Add parsing of EXIF chunk

src/ImageSharp/Formats/WebP/Vp8LBitReader.cs

@@ -1,8 +1,12 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.IO;
 
+using SixLabors.ImageSharp.Memory;
+using SixLabors.Memory;
+
 namespace SixLabors.ImageSharp.Formats.WebP
 {
     /// <summary>
@@ -67,13 +71,15 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// Initializes a new instance of the <see cref="Vp8LBitReader"/> class.
         /// </summary>
         /// <param name="inputStream">The input stream to read from.</param>
-        public Vp8LBitReader(Stream inputStream)
+        /// <param name="imageDataSize">The 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)
         {
-            long length = inputStream.Length - inputStream.Position;
+            long length = imageDataSize;
 
             using (var ms = new MemoryStream())
             {
-                inputStream.CopyTo(ms);
+                CopyStream(inputStream, ms, (int)imageDataSize, memoryAllocator);
                 this.data = ms.ToArray();
             }
 
@@ -114,13 +120,15 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 this.ShiftBytes();
                 return (uint)val;
             }
-            else
-            {
-                this.SetEndOfStream();
-                return 0;
-            }
+
+            this.SetEndOfStream();
+            return 0;
         }
 
+        /// <summary>
+        /// Reads a single bit from the stream.
+        /// </summary>
+        /// <returns>True if the bit read was 1, false otherwise.</returns>
         public bool ReadBit()
         {
             uint bit = this.ReadBits(1);
@@ -155,6 +163,9 @@ namespace SixLabors.ImageSharp.Formats.WebP
             return this.eos || ((this.pos == this.len) && (this.bitPos > Vp8LLbits));
         }
 
+        /// <summary>
+        /// If not at EOS, reload up to Vp8LLbits byte-by-byte.
+        /// </summary>
         private void ShiftBytes()
         {
             while (this.bitPos >= 8 && this.pos < this.len)
@@ -176,5 +187,24 @@ namespace SixLabors.ImageSharp.Formats.WebP
             this.eos = true;
             this.bitPos = 0; // To avoid undefined behaviour with shifts.
         }
+
+        private static void CopyStream(Stream input, Stream output, int bytesToRead, MemoryAllocator memoryAllocator)
+        {
+            using (IManagedByteBuffer buffer = memoryAllocator.AllocateManagedByteBuffer(4096))
+            {
+                Span<byte> bufferSpan = buffer.GetSpan();
+                int read;
+                while (bytesToRead > 0 && (read = input.Read(buffer.Array, 0, Math.Min(bufferSpan.Length, bytesToRead))) > 0)
+                {
+                    output.Write(buffer.Array, 0, read);
+                    bytesToRead -= read;
+                }
+
+                if (bytesToRead > 0)
+                {
+                    WebPThrowHelper.ThrowImageFormatException("image file has insufficient data");
+                }
+            }
+        }
     }
 }

src/ImageSharp/Formats/WebP/WebPDecoderCore.cs

@@ -7,6 +7,7 @@ using System.IO;
 
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
+using SixLabors.ImageSharp.Metadata.Profiles.Exif;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 
@@ -32,21 +33,11 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// </summary>
         private readonly MemoryAllocator memoryAllocator;
 
-        /// <summary>
-        /// The bitmap decoder options.
-        /// </summary>
-        private readonly IWebPDecoderOptions options;
-
         /// <summary>
         /// The stream to decode from.
         /// </summary>
         private Stream currentStream;
 
-        /// <summary>
-        /// The metadata.
-        /// </summary>
-        private ImageMetadata metadata;
-
         /// <summary>
         /// The webp specific metadata.
         /// </summary>
@@ -61,9 +52,19 @@ namespace SixLabors.ImageSharp.Formats.WebP
         {
             this.configuration = configuration;
             this.memoryAllocator = configuration.MemoryAllocator;
-            this.options = options;
+            this.IgnoreMetadata = options.IgnoreMetadata;
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the metadata should be ignored when the image is being decoded.
+        /// </summary>
+        public bool IgnoreMetadata { get; }
+
+        /// <summary>
+        /// Gets the <see cref="ImageMetadata"/> decoded by this decoder instance.
+        /// </summary>
+        public ImageMetadata Metadata { get; private set; }
+
         /// <summary>
         /// Decodes the image from the specified <see cref="Stream"/> and sets the data to the image.
         /// </summary>
@@ -73,6 +74,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
         public Image<TPixel> Decode<TPixel>(Stream stream)
             where TPixel : struct, IPixel<TPixel>
         {
+            this.Metadata = new ImageMetadata();
             this.currentStream = stream;
 
             uint fileSize = this.ReadImageHeader();
@@ -82,7 +84,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 WebPThrowHelper.ThrowNotSupportedException("Animations are not supported");
             }
 
