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Add parsing optional chunks at the end

pull/1552/head
Brian Popow 7 years ago
parent
506967a86e
commit
d88ba617e1
3 changed files with 62 additions and 45 deletions
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  1. 100
      src/ImageSharp/Formats/WebP/WebPDecoderCore.cs
  2. 5
      src/ImageSharp/Formats/WebP/WebPImageInfo.cs
  3. 2
      tests/ImageSharp.Tests/Formats/WebP/WebPDecoderTests.cs

100
src/ImageSharp/Formats/WebP/WebPDecoderCore.cs
View File

@ -66,21 +66,21 @@ namespace SixLabors.ImageSharp.Formats.WebP
WebPMetadata webpMetadata = metadata.GetFormatMetadata(WebPFormat.Instance);
this.currentStream = stream;
uint chunkSize = this.ReadImageHeader();
uint fileSize = this.ReadImageHeader();
WebPImageInfo imageInfo = this.ReadVp8Info();
var image = new Image<TPixel>(this.configuration, imageInfo.Width, imageInfo.Height, this.metadata);
Buffer2D<TPixel> pixels = image.GetRootFramePixelBuffer();
if (imageInfo.IsLossLess)
{
ReadSimpleLossless(pixels, image.Width, image.Height, (int)imageInfo.DataSize);
ReadSimpleLossless(pixels, image.Width, image.Height, (int)imageInfo.ImageDataSize);
}
else
{
ReadSimpleLossy(pixels, image.Width, image.Height, (int)imageInfo.DataSize);
ReadSimpleLossy(pixels, image.Width, image.Height, (int)imageInfo.ImageDataSize);
}
// TODO: there can be optional chunks after the image data, like EXIF, XMP etc.
// There can be optional chunks after the image data, like EXIF, XMP etc.
this.ParseOptionalChunks();
return image;
@ -107,7 +107,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
// Skip FourCC header, we already know its a RIFF file at this point.
this.currentStream.Skip(4);
// Read Chunk size.
// Read file size.
// The size of the file in bytes starting at offset 8.
// The file size in the header is the total size of the chunks that follow plus 4 bytes for the ‘WEBP’ FourCC.
uint chunkSize = this.ReadChunkSize();
@ -179,9 +179,10 @@ namespace SixLabors.ImageSharp.Formats.WebP
int height = BinaryPrimitives.ReadInt32LittleEndian(this.buffer) + 1;
// Optional chunks ALPH, ICCP and ANIM can follow here. Ignoring them for now.
WebPChunkType chunkType;
if (isIccPresent)
{
WebPChunkType chunkType = this.ReadChunkType();
chunkType = this.ReadChunkType();
uint iccpChunkSize = this.ReadChunkSize();
this.currentStream.Skip((int)iccpChunkSize);
}
@ -189,34 +190,42 @@ namespace SixLabors.ImageSharp.Formats.WebP
if (isAnimationPresent)
{
// ANIM chunk will be followed by n ANMF chunks
WebPChunkType chunkType = this.ReadChunkType();
chunkType = this.ReadChunkType();
uint animationParameterChunkSize = this.ReadChunkSize();
this.currentStream.Skip((int)animationParameterChunkSize);
chunkType = this.ReadChunkType();
// TODO: not sure yet how to determine how many animation chunks there will be.
while (chunkType == WebPChunkType.Animation)
{
uint animationChunkSize = this.ReadChunkSize();
this.currentStream.Skip((int)animationChunkSize);
chunkType = this.ReadChunkType();
}
// TODO: there seems to follow something here after the last ANMF, im not sure yet how to parse.
}
if (isAlphaPresent)
{
WebPChunkType chunkType = this.ReadChunkType();
chunkType = this.ReadChunkType();
uint alphaChunkSize = this.ReadChunkSize();
this.currentStream.Skip((int)alphaChunkSize);
}
return new WebPImageInfo()
{
Width = width,
Height = height,
IsLossLess = false,
DataSize = chunkSize
};
// A VP8 or VP8L chunk should follow here.
chunkType = this.ReadChunkType();
// TOOD: image width and height from VP8X should overrule VP8 or VP8L info, because its 3 bytes instead of just 14 bit.
switch (chunkType)
{
case WebPChunkType.Vp8:
return this.ReadVp8Header();
case WebPChunkType.Vp8L:
return this.ReadVp8LHeader();
}
WebPThrowHelper.ThrowImageFormatException("Unexpected chunk followed VP8X header");
return new WebPImageInfo();
}
private WebPImageInfo ReadVp8Header()
@ -256,11 +265,11 @@ namespace SixLabors.ImageSharp.Formats.WebP
Width = width,
Height = height,
IsLossLess = false,
DataSize = dataSize
ImageDataSize = dataSize
