Merge branch 'main' into js/premultiply

Author: JimBobSquarePants

src/ImageSharp/Formats/Webp/AlphaDecoder.cs

@@ -1,8 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics;
@@ -38,7 +38,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
         this.LastRow = 0;
         int totalPixels = width * height;
 
-        var compression = (WebpAlphaCompressionMethod)(alphaChunkHeader & 0x03);
+        WebpAlphaCompressionMethod compression = (WebpAlphaCompressionMethod)(alphaChunkHeader & 0x03);
         if (compression is not WebpAlphaCompressionMethod.NoCompression and not WebpAlphaCompressionMethod.WebpLosslessCompression)
         {
             WebpThrowHelper.ThrowImageFormatException($"unexpected alpha compression method {compression} found");
@@ -59,7 +59,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
 
         if (this.Compressed)
         {
-            var bitReader = new Vp8LBitReader(data);
+            Vp8LBitReader bitReader = new(data);
             this.LosslessDecoder = new WebpLosslessDecoder(bitReader, memoryAllocator, configuration);
             this.LosslessDecoder.DecodeImageStream(this.Vp8LDec, width, height, true);
 
@@ -110,6 +110,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
     /// <summary>
     /// Gets a value indicating whether the alpha channel uses compression.
     /// </summary>
+    [MemberNotNullWhen(true, nameof(LosslessDecoder))]
     private bool Compressed { get; }
 
     /// <summary>
@@ -120,7 +121,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
     /// <summary>
     /// Gets the Vp8L decoder which is used to de compress the alpha channel, if needed.
     /// </summary>
-    private WebpLosslessDecoder LosslessDecoder { get; }
+    private WebpLosslessDecoder? LosslessDecoder { get; }
 
     /// <summary>
     /// Gets a value indicating whether the decoding needs 1 byte per pixel for decoding.
@@ -173,17 +174,14 @@ public void Decode()
                 dst = dst[this.Width..];
             }
         }
+        else if (this.Use8BDecode)
+        {
+            this.LosslessDecoder.DecodeAlphaData(this);
+        }
         else
         {
-            if (this.Use8BDecode)
-            {
-                this.LosslessDecoder.DecodeAlphaData(this);
-            }
-            else
-            {
-                this.LosslessDecoder.DecodeImageData(this.Vp8LDec, this.Vp8LDec.Pixels.Memory.Span);
-                this.ExtractAlphaRows(this.Vp8LDec);
-            }
+            this.LosslessDecoder.DecodeImageData(this.Vp8LDec, this.Vp8LDec.Pixels.Memory.Span);
+            this.ExtractAlphaRows(this.Vp8LDec);
         }
     }
 
@@ -261,8 +259,7 @@ private void ExtractAlphaRows(Vp8LDecoder dec)
     {
         int numRowsToProcess = dec.Height;
         int width = dec.Width;
-        Span<uint> pixels = dec.Pixels.Memory.Span;
-        Span<uint> input = pixels;
+        Span<uint> input = dec.Pixels.Memory.Span;
         Span<byte> output = this.Alpha.Memory.Span;
 
