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Fix the png ecoder

af/merge-core
James Jackson-South 9 years ago
parent
88b0f2f0b4
commit
4f76f8a110
6 changed files with 42 additions and 48 deletions
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  1. 4
      src/ImageSharp/Formats/Png/Filters/AverageFilter.cs
  2. 7
      src/ImageSharp/Formats/Png/Filters/NoneFilter.cs
  3. 4
      src/ImageSharp/Formats/Png/Filters/PaethFilter.cs
  4. 4
      src/ImageSharp/Formats/Png/Filters/SubFilter.cs
  5. 4
      src/ImageSharp/Formats/Png/Filters/UpFilter.cs
  6. 67
      src/ImageSharp/Formats/Png/PngEncoderCore.cs

4
src/ImageSharp/Formats/Png/Filters/AverageFilter.cs
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@ -49,13 +49,13 @@ namespace ImageSharp.Formats
/// </summary>
/// <param name="scanline">The scanline to encode</param>
/// <param name="previousScanline">The previous scanline.</param>
/// <param name="result">The encoded scanline.</param>
/// <param name="bytesPerPixel">The bytes per pixel.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <returns>The <see cref="T:byte[]"/></returns>
public static byte[] Encode(byte[] scanline, byte[] previousScanline, byte[] result, int bytesPerPixel, int bytesPerScanline)
public static byte[] Encode(byte[] scanline, byte[] previousScanline, int bytesPerPixel, int bytesPerScanline)
{
// Average(x) = Raw(x) - floor((Raw(x-bpp)+Prior(x))/2)
byte[] result = new byte[bytesPerScanline + 1];
fixed (byte* scan = scanline)
fixed (byte* prev = previousScanline)
fixed (byte* res = result)

7
src/ImageSharp/Formats/Png/Filters/NoneFilter.cs
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@ -29,13 +29,14 @@ namespace ImageSharp.Formats
/// Encodes the scanline
/// </summary>
/// <param name="scanline">The scanline to encode</param>
/// <param name="result">The encoded scanline.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
public static void Encode(byte[] scanline, byte[] result, int bytesPerScanline)
/// <returns>The <see cref="T:byte[]"/></returns>
public static byte[] Encode(byte[] scanline, int bytesPerScanline)
{
// Insert a byte before the data.
result[0] = 0;
byte[] result = new byte[bytesPerScanline + 1];
Buffer.BlockCopy(scanline, 0, result, 1, bytesPerScanline);
return result;
}
}
}

4
src/ImageSharp/Formats/Png/Filters/PaethFilter.cs
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@ -49,13 +49,13 @@ namespace ImageSharp.Formats
/// </summary>
/// <param name="scanline">The scanline to encode</param>
/// <param name="previousScanline">The previous scanline.</param>
/// <param name="result">The encoded scanline.</param>
/// <param name="bytesPerPixel">The bytes per pixel.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <returns>The <see cref="T:byte[]"/></returns>
public static byte[] Encode(byte[] scanline, byte[] previousScanline, byte[] result, int bytesPerPixel, int bytesPerScanline)
public static byte[] Encode(byte[] scanline, byte[] previousScanline, int bytesPerPixel, int bytesPerScanline)
{
// Paeth(x) = Raw(x) - PaethPredictor(Raw(x-bpp), Prior(x), Prior(x - bpp))
byte[] result = new byte[bytesPerScanline + 1];
fixed (byte* scan = scanline)
fixed (byte* prev = previousScanline)
fixed (byte* res = result)

4
src/ImageSharp/Formats/Png/Filters/SubFilter.cs
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@ -41,13 +41,13 @@ namespace ImageSharp.Formats
/// Encodes the scanline
/// </summary>
/// <param name="scanline">The scanline to encode</param>
/// <param name="result">The encoded scanline.</param>
/// <param name="bytesPerPixel">The bytes per pixel.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <returns>The <see cref="T:byte[]"/></returns>
public static byte[] Encode(byte[] scanline, byte[] result, int bytesPerPixel, int bytesPerScanline)
public static byte[] Encode(byte[] scanline, int bytesPerPixel, int bytesPerScanline)
{
// Sub(x) = Raw(x) - Raw(x-bpp)
byte[] result = new byte[bytesPerScanline + 1];
fixed (byte* scan = scanline)
fixed (byte* res = result)
{

