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WebP: split Filter classes to different files

pull/1552/head
Peter Amrehn 6 years ago
parent
fcd5a37404
commit
72f3499146
7 changed files with 388 additions and 371 deletions
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  1. 94
      src/ImageSharp/Formats/WebP/Filters/WebPFilterBase.cs
  2. 103
      src/ImageSharp/Formats/WebP/Filters/WebPFilterGradient.cs
  3. 92
      src/ImageSharp/Formats/WebP/Filters/WebPFilterHorizontal.cs
  4. 14
      src/ImageSharp/Formats/WebP/Filters/WebPFilterNone.cs
  5. 84
      src/ImageSharp/Formats/WebP/Filters/WebPFilterVertical.cs
  6. 371
      src/ImageSharp/Formats/WebP/WebPFilterType.cs
  7. 1
      src/ImageSharp/Formats/WebP/WebPLossyDecoder.cs

94
src/ImageSharp/Formats/WebP/Filters/WebPFilterBase.cs
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@ -0,0 +1,94 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
using System;
using System.Diagnostics;
namespace SixLabors.ImageSharp.Formats.WebP.Filters
{
// TODO from dsp.h
// public enum WebPFilterType
// {
// None = 0,
// Horizontal,
// Vertical,
// Gradient,
// Last = Gradient + 1, // end marker
// Best, // meta types
// Fast
// }
abstract class WebPFilterBase
{
/// <summary>
/// </summary>
/// <param name="prevLine"></param>
/// <param name="prevLineOffset">nullable as prevLine is nullable in the original but Span'T can't be null.</param>
/// <param name="preds"></param>
/// <param name="predsOffset"></param>
/// <param name="currentLine"></param>
/// <param name="currentLineOffset"></param>
/// <param name="width"></param>
public abstract void Unfilter(
Span<byte> prevLine,
int? prevLineOffset,
Span<byte> preds,
int predsOffset,
Span<byte> currentLine,
int currentLineOffset,
int width);
public abstract void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset);
protected static void SanityCheck(
Span<byte> input, Span<byte> output, int width, int numRows, int height, int stride, int row)
{
Debug.Assert(input != null);
Debug.Assert(output != null);
Debug.Assert(width > 0);
Debug.Assert(height > 0);
Debug.Assert(stride > width);
Debug.Assert(row >= 0);
Debug.Assert(height > 0);
Debug.Assert(row + numRows <= height);
}
protected static void PredictLine(
Span<byte> src, int srcOffset,
Span<byte> pred, int predOffset,
Span<byte> dst, int dstOffset,
int length, bool inverse)
{
if (inverse)
{
for (int i = 0; i < length; i++)
{
dst[i] = (byte)(src[i] + pred[i]);
}
}
else
{
for (int i = 0; i < length; i++)
{
dst[i] = (byte)(src[i] - pred[i]);
}
}
}
protected void UnfilterHorizontalOrVerticalCore(
byte pred,
Span<byte> input, int inputOffset,
Span<byte> output, int outputOffset,
int width)
{
for (int i = 0; i < width; i++)
{
output[outputOffset + i] = (byte)(pred + input[inputOffset + i]);
pred = output[i];
}
}
}
}

