geo/GpxUtils.java

   1 package org.argeo.app.geo;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5 import java.util.ArrayList;
   6 import java.util.List;
   7
   8 import javax.xml.parsers.ParserConfigurationException;
   9 import javax.xml.parsers.SAXParser;
  10 import javax.xml.parsers.SAXParserFactory;
  11
  12 import org.geotools.data.DataUtilities;
  13 import org.geotools.feature.SchemaException;
  14 import org.geotools.feature.simple.SimpleFeatureBuilder;
  15 import org.geotools.geometry.jts.JTSFactoryFinder;
  16 import org.locationtech.jts.geom.Coordinate;
  17 import org.locationtech.jts.geom.GeometryFactory;
  18 import org.locationtech.jts.geom.Polygon;
  19 import org.opengis.feature.simple.SimpleFeature;
  20 import org.opengis.feature.simple.SimpleFeatureType;
  21 import org.xml.sax.Attributes;
  22 import org.xml.sax.SAXException;
  23 import org.xml.sax.helpers.DefaultHandler;
  24
  25 /** Utilities around the GPX format. */
  26 public class GpxUtils {
  27
  28         public static SimpleFeature parseGpxToPolygon(InputStream in) {
  29                 try {
  30                         final SimpleFeatureType TYPE = DataUtilities.createType("Area", "the_geom:Polygon:srid=4326");
  31                         SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
  32
  33                         GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory();
  34                         List<Coordinate> coordinates = new ArrayList<>();
  35                         SAXParserFactory factory = SAXParserFactory.newInstance();
  36                         SAXParser saxParser = factory.newSAXParser();
  37
  38                         saxParser.parse(in, new DefaultHandler() {
  39
  40                                 @Override
  41                                 public void startElement(String uri, String localName, String qName, Attributes attributes)
  42                                                 throws SAXException {
  43                                         if ("trkpt".equals(qName)) {
  44                                                 Double latitude = Double.parseDouble(attributes.getValue("lat"));
  45                                                 Double longitude = Double.parseDouble(attributes.getValue("lon"));
  46                                                 Coordinate coordinate = new Coordinate(longitude, latitude);
  47                                                 coordinates.add(coordinate);
  48                                         }
  49                                 }
  50
  51                         });
  52                         // close the line string
  53                         coordinates.add(coordinates.get(0));
  54
  55                         Polygon polygon = geometryFactory.createPolygon(coordinates.toArray(new Coordinate[coordinates.size()]));
  56                         featureBuilder.add(polygon);
  57                         SimpleFeature area = featureBuilder.buildFeature(null);
  58                         return area;
  59                 } catch (ParserConfigurationException | SAXException | IOException | SchemaException e) {
  60                         throw new RuntimeException("Cannot convert GPX", e);
  61                 }
  62         }
  63
  64         /** Singleton. */
  65         private GpxUtils() {
  66         }
  67 }