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Refactor scanline processing so it is readable.

af/merge-core
James Jackson-South 8 years ago
parent
edcb2ec52f
commit
5ccf557c9f
2 changed files with 678 additions and 439 deletions
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  1. 517
      src/ImageSharp/Formats/Png/PngDecoderCore.cs
  2. 600
      src/ImageSharp/Formats/Png/PngScanlineProcessor.cs

517
src/ImageSharp/Formats/Png/PngDecoderCore.cs
View File

@ -722,7 +722,6 @@ namespace SixLabors.ImageSharp.Formats.Png
private void ProcessDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, ImageFrame<TPixel> pixels) private void ProcessDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, ImageFrame<TPixel> pixels)
where TPixel : struct, IPixel<TPixel> where TPixel : struct, IPixel<TPixel>
{ {
TPixel pixel = default;
Span<TPixel> rowSpan = pixels.GetPixelRowSpan(this.currentRow); Span<TPixel> rowSpan = pixels.GetPixelRowSpan(this.currentRow);
// Trim the first marker byte from the buffer // Trim the first marker byte from the buffer
@ -733,241 +732,64 @@ namespace SixLabors.ImageSharp.Formats.Png
? buffer.GetSpan() ? buffer.GetSpan()
: trimmed; : trimmed;
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
switch (this.pngColorType) switch (this.pngColorType)
{ {
case PngColorType.Grayscale: case PngColorType.Grayscale:
int factor = 255 / (ImageMaths.GetColorCountForBitDepth(this.header.BitDepth) - 1); PngScanlineProcessor.ProcessGrayscaleScanline(
this.header,
if (!this.hasTrans) scanlineSpan,
{ rowSpan,
if (this.header.BitDepth == 16) this.hasTrans,
{ this.luminance16Trans,
Rgb48 rgb48 = default; this.luminanceTrans);
for (int x = 0, o = 0; x < this.header.Width; x++, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.R = luminance;
rgb48.G = luminance;
rgb48.B = luminance;
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = 0; x < this.header.Width; x++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * factor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
else
{
if (this.header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < this.header.Width; x++, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = luminance.Equals(this.luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = 0; x < this.header.Width; x++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * factor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = luminance.Equals(this.luminanceTrans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
break; break;
case PngColorType.GrayscaleWithAlpha: case PngColorType.GrayscaleWithAlpha:
if (this.header.BitDepth == 16) PngScanlineProcessor.ProcessGrayscaleWithAlphaScanline(
{ this.header,
Rgba64 rgba64 = default; scanlineSpan,
for (int x = 0, o = 0; x < this.header.Width; x++, o += 4) rowSpan,
{ this.bytesPerPixel,
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); this.bytesPerSample);
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = alpha;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
int bps = this.bytesPerSample;
for (int x = 0; x < this.header.Width; x++)
{
int offset = x * this.bytesPerPixel;
byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + bps);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = alpha;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
break; break;
case PngColorType.Palette: case PngColorType.Palette:
ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(this.palette); PngScanlineProcessor.ProcessPaletteScanline(
ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels); this.header,
scanlineSpan,
if (this.paletteAlpha?.Length > 0) rowSpan,
{ this.palette,
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha this.paletteAlpha);
// channel and we should try to read it.
Rgba32 rgba = default;
ref byte paletteAlphaRef = ref this.paletteAlpha[0];
for (int x = 0; x < this.header.Width; x++)
{
int index = Unsafe.Add(ref scanlineSpanRef, x);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
rgba.A = this.paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should have PackFromRgb24.
