cleanCoords function

Feature<GeometryObject> cleanCoords(GeoJSONObject geojson, { bool mutate = false, })

Removes redundant coordinates from any GeometryType. Takes a Feature or GeometryType mutate allows GeoJSON input to be mutated Returns the cleaned input Feature example:

var line = LineString(coordinates:[Position.of([0, 0]), Position.of([0, 2]), Position.of([0, 5]), Position.of([0, 8]), Position.of([0, 8]), Position.of([0, 10])]);
var multiPoint = MultiPoint(coordinates:[Position.of([0, 0]), Position.of([0, 0]), Position.of([2, 2])]);
cleanCoords(line).geometry.coordinates;
//= [Position.of([0, 0]), Position.of([0, 10])]
cleanCoords(multiPoint).geometry.coordinates;
//= [Position.of([0, 0]), Position.of([2, 2])]

Implementation

Feature cleanCoords(
  GeoJSONObject geojson, {
  bool mutate = false,
}) {
  if (geojson is Feature && geojson.geometry == null) {
    throw Exception("Geometry of the Feature is null");
  }
  GeometryObject geom = getGeom(geojson);
  geom = mutate ? geom : geom.clone() as GeometryObject;

  if (geojson is GeometryCollection || geojson is FeatureCollection) {
    throw Exception("${geojson.type} is not supported");
  } else if (geom is LineString) {
    var newCoords = _cleanLine(geom.coordinates, geojson);
    geom.coordinates = newCoords;
  } else if (geom is MultiLineString || geom is Polygon) {
    var newCoords = <List<Position>>[];
    for (var coord in (getCoords(geom) as List<List<Position>>)) {
      newCoords.add(_cleanLine(coord, geom));
    }
    (geom as GeometryType).coordinates = newCoords;
  } else if (geom is MultiPolygon) {
    var newCoords = <List<List<Position>>>[];
    for (var polyList in (getCoords(geom) as List<List<List<Position>>>)) {
      var listPoly = <List<Position>>[];
      for (var poly in polyList) {
        listPoly.add(_cleanLine(poly, geom));
      }
      newCoords.add(listPoly);
    }
    geom.coordinates = newCoords;
  } else if (geom is MultiPoint) {
    var newCoords = <Position>[];
    Set set = <String>{};
    var list = getCoords(geom) as List<Position>;
    for (var element in list) {
      if (!set.contains([element.alt, element.lat, element.lng].join('-'))) {
        newCoords.add(element);
      }
      set.add([element.alt, element.lat, element.lng].join('-'));
    }
    geom.coordinates = newCoords;
  }

  if (geojson is GeometryType) {
    return Feature(geometry: geom);
  } else if (geojson is Feature) {
    if (mutate) {
      return geojson;
    } else {
      return Feature(
        geometry: geom,
        properties: Map.of(geojson.properties ?? {}),
        bbox: geojson.bbox?.clone(),
        id: geojson.id,
      );
    }
  } else {
    throw Exception('${geojson.type} is not a supported type');
  }
}