com.vividsolutions.jts.noding.snapround.GeometryNoder Maven / Gradle / Ivy
/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.noding.snapround;
import java.util.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geom.util.*;
import com.vividsolutions.jts.noding.*;
import com.vividsolutions.jts.noding.snapround.*;
/**
* Nodes the linework in a list of {@link Geometry}s using Snap-Rounding
* to a given {@link PrecisionModel}.
*
* The input coordinates are expected to be rounded
* to the given precision model.
* This class does not perform that function.
* GeometryPrecisionReducer may be used to do this.
*
* This class does not dissolve the output linework,
* so there may be duplicate linestrings in the output.
* Subsequent processing (e.g. polygonization) may require
* the linework to be unique. Using UnaryUnion is one way
* to do this (although this is an inefficient approach).
*
*
*/
public class GeometryNoder
{
private GeometryFactory geomFact;
private PrecisionModel pm;
private boolean isValidityChecked = false;
/**
* Creates a new noder which snap-rounds to a grid specified
* by the given {@link PrecisionModel}.
*
* @param pm the precision model for the grid to snap-round to
*/
public GeometryNoder(PrecisionModel pm) {
this.pm = pm;
}
/**
* Sets whether noding validity is checked after noding is performed.
*
* @param isValidityChecked
*/
public void setValidate(boolean isValidityChecked)
{
this.isValidityChecked = isValidityChecked;
}
/**
* Nodes the linework of a set of Geometrys using SnapRounding.
*
* @param geoms a Collection of Geometrys of any type
* @return a List of LineStrings representing the noded linework of the input
*/
public List node(Collection geoms)
{
// get geometry factory
Geometry geom0 = (Geometry) geoms.iterator().next();
geomFact = geom0.getFactory();
List segStrings = toSegmentStrings(extractLines(geoms));
//Noder sr = new SimpleSnapRounder(pm);
Noder sr = new MCIndexSnapRounder(pm);
sr.computeNodes(segStrings);
Collection nodedLines = sr.getNodedSubstrings();
//TODO: improve this to check for full snap-rounded correctness
if (isValidityChecked) {
NodingValidator nv = new NodingValidator(nodedLines);
nv.checkValid();
}
return toLineStrings(nodedLines);
}
private List toLineStrings(Collection segStrings)
{
List lines = new ArrayList();
for (Iterator it = segStrings.iterator(); it.hasNext(); ) {
SegmentString ss = (SegmentString) it.next();
// skip collapsed lines
if (ss.size() < 2)
continue;
lines.add(geomFact.createLineString(ss.getCoordinates()));
}
return lines;
}
private List extractLines(Collection geoms)
{
List lines = new ArrayList();
LinearComponentExtracter lce = new LinearComponentExtracter(lines);
for (Iterator it = geoms.iterator(); it.hasNext(); ) {
Geometry geom = (Geometry) it.next();
geom.apply(lce);
}
return lines;
}
private List toSegmentStrings(Collection lines)
{
List segStrings = new ArrayList();
for (Iterator it = lines.iterator(); it.hasNext(); ) {
LineString line = (LineString) it.next();
segStrings.add(new NodedSegmentString(line.getCoordinates(), null));
}
return segStrings;
}
}