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Merged
merged 7 commits into from
Aug 6, 2022
Merged

TGA Encoder/Decoder Improvements #2197

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95ae124
Use DangerousGetRowSpan when run length encode image
brianpopow Jul 30, 2022
d1d6728
A little cleanup
brianpopow Jul 30, 2022
23ae060
Throw exception, if not enough data is available in the stream
brianpopow Jul 30, 2022
57c2137
Add test for legacy tga format
brianpopow Aug 2, 2022
5fff1e4
Only write RLE packet, if more then 1 equal pixel is found. Write Raw…
brianpopow Aug 2, 2022
e717332
Add test making sure not always RLE packets are written
brianpopow Aug 3, 2022
343b4af
Add another test case for #2172
brianpopow Aug 4, 2022
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143 changes: 98 additions & 45 deletions src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ public TgaDecoderCore(Configuration configuration, ITgaDecoderOptions options)
/// <summary>
/// Gets the dimensions of the image.
/// </summary>
public Size Dimensions => new Size(this.fileHeader.Width, this.fileHeader.Height);
public Size Dimensions => new(this.fileHeader.Width, this.fileHeader.Height);

/// <inheritdoc />
public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
Expand All @@ -87,7 +87,7 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
this.currentStream.Skip(this.fileHeader.IdLength);

// Parse the color map, if present.
if (this.fileHeader.ColorMapType != 0 && this.fileHeader.ColorMapType != 1)
if (this.fileHeader.ColorMapType is not 0 and not 1)
{
TgaThrowHelper.ThrowNotSupportedException($"Unknown tga colormap type {this.fileHeader.ColorMapType} found");
}
Expand Down Expand Up @@ -117,7 +117,11 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
using (IMemoryOwner<byte> palette = this.memoryAllocator.Allocate<byte>(colorMapSizeInBytes, AllocationOptions.Clean))
{
Span<byte> paletteSpan = palette.GetSpan();
this.currentStream.Read(paletteSpan, this.fileHeader.CMapStart, colorMapSizeInBytes);
int bytesRead = this.currentStream.Read(paletteSpan, this.fileHeader.CMapStart, colorMapSizeInBytes);
if (bytesRead != colorMapSizeInBytes)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read the color map");
}

if (this.fileHeader.ImageType == TgaImageType.RleColorMapped)
{
Expand Down Expand Up @@ -308,8 +312,7 @@ private void ReadPaletted<TPixel>(int width, int height, Buffer2D<TPixel> pixels
private void ReadPalettedRle<TPixel>(int width, int height, Buffer2D<TPixel> pixels, Span<byte> palette, int colorMapPixelSizeInBytes, TgaImageOrigin origin)
where TPixel : unmanaged, IPixel<TPixel>
{
int bytesPerPixel = 1;
using (IMemoryOwner<byte> buffer = this.memoryAllocator.Allocate<byte>(width * height * bytesPerPixel, AllocationOptions.Clean))
using (IMemoryOwner<byte> buffer = this.memoryAllocator.Allocate<byte>(width * height, AllocationOptions.Clean))
{
TPixel color = default;
Span<byte> bufferSpan = buffer.GetSpan();
Expand All @@ -319,7 +322,7 @@ private void ReadPalettedRle<TPixel>(int width, int height, Buffer2D<TPixel> pix
{
int newY = InvertY(y, height, origin);
Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(newY);
int rowStartIdx = y * width * bytesPerPixel;
int rowStartIdx = y * width;
for (int x = 0; x < width; x++)
{
int idx = rowStartIdx + x;
Expand Down Expand Up @@ -418,7 +421,12 @@ private void ReadBgra16<TPixel>(int width, int height, Buffer2D<TPixel> pixels,
{
for (int x = width - 1; x >= 0; x--)
{
this.currentStream.Read(this.scratchBuffer, 0, 2);
int bytesRead = this.currentStream.Read(this.scratchBuffer, 0, 2);
if (bytesRead != 2)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
}