103
src/ImageSharp/Formats/WebP/Filters/WebPFilterGradient.cs
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@ -0,0 +1,103 @@
using System;
namespace SixLabors.ImageSharp.Formats.WebP.Filters
{
class WebPFilterGradient : WebPFilterBase
{
public override void Unfilter(
Span<byte> prevLine,
int? prevLineOffsetNullable,
Span<byte> input,
int inputOffset,
Span<byte> output,
int outputOffset,
int width)
{
if (prevLineOffsetNullable is int prevLineOffset)
{
byte top = prevLine[prevLineOffset];
byte topLeft = top;
byte left = top;
for (int i = 0; i < width; i++)
{
top = prevLine[prevLineOffset + i]; // need to read this first in case prev==out
left = (byte)(input[inputOffset + i] + GradientPredictor(left, top, topLeft));
topLeft = top;
output[outputOffset + i] = left;
}
}
else
{
this.UnfilterHorizontalOrVerticalCore(0, input, inputOffset, output, outputOffset, width);
}
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
// calling (input, width, height, stride, 0, height, 0, output
int row = 0;
int numRows = height;
bool inverse = false;
int startOffset = row * stride;
int lastRow = row + numRows;
SanityCheck(input, output, width, numRows, height, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
output[outputOffset] = input[inputOffset];
PredictLine(
input, inputOffset+1,
preds, predsOffset,
output, outputOffset+1,
width-1,
inverse);
}
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset-stride,
output, outputOffset,
1, inverse);
for (int w = 1; w < width; w++)
{
int pred = GradientPredictor(preds[w - 1], preds[w - stride], preds[w - stride - 1]);
int signedPred = inverse ? pred : -pred;
output[outputOffset + w] = (byte)(input[inputOffset + w] + signedPred);
}
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
private static int GradientPredictor(byte a, byte b, byte c)
{
int g = a + b + c;
return (g & ~0xff) == 0 ? g : (g < 0) ? 0 : 255;
}
}
}

92
src/ImageSharp/Formats/WebP/Filters/WebPFilterHorizontal.cs
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@ -0,0 +1,92 @@
using System;
namespace SixLabors.ImageSharp.Formats.WebP.Filters
{
class WebPFilterHorizontal : WebPFilterBase
{
public override void Unfilter(
Span<byte> prevLine, int? prevLineOffsetNullable,
Span<byte> input, int inputOffset,
Span<byte> output, int outputOffset,
int width)
{
byte pred = prevLineOffsetNullable is int prevLineOffset
? prevLine[prevLineOffset]
: (byte)0;
this.UnfilterHorizontalOrVerticalCore(
pred,
input, inputOffset,
output, outputOffset,
width);
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
int numRows = height;
int row = 0;
const bool inverse = false;
int startOffset = row * stride;
int lastRow = row + height;
SanityCheck(input, output, width, height, numRows, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
// leftmost pixel is the same as Input for topmost scanline
output[0] = input[0];
PredictLine(
input, inputOffset + 1,
preds, predsOffset,
output, outputOffset + 1,
width - 1, inverse);
row = 1;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
// filter line by line
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset - stride,
output, 0,
1, inverse);
PredictLine(
input, inputOffset,
preds, predsOffset,
output,outputOffset + 1,
width - 1, inverse);
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
}
}

14
src/ImageSharp/Formats/WebP/Filters/WebPFilterNone.cs
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@ -0,0 +1,14 @@
using System;
namespace SixLabors.ImageSharp.Formats.WebP.Filters
{
// TODO: check if this is a filter or just a placeholder from the C implementation details
class WebPFilterNone : WebPFilterBase
{
public override void Unfilter(Span<byte> prevLine, int? prevLineOffset, Span<byte> input, int inputOffset, Span<byte> output, int outputOffset, int width)
{ }
public override void Filter(Span<byte> input, int inputOffset, int width, int height, int stride, Span<byte> output, int outputOffset)
{ }
}
}

84
src/ImageSharp/Formats/WebP/Filters/WebPFilterVertical.cs
View File

@ -0,0 +1,84 @@
using System;
namespace SixLabors.ImageSharp.Formats.WebP.Filters
{
class WebPFilterVertical : WebPFilterBase
{
public override void Unfilter(Span<byte> prevLine, int? prevLineOffsetNullable, Span<byte> input, int inputOffset, Span<byte> output, int outputOffset, int width)
{
if (prevLineOffsetNullable is int prevLineOffset)
{
for (int i = 0; i < width; i++)
{
output[outputOffset + i] = (byte)(prevLine[prevLineOffset + i] + input[inputOffset + i]);
}
}
else
{
this.UnfilterHorizontalOrVerticalCore(0, input, inputOffset, output, outputOffset, width);
}
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
int row = 0;
bool inverse = false;
// TODO: DoVerticalFilter_C with parameters after stride and after height set to 0
int startOffset = row * stride;
int lastRow = row + height;
SanityCheck(input, output, width, height, height, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
// very first top-left pixel is copied.
output[0] = input[0];
// rest of top scan-line is left-predicted:
PredictLine(
input, inputOffset + 1,
preds, predsOffset,
output, outputOffset + 1,
width - 1, inverse);
row = 1;
inputOffset += stride;
outputOffset += stride;
}
else
{
predsOffset -= stride;
}
// filter line-by-line
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset,
output, outputOffset,
width, inverse);
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
}
}