         // Extract alpha (which is stored in the green plane).
@@ -327,7 +324,7 @@ private static void HorizontalUnfilter(Span<byte> prev, Span<byte> input, Span<b
             ref byte srcRef = ref MemoryMarshal.GetReference(input);
             for (i = 1; i + 8 <= width; i += 8)
             {
-                var a0 = Vector128.Create(Unsafe.As<byte, long>(ref Unsafe.Add(ref srcRef, i)), 0);
+                Vector128<long> a0 = Vector128.Create(Unsafe.As<byte, long>(ref Unsafe.Add(ref srcRef, i)), 0);
                 Vector128<byte> a1 = Sse2.Add(a0.AsByte(), last.AsByte());
                 Vector128<byte> a2 = Sse2.ShiftLeftLogical128BitLane(a1, 1);
                 Vector128<byte> a3 = Sse2.Add(a1, a2);
@@ -365,32 +362,29 @@ private static void VerticalUnfilter(Span<byte> prev, Span<byte> input, Span<byt
         {
             HorizontalUnfilter(null, input, dst, width);
         }
-        else
+        else if (Avx2.IsSupported)
         {
-            if (Avx2.IsSupported)
+            nint i;
+            int maxPos = width & ~31;
+            for (i = 0; i < maxPos; i += 32)
             {
-                nint i;
-                int maxPos = width & ~31;
-                for (i = 0; i < maxPos; i += 32)
-                {
-                    Vector256<int> a0 = Unsafe.As<byte, Vector256<int>>(ref Unsafe.Add(ref MemoryMarshal.GetReference(input), i));
-                    Vector256<int> b0 = Unsafe.As<byte, Vector256<int>>(ref Unsafe.Add(ref MemoryMarshal.GetReference(prev), i));
-                    Vector256<byte> c0 = Avx2.Add(a0.AsByte(), b0.AsByte());
-                    ref byte outputRef = ref Unsafe.Add(ref MemoryMarshal.GetReference(dst), i);
-                    Unsafe.As<byte, Vector256<byte>>(ref outputRef) = c0;
-                }
+                Vector256<int> a0 = Unsafe.As<byte, Vector256<int>>(ref Unsafe.Add(ref MemoryMarshal.GetReference(input), i));
+                Vector256<int> b0 = Unsafe.As<byte, Vector256<int>>(ref Unsafe.Add(ref MemoryMarshal.GetReference(prev), i));
+                Vector256<byte> c0 = Avx2.Add(a0.AsByte(), b0.AsByte());
+                ref byte outputRef = ref Unsafe.Add(ref MemoryMarshal.GetReference(dst), i);
+                Unsafe.As<byte, Vector256<byte>>(ref outputRef) = c0;
+            }
 
-                for (; i < width; i++)
-                {
-                    dst[(int)i] = (byte)(prev[(int)i] + input[(int)i]);
-                }
+            for (; i < width; i++)
+            {
+                dst[(int)i] = (byte)(prev[(int)i] + input[(int)i]);
             }
-            else
+        }
+        else
+        {
+            for (int i = 0; i < width; i++)
             {
-                for (int i = 0; i < width; i++)
-                {
-                    dst[i] = (byte)(prev[i] + input[i]);
-                }
+                dst[i] = (byte)(prev[i] + input[i]);
             }
         }
     }

src/ImageSharp/Formats/Webp/AlphaEncoder.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using SixLabors.ImageSharp.Advanced;
@@ -13,10 +12,8 @@ namespace SixLabors.ImageSharp.Formats.Webp;
 /// <summary>
 /// Methods for encoding the alpha data of a VP8 image.
 /// </summary>
-internal class AlphaEncoder : IDisposable
+internal static class AlphaEncoder
 {
-    private IMemoryOwner<byte> alphaData;
-
     /// <summary>
     /// Encodes the alpha channel data.
     /// Data is either compressed as lossless webp image or uncompressed.
@@ -29,12 +26,18 @@ internal class AlphaEncoder : IDisposable
     /// <param name="compress">Indicates, if the data should be compressed with the lossless webp compression.</param>
     /// <param name="size">The size in bytes of the alpha data.</param>
     /// <returns>The encoded alpha data.</returns>
-    public IMemoryOwner<byte> EncodeAlpha<TPixel>(Image<TPixel> image, Configuration configuration, MemoryAllocator memoryAllocator, bool skipMetadata, bool compress, out int size)
+    public static IMemoryOwner<byte> EncodeAlpha<TPixel>(
+        Image<TPixel> image,
+        Configuration configuration,
+        MemoryAllocator memoryAllocator,
+        bool skipMetadata,
+        bool compress,
+        out int size)
         where TPixel : unmanaged, IPixel<TPixel>
     {
         int width = image.Width;
         int height = image.Height;
-        this.alphaData = ExtractAlphaChannel(image, configuration, memoryAllocator);
+        IMemoryOwner<byte> alphaData = ExtractAlphaChannel(image, configuration, memoryAllocator);
 
