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@ -1,6 +1,5 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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#nullable disable |
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using System.Buffers; |
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using System.Buffers.Binary; |
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@ -44,32 +43,27 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Gets the <see cref="ImageMetadata"/> decoded by this decoder instance.
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/// </summary>
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private ImageMetadata metadata; |
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private ImageMetadata? metadata; |
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/// <summary>
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/// Gets or sets the alpha data, if an ALPH chunk is present.
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/// </summary>
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private IMemoryOwner<byte> alphaData; |
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private IMemoryOwner<byte>? alphaData; |
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/// <summary>
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/// Used for allocating memory during the decoding operations.
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/// </summary>
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private readonly MemoryAllocator memoryAllocator; |
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/// <summary>
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/// The stream to decode from.
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/// </summary>
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private BufferedReadStream currentStream; |
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/// <summary>
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/// The webp specific metadata.
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/// </summary>
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private WebpMetadata webpMetadata; |
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private WebpMetadata? webpMetadata; |
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/// <summary>
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/// Information about the webp image.
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/// </summary>
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private WebpImageInfo webImageInfo; |
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private WebpImageInfo? webImageInfo; |
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/// <summary>
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/// Initializes a new instance of the <see cref="WebpDecoderCore"/> class.
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@ -88,21 +82,20 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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public DecoderOptions Options { get; } |
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/// <inheritdoc/>
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public Size Dimensions => new((int)this.webImageInfo.Width, (int)this.webImageInfo.Height); |
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public Size Dimensions => new((int)this.webImageInfo!.Width, (int)this.webImageInfo.Height); |
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/// <inheritdoc />
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public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken) |
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where TPixel : unmanaged, IPixel<TPixel> |
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{ |
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Image<TPixel> image = null; |
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Image<TPixel>? image = null; |
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try |
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{ |
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this.metadata = new ImageMetadata(); |
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this.currentStream = stream; |
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uint fileSize = this.ReadImageHeader(); |
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uint fileSize = this.ReadImageHeader(stream); |
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using (this.webImageInfo = this.ReadVp8Info()) |
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using (this.webImageInfo = this.ReadVp8Info(stream)) |
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{ |
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if (this.webImageInfo.Features is { Animation: true }) |
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{ |
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@ -131,7 +124,7 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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// There can be optional chunks after the image data, like EXIF and XMP.
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if (this.webImageInfo.Features != null) |
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{ |
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this.ParseOptionalChunks(this.webImageInfo.Features); |
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this.ParseOptionalChunks(stream, this.webImageInfo.Features); |
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} |
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return image; |
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@ -147,10 +140,8 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <inheritdoc />
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public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken) |
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{ |
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this.currentStream = stream; |
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this.ReadImageHeader(); |
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using (this.webImageInfo = this.ReadVp8Info(true)) |
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this.ReadImageHeader(stream); |
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using (this.webImageInfo = this.ReadVp8Info(stream, true)) |
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{ |
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return new ImageInfo(new PixelTypeInfo((int)this.webImageInfo.BitsPerPixel), (int)this.webImageInfo.Width, (int)this.webImageInfo.Height, this.metadata); |
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} |
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@ -159,19 +150,20 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads and skips over the image header.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <returns>The file size in bytes.</returns>
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private uint ReadImageHeader() |
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private uint ReadImageHeader(BufferedReadStream stream) |
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{ |
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// Skip FourCC header, we already know its a RIFF file at this point.
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this.currentStream.Skip(4); |
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stream.Skip(4); |
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// Read file size.
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// The size of the file in bytes starting at offset 8.
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// The file size in the header is the total size of the chunks that follow plus 4 bytes for the ‘WEBP’ FourCC.
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uint fileSize = WebpChunkParsingUtils.ReadChunkSize(this.currentStream, this.buffer); |
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uint fileSize = WebpChunkParsingUtils.ReadChunkSize(stream, this.buffer); |
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// Skip 'WEBP' from the header.
