Move iOS implementation to base AppleTextureLoaderStore class

osu.Framework.iOS/Graphics/Textures/IOSTextureLoaderStore.cs

@@ -2,22 +2,16 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
-using System.Diagnostics;
 using System.IO;
-using System.Runtime.InteropServices;
-using Accelerate;
-using CoreGraphics;
 using Foundation;
-using ObjCRuntime;
-using osu.Framework.Graphics.Textures;
 using osu.Framework.IO.Stores;
+using osu.Framework.Platform.Apple;
 using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.Advanced;
 using UIKit;
 
 namespace osu.Framework.iOS.Graphics.Textures
 {
-    public class IOSTextureLoaderStore : TextureLoaderStore
+    internal class IOSTextureLoaderStore : AppleTextureLoaderStore
     {
         public IOSTextureLoaderStore(IResourceStore<byte[]> store)
             : base(store)
@@ -26,81 +20,18 @@ namespace osu.Framework.iOS.Graphics.Textures
 
         protected override unsafe Image<TPixel> ImageFromStream<TPixel>(Stream stream)
         {
-            using (var nativeData = NSData.FromStream(stream))
-            {
-                if (nativeData == null)
-                    throw new ArgumentException($"{nameof(Image)} could not be created from {nameof(stream)}.");
+            int length = (int)(stream.Length - stream.Position);
+            using var nativeData = NSMutableData.FromLength(length);
 
-                using (var uiImage = UIImage.LoadFromData(nativeData))
-                {
-                    if (uiImage == null) throw new ArgumentException($"{nameof(Image)} could not be created from {nameof(stream)}.");
+            var bytesSpan = new Span<byte>(nativeData.MutableBytes.ToPointer(), length);
+            stream.ReadExactly(bytesSpan);
 
-                    int width = (int)uiImage.Size.Width;
-                    int height = (int)uiImage.Size.Height;
+            using var uiImage = UIImage.LoadFromData(nativeData);
+            if (uiImage == null)
+                throw new ArgumentException($"{nameof(Image)} could not be created from {nameof(stream)}.");
 
-                    var format = new vImage_CGImageFormat
-                    {
-                        BitsPerComponent = 8,
-                        BitsPerPixel = 32,
-                        ColorSpace = CGColorSpace.CreateDeviceRGB().Handle,
-                        // notably, iOS generally uses premultiplied alpha when rendering image to pixels via CGBitmapContext or otherwise,
-                        // but vImage offers using straight alpha directly without any conversion from our side (by specifying Last instead of PremultipliedLast).
-                        BitmapInfo = (CGBitmapFlags)CGImageAlphaInfo.Last,
-                        Decode = null,
-                        RenderingIntent = CGColorRenderingIntent.Default,
-                    };
-
-                    vImageBuffer accelerateImage = default;
-
-                    // perform initial call to retrieve preferred alignment and bytes-per-row values for the given image dimensions.
-                    nuint alignment = (nuint)vImageBuffer_Init(&accelerateImage, (uint)height, (uint)width, 32, vImageFlags.NoAllocate);
-                    Debug.Assert(alignment > 0);
-
-                    // allocate aligned memory region to contain image pixel data.
-                    int bytesPerRow = accelerateImage.BytesPerRow;
-                    int bytesCount = bytesPerRow * accelerateImage.Height;
-                    accelerateImage.Data = (IntPtr)NativeMemory.AlignedAlloc((nuint)bytesCount, alignment);
-
-                    var result = vImageBuffer_InitWithCGImage(&accelerateImage, &format, null, uiImage.CGImage!.Handle, vImageFlags.NoAllocate);
-                    Debug.Assert(result == vImageError.NoError);
-
-                    var image = new Image<TPixel>(width, height);
-                    byte* data = (byte*)accelerateImage.Data;
-
-                    for (int i = 0; i < height; i++)
-                    {
-                        var imageRow = image.DangerousGetPixelRowMemory(i);
-                        var dataRow = new ReadOnlySpan<TPixel>(&data[bytesPerRow * i], width);
-                        dataRow.CopyTo(imageRow.Span);
-                    }
-
-                    NativeMemory.AlignedFree(accelerateImage.Data.ToPointer());
-                    return image;
-                }
-            }
+            var cgImage = new Platform.Apple.Native.CGImage(uiImage.CGImage!.Handle);
+            return ImageFromCGImage<TPixel>(cgImage);
         }
-
-        #region Accelerate API
-
-        [DllImport(Constants.AccelerateLibrary)]
-        private static extern unsafe vImageError vImageBuffer_Init(vImageBuffer* buf, uint height, uint width, uint pixelBits, vImageFlags flags);
-
-        [DllImport(Constants.AccelerateLibrary)]
-        private static extern unsafe vImageError vImageBuffer_InitWithCGImage(vImageBuffer* buf, vImage_CGImageFormat* format, nfloat* backgroundColour, NativeHandle image, vImageFlags flags);
-
-        // ReSharper disable once InconsistentNaming
-        [StructLayout(LayoutKind.Sequential)]
-        public unsafe struct vImage_CGImageFormat
-        {
-            public uint BitsPerComponent;
-            public uint BitsPerPixel;
-            public NativeHandle ColorSpace;
-            public CGBitmapFlags BitmapInfo;
-            public uint Version;
-            public nfloat* Decode;
-            public CGColorRenderingIntent RenderingIntent;
-        }
-
-        #endregion
     }
 }

