Move android app initialization to custom application class

api/Avalonia.Android.nupkg.xml

@@ -1,6 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- https://learn.microsoft.com/en-us/dotnet/fundamentals/package-validation/diagnostic-ids -->
 <Suppressions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Avalonia.Android.AvaloniaMainActivity`1</Target>
+    <Left>baseline/net8.0-android34.0/Avalonia.Android.dll</Left>
+    <Right>target/net8.0-android34.0/Avalonia.Android.dll</Right>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Avalonia.Android.AndroidViewControlHandle.get_HandleDescriptor</Target>

samples/ControlCatalog.Android/Application.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Android.App;
+using Android.Runtime;
+using Avalonia;
+using Avalonia.Android;
+
+namespace ControlCatalog.Android
+{
+    [Application]
+    public class Application : AvaloniaAndroidApplication<App>
+    {
+        protected Application(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
+        {
+        }
+
+
+        protected override AppBuilder CustomizeAppBuilder(AppBuilder builder)
+        {
+            return base.CustomizeAppBuilder(builder)
+                 .AfterSetup(_ =>
+                 {
+                     Pages.EmbedSample.Implementation = new EmbedSampleAndroid();
+                 });
+        }
+    }
+}

samples/ControlCatalog.Android/MainActivity.cs

@@ -1,7 +1,6 @@
 using Android.App;
 using Android.Content.PM;
 using Android.OS;
-using Avalonia;
 using Avalonia.Android;
 using static Android.Content.Intent;
 
@@ -13,25 +12,17 @@ namespace ControlCatalog.Android
 {
     [Activity(Name = "com.Avalonia.ControlCatalog.MainActivity", Label = "ControlCatalog.Android", Theme = "@style/MyTheme.NoActionBar", Icon = "@drawable/icon", MainLauncher = true, Exported = true, ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize | ConfigChanges.UiMode)]
     // CategoryLeanbackLauncher is required for Android TV.
-    [IntentFilter(new [] { ActionView }, Categories = new [] { CategoryDefault, CategoryLeanbackLauncher })]
-    public class MainActivity : AvaloniaMainActivity<App>
+    [IntentFilter(new[] { ActionView }, Categories = new[] { CategoryDefault, CategoryLeanbackLauncher })]
+    public class MainActivity : AvaloniaMainActivity
     {
-        protected override AppBuilder CustomizeAppBuilder(AppBuilder builder)
-        {
-            return base.CustomizeAppBuilder(builder)
-                 .AfterSetup(_ =>
-                 {
-                     Pages.EmbedSample.Implementation = new EmbedSampleAndroid();
-                 });
-        }
     }
 
     /// <summary>
     /// Special activity to handle OpenUri activation.
     /// `AvaloniaActivity` internally will redirect parameters to the Avalonia Application.
     /// </summary>
     [Activity(NoHistory = true, LaunchMode = LaunchMode.SingleTop, Exported = true, Theme = "@android:style/Theme.NoDisplay")]
-    [IntentFilter(new[] {ActionView}, Categories = new[] {CategoryDefault, CategoryBrowsable}, DataScheme = "avln")]
+    [IntentFilter(new[] { ActionView }, Categories = new[] { CategoryDefault, CategoryBrowsable }, DataScheme = "avln")]
     public class DataSchemeActivity : AvaloniaActivity
     {
         protected override void OnCreate(Bundle? savedInstanceState)

samples/ControlCatalog.Android/Properties/AndroidManifest.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:installLocation="auto">
-  <application android:label="ControlCatalog.Android" android:icon="@drawable/Icon"></application>
+  <application android:name=".Application" android:label="ControlCatalog.Android" android:icon="@drawable/Icon"></application>
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE " />

samples/SafeAreaDemo.Android/Application.cs

@@ -0,0 +1,14 @@
+using Android.App;
+using Android.Runtime;
+using Avalonia.Android;
+
+namespace SafeAreaDemo.Android
+{
+    [Application]
+    public class Application : AvaloniaAndroidApplication<App>
+    {
+        protected Application(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
+        {
+        }
+    }
+}

samples/SafeAreaDemo.Android/MainActivity.cs

@@ -5,7 +5,7 @@
 namespace SafeAreaDemo.Android
 {
     [Activity(Label = "SafeAreaDemo.Android", Theme = "@style/MyTheme.NoActionBar", Icon = "@drawable/icon", MainLauncher = true, ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize | ConfigChanges.UiMode)]
-    public class MainActivity : AvaloniaMainActivity<App>
+    public class MainActivity : AvaloniaMainActivity
     {
     }
 }

samples/SafeAreaDemo.Android/Properties/AndroidManifest.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:installLocation="auto">
 	<uses-permission android:name="android.permission.INTERNET" />
-	<application android:label="SafeAreaDemo" android:icon="@drawable/Icon" />
+	<application android:name=".Application" android:label="SafeAreaDemo" android:icon="@drawable/Icon" />
 </manifest>

samples/SingleProjectSandbox/Platforms/Android/AndroidManifest.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:installLocation="auto">
-  <application android:label="SingleProjectSandbox.Android"></application>
+  <application android:name=".Application" android:label="SingleProjectSandbox.Android"></application>
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 </manifest>

samples/SingleProjectSandbox/Platforms/Android/Application.cs

@@ -0,0 +1,14 @@
+using Android.App;
+using Android.Runtime;
+using Avalonia.Android;
+
+namespace SingleProjectSandbox.Android
+{
+    [Application]
+    public class Application : AvaloniaAndroidApplication<App>
+    {
+        protected Application(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
+        {
+        }
+    }
+}

samples/SingleProjectSandbox/Platforms/Android/MainActivity.cs

@@ -1,15 +1,10 @@
 using Android.App;
 using Android.Content.PM;
-using Avalonia;
 using Avalonia.Android;
 
 namespace SingleProjectSandbox;
 