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = 0; x < this.header.Width; x++)
{
int index = Unsafe.Add(ref scanlineSpanRef, x);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
break; break;
case PngColorType.Rgb: case PngColorType.Rgb:
if (!this.hasTrans) PngScanlineProcessor.ProcessRgbScanline(
{ this.header,
if (this.header.BitDepth == 16) scanlineSpan,
{ rowSpan,
Rgb48 rgb48 = default; this.bytesPerPixel,
for (int x = 0, o = 0; x < this.header.Width; x++, o += 6) this.bytesPerSample,
{ this.hasTrans,
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); this.rgb48Trans,
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2)); this.rgb24Trans);
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
PixelOperations<TPixel>.Instance.PackFromRgb24Bytes(scanlineSpan, rowSpan, this.header.Width);
}
}
else
{
if (this.header.BitDepth == 16)
{
Rgb48 rgb48 = default;
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < this.header.Width; x++, o += 6)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
rgba64.Rgb = rgb48;
rgba64.A = rgb48.Equals(this.rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
ReadOnlySpan<Rgb24> rgb24Span = MemoryMarshal.Cast<byte, Rgb24>(scanlineSpan);
ref Rgb24 rgb24SpanRef = ref MemoryMarshal.GetReference(rgb24Span);
for (int x = 0; x < this.header.Width; x++)
{
ref readonly Rgb24 rgb24 = ref Unsafe.Add(ref rgb24SpanRef, x);
Rgba32 rgba32 = default;
rgba32.Rgb = rgb24;
rgba32.A = rgb24.Equals(this.rgb24Trans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
break; break;
case PngColorType.RgbWithAlpha: case PngColorType.RgbWithAlpha:
if (this.header.BitDepth == 16) PngScanlineProcessor.ProcessRgbaScanline(
{ this.header,
Rgba64 rgba64 = default; scanlineSpan,
for (int x = 0, o = 0; x < this.header.Width; x++, o += 8) rowSpan,
{ this.bytesPerPixel,
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); this.bytesPerSample);
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 6, 2));
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(scanlineSpan, rowSpan, this.header.Width);
}
break; break;
} }
@ -986,8 +808,6 @@ namespace SixLabors.ImageSharp.Formats.Png
private void ProcessInterlacedDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, Span<TPixel> rowSpan, int pixelOffset = 0, int increment = 1) private void ProcessInterlacedDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, Span<TPixel> rowSpan, int pixelOffset = 0, int increment = 1)
where TPixel : struct, IPixel<TPixel> where TPixel : struct, IPixel<TPixel>
{ {
TPixel pixel = default;
// Trim the first marker byte from the buffer // Trim the first marker byte from the buffer
ReadOnlySpan<byte> trimmed = defilteredScanline.Slice(1, defilteredScanline.Length - 1); ReadOnlySpan<byte> trimmed = defilteredScanline.Slice(1, defilteredScanline.Length - 1);
@ -996,255 +816,74 @@ namespace SixLabors.ImageSharp.Formats.Png
? buffer.GetSpan() ? buffer.GetSpan()
: trimmed; : trimmed;
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
switch (this.pngColorType) switch (this.pngColorType)
{ {
case PngColorType.Grayscale: case PngColorType.Grayscale:
int factor = 255 / (ImageMaths.GetColorCountForBitDepth(this.header.BitDepth) - 1); PngScanlineProcessor.ProcessInterlacedGrayscaleScanline(
this.header,
if (!this.hasTrans) scanlineSpan,
{ rowSpan,
if (this.header.BitDepth == 16) pixelOffset,
{ increment,
Rgb48 rgb48 = default; this.hasTrans,
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 2) this.luminance16Trans,
{ this.luminanceTrans);
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.R = luminance;
rgb48.G = luminance;
rgb48.B = luminance;
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, o) * factor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
else
{
if (this.header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = luminance.Equals(this.luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = pixelOffset; x < this.header.Width; x += increment)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * factor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = luminance.Equals(this.luminanceTrans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
break; break;
case PngColorType.GrayscaleWithAlpha: case PngColorType.GrayscaleWithAlpha:
if (this.header.BitDepth == 16) PngScanlineProcessor.ProcessInterlacedGrayscaleWithAlphaScanline(
{ this.header,
Rgba64 rgba64 = default; scanlineSpan,
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 4) rowSpan,
{ pixelOffset,
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); increment,
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2)); this.bytesPerPixel,
rgba64.R = luminance; this.bytesPerSample);
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = alpha;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = pixelOffset; x < this.header.Width; x += increment)
{
int offset = x * this.bytesPerPixel;
byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + this.bytesPerSample);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = alpha;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
break; break;
case PngColorType.Palette: case PngColorType.Palette:
Span<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(this.palette); PngScanlineProcessor.ProcessInterlacedPaletteScanline(
ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels); this.header,
scanlineSpan,
if (this.paletteAlpha?.Length > 0) rowSpan,
{ pixelOffset,
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha increment,
// channel and we should try to read it. this.palette,
Rgba32 rgba = default; this.paletteAlpha);
ref byte paletteAlphaRef = ref this.paletteAlpha[0];
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
int index = Unsafe.Add(ref scanlineSpanRef, o);
rgba.A = this.paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
int index = Unsafe.Add(ref scanlineSpanRef, o);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
break; break;
case PngColorType.Rgb: case PngColorType.Rgb:
if (this.header.BitDepth == 16) PngScanlineProcessor.ProcessInterlacedRgbScanline(
{ this.header,
