Enable nullability in Avalonia.Native (#20378)

src/Avalonia.Native/Avalonia.Native.csproj

@@ -27,4 +27,5 @@
 
   <Import Project="..\..\build\DevAnalyzers.props" />
   <Import Project="..\..\build\TrimmingEnable.props" />
+  <Import Project="..\..\build\NullableEnable.props" />
 </Project>

src/Avalonia.Native/AvaloniaNativeApplicationPlatform.cs

@@ -12,11 +12,11 @@ namespace Avalonia.Native
 {
     internal class AvaloniaNativeApplicationPlatform : NativeCallbackBase, IAvnApplicationEvents, IPlatformLifetimeEventsImpl
     {
-        public event EventHandler<ShutdownRequestedEventArgs> ShutdownRequested;
+        public event EventHandler<ShutdownRequestedEventArgs>? ShutdownRequested;
 
         void IAvnApplicationEvents.FilesOpened(IAvnStringArray urls)
         {
-            ((IApplicationPlatformEvents)Application.Current)?.RaiseUrlsOpened(urls.ToStringArray());
+            ((IApplicationPlatformEvents?)Application.Current)?.RaiseUrlsOpened(urls.ToStringArray());
 
             if (AvaloniaLocator.Current.GetService<IActivatableLifetime>() is ActivatableLifetimeBase lifetime
                 && AvaloniaLocator.Current.GetService<IStorageProviderFactory>() is StorageProviderApi storageApi)
@@ -42,7 +42,7 @@ namespace Avalonia.Native
         void IAvnApplicationEvents.UrlsOpened(IAvnStringArray urls)
         {
             // Raise the urls opened event to be compatible with legacy behavior.
-            ((IApplicationPlatformEvents)Application.Current)?.RaiseUrlsOpened(urls.ToStringArray());
+            ((IApplicationPlatformEvents?)Application.Current)?.RaiseUrlsOpened(urls.ToStringArray());
 
             if (AvaloniaLocator.Current.GetService<IActivatableLifetime>() is ActivatableLifetimeBase lifetime
                 && AvaloniaLocator.Current.GetService<IStorageProviderFactory>() is StorageProviderApi storageApi)

src/Avalonia.Native/AvaloniaNativeDragSource.cs

@@ -19,7 +19,7 @@ namespace Avalonia.Native
 
         class DndCallback : NativeCallbackBase, IAvnDndResultCallback
         {
-            private TaskCompletionSource<DragDropEffects> _tcs;
+            private TaskCompletionSource<DragDropEffects>? _tcs;
 
             public DndCallback(TaskCompletionSource<DragDropEffects> tcs)
             {

src/Avalonia.Native/AvaloniaNativeGlPlatformGraphics.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Avalonia.OpenGL;
 using Avalonia.Native.Interop;
@@ -90,12 +91,12 @@ namespace Avalonia.Native
     class GlContext : IGlContext
     {
         private readonly GlDisplay _display;
-        private readonly GlContext _sharedWith;
+        private readonly GlContext? _sharedWith;
         private readonly GpuHandleWrapFeature _handleWrapFeature;
         private readonly GlExternalObjectsFeature _externalObjects;
-        public IAvnGlContext Context { get; private set; }
+        public IAvnGlContext? Context { get; private set; }
 
-        public GlContext(GlDisplay display, GlContext sharedWith, IAvnGlContext context, GlVersion version)
+        public GlContext(GlDisplay display, GlContext? sharedWith, IAvnGlContext context, GlVersion version)
         {
             _display = display;
             _sharedWith = sharedWith;
@@ -109,14 +110,25 @@ namespace Avalonia.Native
         public GlInterface GlInterface => _display.GlInterface;
         public int SampleCount => _display.SampleCount;
         public int StencilSize => _display.StencilSize;
-        public IDisposable MakeCurrent()
+
+        [MemberNotNull(nameof(Context))]
+        public void ThrowIfLost()
         {
             if (IsLost)
                 throw new PlatformGraphicsContextLostException();
+        }
+
+        [MemberNotNull(nameof(Context))]
+        public IDisposable MakeCurrent()
+        {
+            ThrowIfLost();
             return Context.MakeCurrent();
         }
 
+        [MemberNotNullWhen(false, nameof(Context))]
         public bool IsLost => Context == null;
+
+        [MemberNotNull(nameof(Context))]
         public IDisposable EnsureCurrent() => MakeCurrent();
 
         public bool IsSharedWith(IGlContext context)
@@ -130,16 +142,16 @@ namespace Avalonia.Native
 
         public bool CanCreateSharedContext => true;
 
-        public IGlContext CreateSharedContext(IEnumerable<GlVersion> preferredVersions = null) =>
+        public IGlContext CreateSharedContext(IEnumerable<GlVersion>? preferredVersions = null) =>
             _display.CreateSharedContext(_sharedWith ?? this);
 
         public void Dispose()
         {
-            Context.Dispose();
+            Context?.Dispose();
             Context = null;
         }
 
