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Reduced intermediate allocations: Tga

pull/2415/head
Günther Foidl 3 years ago
parent
1d3ae0ed9d
commit
3c3479ee12
2 changed files with 25 additions and 30 deletions
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  1. 43
      src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
  2. 12
      src/ImageSharp/Formats/Tga/TgaEncoderCore.cs

43
src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
View File

@ -17,11 +17,6 @@ namespace SixLabors.ImageSharp.Formats.Tga;
/// </summary>
internal sealed class TgaDecoderCore : IImageDecoderInternals
{
/// <summary>
/// A scratch buffer to reduce allocations.
/// </summary>
private readonly byte[] scratchBuffer = new byte[4];
/// <summary>
/// General configuration options.
/// </summary>
@ -407,6 +402,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
bool invertX = InvertX(origin);
using IMemoryOwner<byte> row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(width, 2, 0);
Span<byte> rowSpan = row.GetSpan();
Span<byte> scratchBuffer = stackalloc byte[2];
for (int y = 0; y < height; y++)
{
@ -417,7 +413,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
{
for (int x = width - 1; x >= 0; x--)
{
int bytesRead = stream.Read(this.scratchBuffer, 0, 2);
int bytesRead = stream.Read(scratchBuffer);
if (bytesRead != 2)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
@ -425,16 +421,16 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
if (!this.hasAlpha)
{
this.scratchBuffer[1] |= 1 << 7;
scratchBuffer[1] |= 1 << 7;
}
if (this.fileHeader.ImageType == TgaImageType.BlackAndWhite)
{
color.FromLa16(Unsafe.As<byte, La16>(ref MemoryMarshal.GetArrayDataReference(this.scratchBuffer)));
color.FromLa16(Unsafe.As<byte, La16>(ref MemoryMarshal.GetReference(scratchBuffer)));
}
else
{
color.FromBgra5551(Unsafe.As<byte, Bgra5551>(ref MemoryMarshal.GetArrayDataReference(this.scratchBuffer)));
color.FromBgra5551(Unsafe.As<byte, Bgra5551>(ref MemoryMarshal.GetReference(scratchBuffer)));
}
pixelSpan[x] = color;
@ -484,6 +480,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
bool invertX = InvertX(origin);
if (invertX)
{
Span<byte> scratchBuffer = stackalloc byte[4];
TPixel color = default;
for (int y = 0; y < height; y++)
{
@ -491,7 +488,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
Span<TPixel> pixelSpan = pixels.DangerousGetRowSpan(newY);
for (int x = width - 1; x >= 0; x--)
{
this.ReadBgr24Pixel(stream, color, x, pixelSpan);
ReadBgr24Pixel(stream, color, x, pixelSpan, scratchBuffer);
}
}
@ -558,6 +555,8 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
return;
}
Span<byte> scratchBuffer = stackalloc byte[4];
for (int y = 0; y < height; y++)
{
int newY = InvertY(y, height, origin);
@ -566,14 +565,14 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
{
for (int x = width - 1; x >= 0; x--)
{
this.ReadBgra32Pixel(stream, x, color, pixelRow);
this.ReadBgra32Pixel(stream, x, color, pixelRow, scratchBuffer);
}
}
else
{
for (int x = 0; x < width; x++)
{
this.ReadBgra32Pixel(stream, x, color, pixelRow);
this.ReadBgra32Pixel(stream, x, color, pixelRow, scratchBuffer);
}
}
}
@ -687,16 +686,16 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private void ReadBgr24Pixel<TPixel>(BufferedReadStream stream, TPixel color, int x, Span<TPixel> pixelSpan)
private static void ReadBgr24Pixel<TPixel>(BufferedReadStream stream, TPixel color, int x, Span<TPixel> pixelSpan, Span<byte> scratchBuffer)
where TPixel : unmanaged, IPixel<TPixel>
{