if (this.hasTrans) scanlineSpan,
{ rowSpan,
Rgb48 rgb48 = default; pixelOffset,
Rgba64 rgba64 = default; increment,
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 6) this.bytesPerPixel,
{ this.bytesPerSample,
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); this.hasTrans,
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2)); this.rgb48Trans,
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2)); this.rgb24Trans);
rgba64.Rgb = rgb48;
rgba64.A = rgb48.Equals(this.rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgb48 rgb48 = default;
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 6)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
else
{
if (this.hasTrans)
{
Rgba32 rgba = default;
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + this.bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * this.bytesPerSample));
rgba.A = this.rgb24Trans.Equals(rgba.Rgb) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + this.bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * this.bytesPerSample));
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
break; break;
case PngColorType.RgbWithAlpha: case PngColorType.RgbWithAlpha:
if (this.header.BitDepth == 16) PngScanlineProcessor.ProcessInterlacedRgbaScanline(
{ this.header,
Rgba64 rgba64 = default; scanlineSpan,
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 8) rowSpan,
{ pixelOffset,
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2)); increment,
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2)); this.bytesPerPixel,
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2)); this.bytesPerSample);
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 6, 2));
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba = default;
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + this.bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * this.bytesPerSample));
rgba.A = Unsafe.Add(ref scanlineSpanRef, o + (3 * this.bytesPerSample));
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
break; break;
} }

600
src/ImageSharp/Formats/Png/PngScanlineProcessor.cs
View File

@ -0,0 +1,600 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
using System;
using System.Buffers.Binary;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using SixLabors.ImageSharp.PixelFormats;
namespace SixLabors.ImageSharp.Formats.Png
{
/// <summary>
/// Provides methods to allow the decoding of raw scanlines to image rows of different pixel formats.
/// </summary>
internal static class PngScanlineProcessor
{
public static void ProcessGrayscaleScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
bool hasTrans,
ushort luminance16Trans,
byte luminanceTrans)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
int scaleFactor = 255 / (ImageMaths.GetColorCountForBitDepth(header.BitDepth) - 1);
if (!hasTrans)
{
if (header.BitDepth == 16)
{
Rgb48 rgb48 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.R = luminance;
rgb48.G = luminance;
rgb48.B = luminance;
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = 0; x < header.Width; x++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
return;
}
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = luminance.Equals(luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = 0; x < header.Width; x++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = luminance.Equals(luminanceTrans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessInterlacedGrayscaleScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int pixelOffset,
int increment,
bool hasTrans,
ushort luminance16Trans,
byte luminanceTrans)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
int scaleFactor = 255 / (ImageMaths.GetColorCountForBitDepth(header.BitDepth) - 1);
if (!hasTrans)
{
if (header.BitDepth == 16)
{
Rgb48 rgb48 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgb48.R = luminance;
rgb48.G = luminance;
rgb48.B = luminance;
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, o) * scaleFactor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
return;
}
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 2)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = luminance.Equals(luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = pixelOffset; x < header.Width; x += increment)
{
byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = luminance.Equals(luminanceTrans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessGrayscaleWithAlphaScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int bytesPerPixel,
int bytesPerSample)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += 4)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = alpha;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
int bps = bytesPerSample;
for (int x = 0; x < header.Width; x++)
{
int offset = x * bytesPerPixel;
byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + bps);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = alpha;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessInterlacedGrayscaleWithAlphaScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int pixelOffset,
int increment,
int bytesPerPixel,
int bytesPerSample)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 4)
{
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
rgba64.R = luminance;
rgba64.G = luminance;
rgba64.B = luminance;
rgba64.A = alpha;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba32 = default;
for (int x = pixelOffset; x < header.Width; x += increment)
{
int offset = x * bytesPerPixel;
byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + bytesPerSample);
rgba32.R = luminance;
rgba32.G = luminance;
rgba32.B = luminance;
rgba32.A = alpha;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessPaletteScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
ReadOnlySpan<byte> palette,
byte[] paletteAlpha)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(palette);
ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels);
if (paletteAlpha?.Length > 0)
{
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
// channel and we should try to read it.
