Make a pushpin move smoothly on MapControl Windows phone 8.1

Question

i'm trying to creat an app that tracks my current location. Here is my code:

private Image currentLocationPin;
private async void CurrentLocationChanged(Geolocator sender, PositionChangedEventArgs args)
    {
        await dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
        {
            mapControl.Children.Remove(currentLocationPin);
            currentLocationPin = new Image() { Source = new BitmapImage(new Uri(smallIconURI)) };
            var currentGeo = new Geopoint(new BasicGeoposition
            {
                Latitude = args.Position.Coordinate.Point.Position.Latitude,
                Longitude = args.Position.Coordinate.Point.Position.Longitude
            });

            MapControl.SetNormalizedAnchorPoint(currentLocationPin, new Point(0.5, 1));
            MapControl.SetLocation(currentLocationPin, currentGeo);
            mapControl.Children.Add(currentLocationPin);

            currentLocationPin.Tapped += ChildObj_Tapped;
            mapControl.LandmarksVisible = false;
            mapControl.TrafficFlowVisible = false;
            mapControl.PedestrianFeaturesVisible = false;
            currentGeopoint = currentGeo;
        });
    }

This function will be called when my current location changes. It works quite good but this problem. Because i remove previous pin then add a new one so when i see it on the map, there is a delay between each 2 pins. I tried with MapIcon but it didn't work, too. I tried not to remove pin and updated its location only, but there would be a new pin, next to the old one. Thank you.

Answer 1

You shouldn't have to remove-recreate-add the overlay each time the location changes. Updating the existing overlay's location should do the trick (although it sounds like you tried this and it didn't work?)

I haven't tested this, but I adapted your code to update the existing overlay's position rather than recreating it.

    await dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
    {
        // If needed, create the location pin.
        if(currentLocationPin == null)
        {
            currentLocationPin = new Image() { Source = new BitmapImage(new Uri(smallIconURI)) };
            MapControl.SetNormalizedAnchorPoint(currentLocationPin, new Point(0.5, 1));
            mapControl.Children.Add(currentLocationPin);
        }

        // Update the pin's location.  

        var currentGeo = new Geopoint(new BasicGeoposition
        {
            Latitude = args.Position.Coordinate.Point.Position.Latitude,
            Longitude = args.Position.Coordinate.Point.Position.Longitude
        });

        MapControl.SetLocation(currentLocationPin, currentGeo);

        mapControl.LandmarksVisible = false;
        mapControl.TrafficFlowVisible = false;
        mapControl.PedestrianFeaturesVisible = false;
        currentGeopoint = currentGeo;
    });