[BUG] Repositioning the map through MapController in onMapReady prevents initial tiles loading

[MatyasK]

What is the bug?

After migrating to v4 the tiles doesn't load. if you move the map around manually the tiles start to load.

How can we reproduce it?

class CcaMapWidget extends StatelessWidget with CcaLogger {
  CcaMapWidget({
    required this.tripLegs,
    MapController? mapController,
    PopupController? popupLayerController,
    super.key,
  })  : _mapController = mapController ?? MapController(),
        _popupLayerController = popupLayerController ?? PopupController();

  final MapController _mapController;
  final PopupController _popupLayerController;
  final List<TripDetailLeg> tripLegs;

  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => CcaMapCubit()..screenLoaded(tripLegs),
      child: BlocBuilder<CcaMapCubit, CcaMapState>(
        builder: (context, state) {
          if (state.status == MapStatus.loading) {
            return const CcaLoadingIndicator();
          }

          return FlutterMap(
            mapController: _mapController,
            options: MapOptions(
              maxZoom: 13,
              onMapReady: () {
                final markerBounds = LatLngBounds.fromPoints(state.points);

                _mapController.fitBounds(
                  markerBounds,
                  options: const FitBoundsOptions(padding: EdgeInsets.all(70)),
                );
              },
            ),
            children: [
              TileLayer(
                urlTemplate: 'https://api.tomtom.com/map/1/tile/basic/main/'
                    '{z}/{x}/{y}.png?key={apiKey}',
                additionalOptions: {
                  'apiKey': getIt<UserRepository>().tomtomApiKey,
                },
                errorTileCallback: (image, error, stackTrace) {
                  logger.warning('Error: $error, $stackTrace');
                },
              ),
              PolylineLayer(
                polylines: [
                  Polyline(
                    strokeWidth: 3,
                    points: state.points,
                    color: kcPrimary,
                  ),
                ],
              ),
              PopupMarkerLayerWidget(
                options: PopupMarkerLayerOptions(
                  popupController: _popupLayerController,
                  markers: state.waypoints
                      .map((e) => WaypointMarker(wayPoint: e))
                      .toList(),
                  markerRotateAlignment:
                      PopupMarkerLayerOptions.rotationAlignmentFor(
                    AnchorAlign.top,
                  ),
                  popupBuilder: (BuildContext context, Marker marker) {
                    if (marker is WaypointMarker) {
                      return WaypointMarkerPopup(wayPoint: marker.wayPoint);
                    }

                    return const Card(child: Text('Not a waypoint'));
                  },
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}

Do you have a potential solution?

No response

Platforms

Android

Severity

Obtrusive: Prevents normal functioning but causes no errors in the console

[JaffaKetchup]

Hey @MatyasK,
Can you please strip down your code to create an MRE? At the moment, it's difficult for us to test, as there's lots of state management surrounding it.

[MatyasK]

I created a sample app, the app bevahes the same way, so the map only loads after you move the camera around. (I created a test api key so you can use that).

import 'package:flutter/material.dart';
import 'package:flutter_map/plugin_api.dart';
import 'package:latlong2/latlong.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
      ),
      home: MapView(),
    );
  }
}

class MapView extends StatelessWidget {
  MapView({Key? key}) : super(key: key);

  final MapController _mapController = MapController();
  final mapPoints = <LatLng>[
    LatLng(51.5, -0.09),
    LatLng(53.3498, -6.2603),
    LatLng(48.8566, 2.3522),
    LatLng(52.5200, 13.4050),
    LatLng(51.5074, -0.1278),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: const Text('Map View')),
        body: FlutterMap(
          mapController: _mapController,
          options: MapOptions(
            maxZoom: 13,
            onMapReady: () {
              final markerBounds = LatLngBounds.fromPoints(mapPoints);

              _mapController.fitBounds(
                markerBounds,
                options: const FitBoundsOptions(padding: EdgeInsets.all(70)),
              );
            },
          ),
          children: [
            TileLayer(
              urlTemplate: 'https://api.tomtom.com/map/1/tile/basic/main/'
                  '{z}/{x}/{y}.png?key={apiKey}',
              additionalOptions: const {
                'apiKey': 'FnfFpG2MWmBYXNsvAFOAyJCJB7ftnoGd',
              },
            ),
            PolylineLayer(
              polylines: [
                Polyline(
                  strokeWidth: 3,
                  points: mapPoints,
                  color: Colors.green,
                ),
              ],
            ),
         
          ],
        ));
  }
}

[JaffaKetchup]

Reproducible. The issue seems to be with running the fitBounds call when the map loads. Can you use bounds in MapOptions instead?

[MatyasK]

@JaffaKetchup That solves the issue, thanks for your quick reply!

[JaffaKetchup]

This is likely related to #1475.
@ibrierley @mootw @TesteurManiak Is this issue worth fixing? Users shouldn't setup their map in this way - except from when they need data from asynchronous sources first. But in that case, they can just delay the whole map from loading.

[TesteurManiak]

I agree with you @JaffaKetchup. Maybe we should mention something about this in the documentation of either MapController or onMapReady.

[ibrierley]

hmm I think it depends if this is part of a more subtle bug. I think its fine to leave this as is for this current issue (i.e there's a more correct fix).

But I'm also wondering if its related to something like some bits in rorystephenson@a13353f (it may also be completely unrelated, just maybe the first place I'd look by the description of the problem). eg

Remove unnecessary setState in FlutterMapState’s emitMapEvent. The
event emitting does not change the map's state and was causing double
calls to setState in some code paths.

• Removed the workaround for the initial map size being zero in TileLayer
  which caused tiles to not be loaded. The new MapEventNonRotatedSizeChange
  event removes the need for this workaround as during startup either:
  - The platform has already set flutter's resolution and thus all
  tiles are successfully loaded.
  - The platform has not set flutter's resolution but when it does it
  will cause LayoutBuilder to rebuild with the new size which will
  trigger a MapEventNonRotatedSizeChange event. This event will in
  turn trigger a tile load in TileLayer.

For example, if there's a condition where previously we didn't have a size in the layout builder, and previously didn't send a map ready event until the size was resolved but now we do. We may find there are some other sneaky bugs that come in where people are doing things on a map ready when it isn't correctly sized or tiles loaded. I don't know this is the case at all, just kinda worth being aware that it could be part of a larger issue that pops up a few times. The whole layoutbuilder sizing thing has always been a bit of a pita :).

[JaffaKetchup]

just kinda worth being aware that it could be part of a larger issue that pops up a few times. The whole layoutbuilder sizing thing has always been a bit of a pita :).

Absolutely, whatever anyone does, it never seems to properly fix it!

Maybe we should mention something about this in the documentation of either MapController or onMapReady.

I'll mention it in https://docs.fleaflet.dev/usage/controller#usage-in-initstate - on a related note, I've recently changed the guidance for MapController in initState again to use onMapReady, because some people were having issues with the SchedulerBinding methods, and it's more clear now.

I think its fine to leave this as is for this current issue (i.e there's a more correct fix).

Maybe this should be converted to a general tracking issue then, for issues with initial sizing?

[JaffaKetchup]

Closing for now. More specific issues can be opened as necessary.
Fixed (temporarily-ish?) through documentation update.