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this.currentStream.Skip(4); |
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stream.Skip(4); |
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return fileSize; |
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} |
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@ -179,42 +171,43 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads information present in the image header, about the image content and how to decode the image.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <param name="ignoreAlpha">For identify, the alpha data should not be read.</param>
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/// <returns>Information about the webp image.</returns>
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private WebpImageInfo ReadVp8Info(bool ignoreAlpha = false) |
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private WebpImageInfo ReadVp8Info(BufferedReadStream stream, bool ignoreAlpha = false) |
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{ |
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this.metadata = new ImageMetadata(); |
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this.webpMetadata = this.metadata.GetFormatMetadata(WebpFormat.Instance); |
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WebpChunkType chunkType = WebpChunkParsingUtils.ReadChunkType(this.currentStream, this.buffer); |
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WebpChunkType chunkType = WebpChunkParsingUtils.ReadChunkType(stream, this.buffer); |
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var features = new WebpFeatures(); |
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switch (chunkType) |
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{ |
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case WebpChunkType.Vp8: |
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this.webpMetadata.FileFormat = WebpFileFormatType.Lossy; |
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return WebpChunkParsingUtils.ReadVp8Header(this.memoryAllocator, this.currentStream, this.buffer, features); |
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return WebpChunkParsingUtils.ReadVp8Header(this.memoryAllocator, stream, this.buffer, features); |
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case WebpChunkType.Vp8L: |
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this.webpMetadata.FileFormat = WebpFileFormatType.Lossless; |
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return WebpChunkParsingUtils.ReadVp8LHeader(this.memoryAllocator, this.currentStream, this.buffer, features); |
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return WebpChunkParsingUtils.ReadVp8LHeader(this.memoryAllocator, stream, this.buffer, features); |
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case WebpChunkType.Vp8X: |
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WebpImageInfo webpInfos = WebpChunkParsingUtils.ReadVp8XHeader(this.currentStream, this.buffer, features); |
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while (this.currentStream.Position < this.currentStream.Length) |
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WebpImageInfo webpInfos = WebpChunkParsingUtils.ReadVp8XHeader(stream, this.buffer, features); |
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while (stream.Position < stream.Length) |
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{ |
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chunkType = WebpChunkParsingUtils.ReadChunkType(this.currentStream, this.buffer); |
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chunkType = WebpChunkParsingUtils.ReadChunkType(stream, this.buffer); |
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if (chunkType == WebpChunkType.Vp8) |
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{ |
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this.webpMetadata.FileFormat = WebpFileFormatType.Lossy; |
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webpInfos = WebpChunkParsingUtils.ReadVp8Header(this.memoryAllocator, this.currentStream, this.buffer, features); |
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webpInfos = WebpChunkParsingUtils.ReadVp8Header(this.memoryAllocator, stream, this.buffer, features); |
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} |
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else if (chunkType == WebpChunkType.Vp8L) |
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{ |
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this.webpMetadata.FileFormat = WebpFileFormatType.Lossless; |
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webpInfos = WebpChunkParsingUtils.ReadVp8LHeader(this.memoryAllocator, this.currentStream, this.buffer, features); |
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webpInfos = WebpChunkParsingUtils.ReadVp8LHeader(this.memoryAllocator, stream, this.buffer, features); |
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} |
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else if (WebpChunkParsingUtils.IsOptionalVp8XChunk(chunkType)) |
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{ |
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bool isAnimationChunk = this.ParseOptionalExtendedChunks(chunkType, features, ignoreAlpha); |
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bool isAnimationChunk = this.ParseOptionalExtendedChunks(stream, chunkType, features, ignoreAlpha); |
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if (isAnimationChunk) |
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{ |
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return webpInfos; |
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@ -223,8 +216,8 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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else |
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{ |
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// Ignore unknown chunks.