};
}
private WebPImageInfo ReadVp8LHeader(int vpxWidth = 0, int vpxHeight = 0)
private WebPImageInfo ReadVp8LHeader()
{
// VP8 data size.
uint dataSize = this.ReadChunkSize();
@ -337,40 +346,27 @@ namespace SixLabors.ImageSharp.Formats.WebP
transformPresent = bitReader.ReadBit();
}
// Use the width and height from the VP8X information, if its provided, because its 3 bytes instead of 14 bits.
bool isVpxDimensionsPresent = vpxHeight != 0 || vpxWidth != 0;
return new WebPImageInfo()
{
Width = isVpxDimensionsPresent ? vpxWidth : (int)width,
Height = isVpxDimensionsPresent ? vpxHeight : (int)height,
Width = (int)width,
Height = (int)height,
IsLossLess = true,
DataSize = dataSize
ImageDataSize = dataSize
};
}
private void ParseOptionalChunks()
{
// Read VP8 chunk header.
// WebPChunkType chunkType = this.ReadChunkType();
}
private void ReadSimpleLossy<TPixel>(Buffer2D<TPixel> pixels, int width, int height, int chunkSize)
private void ReadSimpleLossy<TPixel>(Buffer2D<TPixel> pixels, int width, int height, int imageDataSize)
where TPixel : struct, IPixel<TPixel>
{
// TODO: implement decoding, for simulating the decoding, skipping the chunk size bytes.
this.currentStream.Skip(chunkSize);
this.ParseOptionalChunks();
this.currentStream.Skip(imageDataSize - 10); // 10 bytes because of VP8X header.
}
private void ReadSimpleLossless<TPixel>(Buffer2D<TPixel> pixels, int width, int height, int chunkSize)
private void ReadSimpleLossless<TPixel>(Buffer2D<TPixel> pixels, int width, int height, int imageDataSize)
where TPixel : struct, IPixel<TPixel>
{
// TODO: implement decoding, for simulating the decoding, skipping the chunk size bytes.
this.currentStream.Skip(chunkSize);
this.ParseOptionalChunks();
this.currentStream.Skip(imageDataSize - 10); // 10 bytes because of VP8X header.
}
private void ReadExtended<TPixel>(Buffer2D<TPixel> pixels, int width, int height)
@ -379,6 +375,19 @@ namespace SixLabors.ImageSharp.Formats.WebP
// TODO: implement decoding
}
private void ParseOptionalChunks()
{
while (this.currentStream.Position < this.currentStream.Length)
{
// Read chunk header.
WebPChunkType chunkType = this.ReadChunkType();
uint chunkLength = this.ReadChunkSize();
// Skip chunk data for now.
this.currentStream.Skip((int)chunkLength);
}
}
/// <summary>
/// Identifies the chunk type from the chunk.
/// </summary>
@ -393,14 +402,19 @@ namespace SixLabors.ImageSharp.Formats.WebP
}
/// <summary>
/// Reads the chunk size.
/// Reads the chunk size. If Chunk Size is odd, a single padding byte will be added to the payload,
/// so the chunk size will be increased by 1 in those cases.
/// </summary>
/// <returns>The chunk size in bytes.</returns>
private uint ReadChunkSize()
{
return this.currentStream.Read(this.buffer, 0, 4) == 4
? BinaryPrimitives.ReadUInt32LittleEndian(this.buffer)
: throw new ImageFormatException("Invalid WebP data.");
if (this.currentStream.Read(this.buffer, 0, 4) == 4)
{
uint chunkSize = BinaryPrimitives.ReadUInt32LittleEndian(this.buffer);
return (chunkSize % 2 == 0) ? chunkSize : chunkSize + 1;
}
throw new ImageFormatException("Invalid WebP data.");
}
}
}

5
src/ImageSharp/Formats/WebP/WebPImageInfo.cs
View File

@ -20,6 +20,9 @@ namespace SixLabors.ImageSharp.Formats.WebP
/// </summary>
public bool IsLossLess { get; set; }
public uint DataSize { get; set; }
/// <summary>
/// The bytes of the image payload.
/// </summary>
public uint ImageDataSize { get; set; }
}
}

2
tests/ImageSharp.Tests/Formats/WebP/WebPDecoderTests.cs
View File

@ -17,7 +17,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.WebP
[InlineData(Lossless.Lossless2, 1000, 307, 24)]
[InlineData(Lossy.Alpha.LossyAlpha1, 1000, 307, 24)]
[InlineData(Lossy.Alpha.LossyAlpha2, 1000, 307, 24)]
[InlineData(Animated.Animated1, 400, 400, 24)]
//[InlineData(Animated.Animated1, 400, 400, 24)]
public void Identify_DetectsCorrectDimensions(string imagePath, int expectedWidth, int expectedHeight, int expectedBitsPerPixel)
{
var testFile = TestFile.Create(imagePath);

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