mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
6 years ago
13 changed files with 656 additions and 152 deletions
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// Copyright (c) Six Labors and contributors.
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// Licensed under the GNU Affero General Public License, Version 3.
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using System; |
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namespace SixLabors.ImageSharp.Formats.Png |
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{ |
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/// <summary>
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/// Provides enumeration of available PNG optimization methods.
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/// </summary>
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[Flags] |
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public enum PngChunkFilter |
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{ |
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/// <summary>
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/// With the None filter, all chunks will be written.
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/// </summary>
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None = 0, |
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/// <summary>
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/// Excludes the physical dimension information chunk from encoding.
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/// </summary>
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ExcludePhysicalChunk = 1 << 0, |
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/// <summary>
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/// Excludes the gamma information chunk from encoding.
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/// </summary>
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ExcludeGammaChunk = 1 << 1, |
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/// <summary>
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/// Excludes the eXIf chunk from encoding.
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/// </summary>
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ExcludeExifChunk = 1 << 2, |
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/// <summary>
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/// Excludes the tTXt, iTXt or zTXt chunk from encoding.
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/// </summary>
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ExcludeTextChunks = 1 << 3, |
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/// <summary>
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/// All ancillary chunks will be excluded.
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/// </summary>
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ExcludeAll = ~None |
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} |
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} |
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// Copyright (c) Six Labors and contributors.
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// Licensed under the GNU Affero General Public License, Version 3.
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namespace SixLabors.ImageSharp.Formats.Png |
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{ |
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/// <summary>
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/// Enum indicating how the transparency should be handled on encoding.
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/// </summary>
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public enum PngTransparentColorMode |
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{ |
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/// <summary>
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/// The transparency will be kept as is.
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/// </summary>
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Preserve = 0, |
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/// <summary>
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/// Converts fully transparent pixels that may contain R, G, B values which are not 0,
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/// to transparent black, which can yield in better compression in some cases.
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/// </summary>
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Clear = 1, |
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} |
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} |
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@ -0,0 +1,328 @@ |
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// Copyright (c) Six Labors and contributors.
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// Licensed under the GNU Affero General Public License, Version 3.
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using System; |
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using System.Buffers.Binary; |
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using System.Collections.Generic; |
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using System.ComponentModel; |
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using System.IO; |
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using SixLabors.ImageSharp.Formats.Png; |
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using SixLabors.ImageSharp.PixelFormats; |
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using Xunit; |
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// ReSharper disable InconsistentNaming
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namespace SixLabors.ImageSharp.Tests.Formats.Png |
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{ |
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public partial class PngEncoderTests |
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{ |
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[Fact] |
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public void HeaderChunk_ComesFirst() |
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{ |
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// arrange
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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// act
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input.Save(memStream, PngEncoder); |
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// assert
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var type = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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Assert.Equal(PngChunkType.Header, type); |
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} |
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[Fact] |
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public void EndChunk_IsLast() |
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{ |
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// arrange
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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// act
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input.Save(memStream, PngEncoder); |
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// assert
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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bool endChunkFound = false; |
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var type = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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Assert.False(endChunkFound); |
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if (type == PngChunkType.End) |
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{ |
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endChunkFound = true; |
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} |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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} |
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[Theory] |
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[InlineData(PngChunkType.Gamma)] |
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[InlineData(PngChunkType.Chroma)] |
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[InlineData(PngChunkType.EmbeddedColorProfile)] |
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[InlineData(PngChunkType.SignificantBits)] |
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[InlineData(PngChunkType.StandardRgbColourSpace)] |