if (!this.hasAlpha)
{
this.scratchBuffer[1] |= 1 << 7;
Expand All @@ -438,7 +446,11 @@ private void ReadBgra16<TPixel>(int width, int height, Buffer2D<TPixel> pixels,
}
else
{
this.currentStream.Read(rowSpan);
int bytesRead = this.currentStream.Read(rowSpan);
if (bytesRead != rowSpan.Length)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
}

if (!this.hasAlpha)
{
Expand Down Expand Up @@ -579,7 +591,7 @@ private void ReadRle<TPixel>(int width, int height, Buffer2D<TPixel> pixels, int
where TPixel : unmanaged, IPixel<TPixel>
{
TPixel color = default;
var alphaBits = this.tgaMetadata.AlphaChannelBits;
byte alphaBits = this.tgaMetadata.AlphaChannelBits;
using (IMemoryOwner<byte> buffer = this.memoryAllocator.Allocate<byte>(width * height * bytesPerPixel, AllocationOptions.Clean))
{
Span<byte> bufferSpan = buffer.GetSpan();
Expand Down Expand Up @@ -624,8 +636,8 @@ private void ReadRle<TPixel>(int width, int height, Buffer2D<TPixel> pixels, int
}
else
{
var alpha = alphaBits == 0 ? byte.MaxValue : bufferSpan[idx + 3];
color.FromBgra32(new Bgra32(bufferSpan[idx + 2], bufferSpan[idx + 1], bufferSpan[idx], (byte)alpha));
byte alpha = alphaBits == 0 ? byte.MaxValue : bufferSpan[idx + 3];
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@JimBobSquarePants JimBobSquarePants Aug 5, 2022

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Why do we use Bgra here when the buffer is Rgba?

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@brianpopow brianpopow Aug 5, 2022

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Because of the Intel byte ordering, the data needs to be interpreted as bgra. Quote from the Spec:

|  Image Data Field.                                         |
|                                                            |
|  This field specifies (width) x (height) pixels.  Each     |
|  pixel specifies an RGB color value, which is stored as    |
|  an integral number of bytes.                              |
|  The 2 byte entry is broken down as follows:               |
|  ARRRRRGG GGGBBBBB, where each letter represents a bit.    |
|  But, because of the lo-hi storage order, the first byte   |
|  coming from the file will actually be GGGBBBBB, and the   |
|  second will be ARRRRRGG. "A" represents an attribute bit. |
|  The 3 byte entry contains 1 byte each of blue, green,     |
|  and red.                                                  |
|  The 4 byte entry contains 1 byte each of blue, green,     |
|  red, and attribute.  For faster speed (because of the     |
|  hardware of the Targa board itself), Targa 24 images are  |
|  sometimes stored as Targa 32 images.                      |
--------------------------------------------------------------------------------

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@JimBobSquarePants JimBobSquarePants Aug 6, 2022

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Thanks... I was thrown by the assignment order in the Bgra32 constructor. Forgot the order was r,g,b,a.

color.FromBgra32(new Bgra32(bufferSpan[idx + 2], bufferSpan[idx + 1], bufferSpan[idx], alpha));
}

break;
Expand Down Expand Up @@ -653,7 +665,12 @@ public IImageInfo Identify(BufferedReadStream stream, CancellationToken cancella
private void ReadL8Row<TPixel>(int width, Buffer2D<TPixel> pixels, Span<byte> row, int y)
where TPixel : unmanaged, IPixel<TPixel>
{
this.currentStream.Read(row);
int bytesRead = this.currentStream.Read(row);
if (bytesRead != row.Length)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
}