int bytesRead = stream.Read(this.scratchBuffer, 0, 3);
int bytesRead = stream.Read(scratchBuffer, 0, 3);
if (bytesRead != 3)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a bgr pixel");
}
color.FromBgr24(Unsafe.As<byte, Bgr24>(ref MemoryMarshal.GetArrayDataReference(this.scratchBuffer)));
color.FromBgr24(Unsafe.As<byte, Bgr24>(ref MemoryMarshal.GetReference(scratchBuffer)));
pixelSpan[x] = color;
}
@ -715,10 +714,10 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private void ReadBgra32Pixel<TPixel>(BufferedReadStream stream, int x, TPixel color, Span<TPixel> pixelRow)
private void ReadBgra32Pixel<TPixel>(BufferedReadStream stream, int x, TPixel color, Span<TPixel> pixelRow, Span<byte> scratchBuffer)
where TPixel : unmanaged, IPixel<TPixel>
{
int bytesRead = stream.Read(this.scratchBuffer, 0, 4);
int bytesRead = stream.Read(scratchBuffer, 0, 4);
if (bytesRead != 4)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a bgra pixel");
@ -726,8 +725,8 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
Guard.NotNull(this.tgaMetadata);
byte alpha = this.tgaMetadata.AlphaChannelBits == 0 ? byte.MaxValue : this.scratchBuffer[3];
color.FromBgra32(new Bgra32(this.scratchBuffer[2], this.scratchBuffer[1], this.scratchBuffer[0], alpha));
byte alpha = this.tgaMetadata.AlphaChannelBits == 0 ? byte.MaxValue : scratchBuffer[3];
color.FromBgra32(new Bgra32(scratchBuffer[2], scratchBuffer[1], scratchBuffer[0], alpha));
pixelRow[x] = color;
}
@ -814,7 +813,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
private void UncompressRle(BufferedReadStream stream, int width, int height, Span<byte> buffer, int bytesPerPixel)
{
int uncompressedPixels = 0;
Span<byte> pixel = this.scratchBuffer.AsSpan(0, bytesPerPixel);
Span<byte> pixel = stackalloc byte[bytesPerPixel];
int totalPixels = width * height;
while (uncompressedPixels < totalPixels)
{
@ -825,7 +824,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
if (highBit == 1)
{
int runLength = runLengthByte & 127;
int bytesRead = stream.Read(pixel, 0, bytesPerPixel);
int bytesRead = stream.Read(pixel);
if (bytesRead != bytesPerPixel)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel from the stream");
@ -845,7 +844,7 @@ internal sealed class TgaDecoderCore : IImageDecoderInternals
int bufferIdx = uncompressedPixels * bytesPerPixel;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
int bytesRead = stream.Read(pixel, 0, bytesPerPixel);
int bytesRead = stream.Read(pixel);
if (bytesRead != bytesPerPixel)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel from the stream");

12
src/ImageSharp/Formats/Tga/TgaEncoderCore.cs
View File

@ -22,11 +22,6 @@ internal sealed class TgaEncoderCore : IImageEncoderInternals
/// </summary>
private readonly MemoryAllocator memoryAllocator;
/// <summary>
/// Reusable buffer for writing data.
/// </summary>
private readonly byte[] buffer = new byte[2];
/// <summary>
/// The color depth, in number of bits per pixel.
/// </summary>
@ -221,9 +216,10 @@ internal sealed class TgaEncoderCore : IImageEncoderInternals
case TgaBitsPerPixel.Pixel16:
Bgra5551 bgra5551 = new(color.ToVector4());
BinaryPrimitives.WriteInt16LittleEndian(this.buffer, (short)bgra5551.PackedValue);
stream.WriteByte(this.buffer[0]);
stream.WriteByte(this.buffer[1]);
Span<byte> buffer = stackalloc byte[2];
BinaryPrimitives.WriteInt16LittleEndian(buffer, (short)bgra5551.PackedValue);
stream.WriteByte(buffer[0]);
stream.WriteByte(buffer[1]);
break;

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