-            var image = new Image<TPixel>(this.configuration, imageInfo.Width, imageInfo.Height, this.metadata);
+            var image = new Image<TPixel>(this.configuration, imageInfo.Width, imageInfo.Height, this.Metadata);
             Buffer2D<TPixel> pixels = image.GetRootFramePixelBuffer();
             if (imageInfo.IsLossLess)
             {
@@ -95,7 +97,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 lossyDecoder.Decode(pixels, image.Width, image.Height, (int)imageInfo.ImageDataSize);
             }
 
-            // There can be optional chunks after the image data, like EXIF, XMP etc.
+            // There can be optional chunks after the image data, like EXIF and XMP.
             if (imageInfo.Features != null)
             {
                 this.ParseOptionalChunks(imageInfo.Features);
@@ -117,7 +119,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
 
             // TODO: not sure yet where to get this info. Assuming 24 bits for now.
             int bitsPerPixel = 24;
-            return new ImageInfo(new PixelTypeInfo(bitsPerPixel), imageInfo.Width, imageInfo.Height, this.metadata);
+            return new ImageInfo(new PixelTypeInfo(bitsPerPixel), imageInfo.Width, imageInfo.Height, this.Metadata);
         }
 
         /// <summary>
@@ -142,8 +144,8 @@ namespace SixLabors.ImageSharp.Formats.WebP
 
         private WebPImageInfo ReadVp8Info()
         {
-            this.metadata = new ImageMetadata();
-            this.webpMetadata = this.metadata.GetFormatMetadata(WebPFormat.Instance);
+            this.Metadata = new ImageMetadata();
+            this.webpMetadata = this.Metadata.GetFormatMetadata(WebPFormat.Instance);
 
             WebPChunkType chunkType = this.ReadChunkType();
 
@@ -322,10 +324,11 @@ namespace SixLabors.ImageSharp.Formats.WebP
             this.webpMetadata.Format = WebPFormatType.Lossless;
 
             // VP8 data size.
-            uint dataSize = this.ReadChunkSize();
+            uint imageDataSize = this.ReadChunkSize();
+
+            var bitReader = new Vp8LBitReader(this.currentStream, imageDataSize, this.memoryAllocator);
 
             // One byte signature, should be 0x2f.
-            var bitReader = new Vp8LBitReader(this.currentStream);
             uint signature = bitReader.ReadBits(8);
             if (signature != WebPConstants.Vp8LMagicByte)
             {
@@ -349,7 +352,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                        Width = (int)width,
                        Height = (int)height,
                        IsLossLess = true,
-                       ImageDataSize = dataSize,
+                       ImageDataSize = imageDataSize,
                        Features = features,
                        Vp9LBitReader = bitReader
                    };
@@ -363,7 +366,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// <param name="features">The webp features.</param>
         private void ParseOptionalChunks(WebPFeatures features)
         {
-            if (features.ExifProfile is false && features.XmpMetaData is false)
+            if (this.IgnoreMetadata || (features.ExifProfile is false && features.XmpMetaData is false))
             {
                 return;
             }
@@ -374,8 +377,17 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 WebPChunkType chunkType = this.ReadChunkType();
                 uint chunkLength = this.ReadChunkSize();
 
-                // Skip chunk data for now.
-                this.currentStream.Skip((int)chunkLength);
+                if (chunkType is WebPChunkType.Exif)
+                {
+                    var exifData = new byte[chunkLength];
+                    this.currentStream.Read(exifData, 0, (int)chunkLength);
+                    this.Metadata.ExifProfile = new ExifProfile(exifData);
+                }
+                else
+                {
+                    // Skip XMP chunk data for now.
+                    this.currentStream.Skip((int)chunkLength);
+                }
             }
         }
 

src/ImageSharp/Formats/WebP/WebPLossyDecoder.cs

@@ -46,7 +46,8 @@ namespace SixLabors.ImageSharp.Formats.WebP
             // TODO weiter bei  S.11
 
             // bit STREAM: See https://tools.ietf.org/html/rfc6386#page-29 ("Frame Header")
-            Vp8LBitReader bitReader = new Vp8LBitReader(this.currentStream);
+            // TODO: Vp8BitReader should be used here instead
+            /*Vp8LBitReader bitReader = new Vp8LBitReader(this.currentStream);
             bool isInterframe = bitReader.ReadBit();
             if (isInterframe)
             {
@@ -58,7 +59,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
 
             bool isShowFrame = bitReader.ReadBit();
 
-            uint firstPartitionSize = (bitReader.ReadBits(16) << 3) | bitReader.ReadBits(3);
+            uint firstPartitionSize = (bitReader.ReadBits(16) << 3) | bitReader.ReadBits(3);*/
         }
 
         private (ReconstructionFilter, LoopFilter) DecodeVersion(byte version)