-        public object TryGetFeature(Type featureType)
+        public object? TryGetFeature(Type featureType)
         {
             if (featureType == typeof(IExternalObjectsHandleWrapRenderInterfaceContextFeature))
                 return _handleWrapFeature;
@@ -152,7 +164,7 @@ namespace Avalonia.Native
 
     class GlPlatformSurfaceRenderTarget : IGlPlatformSurfaceRenderTarget
     {
-        private IAvnGlSurfaceRenderTarget _target;
+        private IAvnGlSurfaceRenderTarget? _target;
         private readonly IGlContext _context;
 
         public GlPlatformSurfaceRenderTarget(IAvnGlSurfaceRenderTarget target, IGlContext context)
@@ -163,6 +175,7 @@ namespace Avalonia.Native
 
         public IGlPlatformSurfaceRenderingSession BeginDraw()
         {
+            ObjectDisposedException.ThrowIf(_target is null, this);
             return new GlPlatformSurfaceRenderingSession(_context, _target.BeginDrawing());
         }
 
@@ -175,7 +188,7 @@ namespace Avalonia.Native
 
     class GlPlatformSurfaceRenderingSession : IGlPlatformSurfaceRenderingSession
     {
-        private IAvnGlSurfaceRenderingSession _session;
+        private IAvnGlSurfaceRenderingSession? _session;
 
         public GlPlatformSurfaceRenderingSession(IGlContext context, IAvnGlSurfaceRenderingSession session)
         {
@@ -185,17 +198,25 @@ namespace Avalonia.Native
 
         public IGlContext Context { get; }
 
+        private IAvnGlSurfaceRenderingSession Session
+        {
+            get
+            {
+                ObjectDisposedException.ThrowIf(_session is null, this);
+                return _session;
+            }
+        }
+
         public PixelSize Size
         {
             get
             {
-                var s = _session.PixelSize;
+                var s = Session.PixelSize;
                 return new PixelSize(s.Width, s.Height);
             }
         }
 
-        public double Scaling => _session.Scaling;
+        public double Scaling => Session.Scaling;
-
 
         public bool IsYFlipped => true;
         
@@ -230,9 +251,12 @@ namespace Avalonia.Native
 
         public unsafe GlExternalObjectsFeature(GlContext context, GlDisplay display)
         {
+            context.ThrowIfLost();
+
             _context = context;
             _display = display;
             ulong registryId = 0;
+
             if (context.Context.GetIOKitRegistryId(&registryId) != 0)
             {
                 // We are reversing bytes to match MoltenVK (LUID is a Vulkan term after all)
@@ -306,8 +330,8 @@ namespace Avalonia.Native
                    CompositionGpuImportedImageSynchronizationCapabilities.TimelineSemaphores;
         }
 
-        public byte[] DeviceLuid { get; }
+        public byte[]? DeviceLuid { get; }
-        public byte[] DeviceUuid { get; }
+        public byte[]? DeviceUuid { get; }
     }
 
     class MtlEventSemaphore(IAvnMTLSharedEvent inner) : IGlExternalSemaphore

src/Avalonia.Native/AvaloniaNativeMenuExporter.cs

@@ -15,10 +15,10 @@ namespace Avalonia.Native
         private readonly IAvaloniaNativeFactory _factory;
         private bool _resetQueued = true;
         private bool _exported;
-        private readonly IAvnWindow _nativeWindow;
+        private readonly IAvnWindow? _nativeWindow;
-        private NativeMenu _menu;
+        private NativeMenu? _menu;
-        private __MicroComIAvnMenuProxy _nativeMenu;
+        private __MicroComIAvnMenuProxy? _nativeMenu;
-        private readonly IAvnTrayIcon _trayIcon;
+        private readonly IAvnTrayIcon? _trayIcon;
         private readonly IAvnApplicationCommands _applicationCommands;
 
         public AvaloniaNativeMenuExporter(IAvnWindow nativeWindow, IAvaloniaNativeFactory factory)
@@ -51,7 +51,7 @@ namespace Avalonia.Native
 
         public event EventHandler OnIsNativeMenuExportedChanged { add { } remove { } }
 
-        public void SetNativeMenu(NativeMenu menu)
+        public void SetNativeMenu(NativeMenu? menu)
         {
             _menu = menu ?? new NativeMenu();
             DoLayoutReset(true);
@@ -152,7 +152,7 @@ namespace Avalonia.Native
 
         private void DoLayoutReset() => DoLayoutReset(false);
 
-        private void DoLayoutReset(bool forceUpdate = false)
+        private void DoLayoutReset(bool forceUpdate)
         {
             var macOpts = AvaloniaLocator.Current.GetService<MacOSPlatformOptions>() ?? new MacOSPlatformOptions();
 
@@ -169,12 +169,15 @@ namespace Avalonia.Native
                 {
                     if (_trayIcon is null)
                     {
-                        var appMenu = NativeMenu.GetMenu(Application.Current);
+                        var app = Application.Current;
+                        var appMenu = app is null ? null : NativeMenu.GetMenu(app);
 