Rgba32 rgba = default;
ref byte paletteAlphaRef = ref paletteAlpha[0];
for (int x = 0; x < header.Width; x++)
{
int index = Unsafe.Add(ref scanlineSpanRef, x);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
rgba.A = paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
// TODO: We should have PackFromRgb24.
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = 0; x < header.Width; x++)
{
int index = Unsafe.Add(ref scanlineSpanRef, x);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessInterlacedPaletteScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int pixelOffset,
int increment,
ReadOnlySpan<byte> palette,
byte[] paletteAlpha)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(palette);
ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels);
if (paletteAlpha?.Length > 0)
{
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
// channel and we should try to read it.
Rgba32 rgba = default;
ref byte paletteAlphaRef = ref paletteAlpha[0];
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
{
int index = Unsafe.Add(ref scanlineSpanRef, o);
rgba.A = paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
{
int index = Unsafe.Add(ref scanlineSpanRef, o);
rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessRgbScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int bytesPerPixel,
int bytesPerSample,
bool hasTrans,
Rgb48 rgb48Trans,
Rgb24 rgb24Trans)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (!hasTrans)
{
if (header.BitDepth == 16)
{
Rgb48 rgb48 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
PixelOperations<TPixel>.Instance.PackFromRgb24Bytes(scanlineSpan, rowSpan, header.Width);
}
return;
}
if (header.BitDepth == 16)
{
Rgb48 rgb48 = default;
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
rgba64.Rgb = rgb48;
rgba64.A = rgb48.Equals(rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
ReadOnlySpan<Rgb24> rgb24Span = MemoryMarshal.Cast<byte, Rgb24>(scanlineSpan);
ref Rgb24 rgb24SpanRef = ref MemoryMarshal.GetReference(rgb24Span);
for (int x = 0; x < header.Width; x++)
{
ref readonly Rgb24 rgb24 = ref Unsafe.Add(ref rgb24SpanRef, x);
Rgba32 rgba32 = default;
rgba32.Rgb = rgb24;
rgba32.A = rgb24.Equals(rgb24Trans) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba32);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessInterlacedRgbScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int pixelOffset,
int increment,
int bytesPerPixel,
int bytesPerSample,
bool hasTrans,
Rgb48 rgb48Trans,
Rgb24 rgb24Trans)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (header.BitDepth == 16)
{
if (hasTrans)
{
Rgb48 rgb48 = default;
Rgba64 rgba64 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
rgba64.Rgb = rgb48;
rgba64.A = rgb48.Equals(rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgb48 rgb48 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
pixel.PackFromRgb48(rgb48);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
return;
}
if (hasTrans)
{
Rgba32 rgba = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
rgba.A = rgb24Trans.Equals(rgba.Rgb) ? byte.MinValue : byte.MaxValue;
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
public static void ProcessRgbaScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int bytesPerPixel,
int bytesPerSample)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
{
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (3 * bytesPerSample), bytesPerSample));
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(scanlineSpan, rowSpan, header.Width);
}
}
public static void ProcessInterlacedRgbaScanline<TPixel>(
in PngHeader header,
ReadOnlySpan<byte> scanlineSpan,
Span<TPixel> rowSpan,
int pixelOffset,
int increment,
int bytesPerPixel,
int bytesPerSample)
where TPixel : struct, IPixel<TPixel>
{
TPixel pixel = default;
ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
if (header.BitDepth == 16)
{
Rgba64 rgba64 = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (3 * bytesPerSample), bytesPerSample));
pixel.PackFromRgba64(rgba64);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
else
{
Rgba32 rgba = default;
for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
{
rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
rgba.A = Unsafe.Add(ref scanlineSpanRef, o + (3 * bytesPerSample));
pixel.PackFromRgba32(rgba);
Unsafe.Add(ref rowSpanRef, x) = pixel;
}
}
}
}
}
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