addMarker method
Add a marker on the map point
and returned callback
when you clicked on it
Implementation
@override
addMarker(LatLng point, Function(LatLng point)? callback) {
if (callback != null) {
super.markers[point] = callback;
}
NtkMapViewState.controller.runJavaScript("L.marker(L.latLng(${point.latitude}, ${point.longitude})).addTo(map);");
}