Span<TPixel> pixelSpan = pixels.DangerousGetRowSpan(y);
PixelOperations<TPixel>.Instance.FromL8Bytes(this.Configuration, row, pixelSpan, width);
}
Expand All @@ -662,7 +679,7 @@ private void ReadL8Row<TPixel>(int width, Buffer2D<TPixel> pixels, Span<byte> ro
private void ReadL8Pixel<TPixel>(TPixel color, int x, Span<TPixel> pixelSpan)
where TPixel : unmanaged, IPixel<TPixel>
{
var pixelValue = (byte)this.currentStream.ReadByte();
byte pixelValue = (byte)this.currentStream.ReadByte();
color.FromL8(Unsafe.As<byte, L8>(ref pixelValue));
pixelSpan[x] = color;
}
Expand All @@ -671,7 +688,12 @@ private void ReadL8Pixel<TPixel>(TPixel color, int x, Span<TPixel> pixelSpan)
private void ReadBgr24Pixel<TPixel>(TPixel color, int x, Span<TPixel> pixelSpan)
where TPixel : unmanaged, IPixel<TPixel>
{
this.currentStream.Read(this.scratchBuffer, 0, 3);
int bytesRead = this.currentStream.Read(this.scratchBuffer, 0, 3);
if (bytesRead != 3)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a bgr pixel");
}

color.FromBgr24(Unsafe.As<byte, Bgr24>(ref this.scratchBuffer[0]));
pixelSpan[x] = color;
}
Expand All @@ -680,7 +702,12 @@ private void ReadBgr24Pixel<TPixel>(TPixel color, int x, Span<TPixel> pixelSpan)
private void ReadBgr24Row<TPixel>(int width, Buffer2D<TPixel> pixels, Span<byte> row, int y)
where TPixel : unmanaged, IPixel<TPixel>
{
this.currentStream.Read(row);
int bytesRead = this.currentStream.Read(row);
if (bytesRead != row.Length)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
}

Span<TPixel> pixelSpan = pixels.DangerousGetRowSpan(y);
PixelOperations<TPixel>.Instance.FromBgr24Bytes(this.Configuration, row, pixelSpan, width);
}
Expand All @@ -689,8 +716,13 @@ private void ReadBgr24Row<TPixel>(int width, Buffer2D<TPixel> pixels, Span<byte>
private void ReadBgra32Pixel<TPixel>(int x, TPixel color, Span<TPixel> pixelRow)
where TPixel : unmanaged, IPixel<TPixel>
{
this.currentStream.Read(this.scratchBuffer, 0, 4);
var alpha = this.tgaMetadata.AlphaChannelBits == 0 ? byte.MaxValue : this.scratchBuffer[3];
int bytesRead = this.currentStream.Read(this.scratchBuffer, 0, 4);
if (bytesRead != 4)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a bgra pixel");
}

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));
pixelRow[x] = color;
}
Expand All @@ -699,7 +731,12 @@ private void ReadBgra32Pixel<TPixel>(int x, TPixel color, Span<TPixel> pixelRow)
private void ReadBgra32Row<TPixel>(int width, Buffer2D<TPixel> pixels, Span<byte> row, int y)
where TPixel : unmanaged, IPixel<TPixel>
{
this.currentStream.Read(row);
int bytesRead = this.currentStream.Read(row);
if (bytesRead != row.Length)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel row");
}

Span<TPixel> pixelSpan = pixels.DangerousGetRowSpan(y);
PixelOperations<TPixel>.Instance.FromBgra32Bytes(this.Configuration, row, pixelSpan, width);
}
Expand All @@ -709,6 +746,11 @@ private void ReadPalettedBgra16Pixel<TPixel>(Span<byte> palette, int colorMapPix
where TPixel : unmanaged, IPixel<TPixel>
{
int colorIndex = this.currentStream.ReadByte();
if (colorIndex == -1)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read color index");
}

this.ReadPalettedBgra16Pixel(palette, colorIndex, colorMapPixelSizeInBytes, ref color);
pixelRow[x] = color;
}
Expand All @@ -734,6 +776,11 @@ private void ReadPalettedBgr24Pixel<TPixel>(Span<byte> palette, int colorMapPixe
where TPixel : unmanaged, IPixel<TPixel>
{
int colorIndex = this.currentStream.ReadByte();
if (colorIndex == -1)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read color index");
}

color.FromBgr24(Unsafe.As<byte, Bgr24>(ref palette[colorIndex * colorMapPixelSizeInBytes]));
pixelRow[x] = color;
}
Expand All @@ -743,6 +790,11 @@ private void ReadPalettedBgra32Pixel<TPixel>(Span<byte> palette, int colorMapPix
where TPixel : unmanaged, IPixel<TPixel>
{
int colorIndex = this.currentStream.ReadByte();
if (colorIndex == -1)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read color index");
}