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uint chunkSize = this.ReadChunkSize(); |
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this.currentStream.Skip((int)chunkSize); |
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uint chunkSize = this.ReadChunkSize(stream); |
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stream.Skip((int)chunkSize); |
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} |
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} |
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@ -239,32 +232,33 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Parses optional VP8X chunks, which can be ICCP, XMP, ANIM or ALPH chunks.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <param name="chunkType">The chunk type.</param>
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/// <param name="features">The webp image features.</param>
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/// <param name="ignoreAlpha">For identify, the alpha data should not be read.</param>
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/// <returns>true, if its a alpha chunk.</returns>
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private bool ParseOptionalExtendedChunks(WebpChunkType chunkType, WebpFeatures features, bool ignoreAlpha) |
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private bool ParseOptionalExtendedChunks(BufferedReadStream stream, WebpChunkType chunkType, WebpFeatures features, bool ignoreAlpha) |
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{ |
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switch (chunkType) |
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{ |
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case WebpChunkType.Iccp: |
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this.ReadIccProfile(); |
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this.ReadIccProfile(stream); |
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break; |
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case WebpChunkType.Exif: |
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this.ReadExifProfile(); |
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this.ReadExifProfile(stream); |
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break; |
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case WebpChunkType.Xmp: |
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this.ReadXmpProfile(); |
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this.ReadXmpProfile(stream); |
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break; |
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case WebpChunkType.AnimationParameter: |
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this.ReadAnimationParameters(features); |
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this.ReadAnimationParameters(stream, features); |
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return true; |
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case WebpChunkType.Alpha: |
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this.ReadAlphaData(features, ignoreAlpha); |
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this.ReadAlphaData(stream, features, ignoreAlpha); |
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break; |
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default: |
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WebpThrowHelper.ThrowImageFormatException("Unexpected chunk followed VP8X header"); |
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@ -277,32 +271,33 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads the optional metadata EXIF of XMP profiles, which can follow the image data.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <param name="features">The webp features.</param>
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private void ParseOptionalChunks(WebpFeatures features) |
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private void ParseOptionalChunks(BufferedReadStream stream, WebpFeatures features) |
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{ |
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if (this.skipMetadata || (!features.ExifProfile && !features.XmpMetaData)) |
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{ |
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return; |
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} |
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long streamLength = this.currentStream.Length; |
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while (this.currentStream.Position < streamLength) |
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long streamLength = stream.Length; |
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while (stream.Position < streamLength) |
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{ |
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// Read chunk header.
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WebpChunkType chunkType = this.ReadChunkType(); |
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if (chunkType == WebpChunkType.Exif && this.metadata.ExifProfile == null) |
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WebpChunkType chunkType = this.ReadChunkType(stream); |
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if (chunkType == WebpChunkType.Exif && this.metadata!.ExifProfile == null) |
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{ |
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this.ReadExifProfile(); |
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this.ReadExifProfile(stream); |
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} |
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else if (chunkType == WebpChunkType.Xmp && this.metadata.XmpProfile == null) |
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else if (chunkType == WebpChunkType.Xmp && this.metadata!.XmpProfile == null) |
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{ |
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this.ReadXmpProfile(); |
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this.ReadXmpProfile(stream); |
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} |
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else |
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{ |
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// Skip duplicate XMP or EXIF chunk.
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uint chunkLength = this.ReadChunkSize(); |
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this.currentStream.Skip((int)chunkLength); |
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uint chunkLength = this.ReadChunkSize(stream); |
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stream.Skip((int)chunkLength); |
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} |
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} |
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} |
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@ -310,17 +305,18 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads the EXIF profile from the stream.
