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Reduce allocatoins, check bit depth and rename.

pull/764/head
James Jackson-South 8 years ago
parent
dafbe94fe9
commit
f79f1894a3
5 changed files with 56 additions and 65 deletions
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  1. 4
      src/ImageSharp/Formats/Png/PngChunkType.cs
  2. 6
      src/ImageSharp/Formats/Png/PngDecoderCore.cs
  3. 107
      src/ImageSharp/Formats/Png/PngEncoderCore.cs
  4. 2
      tests/ImageSharp.Tests/Formats/Png/PngChunkTypeTests.cs
  5. 2
      tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.Chunks.cs

4
src/ImageSharp/Formats/Png/PngChunkType.cs
View File

@ -56,10 +56,10 @@ namespace SixLabors.ImageSharp.Formats.Png
Text = 0x74455874U,
/// <summary>
/// This chunk specifies that the image uses simple transparency:
/// The tRNS chunk specifies that the image uses simple transparency:
/// either alpha values associated with palette entries (for indexed-color images)
/// or a single transparent color (for grayscale and true color images).
/// </summary>
PaletteAlpha = 0x74524E53U
Transparency = 0x74524E53U
}
}

6
src/ImageSharp/Formats/Png/PngDecoderCore.cs
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@ -197,7 +197,7 @@ namespace SixLabors.ImageSharp.Formats.Png
Buffer.BlockCopy(chunk.Data.Array, 0, pal, 0, chunk.Length);
this.palette = pal;
break;
case PngChunkType.PaletteAlpha:
case PngChunkType.Transparency:
byte[] alpha = new byte[chunk.Length];
Buffer.BlockCopy(chunk.Data.Array, 0, alpha, 0, chunk.Length);
this.paletteAlpha = alpha;
@ -306,9 +306,7 @@ namespace SixLabors.ImageSharp.Formats.Png
/// <returns>The <see cref="int"/></returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static byte ReadByteLittleEndian(ReadOnlySpan<byte> buffer, int offset)
{
return (byte)(((buffer[offset] & 0xFF) << 16) | (buffer[offset + 1] & 0xFF));
}
=> (byte)(((buffer[offset] & 0xFF) << 16) | (buffer[offset + 1] & 0xFF));
/// <summary>
/// Attempts to convert a byte array to a new array where each value in the original array is represented by the

