I'm still fairly new to Visual Studio/Xamarin but I had a simple OpenStreetMap sample running awhile ago for Android that did display a map but that doesn't seem to display map anymore though I haven't changed the code for this sample in awhile as far as I recall. I'm not sure if some Visual Studio/Xamarin or MacOS update might have caused it to not work anymore.
I'm using Visual Studio for Mac community 8.4.4 (build 91) on macOS Mojava 10.14.6 and the following Packages:
My MainActivity.cs file contains the following code:
using System;
using Android.App;
using Android.OS;
using Android.Runtime;
using Android.Support.Design.Widget;
using Android.Support.V7.App;
using Android.Views;
using Android.Widget;
using Mapsui;
using Mapsui.Geometries;
using Mapsui.Projection;
using Mapsui.Styles;
using Mapsui.Utilities;
using Mapsui.UI.Android;
using Mapsui.Widgets.ScaleBar;
using Mapsui.Widgets.Zoom;
using Xamarin.Essentials;
namespace mvp_android
{
[Activity(Label = "@string/app_name", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
SetContentView(Resource.Layout.Main);
var mapControl = FindViewById<MapControl>(Resource.Id.mapcontrol);
var map = new Mapsui.Map();
map.Layers.Add(OpenStreetMap.CreateTileLayer());
map.Widgets.Add(
new ZoomInOutWidget(map) {
HorizontalAlignment = Mapsui.Widgets.HorizontalAlignment.Left,
VerticalAlignment = Mapsui.Widgets.VerticalAlignment.Top,
Orientation = Mapsui.Widgets.Zoom.Orientation.Horizontal,
}
);
var centerOfLondonOntario = new Point(-81.2497, 42.9837);
map.NavigateTo(SphericalMercator.FromLonLat(centerOfLondonOntario.X, centerOfLondonOntario.Y));
map.NavigateTo(map.Resolutions[9]);
mapControl.Map = map;
}
public override bool OnCreateOptionsMenu(IMenu menu)
{
MenuInflater.Inflate(Resource.Menu.menu_main, menu);
return true;
}
public override bool OnOptionsItemSelected(IMenuItem item)
{
int id = item.ItemId;
if (id == Resource.Id.action_settings)
{
return true;
}
return base.OnOptionsItemSelected(item);
}
private void FabOnClick(object sender, EventArgs eventArgs)
{
View view = (View)sender;
Snackbar.Make(view, "Replace with your own action", Snackbar.LengthLong)
.SetAction("Action", (Android.Views.View.IOnClickListener)null).Show();
}
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
{
Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
And my Main.xml contains the following code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Mapsui.UI.Android.MapControl
android:id="@+id/mapcontrol"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
Originally, this sample showed the OpenStreetMap's map centering on the London, Ontario location with zoom in/out buttons, but now it just shows a white where the map should be, still shows the zoom in/out buttons and does display the (c)OpenStreetMap watermark.
What am I missing here?
Update 2021-03-23: Since last week the "BruTile Tile Library" user agent is blocked by OpenStreetMap. This is the default of BruTile's KnownTileSource.Create. This method has a parameter to pass in your own user agent. The fix is to provide a string that is specific to your app.
The version of BruTile used in Mapsui 1.4.8 did not send the user-agent as part of it's request and at some point the openstreetmap server started blocking requests for this reason.
As a workaround you could create a custom ITileSource as described here by Matt Schneeberger: https://github.com/Mapsui/Mapsui/issues/668#issuecomment-497947690