
57	*/
58	public static List getPolygons(Geometry geom)
59	{
60	return getPolygons(geom, new ArrayList());
61	}
62
63	private List comps;
64	/**
65	* Constructs a PolygonExtracterFilter with a list in which to store Polygons found.
66	*/
67	public PolygonExtracter(List comps)
68	{
69	this.comps = comps;
70	}
71
72	public void filter(Geometry geom)
73	{
74	if (geom instanceof Polygon) comps.add(geom);
75	}
76
77	}
78