osu.Framework/Platform/Apple/AppleTextureLoaderStore.cs

@@ -0,0 +1,69 @@
+// 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.Diagnostics;
+using System.Runtime.InteropServices;
+using osu.Framework.Graphics.Textures;
+using osu.Framework.IO.Stores;
+using osu.Framework.Platform.Apple.Native;
+using osu.Framework.Platform.Apple.Native.Accelerate;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace osu.Framework.Platform.Apple
+{
+    internal abstract class AppleTextureLoaderStore : TextureLoaderStore
+    {
+        protected AppleTextureLoaderStore(IResourceStore<byte[]> store)
+            : base(store)
+        {
+        }
+
+        protected unsafe Image<TPixel> ImageFromCGImage<TPixel>(CGImage cgImage)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            int width = (int)cgImage.Width;
+            int height = (int)cgImage.Height;
+
+            var format = new vImage_CGImageFormat
+            {
+                BitsPerComponent = 8,
+                BitsPerPixel = 32,
+                ColorSpace = CGColorSpace.CreateDeviceRGB(),
+                // notably, macOS & iOS generally use premultiplied alpha when rendering image to pixels via CGBitmapContext or otherwise,
+                // but vImage offers rendering as straight alpha by specifying Last instead of PremultipliedLast.
+                BitmapInfo = (CGBitmapInfo)CGImageAlphaInfo.Last,
+                Decode = null,
+                RenderingIntent = CGColorRenderingIntent.Default,
+            };
+
+            vImage_Buffer accImage = default;
+
+            // perform initial call to retrieve preferred alignment and bytes-per-row values for the given image dimensions.
+            nuint alignment = (nuint)vImage.Init(&accImage, (uint)height, (uint)width, 32, vImage_Flags.NoAllocate);
+            Debug.Assert(alignment > 0);
+
+            // allocate aligned memory region to contain image pixel data.
+            nuint bytesPerRow = accImage.BytesPerRow;
+            nuint bytesCount = bytesPerRow * accImage.Height;
+            accImage.Data = (byte*)NativeMemory.AlignedAlloc(bytesCount, alignment);
+
+            var result = vImage.InitWithCGImage(&accImage, &format, null, cgImage.Handle, vImage_Flags.NoAllocate);
+            Debug.Assert(result == vImage_Error.NoError);
+
+            var image = new Image<TPixel>(width, height);
+
+            for (int i = 0; i < height; i++)
+            {
+                var imageRow = image.DangerousGetPixelRowMemory(i);
+                var dataRow = new ReadOnlySpan<TPixel>(&accImage.Data[(int)bytesPerRow * i], width);
+                dataRow.CopyTo(imageRow.Span);
+            }
+
+            NativeMemory.AlignedFree(accImage.Data);
+            return image;
+        }
+    }
+}