private async Task OnAfterInitAsync() { List <OverlayType> overlayTypes = new List <OverlayType>(); overlayTypes.Add(OverlayType.Polygon); var drawingControlOptions = new DrawingControlOptions() { Position = ControlPosition.TopCenter, DrawingModes = overlayTypes }; managerOptions = new DrawingManagerOptions() { Map = map1.InteropObject, PolygonOptions = polygonOptions, DrawingMode = OverlayType.Polygon, DrawingControl = true, //DrawingControlOptions = drawingControlOptions }; drawingManager = await DrawingManager.CreateAsync(JsRuntime, managerOptions); //https://developers.google.com/maps/documentation/javascript/drawinglayer await drawingManager.AddListener <OverlayCompleteEvent>("overlaycomplete", (arg) => { //Overlay object is JObject with all properties, //so need to serialize, extract required info depending on your needs var json = arg.Overlay.ToString(); }); }