                         if (appMenu == null)
                         {
                             appMenu = CreateDefaultAppMenu();
-                            NativeMenu.SetMenu(Application.Current, appMenu);
+
+                            if (app is not null)
+                                NativeMenu.SetMenu(app, appMenu);
                         }
 
                         SetMenu(appMenu);

src/Avalonia.Native/AvaloniaNativePlatform.cs

@@ -12,7 +12,6 @@ using Avalonia.Rendering;
 using Avalonia.Rendering.Composition;
 using Avalonia.Threading;
 using MicroCom.Runtime;
-#nullable enable
 
 namespace Avalonia.Native
 {
@@ -199,7 +198,7 @@ namespace Avalonia.Native
 
         public IWindowImpl CreateWindow()
         {
-            return new WindowImpl(_factory, _options);
+            return new WindowImpl(_factory, _options ?? new AvaloniaNativePlatformOptions());
         }
 
         public IWindowImpl CreateEmbeddableWindow()

src/Avalonia.Native/AvaloniaNativePlatformExtensions.cs

@@ -79,7 +79,7 @@ namespace Avalonia
         /// This property should be used in case you want to build Avalonia OSX native part by yourself
         /// and make your Avalonia app run with it. The default value is null.
         /// </summary>
-        public string AvaloniaNativeLibraryPath { get; set; }
+        public string? AvaloniaNativeLibraryPath { get; set; }
 
         /// <summary>
         /// If you distribute your app in App Store - it should be with sandbox enabled.

src/Avalonia.Native/AvaloniaNativeRenderTimer.cs

@@ -1,9 +1,7 @@
 using System;
 using System.Diagnostics;
-using System.Runtime.InteropServices;
 using Avalonia.Native.Interop;
 using Avalonia.Rendering;
-#nullable enable
 
 namespace Avalonia.Native;
 

src/Avalonia.Native/AvaloniaNativeTextInputMethod.cs

@@ -1,10 +1,7 @@
 using System;
 using Avalonia.Input.TextInput;
-using Avalonia.Media.TextFormatting;
 using Avalonia.Native.Interop;
 
-#nullable enable
-
 namespace Avalonia.Native
 {
     internal class AvaloniaNativeTextInputMethod : ITextInputMethodImpl, IDisposable

src/Avalonia.Native/AvnAutomationPeer.cs

@@ -6,12 +6,9 @@ using System.Runtime.CompilerServices;
 using Avalonia.Automation;
 using Avalonia.Automation.Peers;
 using Avalonia.Automation.Provider;
-using Avalonia.Controls;
 using Avalonia.Controls.Automation.Peers;
 using Avalonia.Native.Interop;
 
-#nullable enable
-
 namespace Avalonia.Native
 {
     internal class AvnAutomationPeer : NativeCallbackBase, IAvnAutomationPeer
@@ -36,10 +33,10 @@ namespace Avalonia.Native
         public IAvnString? AutomationId => _inner.GetAutomationId().ToAvnString();
         public AvnRect BoundingRectangle => _inner.GetBoundingRectangle().ToAvnRect();
         public IAvnAutomationPeerArray Children => new AvnAutomationPeerArray(_inner.GetChildren());
-        public IAvnString ClassName => _inner.GetClassName().ToAvnString();
+        public IAvnString? ClassName => _inner.GetClassName().ToAvnString();
         public IAvnAutomationPeer? LabeledBy => Wrap(_inner.GetLabeledBy());
-        public IAvnString Name => _inner.GetName().ToAvnString();
+        public IAvnString? Name => _inner.GetName().ToAvnString();
-        public IAvnString HelpText => _inner.GetHelpText().ToAvnString();
+        public IAvnString? HelpText => _inner.GetHelpText().ToAvnString();
         public AvnLandmarkType LandmarkType => (AvnLandmarkType?)_inner.GetLandmarkType() ?? AvnLandmarkType.LandmarkNone;
         public int HeadingLevel => _inner.GetHeadingLevel();
         public IAvnAutomationPeer? Parent => Wrap(_inner.GetParent());
@@ -173,7 +170,7 @@ namespace Avalonia.Native
         public void ToggleProvider_Toggle() => ToggleProvider.Toggle();
 
         public int IsValueProvider() => IsProvider<IValueProvider>();
-        public IAvnString ValueProvider_GetValue() => ValueProvider.Value.ToAvnString();
+        public IAvnString? ValueProvider_GetValue() => ValueProvider.Value.ToAvnString();
         public void ValueProvider_SetValue(string value) => ValueProvider.SetValue(value);
 
         [return: NotNullIfNotNull("peer")]

src/Avalonia.Native/AvnString.cs

@@ -8,7 +8,7 @@ namespace Avalonia.Native.Interop
 {
     partial interface IAvnString
     {
-        public string String { get; }
+        public string? String { get; }
         public byte[] Bytes { get; }
     }
 
@@ -73,7 +73,7 @@ namespace Avalonia.Native.Interop
             _items = items.Select(s => s.ToAvnString()).ToArray();
         }
 
