I have dynamically created Markers with LabelMarkers. I add all of them to a Set of Markers to use on GoogleMap.

static Set<Marker> allMarkers = {};
...
allLocationsList.forEach((location) async {
...
allMarkers.addLabelMarker(
            LabelMarker(
              visible: **_isItVisible**,
              label: _name,
              markerId: MarkerId(_name),
              draggable: false,
              backgroundColor: **_amIclose**
                  ? Colors.green
                  : Colors.red,
              position: LatLng(_latitude, _longitude),
              onTap: **_isItEnabled**
                  ? pressButton()
                  : null,
            ),
          );
}
...
return GoogleMap(
            style: _mapStyle,
            gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
              Factory<OneSequenceGestureRecognizer>(
                () => EagerGestureRecognizer(),
              ),
            },
            zoomGesturesEnabled: true,
            tiltGesturesEnabled: false,
            compassEnabled: true,
            rotateGesturesEnabled: true,
            scrollGesturesEnabled: true,
            mapToolbarEnabled: false,
            myLocationEnabled: false,
            myLocationButtonEnabled: false,
            initialCameraPosition: CameraPosition(
              target: _center,
              zoom: 6.2,
            ),
            markers: allMarkers,
            onMapCreated: (GoogleMapController controller) async {
              mapController = controller;
              setState(
                () {
                  mapController?.animateCamera(...);
                },
              );
            },
      );

As you see I have many variables. _isItVisible, _isItEnabled and _amIclose probably should be checked in a Stream. Now there are two problems:

1. I can’t return LabelMaker from StatefulWidget as this is not a Widget (I would use a Stream in every Label to check for variables).
2. If I would check and update all Markers constantly in one Stream the app would loose a lot of Frames and “die”.

I have wasted hours and even days to find a way to update only Markers with changed variable (_isItVisible, _isItEnabled and _amIclose) values. Please help!