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Huffman tables are now handled by scan decoder, not decoder core

pull/1702/head
Dmitry Pentin 5 years ago
parent
61b137d4a8
commit
6f45485203
2 changed files with 42 additions and 52 deletions
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  1. 54
      src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanDecoder.cs
  2. 40
      src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

54
src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanDecoder.cs
View File

@ -31,6 +31,16 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
// The End-Of-Block countdown for ending the sequence prematurely when the remaining coefficients are zero.
private int eobrun;
/// <summary>
/// The DC Huffman tables.
/// </summary>
private readonly HuffmanTable[] dcHuffmanTables;
/// <summary>
/// The AC Huffman tables
/// </summary>
private readonly HuffmanTable[] acHuffmanTables;
// The unzig data.
private ZigZag dctZigZag;
@ -55,12 +65,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
this.stream = stream;
this.spectralConverter = converter;
this.cancellationToken = cancellationToken;
}
// huffman tables
public HuffmanTable[] DcHuffmanTables { get; set; }
public HuffmanTable[] AcHuffmanTables { get; set; }
// TODO: this is actually a variable value depending on component count
const int maxTables = 4;
this.dcHuffmanTables = new HuffmanTable[maxTables];
this.acHuffmanTables = new HuffmanTable[maxTables];
}
// Reset interval
public int ResetInterval
@ -148,8 +158,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
int order = this.frame.ComponentOrder[i];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.AcHuffmanTables[component.ACHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
dcHuffmanTable.Configure();
acHuffmanTable.Configure();
}
@ -168,8 +178,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
int order = this.frame.ComponentOrder[k];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.AcHuffmanTables[component.ACHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
int h = component.HorizontalSamplingFactor;
int v = component.VerticalSamplingFactor;
@ -221,8 +231,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
int w = component.WidthInBlocks;
int h = component.HeightInBlocks;
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.AcHuffmanTables[component.ACHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
dcHuffmanTable.Configure();
acHuffmanTable.Configure();
@ -327,7 +337,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
{
int order = this.frame.ComponentOrder[k];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
dcHuffmanTable.Configure();
}
@ -342,7 +352,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
{
int order = this.frame.ComponentOrder[k];
JpegComponent component = this.components[order];
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
int h = component.HorizontalSamplingFactor;
int v = component.VerticalSamplingFactor;
@ -390,7 +400,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
if (this.SpectralStart == 0)
{
ref HuffmanTable dcHuffmanTable = ref this.DcHuffmanTables[component.DCHuffmanTableId];
ref HuffmanTable dcHuffmanTable = ref this.dcHuffmanTables[component.DCHuffmanTableId];
dcHuffmanTable.Configure();
for (int j = 0; j < h; j++)
@ -418,7 +428,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
}
else
{
ref HuffmanTable acHuffmanTable = ref this.AcHuffmanTables[component.ACHuffmanTableId];
ref HuffmanTable acHuffmanTable = ref this.acHuffmanTables[component.ACHuffmanTableId];
acHuffmanTable.Configure();
for (int j = 0; j < h; j++)
@ -722,5 +732,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
return false;
}
/// <summary>
/// Build the huffman table using code lengths and code values.
/// </summary>
/// <param name="type">Table type.</param>
/// <param name="index">Table index.</param>
/// <param name="codeLengths">Code lengths.</param>
/// <param name="values">Code values.</param>
[MethodImpl(InliningOptions.ShortMethod)]
public void BuildHuffmanTable(int type, int index, ReadOnlySpan<byte> codeLengths, ReadOnlySpan<byte> values)
{
HuffmanTable[] tables = type == 0 ? this.dcHuffmanTables : this.acHuffmanTables;
tables[index] = new HuffmanTable(codeLengths, values);
}
}
}

40
src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs
View File

@ -42,16 +42,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
/// </summary>
private readonly byte[] markerBuffer = new byte[2];
/// <summary>
/// The DC Huffman tables.
/// </summary>
private HuffmanTable[] dcHuffmanTables;
/// <summary>
/// The AC Huffman tables
/// </summary>
private HuffmanTable[] acHuffmanTables;
/// <summary>
/// The reset interval determined by RST markers.
/// </summary>
@ -270,14 +260,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
fileMarker = new JpegFileMarker(marker, (int)stream.Position - 2);
this.QuantizationTables = new Block8x8F[4];
// Only assign what we need
if (!metadataOnly)
{
const int maxTables = 4;
this.dcHuffmanTables = new HuffmanTable[maxTables];
this.acHuffmanTables = new HuffmanTable[maxTables];
}
// Break only when we discover a valid EOI marker.
// https://github.com/SixLabors/ImageSharp/issues/695
while (fileMarker.Marker != JpegConstants.Markers.EOI
@ -392,8 +374,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
// Set large fields to null.
this.Frame = null;
this.dcHuffmanTables = null;
this.acHuffmanTables = null;
this.scanDecoder = null;
}
/// <summary>
@ -996,8 +977,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
i += 17 + codeLengthSum;
this.BuildHuffmanTable(
tableType == 0 ? this.dcHuffmanTables : this.acHuffmanTables,
this.scanDecoder.BuildHuffmanTable(
tableType,
tableIndex,
codeLengthsSpan,
huffmanValuesSpan);
@ -1071,10 +1052,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
// All the comments below are for separate refactoring PR
// Main reason it's not fixed here is to make this commit less intrusive
// Huffman tables can be calculated directly in the scan decoder class
this.scanDecoder.DcHuffmanTables = this.dcHuffmanTables;
this.scanDecoder.AcHuffmanTables = this.acHuffmanTables;
// This can be injectd in DRI marker callback
this.scanDecoder.ResetInterval = this.resetInterval;
@ -1090,17 +1067,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
this.scanDecoder.ParseEntropyCodedData();
}
/// <summary>
/// Builds the huffman tables
/// </summary>
/// <param name="tables">The tables</param>
/// <param name="index">The table index</param>
/// <param name="codeLengths">The codelengths</param>
/// <param name="values">The values</param>
[MethodImpl(InliningOptions.ShortMethod)]
private void BuildHuffmanTable(HuffmanTable[] tables, int index, ReadOnlySpan<byte> codeLengths, ReadOnlySpan<byte> values)
=> tables[index] = new HuffmanTable(codeLengths, values);
/// <summary>
/// Reads a <see cref="ushort"/> from the stream advancing it by two bytes
/// </summary>

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