Add macOS implementation

Author: frenzibyte

osu.Framework/Platform/MacOS/MacOSGameHost.cs

@@ -7,10 +7,12 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using osu.Framework.Graphics.Textures;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Handlers;
 using osu.Framework.Input.Handlers.Mouse;
+using osu.Framework.IO.Stores;
 using osu.Framework.Logging;
 using osu.Framework.Platform.MacOS.Native;
 
@@ -44,6 +46,9 @@ public override IEnumerable<string> UserStoragePaths
 
         protected override ReadableKeyCombinationProvider CreateReadableKeyCombinationProvider() => new MacOSReadableKeyCombinationProvider();
 
+        public override IResourceStore<TextureUpload> CreateTextureLoaderStore(IResourceStore<byte[]> underlyingStore)
+            => new MacOSTextureLoaderStore(underlyingStore);
+
         protected override void Swap()
         {
             base.Swap();

osu.Framework/Platform/MacOS/MacOSTextureLoaderStore.cs

@@ -0,0 +1,37 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.IO;
+using osu.Framework.IO.Stores;
+using osu.Framework.Platform.Apple;
+using osu.Framework.Platform.Apple.Native;
+using osu.Framework.Platform.MacOS.Native;
+using SixLabors.ImageSharp;
+
+namespace osu.Framework.Platform.MacOS
+{
+    internal class MacOSTextureLoaderStore : AppleTextureLoaderStore
+    {
+        public MacOSTextureLoaderStore(IResourceStore<byte[]> store)
+            : base(store)
+        {
+        }
+
+        protected override unsafe Image<TPixel> ImageFromStream<TPixel>(Stream stream)
+        {
+            int length = (int)(stream.Length - stream.Position);
+            using var nativeData = NSMutableData.FromLength(length);
+
+            var bytesSpan = new Span<byte>(nativeData.MutableBytes, length);
+            stream.ReadExactly(bytesSpan);
+
+            using var nsImage = NSImage.LoadFromData(nativeData);
+            if (nsImage.Handle == IntPtr.Zero)
+                throw new ArgumentException($"{nameof(Image)} could not be created from {nameof(stream)}.");
+
+            var cgImage = nsImage.CGImage;
+            return ImageFromCGImage<TPixel>(cgImage);
+        }
+    }
+}