Xamarin: Navigate from MapRenderer Class to ContentPage - xamarin

Question

I am facing the following issue.
I am developing a Cross Platform Project on Xamarin and I am trying to open a ContentPage from a MapInfoWindow.
The Map ContentPage is inside the Portable Project and inside the Droid Project I have a the following class that is where I am trying to open the ContenPage:
public class CustomMapRenderer: MapRenderer, GoogleMap.IInfoWindowAdapter, IOnMapReadyCallback
{
GoogleMap map;
List<CustomPin> customPins;
bool isDrawn;
protected override void OnElementChanged(Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
map.InfoWindowClick -= OnInfoWindowClick;
}
if (e.NewElement != null)
{
var formsMap = (CustomMap)e.NewElement;
customPins = formsMap.CustomPins;
((MapView)Control).GetMapAsync(this);
}
}
public void OnMapReady(GoogleMap googleMap)
{
map = googleMap;
map.InfoWindowClick += OnInfoWindowClick;
map.SetInfoWindowAdapter(this);
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName.Equals("VisibleRegion") && !isDrawn)
{
map.Clear();
if (customPins != null)
{
foreach (var pin in customPins)
{
var marker = new MarkerOptions();
marker.SetPosition(new LatLng(pin.Pin.Position.Latitude, pin.Pin.Position.Longitude));
marker.SetTitle(pin.Pin.Label);
marker.SetSnippet(pin.Pin.Address);
marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
map.AddMarker(marker);
}
isDrawn = true;
}
}
}
protected override void OnLayout(bool changed, int l, int t, int r, int b)
{
base.OnLayout(changed, l, t, r, b);
if (changed)
{
isDrawn = false;
}
}
void OnInfoWindowClick(object sender, GoogleMap.InfoWindowClickEventArgs e)
{
var customPin = GetCustomPin(e.Marker);
if (customPin == null)
{
throw new Exception("Custom pin not found");
}
//Here I want to open the content page
}
public Android.Views.View GetInfoContents(Marker marker)
{
var inflater = Android.App.Application.Context.GetSystemService(Context.LayoutInflaterService) as Android.Views.LayoutInflater;
if (inflater != null)
{
Android.Views.View view;
var customPin = GetCustomPin(marker);
if (customPin == null)
{
throw new Exception("Custom pin not found");
}
if (customPin.Id == "Xamarin")
{
view = inflater.Inflate(Resource.Layout.XamarinMapInfoWindow, null);
}
else
{
view = inflater.Inflate(Resource.Layout.MapInfoWindow, null);
}
var infoTitle = view.FindViewById<TextView>(Resource.Id.InfoWindowTitle);
var infoSubtitle = view.FindViewById<TextView>(Resource.Id.InfoWindowSubtitle);
if (infoTitle != null)
{
infoTitle.Text = marker.Title;
}
if (infoSubtitle != null)
{
infoSubtitle.Text = marker.Snippet;
}
return view;
}
return null;
}
public Android.Views.View GetInfoWindow(Marker marker)
{
return null;
}
CustomPin GetCustomPin(Marker annotation)
{
var position = new Position(annotation.Position.Latitude, annotation.Position.Longitude);
foreach (var pin in customPins)
{
if (pin.Pin.Position == position)
{
return pin;
}
}
return null;
}
}

Answer 1

So I believe creating an EventHandler in your CustomMap class might be the way to go. In your CustomMap class, add the following:
public event EventHandler InfoTapped;
public virtual void OnInfoTapped(EventArgs e)
{
EventHandler handler = InfoTapped;
if (handler != null)
{
handler(this, e);
}
}
Then in your Forms shared code subscribe to the InfoTapped event and push your new ContentPage:
customMap.InfoTapped += async (sender, e) => {
await Navigation.PushAsync(new ContentPage());
};
Now in your renderer, create a class level field to hold a reference to your CustomMap:
CustomMap formsMap;
And then set this field in your OnElementChanged method:
if (e.NewElement != null)
{
// Remove the var to set your CustomMap field created
// above so you can use it elsewhere in the class
formsMap = (CustomMap)e.NewElement;
...
}
Now you can raise the event you created in CustomMap by calling:
formsMap.OnInfoTapped(e);
E.G.:
void OnInfoWindowClick(object sender, GoogleMap.InfoWindowClickEventArgs e)
{
var customPin = GetCustomPin(e.Marker);
if (customPin == null)
{
throw new Exception("Custom pin not found");
}
//Here I want to open the content page
formsMap.OnInfoTapped(e);
}
And the code you added to the customMap.InfoTapped event handler will be called, in this case to push a new page.