Flutter/Dart Add custom Tap Events for Google Maps Marker

Keep in mind that the current release is a developer preview at version 0.0.3. Give it a bit of time to get things working, please!

     void _onMapCreated(GoogleMapController controller){
    this._controller = controller;
    controller.onMarkerTapped.add(_onMarkerTapped);
}

void _onMarkerTapped(Marker marker) {
...
}

Widget build(BuildContext context) {
 ... GoogleMap(
        onMapCreated: _onMapCreated,
        options: GoogleMapOptions(
          ...
        ));
}

You can use onTap or onLongPress option in the map plugin to monitor tap events. Then you can add the marker in following way on the tapped position

    final Set<Marker> _markers = {};



 GoogleMap(onMapCreated: _onMapCreated,
        initialCameraPosition: CameraPosition(
          target: _center,
          zoom: 13.0,
        ),
        compassEnabled: true,
        tiltGesturesEnabled: false,
        onTap: (latlang){
          if(_markers.length>=1)
            {
              _markers.clear();
            }

          _onAddMarkerButtonPressed(latlang);
        },
        myLocationEnabled: true,
        myLocationButtonEnabled: true,
        mapType: mapType,
        markers: _markers,
        onCameraMove: _onCameraMove,
      ),

where the _onAddMarkerButtonPressed function is

 void _onAddMarkerButtonPressed(LatLng latlang) {
loadAddress(latlang);
_latLng = latlang;
 setState(() {
  _markers.add(Marker(
    // This marker id can be anything that uniquely identifies each marker.
    markerId: MarkerId(_lastMapPosition.toString()),
    position: latlang,
    infoWindow: InfoWindow(
      title: address,
    //  snippet: '5 Star Rating',
    ),
    icon: BitmapDescriptor.defaultMarker,
  ));
});
}

With the release of version ^0.3.0+1 a new Marker API was introduced which handles markers as widgets (including an onTap() method). This way a Google Map has a markers: option which admits a list of Marker objects. Each of the elements can be defined like this:

Marker(
  markerId: MarkerId("id"), // a string for marker unique id
  icon: BitmapDescriptor.defaultMarker(), // options for hues and custom imgs
  position: LatLng(lat, long), // lat and long doubles

  onTap: () {
    //this is what you're looking for!
  }

),

Much easier than the former controller approach!