-        public string[] ToStringArray() => _items.Select(n => n.String).ToArray();
+        public string[] ToStringArray() => _items.Select(n => n.String ?? string.Empty).ToArray();
 
         public uint Count => (uint)_items.Length;
         public IAvnString Get(uint index) => _items[(int)index];
@@ -91,10 +91,10 @@ namespace Avalonia.Native.Interop.Impl
 {
     unsafe partial class __MicroComIAvnStringProxy
     {
-        private string _managed;
+        private string? _managed;
-        private byte[] _bytes;
+        private byte[]? _bytes;
 
-        public string String
+        public string? String
         {
             get
             {
@@ -124,7 +124,7 @@ namespace Avalonia.Native.Interop.Impl
             }
         }
 
-        public override string ToString() => String;
+        public override string? ToString() => String;
     }
     
     partial class __MicroComIAvnStringArrayProxy
@@ -134,7 +134,7 @@ namespace Avalonia.Native.Interop.Impl
             var arr = new string[Count];
             for(uint c = 0; c<arr.Length;c++)
                 using (var s = Get(c))
-                    arr[c] = s.String;
+                    arr[c] = s.String ?? string.Empty;
             return arr;
         }
     }

src/Avalonia.Native/ClipboardDataFormatHelper.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using Avalonia.Input;
 using Avalonia.Native.Interop;
@@ -28,7 +26,7 @@ internal static class ClipboardDataFormatHelper
         for (var c = 0u; c < count; c++)
         {
             using var nativeFormat = nativeFormats.Get(c);
-            results[c] = ToDataFormat(nativeFormat.String, isTextFormat);
+            results[c] = ToDataFormat(nativeFormat.String ?? string.Empty, isTextFormat);
         }
 
         return results;

src/Avalonia.Native/ClipboardDataTransfer.cs

@@ -1,6 +1,4 @@
-#nullable enable
+using System.Collections.Generic;
-
-using System.Collections.Generic;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 

src/Avalonia.Native/ClipboardDataTransferItem.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.IO;
 using System.Text;

src/Avalonia.Native/ClipboardImpl.cs

@@ -1,6 +1,4 @@
-#nullable enable
+using System;
-
-using System;
 using System.Threading.Tasks;
 using Avalonia.Input;
 using Avalonia.Input.Platform;

src/Avalonia.Native/ClipboardReadSession.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Runtime.InteropServices;
 using Avalonia.Native.Interop;

src/Avalonia.Native/Cursor.cs

@@ -8,7 +8,7 @@ namespace Avalonia.Native
 {
     class AvaloniaNativeCursor : ICursorImpl, IDisposable
     {
-        public IAvnCursor Cursor { get; private set; }
+        public IAvnCursor? Cursor { get; private set; }
         public IntPtr Handle => IntPtr.Zero;
 
         public string HandleDescriptor => "<none>";
@@ -20,7 +20,7 @@ namespace Avalonia.Native
 
         public void Dispose()
         {
-            Cursor.Dispose();
+            Cursor?.Dispose();
             Cursor = null;
         }
     }

src/Avalonia.Native/DataTransferItemToAvnClipboardDataItemWrapper.cs

@@ -1,12 +1,9 @@
-#nullable enable
-
 using System;
 using System.IO;
 using System.Linq;
 using Avalonia.Input;
 using Avalonia.Logging;
 using Avalonia.Native.Interop;
-using Avalonia.Utilities;
 
 namespace Avalonia.Native;
 

src/Avalonia.Native/DataTransferToAvnClipboardDataSourceWrapper.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Linq;
 using Avalonia.Input;

src/Avalonia.Native/DispatcherImpl.cs

@@ -1,4 +1,3 @@
-#nullable enable
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;

src/Avalonia.Native/GpuHandleWrapFeature.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using Avalonia.Native.Interop;
 using Avalonia.Platform;

src/Avalonia.Native/Helpers.cs

@@ -1,4 +1,5 @@
-using Avalonia.Native.Interop;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Native.Interop;
 
 namespace Avalonia.Native
 {
@@ -34,7 +35,8 @@ namespace Avalonia.Native
             return new AvnSize { Height = size.Height, Width = size.Width };
         }
 
-        public static IAvnString ToAvnString(this string s)
+        [return: NotNullIfNotNull(nameof(s))]
+        public static IAvnString? ToAvnString(this string? s)
         {
             return s != null ? new AvnString(s) : null;
         }

src/Avalonia.Native/IAvnMenu.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Native.Interop
 {
     class MenuEvents : NativeCallbackBase, IAvnMenuEvents
     {
-        private IAvnMenu _parent;
+        private IAvnMenu? _parent;
 
         public void Initialise(IAvnMenu parent)
         {
@@ -49,7 +49,7 @@ namespace Avalonia.Native.Interop.Impl
         private List<__MicroComIAvnMenuItemProxy> _menuItems = new List<__MicroComIAvnMenuItemProxy>();
         private Dictionary<NativeMenuItemBase, __MicroComIAvnMenuItemProxy> _menuItemLookup = new Dictionary<NativeMenuItemBase, __MicroComIAvnMenuItemProxy>();
 
