Use bulk pixel conversion

src/ImageSharp/Formats/WebP/AlphaDecoder.cs

@@ -22,7 +22,8 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// <param name="data">The (maybe compressed) alpha data.</param>
         /// <param name="alphaChunkHeader">The first byte of the alpha image stream contains information on ow to decode the stream.</param>
         /// <param name="memoryAllocator">Used for allocating memory during decoding.</param>
-        public AlphaDecoder(int width, int height, byte[] data, byte alphaChunkHeader, MemoryAllocator memoryAllocator)
+        /// <param name="configuration">The configuration.</param>
+        public AlphaDecoder(int width, int height, byte[] data, byte alphaChunkHeader, MemoryAllocator memoryAllocator, Configuration configuration)
         {
             this.Width = width;
             this.Height = height;
@@ -59,7 +60,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
             if (this.Compressed)
             {
                 var bitReader = new Vp8LBitReader(data);
-                this.LosslessDecoder = new WebPLosslessDecoder(bitReader, memoryAllocator);
+                this.LosslessDecoder = new WebPLosslessDecoder(bitReader, memoryAllocator, configuration);
                 this.LosslessDecoder.DecodeImageStream(this.Vp8LDec, width, height, true);
             }
         }

src/ImageSharp/Formats/WebP/WebPDecoderCore.cs

@@ -89,12 +89,12 @@ namespace SixLabors.ImageSharp.Formats.WebP
             Buffer2D<TPixel> pixels = image.GetRootFramePixelBuffer();
             if (imageInfo.IsLossLess)
             {
-                var losslessDecoder = new WebPLosslessDecoder(imageInfo.Vp8LBitReader, this.memoryAllocator);
+                var losslessDecoder = new WebPLosslessDecoder(imageInfo.Vp8LBitReader, this.memoryAllocator, this.configuration);
                 losslessDecoder.Decode(pixels, image.Width, image.Height);
             }
             else
             {
-                var lossyDecoder = new WebPLossyDecoder(imageInfo.Vp8BitReader, this.memoryAllocator);
+                var lossyDecoder = new WebPLossyDecoder(imageInfo.Vp8BitReader, this.memoryAllocator, this.configuration);
                 lossyDecoder.Decode(pixels, image.Width, image.Height, imageInfo);
             }
 

src/ImageSharp/Formats/WebP/WebPLosslessDecoder.cs

@@ -27,6 +27,16 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// </summary>
         private readonly Vp8LBitReader bitReader;
 
+        /// <summary>
+        /// The global configuration.
+        /// </summary>
+        private readonly Configuration configuration;
+
+        /// <summary>
+        /// Used for allocating memory during processing operations.
+        /// </summary>
+        private readonly MemoryAllocator memoryAllocator;
+
         private static readonly int BitsSpecialMarker = 0x100;
 
         private static readonly int NumArgbCacheRows = 16;
@@ -62,20 +72,17 @@ namespace SixLabors.ImageSharp.Formats.WebP
             0, 1, 1, 1, 0
         };
 
-        /// <summary>
-        /// Used for allocating memory during processing operations.
-        /// </summary>
-        private readonly MemoryAllocator memoryAllocator;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="WebPLosslessDecoder"/> class.
         /// </summary>
         /// <param name="bitReader">Bitreader to read from the stream.</param>
         /// <param name="memoryAllocator">Used for allocating memory during processing operations.</param>
-        public WebPLosslessDecoder(Vp8LBitReader bitReader, MemoryAllocator memoryAllocator)
+        /// <param name="configuration">The configuration.</param>
+        public WebPLosslessDecoder(Vp8LBitReader bitReader, MemoryAllocator memoryAllocator, Configuration configuration)
         {
             this.bitReader = bitReader;
             this.memoryAllocator = memoryAllocator;
+            this.configuration = configuration;
         }
 
         /// <summary>
@@ -181,25 +188,21 @@ namespace SixLabors.ImageSharp.Formats.WebP
             where TPixel : struct, IPixel<TPixel>
         {
             Span<uint> pixelData = decoder.Pixels.GetSpan();
+            int width = decoder.Width;
 
             // Apply reverse transformations, if any are present.
             this.ApplyInverseTransforms(decoder, pixelData);
 