4
src/ImageSharp/Formats/Png/Filters/UpFilter.cs
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@ -43,12 +43,12 @@ namespace ImageSharp.Formats
/// </summary>
/// <param name="scanline">The scanline to encode</param>
/// <param name="previousScanline">The previous scanline.</param>
/// <param name="result">The encoded scanline.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <returns>The <see cref="T:byte[]"/></returns>
public static byte[] Encode(byte[] scanline, byte[] previousScanline, byte[] result, int bytesPerScanline)
public static byte[] Encode(byte[] scanline, byte[] previousScanline, int bytesPerScanline)
{
// Up(x) = Raw(x) - Prior(x)
byte[] result = new byte[bytesPerScanline + 1];
fixed (byte* scan = scanline)
fixed (byte* prev = previousScanline)
fixed (byte* res = result)

67
src/ImageSharp/Formats/Png/PngEncoderCore.cs
View File

@ -15,7 +15,6 @@ namespace ImageSharp.Formats
/// <summary>
/// Performs the png encoding operation.
/// TODO: Perf. There's lots of array parsing and copying going on here. This should be unmanaged.
/// </summary>
internal sealed class PngEncoderCore
{
@ -295,6 +294,7 @@ namespace ImageSharp.Formats
where TColor : struct, IPackedPixel<TPacked>
where TPacked : struct
{
// TODO: This should be possible one row at a time
int bpp = this.bytesPerPixel;
for (int x = 0; x < this.width; x++)
{
@ -312,9 +312,9 @@ namespace ImageSharp.Formats
/// <param name="row">The row.</param>
/// <param name="previousScanline">The previous scanline.</param>
/// <param name="rawScanline">The raw scanline.</param>
/// <param name="result">The resultant filtered scanline.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline.</param>
private void EncodePixelRow<TColor, TPacked>(PixelAccessor<TColor, TPacked> pixels, int row, byte[] previousScanline, byte[] rawScanline, byte[] result, int bytesPerScanline)
/// <returns>The <see cref="T:byte[]"/></returns>
private byte[] EncodePixelRow<TColor, TPacked>(PixelAccessor<TColor, TPacked> pixels, int row, byte[] previousScanline, byte[] rawScanline, int bytesPerScanline)
where TColor : struct, IPackedPixel<TPacked>
where TPacked : struct
{
@ -332,7 +332,7 @@ namespace ImageSharp.Formats
break;
}
this.GetOptimalFilteredScanline(rawScanline, previousScanline, result, bytesPerScanline);
return this.GetOptimalFilteredScanline(rawScanline, previousScanline, bytesPerScanline);
}
/// <summary>
@ -341,30 +341,30 @@ namespace ImageSharp.Formats
/// </summary>
/// <param name="rawScanline">The raw scanline</param>
/// <param name="previousScanline">The previous scanline</param>
/// <param name="result">The filtered scanline result</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
private void GetOptimalFilteredScanline(byte[] rawScanline, byte[] previousScanline, byte[] result, int bytesPerScanline)
/// <returns>The <see cref="T:byte[]"/></returns>
private byte[] GetOptimalFilteredScanline(byte[] rawScanline, byte[] previousScanline, int bytesPerScanline)
{
// Palette images don't compress well with adaptive filtering.
if (this.PngColorType == PngColorType.Palette)
{
NoneFilter.Encode(rawScanline, result, bytesPerScanline);
return;
return NoneFilter.Encode(rawScanline, bytesPerScanline);
}
// TODO: it would be nice to avoid the memory allocation here.
Tuple<byte[], int>[] candidates = new Tuple<byte[], int>[4];
byte[] sub = SubFilter.Encode(rawScanline, result, this.bytesPerPixel, bytesPerScanline);
candidates[0] = new Tuple<byte[], int>(sub, this.CalculateTotalVariation(sub));
byte[] sub = SubFilter.Encode(rawScanline, this.bytesPerPixel, bytesPerScanline);
candidates[0] = new Tuple<byte[], int>(sub, this.CalculateTotalVariation(sub, bytesPerScanline));
byte[] up = UpFilter.Encode(rawScanline, previousScanline, result, bytesPerScanline);
candidates[1] = new Tuple<byte[], int>(up, this.CalculateTotalVariation(up));
byte[] up = UpFilter.Encode(rawScanline, previousScanline, bytesPerScanline);
candidates[1] = new Tuple<byte[], int>(up, this.CalculateTotalVariation(up, bytesPerScanline));