-        private void UpdateTitle(string title)
+        private void UpdateTitle(string? title)
         {
             if (OperatingSystemEx.IsMacOS())
             {
@@ -136,7 +136,7 @@ namespace Avalonia.Native.Interop.Impl
             return nativeItem;
         }
 
-        internal void Initialize(AvaloniaNativeMenuExporter exporter, NativeMenu managedMenu, string title)
+        internal void Initialize(AvaloniaNativeMenuExporter exporter, NativeMenu managedMenu, string? title)
         {
             _exporter = exporter;
             ManagedMenu = managedMenu;
@@ -166,7 +166,7 @@ namespace Avalonia.Native.Interop.Impl
 
             for (int i = 0; i < menu.Items.Count; i++)
             {
-                __MicroComIAvnMenuItemProxy nativeItem;
+                __MicroComIAvnMenuItemProxy? nativeItem;
 
                 if (i >= _menuItems.Count)
                 {
@@ -197,7 +197,7 @@ namespace Avalonia.Native.Interop.Impl
             }
         }
 
-        private void OnMenuItemsChanged(object sender, NotifyCollectionChangedEventArgs e)
+        private void OnMenuItemsChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             _exporter.QueueReset();
         }

src/Avalonia.Native/IAvnMenuItem.cs

@@ -18,13 +18,13 @@ namespace Avalonia.Native.Interop.Impl
 {
     partial class __MicroComIAvnMenuItemProxy
     {
-        private __MicroComIAvnMenuProxy _subMenu;
+        private __MicroComIAvnMenuProxy? _subMenu;
         private CompositeDisposable _propertyDisposables = new CompositeDisposable();
-        private IDisposable _currentActionDisposable;
+        private IDisposable? _currentActionDisposable;
 
         public NativeMenuItemBase ManagedMenuItem { get; set; }
 
-        private void UpdateTitle(string title)
+        private void UpdateTitle(string? title)
         {
             if (OperatingSystemEx.IsMacOS())
             {
@@ -38,7 +38,7 @@ namespace Avalonia.Native.Interop.Impl
             SetTitle(title);
         }
 
-        private void UpdateToolTip(string toolTip) => SetToolTip(toolTip ?? "");
+        private void UpdateToolTip(string? toolTip) => SetToolTip(toolTip ?? "");
 
         private void UpdateIsVisible(bool isVisible) => SetIsVisible(isVisible.AsComBool());
         private void UpdateIsChecked(bool isChecked) => SetIsChecked(isChecked.AsComBool());
@@ -48,7 +48,7 @@ namespace Avalonia.Native.Interop.Impl
             SetToggleType((AvnMenuItemToggleType)toggleType);
         }
 
-        private unsafe void UpdateIcon (IBitmap icon)
+        private unsafe void UpdateIcon (IBitmap? icon)
         {
             if(icon is null)
             {
@@ -70,20 +70,20 @@ namespace Avalonia.Native.Interop.Impl
             }
         }
 
-        private void UpdateGesture(Input.KeyGesture gesture)
+        private void UpdateGesture(Input.KeyGesture? gesture)
         {
             var modifiers = gesture == null ? AvnInputModifiers.AvnInputModifiersNone : (AvnInputModifiers)gesture.KeyModifiers;
             var key = gesture == null ? AvnKey.AvnKeyNone : (AvnKey)gesture.Key;
             SetGesture(key, modifiers);
         }
 
-        private void UpdateAction(NativeMenuItem item)
+        private void UpdateAction(NativeMenuItem? item)
         {
             _currentActionDisposable?.Dispose();
 
             var action = new PredicateCallback(() =>
             {
-                if (item.Command != null || item.HasClickHandlers)
+                if (item is not null && (item.Command is not null || item.HasClickHandlers))
                 {
                     return item.IsEnabled;
                 }
@@ -160,7 +160,7 @@ namespace Avalonia.Native.Interop.Impl
                 _subMenu = null;
             }
 
-            _propertyDisposables?.Dispose();
+            _propertyDisposables.Dispose();
             _currentActionDisposable?.Dispose();
         }
 

src/Avalonia.Native/IconLoader.cs

@@ -27,13 +27,13 @@ namespace Avalonia.Native
         public IWindowIconImpl LoadIcon(string fileName)
         {
             return new IconStub(
-                AvaloniaLocator.Current.GetService<IPlatformRenderInterface>().LoadBitmap(fileName));
+                AvaloniaLocator.Current.GetRequiredService<IPlatformRenderInterface>().LoadBitmap(fileName));
         }
 
         public IWindowIconImpl LoadIcon(Stream stream)
         {
             return new IconStub(
-                AvaloniaLocator.Current.GetService<IPlatformRenderInterface>().LoadBitmap(stream));
+                AvaloniaLocator.Current.GetRequiredService<IPlatformRenderInterface>().LoadBitmap(stream));
         }
 
         public IWindowIconImpl LoadIcon(IBitmapImpl bitmap)

src/Avalonia.Native/MacOSActivatableLifetime.cs

@@ -1,11 +1,8 @@
-using System;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Controls.Platform;
 
 namespace Avalonia.Native;
 
