Location lat-lng getting wrong when using Yandex Map with flutter_map package - flutter

Question

I am using flutter_map with yandex map like below. When I mark a location, Getting location lat and lon are wrong. So If I draw a polygon on the map, It drawn on wrong location. How to fix this?
FlutterMap(
options: MapOptions(
center: LatLng(41.334554,36.269617),
zoom: 11.0,
maxZoom: 18,
minZoom: 5,
plugins: [
DragMarkerPlugin(),
],
onTap: (value){
print(value.toString());
markLocation(value);
},
),
layers: [
TileLayerOptions(
urlTemplate: 'https://core-sat.maps.yandex.net/tiles?l=sat&v=3.569.0&x={x}&y={y}&z={z}&lang=tr_TR'
),
TileLayerOptions(
urlTemplate: 'http://vec{s}.maps.yandex.net/tiles?l=skl&v=20.06.03&z={z}&x={x}&y={y}&scale=1&lang=tr_TR',
subdomains: ['01', '02', '03', '04'],
backgroundColor: Colors.transparent
),
CircleLayerOptions(
circles: _circles
),
PolygonLayerOptions(
polygons: getPolygons()
),
DragMarkerPluginOptions(
markers: _markers
)
],
mapController: _mapController,
)
Actual position of polygon:
And How to looks on device?

Answer 1

I used custom csr for solve this problem. Thanks to dmitrienkop for his answer.
https://github.com/fleaflet/flutter_map/issues/642
import 'dart:math' as math;
import 'package:flutter_map/plugin_api.dart';
import 'package:latlong/latlong.dart';
class Epsg3395 extends Earth {
#override
final String code = 'EPSG:3395';
#override
final Projection projection = const Mercator();
#override
final Transformation transformation = const Transformation(_scale, 0.5, -_scale, 0.5);
static const num _scale = 0.5 / (math.pi * Mercator.r);
const Epsg3395() : super();
}
class Mercator extends Projection {
static const int r = 6378137;
static const double rMinor = 6356752.314245179;
static final Bounds<double> _bounds = Bounds<double>(
CustomPoint<double>(-20037508.34279, -15496570.73972),
CustomPoint<double>(20037508.34279, 18764656.23138),
);
const Mercator() : super();
#override
Bounds<double> get bounds => _bounds;
#override
CustomPoint project(LatLng latlng) {
var d = math.pi / 180;
var y = latlng.latitude * d;
var tmp = rMinor / r;
var e = math.sqrt(1 - tmp * tmp);
var con = e * math.sin(y);
var ts = math.tan(math.pi / 4 - y / 2) / math.pow((1 - con) / (1 + con), e / 2);
y = -r * math.log(math.max(ts, 1E-10));
return CustomPoint(latlng.longitude * d * r, y);
}
#override
LatLng unproject(CustomPoint point) {
var d = 180 / math.pi;
var tmp = rMinor / r;
var e = math.sqrt(1 - tmp * tmp);
var ts = math.exp(-point.y / r);
var phi = math.pi / 2 - 2 * math.atan(ts);
for (var i = 0, dphi = 0.1, con; i < 15 && dphi.abs() > 1e-7; i++) {
con = e * math.sin(phi);
con = math.pow((1 - con) / (1 + con), e / 2);
dphi = math.pi / 2 - 2 * math.atan(ts * con) - phi;
phi += dphi;
}
return LatLng(phi * d, point.x * d / r);
}
}