Make IRuntimePlatform private API and remove some members that are always have single implementation

src/Avalonia.Base/Platform/IRuntimePlatform.cs

@@ -3,24 +3,13 @@ using Avalonia.Metadata;
 
 namespace Avalonia.Platform
 {
-    [Unstable]
+    [PrivateApi]
     public interface IRuntimePlatform
     {
-        IDisposable StartSystemTimer(TimeSpan interval, Action tick);
         RuntimePlatformInfo GetRuntimeInfo();
-        IUnmanagedBlob AllocBlob(int size);
     }
 
-    [Unstable]
-    public interface IUnmanagedBlob : IDisposable
-    {
-        IntPtr Address { get; }
-        int Size { get; }
-        bool IsDisposed { get; }
-
-    }
-
-    [Unstable]
+    [PrivateApi]
     public record struct RuntimePlatformInfo
     {
         public FormFactorType FormFactor => IsDesktop ? FormFactorType.Desktop :

src/Avalonia.Base/Platform/Internal/UnmanagedBlob.cs

@@ -6,7 +6,7 @@ using System.Threading;
 
 namespace Avalonia.Platform.Internal;
 
-internal class UnmanagedBlob : IUnmanagedBlob
+internal class UnmanagedBlob
 {
     private IntPtr _address;
     private readonly object _lock = new object();

src/Avalonia.Base/Platform/StandardRuntimePlatform.cs

@@ -1,26 +1,20 @@
 using System;
 using System.Threading;
 using Avalonia.Compatibility;
+using Avalonia.Metadata;
 using Avalonia.Platform.Internal;
 
 namespace Avalonia.Platform
 {
+    [PrivateApi]
     public class StandardRuntimePlatform : IRuntimePlatform
     {
-        public IDisposable StartSystemTimer(TimeSpan interval, Action tick)
-        {
-            return new Timer(_ => tick(), null, interval, interval);
-        }
-
-        public IUnmanagedBlob AllocBlob(int size) => new UnmanagedBlob(size);
-        
         private static readonly RuntimePlatformInfo s_info = new()
         {
             IsDesktop = OperatingSystemEx.IsWindows() || OperatingSystemEx.IsMacOS() || OperatingSystemEx.IsLinux(),
             IsMobile = OperatingSystemEx.IsAndroid() || OperatingSystemEx.IsIOS()
         };
-
-
+        
         public virtual RuntimePlatformInfo GetRuntimeInfo() => s_info;
     }
 }

src/Avalonia.Base/Rendering/DefaultRenderTimer.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading;
 using Avalonia.Metadata;
 using Avalonia.Platform;
 
@@ -14,7 +15,6 @@ namespace Avalonia.Rendering
     [PrivateApi]
     public class DefaultRenderTimer : IRenderTimer
     {
-        private IRuntimePlatform? _runtime;
         private int _subscriberCount;
         private Action<TimeSpan>? _tick;
         private IDisposable? _subscription;
@@ -80,11 +80,9 @@ namespace Avalonia.Rendering
         /// </remarks>
         protected virtual IDisposable StartCore(Action<TimeSpan> tick)
         {
-            _runtime ??= AvaloniaLocator.Current.GetRequiredService<IRuntimePlatform>();
+            var interval = TimeSpan.FromSeconds(1.0 / FramesPerSecond);
 
-            return _runtime.StartSystemTimer(
-                TimeSpan.FromSeconds(1.0 / FramesPerSecond),
-                () => tick(TimeSpan.FromMilliseconds(Environment.TickCount)));
+            return new Timer(_ => tick(TimeSpan.FromMilliseconds(Environment.TickCount)), null, interval, interval);
         }
 
         /// <summary>

src/Avalonia.X11/X11CursorFactory.cs

@@ -5,6 +5,7 @@ using System.Runtime.InteropServices;
 using Avalonia.Controls.Platform.Surfaces;
 using Avalonia.Input;
 using Avalonia.Platform;
+using Avalonia.Platform.Internal;
 using Avalonia.SourceGenerator;
 using Avalonia.Utilities;
 
@@ -92,17 +93,16 @@ namespace Avalonia.X11
         private unsafe class XImageCursor : CursorImpl, IFramebufferPlatformSurface, IPlatformHandle
         {
             private readonly PixelSize _pixelSize;
-            private readonly IUnmanagedBlob _blob;
+            private readonly UnmanagedBlob _blob;
 
             public XImageCursor(IntPtr display, IBitmapImpl bitmap, PixelPoint hotSpot)
             {
                 var size = Marshal.SizeOf<XcursorImage>() +
                     (bitmap.PixelSize.Width * bitmap.PixelSize.Height * 4);
-                var runtimePlatform = AvaloniaLocator.Current.GetRequiredService<IRuntimePlatform>();
                 var platformRenderInterface = AvaloniaLocator.Current.GetRequiredService<IPlatformRenderInterface>();
 