-#nullable enable
-
 internal class MacOSActivatableLifetime : ActivatableLifetimeBase
 {
     public override bool TryLeaveBackground()

src/Avalonia.Native/Metal.cs

@@ -28,26 +28,34 @@ class MetalPlatformGraphics : IPlatformGraphics
 
 class MetalDevice : IMetalDevice
 {
-    public IAvnMetalDevice Native { get; private set; }
+    private readonly DisposableLock _syncRoot = new();
-    private DisposableLock _syncRoot = new();
     private readonly GpuHandleWrapFeature _handleWrapFeature;
     private readonly MetalExternalObjectsFeature _externalObjectsFeature;
-
+    private IAvnMetalDevice? _native;
 
     public MetalDevice(IAvaloniaNativeFactory factory, IAvnMetalDevice native)
     {
-        Native = native;
+        _native = native;
         _handleWrapFeature = new GpuHandleWrapFeature(factory);
         _externalObjectsFeature = new MetalExternalObjectsFeature(native);
     }
 
+    public IAvnMetalDevice Native
+    {
+        get
+        {
+            ObjectDisposedException.ThrowIf(_native is null, this);
+            return _native;
+        }
+    }
+
     public void Dispose()
     {
-        Native?.Dispose();
+        _native?.Dispose();
-        Native = null;
+        _native = null;
     }
 
-    public object TryGetFeature(Type featureType)
+    public object? TryGetFeature(Type featureType)
     {
         if (featureType == typeof(IExternalObjectsHandleWrapRenderInterfaceContextFeature))
             return _handleWrapFeature;
@@ -105,7 +113,7 @@ internal class MetalExternalObjectsFeature : IMetalExternalObjectsFeature
     public IReadOnlyList<string> SupportedSemaphoreTypes { get; } =
         [KnownPlatformGraphicsExternalSemaphoreHandleTypes.MetalSharedEvent];
     
-    public byte[] DeviceLuid { get; }
+    public byte[]? DeviceLuid { get; }
 
     public CompositionGpuImportedImageSynchronizationCapabilities
         GetSynchronizationCapabilities(string imageHandleType) =>
@@ -166,13 +174,22 @@ internal class MetalExternalObjectsFeature : IMetalExternalObjectsFeature
 
 internal class MetalRenderTarget : IMetalPlatformSurfaceRenderTarget
 {
-    private IAvnMetalRenderTarget _native;
+    private IAvnMetalRenderTarget? _native;
 
     public MetalRenderTarget(IAvnMetalRenderTarget native)
     {
         _native = native;
     }
 
+    private IAvnMetalRenderTarget Native
+    {
+        get
+        {
+            ObjectDisposedException.ThrowIf(_native is null, this);
+            return _native;
+        }
+    }
+
     public void Dispose()
     {
         _native?.Dispose();
@@ -181,36 +198,47 @@ internal class MetalRenderTarget : IMetalPlatformSurfaceRenderTarget
 
     public IMetalPlatformSurfaceRenderingSession BeginRendering()
     {
-        var session = _native.BeginDrawing();
+        var session = Native.BeginDrawing();
         return new MetalDrawingSession(session);
     }
 }
 
 internal class MetalDrawingSession : IMetalPlatformSurfaceRenderingSession
 {
-    private IAvnMetalRenderingSession _session;
+    private IAvnMetalRenderingSession? _session;
 
     public MetalDrawingSession(IAvnMetalRenderingSession session)
     {
         _session = session;
     }
 
+    public IAvnMetalRenderingSession Session
+    {
+        get
+        {
+            ObjectDisposedException.ThrowIf(_session is null, this);
+            return _session;
+        }
+    }
+
     public void Dispose()
     {
         _session?.Dispose();
         _session = null;
     }
 
-    public IntPtr Texture => _session.Texture;
+    public IntPtr Texture => Session.Texture;
+
     public PixelSize Size
     {
         get
         {
-            var size = _session.PixelSize;
+            var size = Session.PixelSize;
             return new(size.Width, size.Height);
         }
     }
 
-    public double Scaling => _session.Scaling;
+    public double Scaling => Session.Scaling;
+
     public bool IsYFlipped => false;
 }

src/Avalonia.Native/NativeControlHostImpl.cs

@@ -10,13 +10,22 @@ namespace Avalonia.Native
 {
     class NativeControlHostImpl : IDisposable, INativeControlHostImpl
     {
-        private IAvnNativeControlHost _host;
+        private IAvnNativeControlHost? _host;
 
         public NativeControlHostImpl(IAvnNativeControlHost host)
         {
             _host = host;
         }
 
