com.jejking.hh.nord.gazetteer.osm.RelationWaysToPolygon.java Source code

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Here is the source code for com.jejking.hh.nord.gazetteer.osm.RelationWaysToPolygon.java

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/* 
 *  Hamburg-Nord Geocoder, by John King.
 *  Copyright (C) 2014,  John King
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */
package com.jejking.hh.nord.gazetteer.osm;

import java.util.Map;

import rx.functions.Func1;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.jejking.osm.OsmRelation;
import com.jejking.osm.OsmRelation.Member;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.geom.LinearRing;
import com.vividsolutions.jts.geom.Polygon;

import static com.jejking.hh.nord.gazetteer.osm.OsmConstants.inner;
import static com.jejking.hh.nord.gazetteer.osm.OsmConstants.multipolygon;
import static com.jejking.hh.nord.gazetteer.osm.OsmConstants.outer;
import static com.jejking.hh.nord.gazetteer.osm.OsmConstants.type;

/**
 * Function to map a relation that is a multipolygon to an optional polgyon. The 
 * function returns an actual result if the polygon can be mapped simply (one outer 
 * ring and 1-N inner rings), otherwise the polygon is absent.
 * 
 * @author jejking
 *
 */
public class RelationWaysToPolygon implements Func1<OsmRelation, Optional<Polygon>> {

    private final GeometryFactory geometryFactory;
    private final Map<Long, LineString> osmLineStrings;

    /**
     * Constructor.
     * 
     * @param geometryFactory
     * @param knownOsmWays
     */
    public RelationWaysToPolygon(GeometryFactory geometryFactory, Map<Long, LineString> osmLineStrings) {
        super();
        this.geometryFactory = geometryFactory;
        this.osmLineStrings = osmLineStrings;
    }

    @Override
    public Optional<Polygon> call(OsmRelation osmRelation) {

        try {
            if (osmRelation.getProperties().get(type) != null
                    && osmRelation.getProperties().get(type).equals(multipolygon)) {

                LinearRing shell = buildShell(osmRelation);
                LinearRing[] holes = buildHoles(osmRelation);

                Polygon poly = this.geometryFactory.createPolygon(shell, holes);
                return Optional.of(poly);

            }

            // get any inner....
            return Optional.absent();

        } catch (Exception e) {
            return Optional.absent();
        }

    }

    private LinearRing[] buildHoles(OsmRelation osmRelation) {
        Iterable<LinearRing> linearRings = Iterables.transform(getInners(osmRelation),
                new Function<OsmRelation.Member, LinearRing>() {

                    @Override
                    public LinearRing apply(OsmRelation.Member member) {
                        return linearRingFromMember(member);
                    }

                });
        return Iterables.toArray(linearRings, LinearRing.class);
    }

    private Iterable<OsmRelation.Member> getInners(OsmRelation osmRelation) {
        return Iterables.filter(osmRelation.getMembers(), new Predicate<OsmRelation.Member>() {
            @Override
            public boolean apply(Member member) {
                if (member.getRole().isPresent() && member.getRole().get().equals(inner)) {
                    return true;
                } else {
                    return false;
                }
            }
        });
    }

    private LinearRing buildShell(OsmRelation osmRelation) {
        return linearRingFromMember(getOuter(osmRelation));
    }

    private LinearRing linearRingFromMember(OsmRelation.Member member) {
        return this.geometryFactory.createLinearRing(osmLineStrings.get(member.getRef()).getCoordinates());
    }

    private Member getOuter(OsmRelation osmRelation) {
        return Iterables.filter(osmRelation.getMembers(), new Predicate<OsmRelation.Member>() {

            @Override
            public boolean apply(Member member) {
                if (member.getRole().isPresent() && member.getRole().get().equals(outer)) {
                    return true;
                } else {
                    return false;
                }
            }
        }).iterator().next();
    }

}