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/// </summary>
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private void ReadExifProfile() |
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/// <param name="stream">The stream to decode from.</param>
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private void ReadExifProfile(BufferedReadStream stream) |
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{ |
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uint exifChunkSize = this.ReadChunkSize(); |
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uint exifChunkSize = this.ReadChunkSize(stream); |
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if (this.skipMetadata) |
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{ |
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this.currentStream.Skip((int)exifChunkSize); |
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stream.Skip((int)exifChunkSize); |
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} |
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else |
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{ |
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byte[] exifData = new byte[exifChunkSize]; |
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int bytesRead = this.currentStream.Read(exifData, 0, (int)exifChunkSize); |
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int bytesRead = stream.Read(exifData, 0, (int)exifChunkSize); |
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if (bytesRead != exifChunkSize) |
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{ |
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// Ignore invalid chunk.
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@ -328,24 +324,25 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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} |
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var profile = new ExifProfile(exifData); |
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this.metadata.ExifProfile = profile; |
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this.metadata!.ExifProfile = profile; |
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} |
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} |
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/// <summary>
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/// Reads the XMP profile the stream.
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/// </summary>
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private void ReadXmpProfile() |
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/// <param name="stream">The stream to decode from.</param>
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private void ReadXmpProfile(BufferedReadStream stream) |
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{ |
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uint xmpChunkSize = this.ReadChunkSize(); |
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uint xmpChunkSize = this.ReadChunkSize(stream); |
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if (this.skipMetadata) |
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{ |
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this.currentStream.Skip((int)xmpChunkSize); |
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stream.Skip((int)xmpChunkSize); |
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} |
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else |
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{ |
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byte[] xmpData = new byte[xmpChunkSize]; |
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int bytesRead = this.currentStream.Read(xmpData, 0, (int)xmpChunkSize); |
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int bytesRead = stream.Read(xmpData, 0, (int)xmpChunkSize); |
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if (bytesRead != xmpChunkSize) |
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{ |
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// Ignore invalid chunk.
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@ -353,24 +350,25 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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} |
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var profile = new XmpProfile(xmpData); |
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this.metadata.XmpProfile = profile; |
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this.metadata!.XmpProfile = profile; |
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} |
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} |
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/// <summary>
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/// Reads the ICCP chunk from the stream.
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/// </summary>
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private void ReadIccProfile() |
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/// <param name="stream">The stream to decode from.</param>
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private void ReadIccProfile(BufferedReadStream stream) |
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{ |
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uint iccpChunkSize = this.ReadChunkSize(); |
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uint iccpChunkSize = this.ReadChunkSize(stream); |
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if (this.skipMetadata) |
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{ |
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this.currentStream.Skip((int)iccpChunkSize); |
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stream.Skip((int)iccpChunkSize); |
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} |
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else |
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{ |
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byte[] iccpData = new byte[iccpChunkSize]; |
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int bytesRead = this.currentStream.Read(iccpData, 0, (int)iccpChunkSize); |
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int bytesRead = stream.Read(iccpData, 0, (int)iccpChunkSize); |
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if (bytesRead != iccpChunkSize) |
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{ |
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WebpThrowHelper.ThrowInvalidImageContentException("Not enough data to read the iccp chunk"); |
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@ -379,7 +377,7 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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var profile = new IccProfile(iccpData); |
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if (profile.CheckIsValid()) |
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{ |
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this.metadata.IccProfile = profile; |
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this.metadata!.IccProfile = profile; |
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} |
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} |
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} |
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@ -387,17 +385,18 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads the animation parameters chunk from the stream.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <param name="features">The webp features.</param>
