--- /dev/null
+package org.argeo.app.geo;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.StringTokenizer;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+import org.geotools.data.DataUtilities;
+import org.geotools.feature.SchemaException;
+import org.geotools.feature.simple.SimpleFeatureBuilder;
+import org.geotools.geometry.jts.JTSFactoryFinder;
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.GeometryFactory;
+import org.locationtech.jts.geom.Polygon;
+import org.opengis.feature.simple.SimpleFeature;
+import org.opengis.feature.simple.SimpleFeatureType;
+import org.xml.sax.Attributes;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+/** Utilities around the GPX format. */
+public class GpxUtils {
+
+ public static SimpleFeature parseGpxToPolygon(InputStream in) throws IOException {
+ try {
+ final SimpleFeatureType TYPE = DataUtilities.createType("Area", "the_geom:Polygon:srid=4326");
+ SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
+
+ GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory();
+ List<Coordinate> coordinates = new ArrayList<>();
+ SAXParserFactory factory = SAXParserFactory.newInstance();
+ SAXParser saxParser = factory.newSAXParser();
+
+ saxParser.parse(in, new DefaultHandler() {
+
+ @Override
+ public void startElement(String uri, String localName, String qName, Attributes attributes)
+ throws SAXException {
+ if ("trkpt".equals(qName)) {
+ Double latitude = Double.parseDouble(attributes.getValue("lat"));
+ Double longitude = Double.parseDouble(attributes.getValue("lon"));
+ Coordinate coordinate = new Coordinate(longitude, latitude);
+ coordinates.add(coordinate);
+ }
+ }
+
+ });
+ // close the line string
+ coordinates.add(coordinates.get(0));
+
+ Polygon polygon = geometryFactory.createPolygon(coordinates.toArray(new Coordinate[coordinates.size()]));
+ featureBuilder.add(polygon);
+ SimpleFeature area = featureBuilder.buildFeature(null);
+ return area;
+ } catch (ParserConfigurationException | SAXException | SchemaException e) {
+ throw new RuntimeException("Cannot convert GPX", e);
+ }
+ }
+
+ public static void writeGeoShapeAsGpx(String geoShape, OutputStream out) throws IOException {
+ Objects.requireNonNull(geoShape);
+ Writer writer = new OutputStreamWriter(out, StandardCharsets.UTF_8);
+ writer.append("<gpx><trk><trkseg>");
+ StringTokenizer stSeg = new StringTokenizer(geoShape.trim(), ";");
+ while (stSeg.hasMoreTokens()) {
+ StringTokenizer stPt = new StringTokenizer(stSeg.nextToken().trim(), " ");
+ String lat = stPt.nextToken();
+ String lng = stPt.nextToken();
+ String alt = stPt.nextToken();
+ // String precision = stPt.nextToken();
+ writer.append("<trkpt");
+ writer.append(" lat=\"").append(lat).append('\"');
+ writer.append(" lon=\"").append(lng).append('\"');
+ if (!alt.equals("0.0")) {
+ writer.append('>');
+ writer.append("<ele>").append(alt).append("</ele>");
+ writer.append("</trkpt>");
+ } else {
+ writer.append("/>");
+ }
+ }
+ writer.append("</trkseg></trk></gpx>");
+ writer.flush();
+ }
+
+ /** Singleton. */
+ private GpxUtils() {
+ }
+}