 [Activity(Label = "SingleProjectSandbox.Android", Theme = "@style/Theme.AppCompat.NoActionBar", MainLauncher = true, ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize)]
-public class MainActivity : AvaloniaMainActivity<App>
-{
-    protected override AppBuilder CreateAppBuilder()
+public class MainActivity : AvaloniaMainActivity
     {
-        return App.BuildAvaloniaApp().UseAndroid();
-    }
 }

src/Android/Avalonia.Android/AvaloniaAndroidApplication.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Android.Runtime;
+
+namespace Avalonia.Android
+{
+    internal interface IAndroidApplication
+    {
+        SingleViewLifetime? Lifetime { get; set; }
+    }
+
+    public class AvaloniaAndroidApplication<TApp> : global::Android.App.Application, IAndroidApplication
+        where TApp : Application, new()
+    {
+        SingleViewLifetime? IAndroidApplication.Lifetime { get; set; }
+
+        protected AvaloniaAndroidApplication(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
+        {
+        }
+
+        public override void OnCreate()
+        {
+            base.OnCreate();
+            InitializeAppLifetime();
+        }
+
+        private void InitializeAppLifetime()
+        {
+            var builder = CreateAppBuilder();
+            builder = CustomizeAppBuilder(builder);
+
+            var lifetime = new SingleViewLifetime();
+
+            ((IAndroidApplication)this).Lifetime = lifetime;
+
+            builder.SetupWithLifetime(lifetime);
+        }
+
+        protected virtual AppBuilder CreateAppBuilder() => AppBuilder.Configure<TApp>().UseAndroid();
+        protected virtual AppBuilder CustomizeAppBuilder(AppBuilder builder) => builder;
+    }
+}

src/Android/Avalonia.Android/AvaloniaMainActivity.cs

@@ -8,41 +8,18 @@ namespace Avalonia.Android;
 
 public class AvaloniaMainActivity : AvaloniaActivity
 {
-    private protected static SingleViewLifetime? Lifetime;
-
     private protected override void InitializeAvaloniaView(object? initialContent)
     {
-        // Android can run OnCreate + InitializeAvaloniaView multiple times per process lifetime.
-        // On each call we need to create new AvaloniaView, but we can't recreate Avalonia nor Avalonia controls.
-        // So, if lifetime was already created previously - recreate AvaloniaView.
-        // If not, initialize Avalonia, and create AvaloniaView inside of AfterSetup callback.
-        // We need this AfterSetup callback to match iOS/Browser behavior and ensure that view/toplevel is available in custom AfterSetup calls.
-        if (Lifetime is not null)
+        if (Application is IAndroidApplication application && application.Lifetime is { } lifetime)
         {
-            initialContent ??= Lifetime.MainView; 
+            initialContent ??= lifetime.MainView; 
 
             _view = new AvaloniaView(this) { Content = initialContent };
-            Lifetime.Activity = this;
+            lifetime.Activity = this;
         }
-        else
-        {
-            var builder = CreateAppBuilder();
-            builder = CustomizeAppBuilder(builder);
 
-            Lifetime = new SingleViewLifetime();
-            Lifetime.Activity = this;
-
-            builder
-                .AfterApplicationSetup(_ =>
-                {
-                    _view = new AvaloniaView(this) { Content = initialContent };
-                })
-                .SetupWithLifetime(Lifetime);
-
-            // AfterPlatformServicesSetup should always be called. If it wasn't, we have an unusual problem.
-            if (_view is null)
-                throw new InvalidOperationException("Unknown error: AvaloniaView initialization has failed.");
-        }
+        if (_view is null)
+            throw new InvalidOperationException("Unknown error: AvaloniaView initialization has failed.");
 
         if (Avalonia.Application.Current?.TryGetFeature<IActivatableLifetime>()
             is AndroidActivatableLifetime activatableLifetime)

tests/BuildTests/BuildTests.Android/Application.cs

@@ -0,0 +1,14 @@
+using Android.App;
+using Android.Runtime;
+using Avalonia.Android;
+
+namespace BuildTests.Android
+{
+    [Application]
+    public class Application : AvaloniaAndroidApplication<App>
+    {
+        protected Application(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
+        {
+        }
+    }
+}

tests/BuildTests/BuildTests.Android/MainActivity.cs

@@ -8,4 +8,4 @@ namespace BuildTests.Android;
     Label = "BuildTests.Android",
     MainLauncher = true,
     ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize | ConfigChanges.UiMode)]
-public class MainActivity : AvaloniaMainActivity<App>;
+public class MainActivity : AvaloniaMainActivity;

tests/BuildTests/BuildTests.Android/Properties/AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:installLocation="auto">
 	<uses-permission android:name="android.permission.INTERNET" />
-	<application android:label="BuildTests" />
+	<application android:name=".Application"
+               android:label="BuildTests" />
 </manifest>