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private void ReadAnimationParameters(WebpFeatures features) |
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private void ReadAnimationParameters(BufferedReadStream stream, WebpFeatures features) |
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{ |
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features.Animation = true; |
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uint animationChunkSize = WebpChunkParsingUtils.ReadChunkSize(this.currentStream, this.buffer); |
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byte blue = (byte)this.currentStream.ReadByte(); |
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byte green = (byte)this.currentStream.ReadByte(); |
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byte red = (byte)this.currentStream.ReadByte(); |
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byte alpha = (byte)this.currentStream.ReadByte(); |
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uint animationChunkSize = WebpChunkParsingUtils.ReadChunkSize(stream, this.buffer); |
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byte blue = (byte)stream.ReadByte(); |
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byte green = (byte)stream.ReadByte(); |
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byte red = (byte)stream.ReadByte(); |
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byte alpha = (byte)stream.ReadByte(); |
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features.AnimationBackgroundColor = new Color(new Rgba32(red, green, blue, alpha)); |
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int bytesRead = this.currentStream.Read(this.buffer, 0, 2); |
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int bytesRead = stream.Read(this.buffer, 0, 2); |
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if (bytesRead != 2) |
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{ |
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WebpThrowHelper.ThrowInvalidImageContentException("Not enough data to read the animation loop count"); |
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@ -409,22 +408,23 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Reads the alpha data chunk data from the stream.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <param name="features">The features.</param>
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/// <param name="ignoreAlpha">if set to true, skips the chunk data.</param>
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private void ReadAlphaData(WebpFeatures features, bool ignoreAlpha) |
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private void ReadAlphaData(BufferedReadStream stream, WebpFeatures features, bool ignoreAlpha) |
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{ |
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uint alphaChunkSize = WebpChunkParsingUtils.ReadChunkSize(this.currentStream, this.buffer); |
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uint alphaChunkSize = WebpChunkParsingUtils.ReadChunkSize(stream, this.buffer); |
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if (ignoreAlpha) |
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{ |
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this.currentStream.Skip((int)alphaChunkSize); |
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stream.Skip((int)alphaChunkSize); |
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return; |
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} |
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features.AlphaChunkHeader = (byte)this.currentStream.ReadByte(); |
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features.AlphaChunkHeader = (byte)stream.ReadByte(); |
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int alphaDataSize = (int)(alphaChunkSize - 1); |
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this.alphaData = this.memoryAllocator.Allocate<byte>(alphaDataSize); |
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Span<byte> alphaData = this.alphaData.GetSpan(); |
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int bytesRead = this.currentStream.Read(alphaData, 0, alphaDataSize); |
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int bytesRead = stream.Read(alphaData, 0, alphaDataSize); |
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if (bytesRead != alphaDataSize) |
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{ |
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WebpThrowHelper.ThrowInvalidImageContentException("Not enough data to read the alpha data from the stream"); |
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@ -434,12 +434,13 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// <summary>
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/// Identifies the chunk type from the chunk.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <exception cref="ImageFormatException">
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/// Thrown if the input stream is not valid.
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/// </exception>
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private WebpChunkType ReadChunkType() |
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private WebpChunkType ReadChunkType(BufferedReadStream stream) |
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{ |
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if (this.currentStream.Read(this.buffer, 0, 4) == 4) |
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if (stream.Read(this.buffer, 0, 4) == 4) |
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{ |
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var chunkType = (WebpChunkType)BinaryPrimitives.ReadUInt32BigEndian(this.buffer); |
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return chunkType; |
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@ -452,10 +453,11 @@ internal sealed class WebpDecoderCore : IImageDecoderInternals, IDisposable |
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/// Reads the chunk size. If Chunk Size is odd, a single padding byte will be added to the payload,
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/// so the chunk size will be increased by 1 in those cases.
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/// </summary>
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/// <param name="stream">The stream to decode from.</param>
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/// <returns>The chunk size in bytes.</returns>
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private uint ReadChunkSize() |
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private uint ReadChunkSize(BufferedReadStream stream) |
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{ |
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if (this.currentStream.Read(this.buffer, 0, 4) == 4) |
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if (stream.Read(this.buffer, 0, 4) == 4) |
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{ |
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uint chunkSize = BinaryPrimitives.ReadUInt32LittleEndian(this.buffer); |
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return (chunkSize % 2 == 0) ? chunkSize : chunkSize + 1; |
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Stefan Nikolei
3 years ago