         if (compress)
         {
@@ -55,15 +58,15 @@ public IMemoryOwner<byte> EncodeAlpha<TPixel>(Image<TPixel> image, Configuration
             // The transparency information will be stored in the green channel of the ARGB quadruplet.
             // The green channel is allowed extra transformation steps in the specification -- unlike the other channels,
             // that can improve compression.
-            using Image<Rgba32> alphaAsImage = DispatchAlphaToGreen(image, this.alphaData.GetSpan());
+            using Image<Rgba32> alphaAsImage = DispatchAlphaToGreen(image, alphaData.GetSpan());
 
-            size = lossLessEncoder.EncodeAlphaImageData(alphaAsImage, this.alphaData);
+            size = lossLessEncoder.EncodeAlphaImageData(alphaAsImage, alphaData);
 
-            return this.alphaData;
+            return alphaData;
         }
 
         size = width * height;
-        return this.alphaData;
+        return alphaData;
     }
 
     /// <summary>
@@ -128,7 +131,4 @@ private static IMemoryOwner<byte> ExtractAlphaChannel<TPixel>(Image<TPixel> imag
 
         return alphaDataBuffer;
     }
-
-    /// <inheritdoc/>
-    public void Dispose() => this.alphaData?.Dispose();
 }

src/ImageSharp/Formats/Webp/BitReader/BitReaderBase.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using SixLabors.ImageSharp.Memory;
@@ -14,22 +13,30 @@ internal abstract class BitReaderBase : IDisposable
 {
     private bool isDisposed;
 
+    protected BitReaderBase(IMemoryOwner<byte> data)
+        => this.Data = data;
+
+    protected BitReaderBase(Stream inputStream, int imageDataSize, MemoryAllocator memoryAllocator)
+        => this.Data = ReadImageDataFromStream(inputStream, imageDataSize, memoryAllocator);
+
     /// <summary>
-    /// Gets or sets the raw encoded image data.
+    /// Gets the raw encoded image data.
     /// </summary>
-    public IMemoryOwner<byte> Data { get; set; }
+    public IMemoryOwner<byte> Data { get; }
 
     /// <summary>
     /// Copies the raw encoded image data from the stream into a byte array.
     /// </summary>
     /// <param name="input">The input stream.</param>
     /// <param name="bytesToRead">Number of bytes to read as indicated from the chunk size.</param>
     /// <param name="memoryAllocator">Used for allocating memory during reading data from the stream.</param>
-    protected void ReadImageDataFromStream(Stream input, int bytesToRead, MemoryAllocator memoryAllocator)
+    protected static IMemoryOwner<byte> ReadImageDataFromStream(Stream input, int bytesToRead, MemoryAllocator memoryAllocator)
     {
-        this.Data = memoryAllocator.Allocate<byte>(bytesToRead);
-        Span<byte> dataSpan = this.Data.Memory.Span;
+        IMemoryOwner<byte> data = memoryAllocator.Allocate<byte>(bytesToRead);
+        Span<byte> dataSpan = data.Memory.Span;
         input.Read(dataSpan[..bytesToRead], 0, bytesToRead);
+
+        return data;
     }
 
     protected virtual void Dispose(bool disposing)
@@ -41,7 +48,7 @@ protected virtual void Dispose(bool disposing)
 
         if (disposing)
         {
-            this.Data?.Dispose();
+            this.Data.Dispose();
         }
 
         this.isDisposed = true;

src/ImageSharp/Formats/Webp/BitReader/Vp8BitReader.cs

@@ -57,12 +57,12 @@ internal class Vp8BitReader : BitReaderBase
     /// <param name="partitionLength">The partition length.</param>
     /// <param name="startPos">Start index in the data array. Defaults to 0.</param>
     public Vp8BitReader(Stream inputStream, uint imageDataSize, MemoryAllocator memoryAllocator, uint partitionLength, int startPos = 0)
+        : base(inputStream, (int)imageDataSize, memoryAllocator)
     {
         Guard.MustBeLessThan(imageDataSize, int.MaxValue, nameof(imageDataSize));
 
         this.ImageDataSize = imageDataSize;
         this.PartitionLength = partitionLength;
-        this.ReadImageDataFromStream(inputStream, (int)imageDataSize, memoryAllocator);
         this.InitBitreader(partitionLength, startPos);
     }
 
