/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2011, Open Source Geospatial Foundation (OSGeo)
* (C) 2001-2007 TOPP - www.openplans.org.
*
* 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;
* version 2.1 of the License.
*
* 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.
*/
package org.geotools.process.feature.gs;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.feature.collection.DecoratingSimpleFeatureCollection;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.process.ProcessException;
import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.process.gs.GSProcess;
import org.geotools.process.gs.WrappingIterator;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.simplify.DouglasPeuckerSimplifier;
import com.vividsolutions.jts.simplify.TopologyPreservingSimplifier;
/**
* A process simplifying the geometries in the input feature collection according to a specified
* distance, and using either a topology preserving or a Douglas-Peuker algorithm
*
* @author Andrea Aime - OpenGeo
*
*
* @source $URL$
*/
@DescribeProcess(title = "simplify", description = "Simplifies the geometry")
public class SimplifyProcess implements GSProcess {
@DescribeResult(name = "result", description = "The simplified feature collection")
public SimpleFeatureCollection execute(
@DescribeParameter(name = "features", description = "The feature collection to be simplified") SimpleFeatureCollection features,
@DescribeParameter(name = "distance", description = "The simplification distance (should be positive)") double distance,
@DescribeParameter(name = "preserveTopology", description = "Wheter a topology preserving simplification should be used", min = 0) Boolean preserveTopology)
throws ProcessException {
if (distance < 0) {
throw new ProcessException("Invalid distance, it should be a positive number");
}
return new SimplifyingFeatureCollection(features, distance,
preserveTopology == null ? Boolean.FALSE : preserveTopology);
}
static class SimplifyingFeatureCollection extends DecoratingSimpleFeatureCollection {
double distance;
boolean preserveTopology;
public SimplifyingFeatureCollection(SimpleFeatureCollection delegate, double distance,
boolean preserveTopology) {
super(delegate);
this.distance = distance;
this.preserveTopology = preserveTopology;
}
@Override
public SimpleFeatureIterator features() {
return new SimplifyingFeatureIterator(delegate.features(), distance, preserveTopology,
getSchema());
}
@Override
public Iterator<SimpleFeature> iterator() {
return new WrappingIterator(features());
}
@Override
public void close(Iterator<SimpleFeature> close) {
if (close instanceof WrappingIterator) {
((WrappingIterator) close).close();
}
}
}
static class SimplifyingFeatureIterator implements SimpleFeatureIterator {
SimpleFeatureIterator delegate;
double distance;
boolean preserveTopology;
SimpleFeatureBuilder fb;
public SimplifyingFeatureIterator(SimpleFeatureIterator delegate, double distance,
boolean preserveTopology, SimpleFeatureType schema) {
this.delegate = delegate;
this.distance = distance;
this.preserveTopology = preserveTopology;
fb = new SimpleFeatureBuilder(schema);
}
public void close() {
delegate.close();
}
public boolean hasNext() {
return delegate.hasNext();
}
public SimpleFeature next() throws NoSuchElementException {
SimpleFeature f = delegate.next();
for (Object attribute : f.getAttributes()) {
if (attribute instanceof Geometry) {
if (preserveTopology) {
attribute = DouglasPeuckerSimplifier.simplify((Geometry) attribute,
distance);
} else {
attribute = TopologyPreservingSimplifier.simplify((Geometry) attribute,
distance);
}
}
fb.add(attribute);
}
return fb.buildFeature(f.getID());
}
}
}