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public void Chunk_ComesBeforePlteAndIDat(object chunkTypeObj) |
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{ |
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// arrange
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var chunkType = (PngChunkType)chunkTypeObj; |
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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// act
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input.Save(memStream, PngEncoder); |
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// assert
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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bool palFound = false; |
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bool dataFound = false; |
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var type = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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if (chunkType == type) |
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{ |
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Assert.False(palFound || dataFound, $"{chunkType} chunk should come before data and palette chunk"); |
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} |
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switch (type) |
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{ |
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case PngChunkType.Data: |
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dataFound = true; |
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break; |
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case PngChunkType.Palette: |
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palFound = true; |
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break; |
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} |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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} |
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[Theory] |
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[InlineData(PngChunkType.Physical)] |
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[InlineData(PngChunkType.SuggestedPalette)] |
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public void Chunk_ComesBeforeIDat(object chunkTypeObj) |
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{ |
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// arrange
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var chunkType = (PngChunkType)chunkTypeObj; |
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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// act
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input.Save(memStream, PngEncoder); |
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// assert
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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bool dataFound = false; |
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var type = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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if (chunkType == type) |
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{ |
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Assert.False(dataFound, $"{chunkType} chunk should come before data chunk"); |
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} |
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if (type == PngChunkType.Data) |
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{ |
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dataFound = true; |
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} |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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} |
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[Fact] |
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public void IgnoreMetadata_WillExcludeAllAncillaryChunks() |
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{ |
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// arrange
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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var encoder = new PngEncoder() { IgnoreMetadata = true, TextCompressionThreshold = 8 }; |
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var expectedChunkTypes = new Dictionary<PngChunkType, bool>() |
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{ |
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{ PngChunkType.Header, false }, |
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{ PngChunkType.Palette, false }, |
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{ PngChunkType.Data, false }, |
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{ PngChunkType.End, false } |
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}; |
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var excludedChunkTypes = new List<PngChunkType>() |
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{ |
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PngChunkType.Gamma, |
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PngChunkType.Exif, |
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PngChunkType.Physical, |
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PngChunkType.Text, |
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PngChunkType.InternationalText, |
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PngChunkType.CompressedText, |
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}; |
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// act
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input.Save(memStream, encoder); |
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// assert
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Assert.True(excludedChunkTypes.Count > 0); |
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var chunkType = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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Assert.False(excludedChunkTypes.Contains(chunkType), $"{chunkType} chunk should have been excluded"); |
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if (expectedChunkTypes.ContainsKey(chunkType)) |
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{ |
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expectedChunkTypes[chunkType] = true; |
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} |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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// all expected chunk types should have been seen at least once.
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foreach (PngChunkType chunkType in expectedChunkTypes.Keys) |
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{ |
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Assert.True(expectedChunkTypes[chunkType], $"We expect {chunkType} chunk to be present at least once"); |
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} |
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} |
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[Theory] |
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[InlineData(PngChunkFilter.ExcludeGammaChunk)] |
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[InlineData(PngChunkFilter.ExcludeExifChunk)] |
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[InlineData(PngChunkFilter.ExcludePhysicalChunk)] |
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[InlineData(PngChunkFilter.ExcludeTextChunks)] |
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[InlineData(PngChunkFilter.ExcludeAll)] |
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public void ExcludeFilter_Works(object filterObj) |
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{ |
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// arrange
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var chunkFilter = (PngChunkFilter)filterObj; |
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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var encoder = new PngEncoder() { ChunkFilter = chunkFilter, TextCompressionThreshold = 8 }; |
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var expectedChunkTypes = new Dictionary<PngChunkType, bool>() |
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{ |
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{ PngChunkType.Header, false }, |
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{ PngChunkType.Gamma, false }, |
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{ PngChunkType.Palette, false }, |
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{ PngChunkType.InternationalText, false }, |