371
src/ImageSharp/Formats/WebP/WebPFilterType.cs
View File

@ -1,371 +0,0 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
using System;
using System.Diagnostics;
namespace SixLabors.ImageSharp.Formats.WebP
{
// TODO from dsp.h
// public enum WebPFilterType
// {
// None = 0,
// Horizontal,
// Vertical,
// Gradient,
// Last = Gradient + 1, // end marker
// Best, // meta types
// Fast
// }
abstract class WebPFilterBase
{
/// <summary>
/// </summary>
/// <param name="prevLine"></param>
/// <param name="prevLineOffset">nullable as prevLine is nullable in the original but Span'T can't be null.</param>
/// <param name="preds"></param>
/// <param name="predsOffset"></param>
/// <param name="currentLine"></param>
/// <param name="currentLineOffset"></param>
/// <param name="width"></param>
public abstract void Unfilter(
Span<byte> prevLine,
int? prevLineOffset,
Span<byte> preds,
int predsOffset,
Span<byte> currentLine,
int currentLineOffset,
int width);
public abstract void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset);
protected static void SanityCheck(
Span<byte> input, Span<byte> output, int width, int numRows, int height, int stride, int row)
{
Debug.Assert(input != null);
Debug.Assert(output != null);
Debug.Assert(width > 0);
Debug.Assert(height > 0);
Debug.Assert(stride > width);
Debug.Assert(row >= 0);
Debug.Assert(height > 0);
Debug.Assert(row + numRows <= height);
}
protected static void PredictLine(
Span<byte> src, int srcOffset,
Span<byte> pred, int predOffset,
Span<byte> dst, int dstOffset,
int length, bool inverse)
{
if (inverse)
{
for (int i = 0; i < length; i++)
{
dst[i] = (byte)(src[i] + pred[i]);
}
}
else
{
for (int i = 0; i < length; i++)
{
dst[i] = (byte)(src[i] - pred[i]);
}
}
}
protected void UnfilterHorizontalOrVerticalCore(
byte pred,
Span<byte> input, int inputOffset,
Span<byte> output, int outputOffset,
int width)
{
for (int i = 0; i < width; i++)
{
output[outputOffset + i] = (byte)(pred + input[inputOffset + i]);
pred = output[i];
}
}
}
// TODO: check if this is a filter or just a placeholder from the C implementation details
class WebPFilterNone : WebPFilterBase
{
public override void Unfilter(Span<byte> prevLine, int? prevLineOffset, Span<byte> input, int inputOffset, Span<byte> output, int outputOffset, int width)
{ }
public override void Filter(Span<byte> input, int inputOffset, int width, int height, int stride, Span<byte> output, int outputOffset)
{ }
}
class WebPFilterHorizontal : WebPFilterBase
{
public override void Unfilter(
Span<byte> prevLine, int? prevLineOffsetNullable,
Span<byte> input, int inputOffset,
Span<byte> output, int outputOffset,
int width)
{
byte pred = prevLineOffsetNullable is int prevLineOffset
? prevLine[prevLineOffset]
: (byte)0;
this.UnfilterHorizontalOrVerticalCore(
pred,
input, inputOffset,
output, outputOffset,
width);
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
int numRows = height;
int row = 0;
const bool inverse = false;
int startOffset = row * stride;
int lastRow = row + height;
SanityCheck(input, output, width, height, numRows, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
// leftmost pixel is the same as Input for topmost scanline
output[0] = input[0];
PredictLine(
input, inputOffset + 1,
preds, predsOffset,
output, outputOffset + 1,
width - 1, inverse);
row = 1;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
// filter line by line
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset - stride,
output, 0,
1, inverse);
PredictLine(
input, inputOffset,
preds, predsOffset,
output,outputOffset + 1,
width - 1, inverse);
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
