com.vividsolutions.jts.precision.SimpleGeometryPrecisionReducer Maven / Gradle / Ivy
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/*
* 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.precision;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geom.util.*;
/**
* Reduces the precision of the coordinates of a {@link Geometry}
* according to the supplied {@link PrecisionModel}, without
* attempting to preserve valid topology.
*
* In the case of {@link Polygonal} geometries,
* the topology of the resulting geometry may be invalid if
* topological collapse occurs due to coordinates being shifted.
* It is up to the client to check this and handle it if necessary.
* Collapses may not matter for some uses. An example
* is simplifying the input to the buffer algorithm.
* The buffer algorithm does not depend on the validity of the input geometry.
*
* @version 1.7
*
* @deprecated use GeometryPrecisionReducer
*/
public class SimpleGeometryPrecisionReducer
{
/**
* Convenience method for doing precision reduction on a single geometry,
* with collapses removed and keeping the geometry precision model the same.
*
* @param g
* @param precModel
* @return the reduced geometry
*/
public static Geometry reduce(Geometry g, PrecisionModel precModel)
{
SimpleGeometryPrecisionReducer reducer = new SimpleGeometryPrecisionReducer(precModel);
return reducer.reduce(g);
}
private PrecisionModel newPrecisionModel;
private boolean removeCollapsed = true;
private boolean changePrecisionModel = false;
public SimpleGeometryPrecisionReducer(PrecisionModel pm)
{
newPrecisionModel = pm;
}
/**
* Sets whether the reduction will result in collapsed components
* being removed completely, or simply being collapsed to an (invalid)
* Geometry of the same type.
* The default is to remove collapsed components.
*
* @param removeCollapsed if true collapsed components will be removed
*/
public void setRemoveCollapsedComponents(boolean removeCollapsed)
{
this.removeCollapsed = removeCollapsed;
}
/**
* Sets whether the {@link PrecisionModel} of the new reduced Geometry
* will be changed to be the {@link PrecisionModel} supplied to
* specify the precision reduction.
*
* The default is to not change the precision model
*
* @param changePrecisionModel if true the precision model of the created Geometry will be the
* the precisionModel supplied in the constructor.
*/
public void setChangePrecisionModel(boolean changePrecisionModel)
{
this.changePrecisionModel = changePrecisionModel;
}
public Geometry reduce(Geometry geom)
{
GeometryEditor geomEdit;
if (changePrecisionModel) {
GeometryFactory newFactory = new GeometryFactory(newPrecisionModel, geom.getFactory().getSRID());
geomEdit = new GeometryEditor(newFactory);
}
else
// don't change geometry factory
geomEdit = new GeometryEditor();
return geomEdit.edit(geom, new PrecisionReducerCoordinateOperation());
}
private class PrecisionReducerCoordinateOperation
extends GeometryEditor.CoordinateOperation
{
public Coordinate[] edit(Coordinate[] coordinates, Geometry geom)
{
if (coordinates.length == 0) return null;
Coordinate[] reducedCoords = new Coordinate[coordinates.length];
// copy coordinates and reduce
for (int i = 0; i < coordinates.length; i++) {
Coordinate coord = new Coordinate(coordinates[i]);
newPrecisionModel.makePrecise(coord);
reducedCoords[i] = coord;
}
// remove repeated points, to simplify returned geometry as much as possible
CoordinateList noRepeatedCoordList = new CoordinateList(reducedCoords, false);
Coordinate[] noRepeatedCoords = noRepeatedCoordList.toCoordinateArray();
/**
* Check to see if the removal of repeated points
* collapsed the coordinate List to an invalid length
* for the type of the parent geometry.
* It is not necessary to check for Point collapses, since the coordinate list can
* never collapse to less than one point.
* If the length is invalid, return the full-length coordinate array
* first computed, or null if collapses are being removed.
* (This may create an invalid geometry - the client must handle this.)
*/
int minLength = 0;
if (geom instanceof LineString) minLength = 2;
if (geom instanceof LinearRing) minLength = 4;
Coordinate[] collapsedCoords = reducedCoords;
if (removeCollapsed) collapsedCoords = null;
// return null or orginal length coordinate array
if (noRepeatedCoords.length < minLength) {
return collapsedCoords;
}
// ok to return shorter coordinate array
return noRepeatedCoords;
}
}
}