argeo/app/geo/GeoJSon.java

   1 package org.argeo.app.geo;
   2
   3 import org.locationtech.jts.geom.Coordinate;
   4 import org.locationtech.jts.geom.Envelope;
   5 import org.locationtech.jts.geom.Geometry;
   6 import org.locationtech.jts.geom.LineString;
   7 import org.locationtech.jts.geom.LinearRing;
   8 import org.locationtech.jts.geom.Point;
   9 import org.locationtech.jts.geom.Polygon;
  10
  11 import jakarta.json.stream.JsonGenerator;
  12
  13 /**
  14  * GeoJSon format.
  15  *
  16  * @see https://datatracker.ietf.org/doc/html/rfc7946
  17  */
  18 public class GeoJSon {
  19         public static void writeBBox(JsonGenerator generator, Geometry geometry) {
  20                 generator.writeStartArray("bbox");
  21                 Envelope envelope = geometry.getEnvelopeInternal();
  22                 generator.write(envelope.getMinX());
  23                 generator.write(envelope.getMinY());
  24                 generator.write(envelope.getMaxX());
  25                 generator.write(envelope.getMaxY());
  26                 generator.writeEnd();
  27         }
  28
  29         public static void writeGeometry(JsonGenerator generator, Geometry geometry) {
  30                 generator.writeStartObject("geometry");
  31                 if (geometry instanceof Point point) {
  32                         generator.write("type", "Point");
  33                         generator.writeStartArray("coordinates");
  34                         writeCoordinate(generator, point.getCoordinate());
  35                         generator.writeEnd();// coordinates array
  36                 } else if (geometry instanceof LineString lineString) {
  37                         generator.write("type", "LineString");
  38                         generator.writeStartArray("coordinates");
  39                         writeCoordinates(generator, lineString.getCoordinates());
  40                         generator.writeEnd();// coordinates array
  41                 } else if (geometry instanceof Polygon polygon) {
  42                         generator.write("type", "Polygon");
  43                         generator.writeStartArray("coordinates");
  44                         LinearRing exteriorRing = polygon.getExteriorRing();
  45                         generator.writeStartArray();
  46                         writeCoordinates(generator, exteriorRing.getCoordinates());
  47                         generator.writeEnd();
  48                         for (int i = 0; i < polygon.getNumInteriorRing(); i++) {
  49                                 LinearRing interiorRing = polygon.getInteriorRingN(i);
  50                                 // TODO verify that holes are clockwise
  51                                 generator.writeStartArray();
  52                                 writeCoordinates(generator, interiorRing.getCoordinates());
  53                                 generator.writeEnd();
  54                         }
  55                         generator.writeEnd();// coordinates array
  56                 }
  57                 generator.writeEnd();// geometry object
  58         }
  59
  60         public static void writeCoordinates(JsonGenerator generator, Coordinate[] coordinates) {
  61                 for (Coordinate coordinate : coordinates) {
  62                         generator.writeStartArray();
  63                         writeCoordinate(generator, coordinate);
  64                         generator.writeEnd();
  65                 }
  66         }
  67
  68         public static void writeCoordinate(JsonGenerator generator, Coordinate coordinate) {
  69                 generator.write(coordinate.getX());
  70                 generator.write(coordinate.getY());
  71                 double z = coordinate.getZ();
  72                 if (!Double.isNaN(z)) {
  73                         generator.write(z);
  74                 }
  75         }
  76
  77         /** singleton */
  78         private GeoJSon() {
  79         }
  80
  81 }