}
class WebPFilterVertical : WebPFilterBase
{
public override void Unfilter(Span<byte> prevLine, int? prevLineOffsetNullable, Span<byte> input, int inputOffset, Span<byte> output, int outputOffset, int width)
{
if (prevLineOffsetNullable is int prevLineOffset)
{
for (int i = 0; i < width; i++)
{
output[outputOffset + i] = (byte)(prevLine[prevLineOffset + i] + input[inputOffset + i]);
}
}
else
{
this.UnfilterHorizontalOrVerticalCore(0, input, inputOffset, output, outputOffset, width);
}
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
int row = 0;
bool inverse = false;
// TODO: DoVerticalFilter_C with parameters after stride and after height set to 0
int startOffset = row * stride;
int lastRow = row + height;
SanityCheck(input, output, width, height, height, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
// very first top-left pixel is copied.
output[0] = input[0];
// rest of top scan-line is left-predicted:
PredictLine(
input, inputOffset + 1,
preds, predsOffset,
output, outputOffset + 1,
width - 1, inverse);
row = 1;
inputOffset += stride;
outputOffset += stride;
}
else
{
predsOffset -= stride;
}
// filter line-by-line
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset,
output, outputOffset,
width, inverse);
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
}
class WebPFilterGradient : WebPFilterBase
{
public override void Unfilter(
Span<byte> prevLine,
int? prevLineOffsetNullable,
Span<byte> input,
int inputOffset,
Span<byte> output,
int outputOffset,
int width)
{
if (prevLineOffsetNullable is int prevLineOffset)
{
byte top = prevLine[prevLineOffset];
byte topLeft = top;
byte left = top;
for (int i = 0; i < width; i++)
{
top = prevLine[prevLineOffset + i]; // need to read this first in case prev==out
left = (byte)(input[inputOffset + i] + GradientPredictor(left, top, topLeft));
topLeft = top;
output[outputOffset + i] = left;
}
}
else
{
this.UnfilterHorizontalOrVerticalCore(0, input, inputOffset, output, outputOffset, width);
}
}
public override void Filter(
Span<byte> input, int inputOffset,
int width, int height, int stride,
Span<byte> output, int outputOffset)
{
// calling (input, width, height, stride, 0, height, 0, output
int row = 0;
int numRows = height;
bool inverse = false;
int startOffset = row * stride;
int lastRow = row + numRows;
SanityCheck(input, output, width, numRows, height, stride, row);
inputOffset += startOffset;
outputOffset += startOffset;
Span<byte> preds;
int predsOffset;
if (inverse)
{
preds = output;
predsOffset = outputOffset;
}
else
{
preds = input;
predsOffset = inputOffset;
}
if (row == 0)
{
output[outputOffset] = input[inputOffset];
PredictLine(
input, inputOffset+1,
preds, predsOffset,
output, outputOffset+1,
width-1,
inverse);
}
while (row < lastRow)
{
PredictLine(
input, inputOffset,
preds, predsOffset-stride,
output, outputOffset,
1, inverse);
for (int w = 1; w < width; w++)
{
int pred = GradientPredictor(preds[w - 1], preds[w - stride], preds[w - stride - 1]);
int signedPred = inverse ? pred : -pred;
output[outputOffset + w] = (byte)(input[inputOffset + w] + signedPred);
}
row++;
predsOffset += stride;
inputOffset += stride;
outputOffset += stride;
}
}
private static int GradientPredictor(byte a, byte b, byte c)
{
int g = a + b + c;
return (g & ~0xff) == 0 ? g : (g < 0) ? 0 : 255;
}
}
}

1
src/ImageSharp/Formats/WebP/WebPLossyDecoder.cs
View File

@ -5,6 +5,7 @@ using System;
using System.Collections.Generic;
using System.IO;
using SixLabors.ImageSharp.Formats.Png.Filters;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.Memory;

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