LineStringExtracter.java
/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jts.geom.util;
import java.util.ArrayList;
import java.util.List;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryCollection;
import org.locationtech.jts.geom.GeometryFilter;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.geom.MultiLineString;
/**
* Extracts all the {@link LineString} elements from a {@link Geometry}.
*
* @version 1.7
* @see GeometryExtracter
*/
public class LineStringExtracter
implements GeometryFilter
{
/**
* Extracts the {@link LineString} elements from a single {@link Geometry}
* and adds them to the provided {@link List}.
*
* @param geom the geometry from which to extract
* @param lines the list to add the extracted LineStrings to
* @return the list argument
*/
public static List getLines(Geometry geom, List lines)
{
if (geom instanceof LineString) {
lines.add(geom);
}
else if (geom instanceof GeometryCollection) {
geom.apply(new LineStringExtracter(lines));
}
// skip non-LineString elemental geometries
return lines;
}
/**
* Extracts the {@link LineString} elements from a single {@link Geometry}
* and returns them in a {@link List}.
*
* @param geom the geometry from which to extract
* @return a list containing the linear elements
*/
public static List getLines(Geometry geom)
{
return getLines(geom, new ArrayList());
}
/**
* Extracts the {@link LineString} elements from a single {@link Geometry}
* and returns them as either a {@link LineString} or {@link MultiLineString}.
*
* @param geom the geometry from which to extract
* @return a linear geometry
*/
public static Geometry getGeometry(Geometry geom)
{
return geom.getFactory().buildGeometry(getLines(geom));
}
private List comps;
/**
* Constructs a filter with a list in which to store the elements found.
*/
public LineStringExtracter(List comps)
{
this.comps = comps;
}
public void filter(Geometry geom)
{
if (geom instanceof LineString) comps.add(geom);
}
}