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{ PngChunkType.Text, false }, |
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{ PngChunkType.CompressedText, false }, |
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{ PngChunkType.Exif, false }, |
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{ PngChunkType.Physical, false }, |
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{ PngChunkType.Data, false }, |
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{ PngChunkType.End, false } |
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}; |
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var excludedChunkTypes = new List<PngChunkType>(); |
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switch (chunkFilter) |
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{ |
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case PngChunkFilter.ExcludeGammaChunk: |
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excludedChunkTypes.Add(PngChunkType.Gamma); |
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expectedChunkTypes.Remove(PngChunkType.Gamma); |
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break; |
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case PngChunkFilter.ExcludeExifChunk: |
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excludedChunkTypes.Add(PngChunkType.Exif); |
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expectedChunkTypes.Remove(PngChunkType.Exif); |
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break; |
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case PngChunkFilter.ExcludePhysicalChunk: |
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excludedChunkTypes.Add(PngChunkType.Physical); |
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expectedChunkTypes.Remove(PngChunkType.Physical); |
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break; |
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case PngChunkFilter.ExcludeTextChunks: |
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excludedChunkTypes.Add(PngChunkType.Text); |
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excludedChunkTypes.Add(PngChunkType.InternationalText); |
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excludedChunkTypes.Add(PngChunkType.CompressedText); |
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expectedChunkTypes.Remove(PngChunkType.Text); |
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expectedChunkTypes.Remove(PngChunkType.InternationalText); |
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expectedChunkTypes.Remove(PngChunkType.CompressedText); |
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break; |
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case PngChunkFilter.ExcludeAll: |
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excludedChunkTypes.Add(PngChunkType.Gamma); |
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excludedChunkTypes.Add(PngChunkType.Exif); |
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excludedChunkTypes.Add(PngChunkType.Physical); |
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excludedChunkTypes.Add(PngChunkType.Text); |
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excludedChunkTypes.Add(PngChunkType.InternationalText); |
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excludedChunkTypes.Add(PngChunkType.CompressedText); |
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expectedChunkTypes.Remove(PngChunkType.Gamma); |
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expectedChunkTypes.Remove(PngChunkType.Exif); |
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expectedChunkTypes.Remove(PngChunkType.Physical); |
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expectedChunkTypes.Remove(PngChunkType.Text); |
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expectedChunkTypes.Remove(PngChunkType.InternationalText); |
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expectedChunkTypes.Remove(PngChunkType.CompressedText); |
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break; |
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} |
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// act
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input.Save(memStream, encoder); |
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// assert
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Assert.True(excludedChunkTypes.Count > 0); |
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var chunkType = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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Assert.False(excludedChunkTypes.Contains(chunkType), $"{chunkType} chunk should have been excluded"); |
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if (expectedChunkTypes.ContainsKey(chunkType)) |
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{ |
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expectedChunkTypes[chunkType] = true; |
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} |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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// all expected chunk types should have been seen at least once.
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foreach (PngChunkType chunkType in expectedChunkTypes.Keys) |
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{ |
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Assert.True(expectedChunkTypes[chunkType], $"We expect {chunkType} chunk to be present at least once"); |
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} |
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} |
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[Fact] |
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public void ExcludeFilter_WithNone_DoesNotExcludeChunks() |
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{ |
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// arrange
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var testFile = TestFile.Create(TestImages.Png.PngWithMetadata); |
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using Image<Rgba32> input = testFile.CreateRgba32Image(); |
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using var memStream = new MemoryStream(); |
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var encoder = new PngEncoder() { ChunkFilter = PngChunkFilter.None, TextCompressionThreshold = 8 }; |
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var expectedChunkTypes = new List<PngChunkType>() |
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{ |
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PngChunkType.Header, |
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PngChunkType.Gamma, |
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PngChunkType.Palette, |
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PngChunkType.InternationalText, |
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PngChunkType.Text, |
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PngChunkType.CompressedText, |
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PngChunkType.Exif, |
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PngChunkType.Physical, |
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PngChunkType.Data, |
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PngChunkType.End, |
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}; |
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// act
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input.Save(memStream, encoder); |
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memStream.Position = 0; |
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Span<byte> bytesSpan = memStream.ToArray().AsSpan(8); // Skip header.
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while (bytesSpan.Length > 0) |
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{ |
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int length = BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(0, 4)); |
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var chunkType = (PngChunkType)BinaryPrimitives.ReadInt32BigEndian(bytesSpan.Slice(4, 4)); |
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Assert.True(expectedChunkTypes.Contains(chunkType), $"{chunkType} chunk should have been present"); |
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bytesSpan = bytesSpan.Slice(4 + 4 + length + 4); |
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} |
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} |
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} |
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} |
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