byte[] average = AverageFilter.Encode(rawScanline, previousScanline, result, this.bytesPerPixel, bytesPerScanline);
candidates[2] = new Tuple<byte[], int>(average, this.CalculateTotalVariation(average));
byte[] average = AverageFilter.Encode(rawScanline, previousScanline, this.bytesPerPixel, bytesPerScanline);
candidates[2] = new Tuple<byte[], int>(average, this.CalculateTotalVariation(average, bytesPerScanline));
byte[] paeth = PaethFilter.Encode(rawScanline, previousScanline, result, this.bytesPerPixel, bytesPerScanline);
candidates[3] = new Tuple<byte[], int>(paeth, this.CalculateTotalVariation(paeth));
byte[] paeth = PaethFilter.Encode(rawScanline, previousScanline, this.bytesPerPixel, bytesPerScanline);
candidates[3] = new Tuple<byte[], int>(paeth, this.CalculateTotalVariation(paeth, bytesPerScanline));
int lowestTotalVariation = int.MaxValue;
int lowestTotalVariationIndex = 0;
@ -379,7 +379,7 @@ namespace ImageSharp.Formats
}
// ReSharper disable once RedundantAssignment
result = candidates[lowestTotalVariationIndex].Item1;
return candidates[lowestTotalVariationIndex].Item1;
}
/// <summary>
@ -387,12 +387,13 @@ namespace ImageSharp.Formats
/// neighbor differences.
/// </summary>
/// <param name="input">The scanline bytes</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <returns>The <see cref="int"/></returns>
private int CalculateTotalVariation(byte[] input)
private int CalculateTotalVariation(byte[] input, int bytesPerScanline)
{
int totalVariation = 0;
for (int i = 1; i < input.Length; i++)
for (int i = 1; i < bytesPerScanline; i++)
{
totalVariation += Math.Abs(input[i] - input[i - 1]);
}
@ -591,12 +592,6 @@ namespace ImageSharp.Formats
byte[] previousScanline = ArrayPool<byte>.Shared.Rent(bytesPerScanline);
byte[] rawScanline = ArrayPool<byte>.Shared.Rent(bytesPerScanline);
int resultLength = bytesPerScanline + 1;
byte[] result = ArrayPool<byte>.Shared.Rent(resultLength);
// TODO: Clearing this array makes the visual tests work again when encoding multiple images in a row.
// The png analyser tool I use still cannot decompress the image though my own decoder, chome and edge browsers, and paint can. Twitter also cannot read the file.
// It's 2am now so I'm going to check in what I have and cry. :'(
Array.Clear(result, 0, resultLength);
byte[] buffer;
int bufferLength;
@ -608,26 +603,23 @@ namespace ImageSharp.Formats
{
for (int y = 0; y < this.height; y++)
{
this.EncodePixelRow(pixels, y, previousScanline, rawScanline, result, bytesPerScanline);
deflateStream.Write(result, 0, resultLength);
deflateStream.Write(this.EncodePixelRow(pixels, y, previousScanline, rawScanline, bytesPerScanline), 0, resultLength);
// Do a bit of shuffling;
byte[] tmp = rawScanline;
rawScanline = previousScanline;
previousScanline = tmp;
}
deflateStream.Flush();
buffer = memoryStream.ToArray();
bufferLength = buffer.Length;
}
buffer = memoryStream.ToArray();
bufferLength = buffer.Length;
}
finally
{
memoryStream?.Dispose();
ArrayPool<byte>.Shared.Return(previousScanline);
ArrayPool<byte>.Shared.Return(rawScanline);
ArrayPool<byte>.Shared.Return(result);
}
// Store the chunks in repeated 64k blocks.
@ -682,10 +674,8 @@ namespace ImageSharp.Formats
/// <param name="length">The of the data to write.</param>
private void WriteChunk(Stream stream, string type, byte[] data, int offset, int length)
{
// Chunk length
WriteInteger(stream, length);
// Chunk type
this.chunkTypeBuffer[0] = (byte)type[0];
this.chunkTypeBuffer[1] = (byte)type[1];
this.chunkTypeBuffer[2] = (byte)type[2];
@ -693,13 +683,16 @@ namespace ImageSharp.Formats
stream.Write(this.chunkTypeBuffer, 0, 4);
if (data != null)
{
stream.Write(data, offset, length);
}
Crc32 crc32 = new Crc32();
crc32.Update(this.chunkTypeBuffer);
// Chunk data
if (data != null)
if (data != null && length > 0)
{
stream.Write(data, offset, length);
crc32.Update(data, offset, length);
}

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