107
src/ImageSharp/Formats/Png/PngEncoderCore.cs
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@ -292,7 +292,7 @@ namespace SixLabors.ImageSharp.Formats.Png
if (pngMetaData.HasTrans)
{
this.WriteTransparencyMarkers(stream, pngMetaData);
this.WriteTransparencyChunk(stream, pngMetaData);
}
this.WritePhysicalChunk(stream, metaData);
@ -305,52 +305,6 @@ namespace SixLabors.ImageSharp.Formats.Png
quantized?.Dispose();
}
/// <summary>
/// Writes the transparency markers to the stream
/// </summary>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
/// <param name="pngMetaData">The image meta data.</param>
private void WriteTransparencyMarkers(Stream stream, PngMetaData pngMetaData)
{
if (pngMetaData.ColorType == PngColorType.Rgb)
{
if (pngMetaData.TransparentRgb48 != null)
{
var r = BitConverter.GetBytes(pngMetaData.TransparentRgb48.Value.R);
var g = BitConverter.GetBytes(pngMetaData.TransparentRgb48.Value.R);
var b = BitConverter.GetBytes(pngMetaData.TransparentRgb48.Value.B);
var alphaArray = r.Concat(g).Concat(b).ToArray();
this.WriteChunk(stream, PngChunkType.PaletteAlpha, alphaArray, 0, alphaArray.Length);
}
else if (pngMetaData.TransparentRgb24 != null)
{
var alphaArray = new byte[6];
alphaArray[1] = pngMetaData.TransparentRgb24.Value.R;
alphaArray[3] = pngMetaData.TransparentRgb24.Value.G;
alphaArray[5] = pngMetaData.TransparentRgb24.Value.B;
this.WriteChunk(stream, PngChunkType.PaletteAlpha, alphaArray, 0, alphaArray.Length);
}
}
else if (pngMetaData.ColorType == PngColorType.Grayscale)
{
if (pngMetaData.TransparentGray16 != null)
{
var alphaArray = BitConverter.GetBytes(pngMetaData.TransparentGray16.Value.PackedValue);
this.WriteChunk(stream, PngChunkType.PaletteAlpha, alphaArray, 0, alphaArray.Length);
}
else if (pngMetaData.TransparentGray8 != null)
{
var alphaArray = new byte[2];
alphaArray[1] = pngMetaData.TransparentGray8.Value.PackedValue;
this.WriteChunk(stream, PngChunkType.PaletteAlpha, alphaArray, 0, alphaArray.Length);
}
}
}
/// <inheritdoc />
public void Dispose()
{
@ -377,7 +331,6 @@ namespace SixLabors.ImageSharp.Formats.Png
if (this.pngColorType.Equals(PngColorType.Grayscale))
{
// TODO: Research and add support for grayscale plus tRNS
if (this.use16Bit)
{
// 16 bit grayscale
@ -752,7 +705,7 @@ namespace SixLabors.ImageSharp.Formats.Png
// Write the transparency data
if (anyAlpha)
{
this.WriteChunk(stream, PngChunkType.PaletteAlpha, alphaTable.Array, 0, paletteLength);
this.WriteChunk(stream, PngChunkType.Transparency, alphaTable.Array, 0, paletteLength);
}
}
}
@ -800,6 +753,52 @@ namespace SixLabors.ImageSharp.Formats.Png
}
}
/// <summary>
/// Writes the transparency chunk to the stream
/// </summary>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
/// <param name="pngMetaData">The image meta data.</param>
private void WriteTransparencyChunk(Stream stream, PngMetaData pngMetaData)
{
if (pngMetaData.ColorType.Equals(PngColorType.Rgb))
{
Span<byte> alpha = this.buffer.AsSpan();
if (pngMetaData.TransparentRgb48.HasValue && this.use16Bit)
{
Rgb48 rgb = pngMetaData.TransparentRgb48.Value;
BinaryPrimitives.WriteUInt16LittleEndian(alpha, rgb.R);
BinaryPrimitives.WriteUInt16LittleEndian(alpha.Slice(2, 2), rgb.G);
BinaryPrimitives.WriteUInt16LittleEndian(alpha.Slice(4, 2), rgb.B);
this.WriteChunk(stream, PngChunkType.Transparency, this.buffer, 0, 6);
}
else if (pngMetaData.TransparentRgb24.HasValue)
{
alpha.Clear();
Rgb24 rgb = pngMetaData.TransparentRgb24.Value;
alpha[1] = rgb.R;
alpha[3] = rgb.G;
alpha[5] = rgb.B;
this.WriteChunk(stream, PngChunkType.Transparency, this.buffer, 0, 6);
}
}
else if (pngMetaData.ColorType.Equals(PngColorType.Grayscale))
{
Span<byte> alpha = this.buffer.AsSpan();
if (pngMetaData.TransparentGray16.HasValue && this.bitDepth == 16)
{
BinaryPrimitives.WriteUInt16LittleEndian(alpha, pngMetaData.TransparentGray16.Value.PackedValue);
this.WriteChunk(stream, PngChunkType.Transparency, this.buffer, 0, 2);
}
else if (pngMetaData.TransparentGray8.HasValue)
{
alpha.Clear();
alpha[1] = pngMetaData.TransparentGray8.Value.PackedValue;
this.WriteChunk(stream, PngChunkType.Transparency, this.buffer, 0, 2);
}
}
}
/// <summary>
/// Writes the pixel information to the stream.
/// </summary>
@ -894,10 +893,7 @@ namespace SixLabors.ImageSharp.Formats.Png
/// Writes the chunk end to the stream.
/// </summary>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
private void WriteEndChunk(Stream stream)
{
this.WriteChunk(stream, PngChunkType.End, null);
}
private void WriteEndChunk(Stream stream) => this.WriteChunk(stream, PngChunkType.End, null);
/// <summary>
/// Writes a chunk to the stream.
@ -905,10 +901,7 @@ namespace SixLabors.ImageSharp.Formats.Png
/// <param name="stream">The <see cref="Stream"/> to write to.</param>
/// <param name="type">The type of chunk to write.</param>
/// <param name="data">The <see cref="T:byte[]"/> containing data.</param>
private void WriteChunk(Stream stream, PngChunkType type, byte[] data)
{
this.WriteChunk(stream, type, data, 0, data?.Length ?? 0);
}
private void WriteChunk(Stream stream, PngChunkType type, byte[] data) => this.WriteChunk(stream, type, data, 0, data?.Length ?? 0);
/// <summary>
/// Writes a chunk of a specified length to the stream at the given offset.

2
tests/ImageSharp.Tests/Formats/Png/PngChunkTypeTests.cs
View File

@ -15,7 +15,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
Assert.Equal(PngChunkType.Palette, GetType("PLTE"));
Assert.Equal(PngChunkType.Data, GetType("IDAT"));
Assert.Equal(PngChunkType.End, GetType("IEND"));
Assert.Equal(PngChunkType.PaletteAlpha, GetType("tRNS"));
Assert.Equal(PngChunkType.Transparency, GetType("tRNS"));
Assert.Equal(PngChunkType.Text, GetType("tEXt"));
Assert.Equal(PngChunkType.Gamma, GetType("gAMA"));
Assert.Equal(PngChunkType.Physical, GetType("pHYs"));

2
tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.Chunks.cs
View File

@ -76,7 +76,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
[Theory]
[InlineData((uint)PngChunkType.Gamma)] // gAMA
[InlineData((uint)PngChunkType.PaletteAlpha)] // tRNS
[InlineData((uint)PngChunkType.Transparency)] // tRNS
[InlineData((uint)PngChunkType.Physical)] // pHYs: It's ok to test physical as we don't throw for duplicate chunks.
//[InlineData(PngChunkTypes.Text)] //TODO: Figure out how to test this
public void Decode_IncorrectCRCForNonCriticalChunk_ExceptionIsThrown(uint chunkType)

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