在工具栏上显示警报视图

Question

我想显示一个内部带有滑块的Alertview。我希望Alertview显示在我的地图视图上，当我完成Alertview后，我希望它关闭并再次显示该Mapview。

Widget displayMap() {
mapView = new MapView();
double latitude = 0.0;
double longitude = 0.0;

int radius = 0;

mapView.show(
new MapOptions(

title: "Camera",
hideToolbar: false,
showUserLocation: true,
showMyLocationButton: true,
initialCameraPosition:
 new CameraPosition(new Location(0.0, 0.0), 6.0),
),

toolbarActions: <ToolbarAction>[new ToolbarAction("Change", 1)],

);

mapView.onToolbarAction.listen((identifier){
switch(identifier){
case 1:
  //Display alertview here with a slider???? is it even possible?
  break;
}
});

mapView.onLocationUpdated.listen((location){

double latitude = location.latitude;
double longitude = location.longitude;

for(int i = 0; i < points.length; i++){
  cameraRadius(latitude, longitude, points[i].getY(), points[i].getX(), 
  points);
 }

});

mapView.onMapReady.listen((_){
  mapView.visibleAnnotations;
});

mapView.setMarkers(markers);
}