LatLng methods

latlng_extensions.dart

import 'package:latlong/latlong.dart';
import 'dart:math' as math;

LatLng getCenter(LatLng p1, LatLng p2) {
  double dLon = degToRadian(p2.longitude - p1.longitude);
  final lat1 = degToRadian(p1.latitude);
  final lat2 = degToRadian(p2.latitude);
  final lon1 = degToRadian(p1.longitude);
  double dx = math.cos(lat2) * math.cos(dLon);
  double dy = math.cos(lat2) * math.sin(dLon);
  double lat3 = math.atan2(math.sin(lat1) + math.sin(lat2),
      math.sqrt((math.cos(lat1) + dx) * (math.cos(lat1) + dx) + dy * dy));
  double lon3 = lon1 + math.atan2(dy, math.cos(lat1) + dx);
  final p3 = LatLng(radianToDeg(lat3), radianToDeg(lon3));
  return p3;
}

/// Returns SW and NE locations
LatLngBounds getBounds(List<LatLng> points) {
  LatLng _southWest;
  LatLng _northEast;

  for (LatLng latLng in points) {
    if (_southWest == null && _northEast == null) {
      _southWest = new LatLng(latLng.latitude, latLng.longitude);
      _northEast = new LatLng(latLng.latitude, latLng.longitude);
    } else {
      _southWest.latitude = math.min(latLng.latitude, _southWest.latitude);
      _southWest.longitude = math.min(latLng.longitude, _southWest.longitude);

      _northEast.latitude = math.max(latLng.latitude, _northEast.latitude);
      _northEast.longitude = math.max(latLng.longitude, _northEast.longitude);
    }
  }

  return LatLngBounds(_southWest, _northEast);
}

double getZoom(LatLng point1, LatLng point2, BoxConstraints constraints) {
  var pixelWidth = constraints.maxWidth;
  var bounds = getBounds([point1, point2]);
  var sw = bounds.southWest;
  var ne = bounds.northEast;
  const GLOBE_WIDTH = 256;
  var west = sw.longitude;
  var east = ne.longitude;
  var angle = east - west;
  if (angle < 0) {
    angle += 360;
  }
  var zoom = (math.log(pixelWidth * 360 / angle / GLOBE_WIDTH) / math.ln2)
      .roundToDouble();
  zoom--;
  return zoom > 15 ? 15 : zoom;
}

Stream<LatLng> getLocation() async* {
  Geolocator geolocator = Geolocator();
  LocationPermissions locationPermissions = LocationPermissions();

  // if(await have permission)
  // Check what ever if can get with native plugin
  // else fallback to get from ip
  PermissionStatus permission =
      await locationPermissions.checkPermissionStatus();
  if (permission == PermissionStatus.unknown ||
      permission == PermissionStatus.denied ||
      permission == null) {
    await LocationPermissions().requestPermissions();
  }
  GeolocationStatus perStatus =
      await geolocator.checkGeolocationPermissionStatus();

  if (perStatus == GeolocationStatus.denied ||
      perStatus == GeolocationStatus.disabled ||
      perStatus == null ||
      perStatus == GeolocationStatus.unknown) {
    var response = await http.get("https://ipapi.co/json/");
    var ipapiRes = IpApiCo.fromJson(response.body);
    yield LatLng(ipapiRes.latitude, ipapiRes.longitude);
  } else {
    LocationOptions locationOptions = LocationOptions(
        accuracy: LocationAccuracy.high,
        distanceFilter: 10,
        timeInterval: 3000);
    Stream<LatLng> flow = geolocator
        .getPositionStream(locationOptions)
        .map((pos) => LatLng(pos.latitude, pos.longitude));
    yield* flow;
  }
}