@@ -73,8 +73,8 @@ public Vp8BitReader(Stream inputStream, uint imageDataSize, MemoryAllocator memo
     /// <param name="partitionLength">The partition length.</param>
     /// <param name="startPos">Start index in the data array. Defaults to 0.</param>
     public Vp8BitReader(IMemoryOwner<byte> imageData, uint partitionLength, int startPos = 0)
+        : base(imageData)
     {
-        this.Data = imageData;
         this.ImageDataSize = (uint)imageData.Memory.Length;
         this.PartitionLength = partitionLength;
         this.InitBitreader(partitionLength, startPos);

src/ImageSharp/Formats/Webp/BitReader/Vp8LBitReader.cs

@@ -63,8 +63,8 @@ internal class Vp8LBitReader : BitReaderBase
     /// </summary>
     /// <param name="data">Lossless compressed image data.</param>
     public Vp8LBitReader(IMemoryOwner<byte> data)
+        : base(data)
     {
-        this.Data = data;
         this.len = data.Memory.Length;
         this.value = 0;
         this.bitPos = 0;
@@ -88,11 +88,10 @@ public Vp8LBitReader(IMemoryOwner<byte> data)
     /// <param name="imageDataSize">The raw image data size in bytes.</param>
     /// <param name="memoryAllocator">Used for allocating memory during reading data from the stream.</param>
     public Vp8LBitReader(Stream inputStream, uint imageDataSize, MemoryAllocator memoryAllocator)
+        : base(inputStream, (int)imageDataSize, memoryAllocator)
     {
         long length = imageDataSize;
 
-        this.ReadImageDataFromStream(inputStream, (int)imageDataSize, memoryAllocator);
-
         this.len = length;
         this.value = 0;
         this.bitPos = 0;
@@ -193,7 +192,7 @@ public void FillBitWindow()
     [MethodImpl(InliningOptions.ShortMethod)]
     private void ShiftBytes()
     {
-        System.Span<byte> dataSpan = this.Data.Memory.Span;
+        System.Span<byte> dataSpan = this.Data!.Memory.Span;
         while (this.bitPos >= 8 && this.pos < this.len)
         {
             this.value >>= 8;

src/ImageSharp/Formats/Webp/BitWriter/BitWriterBase.cs

@@ -123,7 +123,7 @@ protected static uint AlphaChunkSize(Span<byte> alphaBytes)
     /// <param name="stream">The stream to write to.</param>
     /// <param name="metadataBytes">The metadata profile's bytes.</param>
     /// <param name="chunkType">The chuck type to write.</param>
-    protected void WriteMetadataProfile(Stream stream, byte[] metadataBytes, WebpChunkType chunkType)
+    protected void WriteMetadataProfile(Stream stream, byte[]? metadataBytes, WebpChunkType chunkType)
     {
         DebugGuard.NotNull(metadataBytes, nameof(metadataBytes));
 
@@ -207,7 +207,7 @@ protected void WriteColorProfile(Stream stream, byte[] iccProfileBytes)
     /// <param name="width">The width of the image.</param>
     /// <param name="height">The height of the image.</param>
     /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
-    protected void WriteVp8XHeader(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, byte[] iccProfileBytes, uint width, uint height, bool hasAlpha)
+    protected void WriteVp8XHeader(Stream stream, ExifProfile? exifProfile, XmpProfile? xmpProfile, byte[]? iccProfileBytes, uint width, uint height, bool hasAlpha)
     {
         if (width > MaxDimension || height > MaxDimension)
         {