Xamarin Forms Maps - how to refresh/update the map - CustomMap Renderer

Question

If you are searching for a full polylines, pins, tiles, UIOptions (and 3D effects soon) renderings/implementations, you should take a loot at the public github I made at

Answer 1

I followed the tutorial available on Xamarin Docs and it worked for me with some changes based on @Sven-Michael Stübe answer

I load the coordinates from a WebService and then I create a separate List, and after this, I set the new list to the RouteCoordinates property on Custom Map.

Some changes are made on Android Renderer

I'm using MVVM.

CustomMap Class:

public static readonly BindableProperty RouteCoordinatesProperty =
        BindableProperty.Create(nameof(RouteCoordinates), typeof(List), typeof(CustomMap), new List(), BindingMode.TwoWay);

public List RouteCoordinates
{
    get { return (List)GetValue(RouteCoordinatesProperty); }
    set { SetValue(RouteCoordinatesProperty, value); }
}

public CustomMap()
{
    RouteCoordinates = new List();
}

ViewModel (Codebehind, in your case):

private async void LoadCoordinates(string oidAula, CustomMap mapa)
{
    IsBusy = true;

    var percurso = await ComunicacaoServidor.GetPercurso(oidAula); // Get coordinates from WebService
    var pontos = percurso.Select(p => new Position(p.Latitude, p.Longitude)).ToList(); // Create coordinates list from webservice result

    var latitudeMedia = percurso[percurso.Count / 2].Latitude;
    var longitudeMedia = percurso[percurso.Count / 2].Longitude;

    mapa.RouteCoordinates = pontos;
    mapa.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(latitudeMedia, longitudeMedia), Distance.FromMiles(1.0)));

    IsBusy = false;
}

XAML:

Android Renderer:

public class CustomMapRenderer : MapRenderer
{
    bool isDrawn;

    protected override void OnElementChanged(ElementChangedEventArgs

This example have more than 3600 points of location and the polyline shows correctly on device:

Screenshot