                 _pixelSize = bitmap.PixelSize;
-                _blob = runtimePlatform.AllocBlob(size);
+                _blob = new UnmanagedBlob(size);
                 
                 var image = (XcursorImage*)_blob.Address;
                 image->version = 1;

src/Avalonia.X11/X11Framebuffer.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using Avalonia.Platform;
+using Avalonia.Platform.Internal;
 using SkiaSharp;
 using static Avalonia.X11.XLib;
 namespace Avalonia.X11
@@ -10,7 +11,7 @@ namespace Avalonia.X11
         private readonly IntPtr _display;
         private readonly IntPtr _xid;
         private readonly int _depth;
-        private IUnmanagedBlob _blob;
+        private UnmanagedBlob _blob;
 
         public X11Framebuffer(IntPtr display, IntPtr xid, int depth, int width, int height, double factor)
         {
@@ -25,7 +26,7 @@ namespace Avalonia.X11
             RowBytes = width * 4;
             Dpi = new Vector(96, 96) * factor;
             Format = PixelFormat.Bgra8888;
-            _blob = AvaloniaLocator.Current.GetRequiredService<IRuntimePlatform>().AllocBlob(RowBytes * height);
+            _blob = new UnmanagedBlob(RowBytes * height);
             Address = _blob.Address;
         }
         

src/Browser/Avalonia.Browser/WindowingPlatform.cs

@@ -57,12 +57,11 @@ namespace Avalonia.Browser
 
         public IDisposable StartTimer(DispatcherPriority priority, TimeSpan interval, Action tick)
         {
-            return GetRuntimePlatform()
-                .StartSystemTimer(interval, () =>
-                {
-                    Dispatcher.UIThread.RunJobs(priority);
-                    tick();
-                });
+            return new Timer(_ =>
+            {
+                Dispatcher.UIThread.RunJobs(priority);
+                tick();
+            }, null, interval, interval);
         }
 
         public void Signal(DispatcherPriority priority)
@@ -71,18 +70,16 @@ namespace Avalonia.Browser
                 return;
 
             _signaled = true;
+            var interval = TimeSpan.FromMilliseconds(1);
 
             IDisposable? disp = null;
+            disp = new Timer(_ =>
+            {
+                _signaled = false;
+                disp?.Dispose();
 
-            disp = GetRuntimePlatform()
-                .StartSystemTimer(TimeSpan.FromMilliseconds(1),
-                    () =>
-                    {
-                        _signaled = false;
-                        disp?.Dispose();
-
-                        Signaled?.Invoke(null);
-                    });
+                Signaled?.Invoke(null);
+            }, null, interval, interval);
         }
 
         public bool CurrentThreadIsLoopThread
@@ -94,10 +91,5 @@ namespace Avalonia.Browser
         }
 
         public event Action<DispatcherPriority?>? Signaled;
-
-        private static IRuntimePlatform GetRuntimePlatform()
-        {
-            return AvaloniaLocator.Current.GetRequiredService<IRuntimePlatform>();
-        }
     }
 }

src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs

@@ -3,6 +3,7 @@ using System.IO;
 using System.Threading;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform;
+using Avalonia.Platform.Internal;
 using Avalonia.Skia.Helpers;
 using SkiaSharp;
 
@@ -97,21 +98,12 @@ namespace Avalonia.Skia
             SKColorType colorType = format.ToSkColorType();
             SKAlphaType alphaType = alphaFormat.ToSkAlphaType();
 
-            var runtimePlatform = AvaloniaLocator.Current.GetService<IRuntimePlatform>();
+            _bitmap = new SKBitmap();
 
-            if (runtimePlatform != null)
-            {
-                _bitmap = new SKBitmap();
-
-                var nfo = new SKImageInfo(size.Width, size.Height, colorType, alphaType);
-                var blob = runtimePlatform.AllocBlob(nfo.BytesSize);
+            var nfo = new SKImageInfo(size.Width, size.Height, colorType, alphaType);
+            var blob = new UnmanagedBlob(nfo.BytesSize);
 
-                _bitmap.InstallPixels(nfo, blob.Address, nfo.RowBytes, s_releaseDelegate, blob);
-            }
-            else
-            {
-                _bitmap = new SKBitmap(size.Width, size.Height, colorType, alphaType);
-            }
+            _bitmap.InstallPixels(nfo, blob.Address, nfo.RowBytes, s_releaseDelegate, blob);
 
             _bitmap.Erase(SKColor.Empty);
         }
@@ -176,7 +168,7 @@ namespace Avalonia.Skia
         /// <param name="ctx">Blob.</param>
         private static void ReleaseProc(IntPtr address, object ctx)
         {
-            ((IUnmanagedBlob)ctx).Dispose();
+            ((UnmanagedBlob)ctx).Dispose();
         }
 
         /// <summary>

src/Windows/Avalonia.Win32/FramebufferManager.cs

@@ -2,6 +2,7 @@
 using System.Threading;
 using Avalonia.Controls.Platform.Surfaces;
 using Avalonia.Platform;
+using Avalonia.Platform.Internal;
 using Avalonia.Win32.Interop;
 
 namespace Avalonia.Win32
@@ -105,8 +106,7 @@ namespace Avalonia.Win32
 
         private static FramebufferData AllocateFramebufferData(int width, int height)
         {
-            var service = AvaloniaLocator.Current.GetRequiredService<IRuntimePlatform>();
-            var bitmapBlob = service.AllocBlob(width * height * _bytesPerPixel);
+            var bitmapBlob = new UnmanagedBlob(width * height * _bytesPerPixel);
 
             return new FramebufferData(bitmapBlob, width, height);
         }
@@ -155,7 +155,7 @@ namespace Avalonia.Win32
 
         private readonly struct FramebufferData
         {
-            public IUnmanagedBlob Data { get; }
+            public UnmanagedBlob Data { get; }
 
             public PixelSize Size { get; }
 
@@ -163,7 +163,7 @@ namespace Avalonia.Win32
 
             public UnmanagedMethods.BITMAPINFOHEADER Header { get; }
 
-            public FramebufferData(IUnmanagedBlob data, int width, int height)
+            public FramebufferData(UnmanagedBlob data, int width, int height)
             {
                 Data = data;
                 Size = new PixelSize(width, height);