decode static method

List<LatLng> decode(String encodedPath)

Implementation

static List<LatLng> decode(final String encodedPath) {
  final len = encodedPath.length;

  // For speed we preallocate to an upper bound on the final length, then
  // truncate the array before returning.
  final path = <LatLng>[];
  var index = 0;
  var lat = 0;
  var lng = 0;

  final big0 = BigInt.from(0);
  final big0x1f = BigInt.from(0x1f);
  final big0x20 = BigInt.from(0x20);

  while (index < len) {
    var shift = 0;
    BigInt b, result;
    result = big0;
    do {
      b = BigInt.from(encodedPath.codeUnitAt(index++) - 63);
      result |= (b & big0x1f) << shift;
      shift += 5;
    } while (b >= big0x20);
    var rShifted = result >> 1;
    int dLat;
    if (result.isOdd) {
      dLat = (~rShifted).toInt();
    } else {
      dLat = rShifted.toInt();
    }
    lat += dLat;

    shift = 0;
    result = big0;
    do {
      b = BigInt.from(encodedPath.codeUnitAt(index++) - 63);
      result |= (b & big0x1f) << shift;
      shift += 5;
    } while (b >= big0x20);
    rShifted = result >> 1;
    int dlng;
    if (result.isOdd) {
      dlng = (~rShifted).toInt();
    } else {
      dlng = rShifted.toInt();
    }
    lng += dlng;

    path.add(LatLng((lat / 1E5).toDouble(), (lng / 1E5).toDouble()));
  }

  return path;
}