-            TPixel color = default;
+            Span<byte> pixelDataAsBytes = MemoryMarshal.Cast<uint, byte>(pixelData);
             for (int y = 0; y < decoder.Height; y++)
             {
-                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
-                for (int x = 0; x < decoder.Width; x++)
-                {
-                    int idx = (y * decoder.Width) + x;
-                    uint pixel = pixelData[idx];
-                    byte a = (byte)((pixel & 0xFF000000) >> 24);
-                    byte r = (byte)((pixel & 0xFF0000) >> 16);
-                    byte g = (byte)((pixel & 0xFF00) >> 8);
-                    byte b = (byte)(pixel & 0xFF);
-                    color.FromRgba32(new Rgba32(r, g, b, a));
-                    pixelRow[x] = color;
-                }
+                Span<byte> row = pixelDataAsBytes.Slice(y * width * 4, width * 4);
+                Span<TPixel> pixelSpan = pixels.GetRowSpan(y);
+                PixelOperations<TPixel>.Instance.FromBgra32Bytes(
+                    this.configuration,
+                    row,
+                    pixelSpan,
+                    width);
             }
         }
 

src/ImageSharp/Formats/WebP/WebPLossyDecoder.cs

@@ -24,15 +24,22 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// </summary>
         private readonly MemoryAllocator memoryAllocator;
 
+        /// <summary>
+        /// The global configuration.
+        /// </summary>
+        private readonly Configuration configuration;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="WebPLossyDecoder"/> class.
         /// </summary>
         /// <param name="bitReader">Bitreader to read from the stream.</param>
         /// <param name="memoryAllocator">Used for allocating memory during processing operations.</param>
-        public WebPLossyDecoder(Vp8BitReader bitReader, MemoryAllocator memoryAllocator)
+        /// <param name="configuration">The configuration.</param>
+        public WebPLossyDecoder(Vp8BitReader bitReader, MemoryAllocator memoryAllocator, Configuration configuration)
         {
-            this.memoryAllocator = memoryAllocator;
             this.bitReader = bitReader;
+            this.memoryAllocator = memoryAllocator;
+            this.configuration = configuration;
         }
 
         public void Decode<TPixel>(Buffer2D<TPixel> pixels, int width, int height, WebPImageInfo info)
@@ -85,7 +92,8 @@ namespace SixLabors.ImageSharp.Formats.WebP
                         height,
                         info.Features.AlphaData,
                         info.Features.AlphaChunkHeader,
-                        this.memoryAllocator))
+                        this.memoryAllocator,
+                        this.configuration))
                     {
                         alphaDecoder.Decode();
                         this.DecodePixelValues(width, height, decoder.Pixels.Memory.Span, pixels, alphaDecoder.Alpha);
@@ -101,39 +109,38 @@ namespace SixLabors.ImageSharp.Formats.WebP
         private void DecodePixelValues<TPixel>(int width, int height, Span<byte> pixelData, Buffer2D<TPixel> pixels, IMemoryOwner<byte> alpha = null)
             where TPixel : struct, IPixel<TPixel>
         {
-            TPixel color = default;
-            bool hasAlpha = false;
-            Span<byte> alphaSpan = null;
             if (alpha != null)
             {
-                hasAlpha = true;
-                alphaSpan = alpha.Memory.Span;
-            }
-
-            for (int y = 0; y < height; y++)
-            {
-                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
-                for (int x = 0; x < width; x++)
+                TPixel color = default;
+                Span<byte> alphaSpan = alpha.Memory.Span;
+                for (int y = 0; y < height; y++)
                 {
-                    int offset = (y * width) + x;
-                    int idxBgr = offset * 3;
-                    byte b = pixelData[idxBgr];
-                    byte g = pixelData[idxBgr + 1];
-                    byte r = pixelData[idxBgr + 2];
-
-                    // TODO: use bulk conversion here.
-                    if (hasAlpha)
+                    Span<TPixel> pixelRow = pixels.GetRowSpan(y);
+                    for (int x = 0; x < width; x++)
                     {
+                        int offset = (y * width) + x;
+                        int idxBgr = offset * 3;
+                        byte b = pixelData[idxBgr];
+                        byte g = pixelData[idxBgr + 1];
+                        byte r = pixelData[idxBgr + 2];
                         byte a = alphaSpan[offset];
                         color.FromBgra32(new Bgra32(r, g, b, a));
+                        pixelRow[x] = color;
                     }
-                    else
-                    {
-                        color.FromBgr24(new Bgr24(r, g, b));
-                    }
-
-                    pixelRow[x] = color;
                 }
+
+                return;
+            }
+
+            for (int y = 0; y < height; y++)
+            {
+                Span<byte> row = pixelData.Slice(y * width * 3, width * 3);
+                Span<TPixel> pixelSpan = pixels.GetRowSpan(y);
+                PixelOperations<TPixel>.Instance.FromBgr24Bytes(
+                    this.configuration,
+                    row,
+                    pixelSpan,
+                    width);
             }
         }