TopologyPreservingSimplificationAlgorithm.java

/**
 * Copyright (C) 2007 - 2016 52°North Initiative for Geospatial Open Source
 * Software GmbH
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * If the program is linked with libraries which are licensed under one of
 * the following licenses, the combination of the program with the linked
 * library is not considered a "derivative work" of the program:
 *
 *       • Apache License, version 2.0
 *       • Apache Software License, version 1.0
 *       • GNU Lesser General Public License, version 3
 *       • Mozilla Public License, versions 1.0, 1.1 and 2.0
 *       • Common Development and Distribution License (CDDL), version 1.0
 *
 * Therefore the distribution of the program linked with libraries licensed
 * under the aforementioned licenses, is permitted by the copyright holders
 * if the distribution is compliant with both the GNU General Public
 * License version 2 and the aforementioned licenses.
 *
 * As an exception to the terms of the GPL, you may copy, modify,
 * propagate, and distribute a work formed by combining 52°North WPS
 * GeoTools Modules with the Eclipse Libraries, or a work derivative of
 * such a combination, even if such copying, modification, propagation, or
 * distribution would otherwise violate the terms of the GPL. Nothing in
 * this exception exempts you from complying with the GPL in all respects
 * for all of the code used other than the Eclipse Libraries. You may
 * include this exception and its grant of permissions when you distribute
 * 52°North WPS GeoTools Modules. Inclusion of this notice with such a
 * distribution constitutes a grant of such permissions. If you do not wish
 * to grant these permissions, remove this paragraph from your
 * distribution. "52°North WPS GeoTools Modules" means the 52°North WPS
 * modules using GeoTools functionality - software licensed under version 2
 * or any later version of the GPL, or a work based on such software and
 * licensed under the GPL. "Eclipse Libraries" means Eclipse Modeling
 * Framework Project and XML Schema Definition software distributed by the
 * Eclipse Foundation and licensed under the Eclipse Public License Version
 * 1.0 ("EPL"), or a work based on such software and licensed under the EPL.
 *
 * This program 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 General
 * Public License for more details.
 */
package org.n52.wps.server.algorithm.simplify;


import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


import org.geotools.feature.FeatureCollection;
import org.geotools.feature.FeatureIterator;
import org.geotools.feature.IllegalAttributeException;
import org.n52.wps.io.data.IData;
import org.n52.wps.io.data.binding.complex.GTVectorDataBinding;
import org.n52.wps.io.data.binding.literal.LiteralDoubleBinding;
import org.n52.wps.server.AbstractAlgorithm;
import org.n52.wps.server.AbstractSelfDescribingAlgorithm;
import org.opengis.feature.Feature;
import org.opengis.feature.simple.SimpleFeature;

import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.geom.MultiLineString;
import com.vividsolutions.jts.geom.MultiPolygon;
import com.vividsolutions.jts.geom.Polygon;
import com.vividsolutions.jts.simplify.TopologyPreservingSimplifier;

/**
 * @author Theodor Foerster, ITC
 *
 */
public class TopologyPreservingSimplificationAlgorithm extends
AbstractSelfDescribingAlgorithm {

	private List<String> errors = new ArrayList<String>();
	
	public Map<String, IData> run(Map<String, List<IData>> inputData) {
		if(inputData==null || !inputData.containsKey("FEATURES")){
			throw new RuntimeException("Error while allocating input parameters");
		}
		List<IData> dataList = inputData.get("FEATURES");
		if(dataList == null || dataList.size() != 1){
			throw new RuntimeException("Error while allocating input parameters");
		}
		IData firstInputData = dataList.get(0);
				
		FeatureCollection featureCollection = ((GTVectorDataBinding) firstInputData).getPayload();
		FeatureIterator iter = featureCollection.features();
		
		if( !inputData.containsKey("width")){
			throw new RuntimeException("Error while allocating input parameters");
		}
		List<IData> widthDataList = inputData.get("TOLERANCE");
		if(widthDataList == null || widthDataList.size() != 1){
			throw new RuntimeException("Error while allocating input parameters");
		}
		Double tolerance = ((LiteralDoubleBinding) widthDataList.get(0)).getPayload();
		while(iter.hasNext()) {
			SimpleFeature f = (SimpleFeature) iter.next();
			Object userData = ((Geometry)f.getDefaultGeometry()).getUserData();
			
			try{
				Geometry in = (Geometry)f.getDefaultGeometry();
				Geometry out = TopologyPreservingSimplifier.simplify(in, tolerance);
                /*
                 * THIS PASSAGE WAS CONTRIBUTED BY GOBE HOBONA.
                 *The simplification of MultiPolygons produces Polygon geometries. This becomes inconsistent with the original schema (which was of MultiPolygons).
                 *To ensure that the output geometries match that of the original schema we add the Polygon(from the simplication) to a MultiPolygon object
                 *
                 *This is issue is known to affect MultiPolygon geometries only, other geometries need to be tested to ensure conformance with the original (input) schema
                 */  
                if(in.getGeometryType().equals("MultiPolygon") && out.getGeometryType().equals("Polygon"))
                {                   
                    MultiPolygon mp = (MultiPolygon)in;                                               
                    Polygon[] p = {(Polygon)out};
                    mp = new MultiPolygon(p,mp.getFactory());                   
                    f.setDefaultGeometry(mp);
                }
                else if(in.getGeometryType().equals("MultiLineString") && out.getGeometryType().equals("LineString")) {
                	MultiLineString ml = (MultiLineString)in;
                	LineString[] l = {(LineString)out};
                    ml = new MultiLineString(l,ml.getFactory());                   
                    f.setDefaultGeometry(ml);
                }
                else
                f.setDefaultGeometry(out);				
				((Geometry)f.getDefaultGeometry()).setUserData(userData);
			}
			catch(IllegalAttributeException e) {
				throw new RuntimeException("geometrytype of result is not matching", e);
			}
		}
		HashMap<String, IData> result = new HashMap<String, IData>();
		result.put("SIMPLIFIED_FEATURES", new GTVectorDataBinding(featureCollection));
		return result;
	}

	public List<String> getErrors() {
		return errors;
	}

	public Class getInputDataType(String id) {
		if(id.equalsIgnoreCase("FEATURES")){
			return GTVectorDataBinding.class;
		}else if(id.equalsIgnoreCase("TOLERANCE")){
			return LiteralDoubleBinding.class;
		}
		return null;
	}

	public Class getOutputDataType(String id) {
		if(id.equalsIgnoreCase("result")){
			return GTVectorDataBinding.class;
		}
		return null;
	}


	@Override
	public List<String> getInputIdentifiers() {
		List<String> identifierList =  new ArrayList<String>();
		identifierList.add("FEATURES");
		identifierList.add("TOLERANCE");
		return identifierList;
	}

	@Override
	public List<String> getOutputIdentifiers() {
		List<String> identifierList =  new ArrayList<String>();
		identifierList.add("result");
		return identifierList;
	}
	

}