+        private IAvnNativeControlHost Host
+        {
+            get
+            {
+                ObjectDisposedException.ThrowIf(_host is null, this);
+                return _host;
+            }
+        }
+
         public void Dispose()
         {
             _host?.Dispose();
@@ -25,7 +34,7 @@ namespace Avalonia.Native
 
         class DestroyableNSView : INativeControlHostDestroyableControlHandle
         {
-            private IAvnNativeControlHost _impl;
+            private IAvnNativeControlHost? _impl;
             private IntPtr _nsView;
 
             public DestroyableNSView(IAvnNativeControlHost impl)
@@ -49,12 +58,12 @@ namespace Avalonia.Native
         }
         
         public INativeControlHostDestroyableControlHandle CreateDefaultChild(IPlatformHandle parent) 
-            => new DestroyableNSView(_host);
+            => new DestroyableNSView(Host);
 
         public INativeControlHostControlTopLevelAttachment CreateNewAttachment(
             Func<IPlatformHandle, IPlatformHandle> create)
         {
-            var a = new Attachment(_host.CreateAttachment());
+            var a = new Attachment(Host.CreateAttachment());
             try
             {
                 var child = create(a.GetParentHandle());
@@ -71,7 +80,7 @@ namespace Avalonia.Native
 
         public INativeControlHostControlTopLevelAttachment CreateNewAttachment(IPlatformHandle handle)
         {
-            var a = new Attachment(_host.CreateAttachment());
+            var a = new Attachment(Host.CreateAttachment());
             a.InitWithChild(handle);
             a.AttachedTo = this;
             return a;
@@ -81,14 +90,25 @@ namespace Avalonia.Native
 
         class Attachment : INativeControlHostControlTopLevelAttachment
         {
-            private IAvnNativeControlHostTopLevelAttachment _native;
+            private IAvnNativeControlHostTopLevelAttachment? _native;
-            private NativeControlHostImpl _attachedTo;
+            private NativeControlHostImpl? _attachedTo;
-            public IPlatformHandle GetParentHandle() => new PlatformHandle(_native.ParentHandle, "NSView");
+
             public Attachment(IAvnNativeControlHostTopLevelAttachment native)
             {
                 _native = native;
             }
-            
+
+            private IAvnNativeControlHostTopLevelAttachment Native
+            {
+                get
+                {
+                    ObjectDisposedException.ThrowIf(_native is null, this);
+                    return _native;
+                }
+            }
+
+            public IPlatformHandle GetParentHandle() => new PlatformHandle(Native.ParentHandle, "NSView");
+
             public void Dispose()
             {
                 if (_native != null)
@@ -99,16 +119,13 @@ namespace Avalonia.Native
                 }
             }
 
-            public INativeControlHostImpl AttachedTo
+            public INativeControlHostImpl? AttachedTo
             {
                 get => _attachedTo;
                 set
                 {
-                    var host = (NativeControlHostImpl)value;
+                    var host = (NativeControlHostImpl?)value;
-                    if(host == null)
+                    Native.AttachTo(host?._host);
-                        _native.AttachTo(null);
-                    else
-                        _native.AttachTo(host._host);
                     _attachedTo = host;
                 }
             }
@@ -117,7 +134,7 @@ namespace Avalonia.Native
 
             public void HideWithSize(Size size)
             {
-                _native.HideWithSize(Math.Max(1, (float)size.Width), Math.Max(1, (float)size.Height));
+                Native.HideWithSize(Math.Max(1, (float)size.Width), Math.Max(1, (float)size.Height));
             }
             
             public void ShowInBounds(Rect bounds)
@@ -126,11 +143,11 @@ namespace Avalonia.Native
                     throw new InvalidOperationException("Native control isn't attached to a toplevel");
                 bounds = new Rect(bounds.X, bounds.Y, Math.Max(1, bounds.Width),
                     Math.Max(1, bounds.Height));
-                _native.ShowInBounds((float) bounds.X, (float) bounds.Y, (float) bounds.Width, (float) bounds.Height);
+                Native.ShowInBounds((float) bounds.X, (float) bounds.Y, (float) bounds.Width, (float) bounds.Height);
             }
 
             public void InitWithChild(IPlatformHandle handle) 
-                => _native.InitializeWithChildHandle(handle.Handle);
+                => Native.InitializeWithChildHandle(handle.Handle);
         }
     }
 }

src/Avalonia.Native/NativeOwned.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Runtime.ExceptionServices;
 using Avalonia.Threading;

src/Avalonia.Native/NativePlatformSettings.cs

@@ -8,7 +8,7 @@ namespace Avalonia.Native;
 internal class NativePlatformSettings : DefaultPlatformSettings
 {
     private readonly IAvnPlatformSettings _platformSettings;
-    private PlatformColorValues _lastColorValues;
+    private PlatformColorValues? _lastColorValues;
 
     public NativePlatformSettings(IAvnPlatformSettings platformSettings)
     {

src/Avalonia.Native/ScreenImpl.cs

@@ -4,8 +4,6 @@ using Avalonia.Native.Interop;
 using Avalonia.Platform;
 using MicroCom.Runtime;
 