color.FromBgra32(Unsafe.As<byte, Bgra32>(ref palette[colorIndex * colorMapPixelSizeInBytes]));
pixelRow[x] = color;
}
Expand All @@ -757,7 +809,7 @@ private void ReadPalettedBgra32Pixel<TPixel>(Span<byte> palette, int colorMapPix
private void UncompressRle(int width, int height, Span<byte> buffer, int bytesPerPixel)
{
int uncompressedPixels = 0;
var pixel = new byte[bytesPerPixel];
Span<byte> pixel = this.scratchBuffer.AsSpan(0, bytesPerPixel);
int totalPixels = width * height;
while (uncompressedPixels < totalPixels)
{
Expand All @@ -768,11 +820,16 @@ private void UncompressRle(int width, int height, Span<byte> buffer, int bytesPe
if (highBit == 1)
{
int runLength = runLengthByte & 127;
this.currentStream.Read(pixel, 0, bytesPerPixel);
int bytesRead = this.currentStream.Read(pixel, 0, bytesPerPixel);
if (bytesRead != bytesPerPixel)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel from the stream");
}

int bufferIdx = uncompressedPixels * bytesPerPixel;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
pixel.CopyTo(buffer.Slice(bufferIdx));
bufferIdx += bytesPerPixel;
}
}
Expand All @@ -783,8 +840,13 @@ private void UncompressRle(int width, int height, Span<byte> buffer, int bytesPe
int bufferIdx = uncompressedPixels * bytesPerPixel;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
this.currentStream.Read(pixel, 0, bytesPerPixel);
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
int bytesRead = this.currentStream.Read(pixel, 0, bytesPerPixel);
if (bytesRead != bytesPerPixel)
{
TgaThrowHelper.ThrowInvalidImageContentException("Not enough data to read a pixel from the stream");
}

pixel.CopyTo(buffer.Slice(bufferIdx));
bufferIdx += bytesPerPixel;
}
}
Expand Down Expand Up @@ -815,17 +877,12 @@ private static int InvertY(int y, int height, TgaImageOrigin origin)
/// <param name="origin">The image origin.</param>
/// <returns>True, if y coordinate needs to be inverted.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool InvertY(TgaImageOrigin origin)
private static bool InvertY(TgaImageOrigin origin) => origin switch
{
switch (origin)
{
case TgaImageOrigin.BottomLeft:
case TgaImageOrigin.BottomRight:
return true;
default:
return false;
}
}
TgaImageOrigin.BottomLeft => true,
TgaImageOrigin.BottomRight => true,
_ => false
};

/// <summary>
/// Returns the x- value based on the given width.
Expand All @@ -851,17 +908,13 @@ private static int InvertX(int x, int width, TgaImageOrigin origin)
/// <param name="origin">The image origin.</param>
/// <returns>True, if x coordinate needs to be inverted.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool InvertX(TgaImageOrigin origin)
{
switch (origin)
private static bool InvertX(TgaImageOrigin origin) =>
origin switch
{
case TgaImageOrigin.TopRight:
case TgaImageOrigin.BottomRight:
return true;
default:
return false;
}
}
TgaImageOrigin.TopRight => true,
TgaImageOrigin.BottomRight => true,
_ => false
};

/// <summary>
/// Reads the tga file header from the stream.
Expand All @@ -880,8 +933,8 @@ private TgaImageOrigin ReadFileHeader(BufferedReadStream stream)
this.tgaMetadata = this.metadata.GetTgaMetadata();
this.tgaMetadata.BitsPerPixel = (TgaBitsPerPixel)this.fileHeader.PixelDepth;

var alphaBits = this.fileHeader.ImageDescriptor & 0xf;
if (alphaBits != 0 && alphaBits != 1 && alphaBits != 8)
int alphaBits = this.fileHeader.ImageDescriptor & 0xf;
if (alphaBits is not 0 and not 1 and not 8)
{
TgaThrowHelper.ThrowInvalidImageContentException("Invalid alpha channel bits");
}
Expand Down
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