-#nullable enable
-
 namespace Avalonia.Native
 {
     internal sealed class AvnScreen(uint displayId)

src/Avalonia.Native/StorageItem.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;

src/Avalonia.Native/StorageProviderApi.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.IO;

src/Avalonia.Native/StorageProviderImpl.cs

@@ -1,6 +1,4 @@
-#nullable enable
+using System;
-
-using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using Avalonia.Platform.Storage;

src/Avalonia.Native/TopLevelImpl.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
@@ -311,7 +309,7 @@ internal class TopLevelImpl : ITopLevelImpl, IFramebufferPlatformSurface
         Native.SetCursor(newCursor?.Cursor);
     }
 
-    public virtual IPopupImpl CreatePopup()
+    public virtual IPopupImpl? CreatePopup()
     {
         return new PopupImpl(Factory, this);
     }
@@ -554,6 +552,8 @@ internal class TopLevelImpl : ITopLevelImpl, IFramebufferPlatformSurface
 
         public ILockedFramebuffer Lock()
         {
+            ObjectDisposedException.ThrowIf(_target is null, this);
+
             var w = _parent._savedLogicalSize.Width * _parent._savedScaling;
             var h = _parent._savedLogicalSize.Height * _parent._savedScaling;
             var dpi = _parent._savedScaling * 96;

src/Avalonia.Native/TrayIconImpl.cs

@@ -4,8 +4,6 @@ using Avalonia.Controls.Platform;
 using Avalonia.Native.Interop;
 using Avalonia.Platform;
 
-#nullable enable
-
 namespace Avalonia.Native
 {
     internal class TrayIconImpl : ITrayIconWithIsTemplateImpl

src/Avalonia.Native/WindowImpl.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Native
     internal class WindowImpl : WindowBaseImpl, IWindowImpl
     {
         private readonly AvaloniaNativePlatformOptions _opts;
-        IAvnWindow _native;
+        private readonly IAvnWindow _native;
         private double _extendTitleBarHeight = -1;
         private DoubleClickHelper _doubleClickHelper;
         private readonly ITopLevelNativeMenuExporter _nativeMenuExporter;
@@ -99,7 +99,7 @@ namespace Avalonia.Native
             _native.SetTitleBarColor(new AvnColor { Alpha = color.A, Red = color.R, Green = color.G, Blue = color.B });
         }
 
-        public void SetTitle(string title)
+        public void SetTitle(string? title)
         {
             _native.SetTitle(title ?? "");
         }
@@ -110,9 +110,9 @@ namespace Avalonia.Native
             set => _native.SetWindowState((AvnWindowState)value);
         }
 
-        public Action<WindowState> WindowStateChanged { get; set; }        
+        public Action<WindowState>? WindowStateChanged { get; set; }
 
-        public Action<bool> ExtendClientAreaToDecorationsChanged { get; set; }
+        public Action<bool>? ExtendClientAreaToDecorationsChanged { get; set; }
 
         public Thickness ExtendedMargins { get; private set; }
 
@@ -226,23 +226,23 @@ namespace Avalonia.Native
             // NO OP On OSX
         }
 
-        public void SetIcon(IWindowIconImpl icon)
+        public void SetIcon(IWindowIconImpl? icon)
         {
             // NO OP on OSX
         }
 
-        public Func<WindowCloseReason, bool> Closing { get; set; }
+        public Func<WindowCloseReason, bool>? Closing { get; set; }
 
         public void Move(PixelPoint point) => Position = point;
 
-        public override IPopupImpl CreatePopup() =>
+        public override IPopupImpl? CreatePopup() =>
             _opts.OverlayPopups ? null : new PopupImpl(Factory, this);
 
-        public Action GotInputWhenDisabled { get; set; }
+        public Action? GotInputWhenDisabled { get; set; }
 
-        public void SetParent(IWindowImpl parent)
+        public void SetParent(IWindowImpl? parent)
         {
-            _native.SetParent(((WindowImpl)parent)?.Native);
+            _native.SetParent(((WindowImpl?)parent)?.Native);
         }
 
         public void SetEnabled(bool enable)
@@ -257,7 +257,7 @@ namespace Avalonia.Native
                 mouse.PlatformCaptureLost();
         }
 
-        public override object TryGetFeature(Type featureType)
+        public override object? TryGetFeature(Type featureType)
         {
             if(featureType == typeof(ITextInputMethodImpl))
             {

src/Avalonia.Native/WindowImplBase.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Linq;
 using Avalonia.Controls;
@@ -57,7 +55,7 @@ namespace Avalonia.Native
                 .OrderBy(x => x.Scaling)
                 .First(m => m.Bounds.Contains(Position));
 
-            Resize(new Size(monitor!.WorkingArea.Width * 0.75d, monitor.WorkingArea.Height * 0.7d), WindowResizeReason.Layout);
+            Resize(new Size(monitor.WorkingArea.Width * 0.75d, monitor.WorkingArea.Height * 0.7d), WindowResizeReason.Layout);
         }
 
         public void Activate()