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Add support for decoding tga image with palette

af/merge-core
Brian Popow 6 years ago
parent
98f4def9a9
commit
462ba485f5
1 changed files with 120 additions and 24 deletions
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  1. 144
      src/ImageSharp/Formats/Tga/TgaDecoderCore.cs

144
src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
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@ -73,9 +73,47 @@ namespace SixLabors.ImageSharp.Formats.Tga
{
this.ReadFileHeader(stream);
// TODO: parse ID
// Parse the color map, if present.
if (this.fileHeader.ColorMapType != 0 && this.fileHeader.ColorMapType != 1)
{
TgaThrowHelper.ThrowNotSupportedException($"Unknown tga colormap type {this.fileHeader.ColorMapType} found");
}
byte[] palette = null;
int colorMapPixelSizeInBytes = 0;
if (this.fileHeader.ColorMapType == 1)
{
if (this.fileHeader.CMapLength <= 0)
{
TgaThrowHelper.ThrowImageFormatException("Missing tga color map length");
}
if (this.fileHeader.CMapDepth <= 0)
{
TgaThrowHelper.ThrowImageFormatException("Missing tga color map depth");
}
colorMapPixelSizeInBytes = this.fileHeader.CMapDepth / 8;
palette = new byte[this.fileHeader.CMapLength * colorMapPixelSizeInBytes];
this.currentStream.Read(palette, this.fileHeader.CMapStart, palette.Length);
}
var image = new Image<TPixel>(this.configuration, this.fileHeader.Width, this.fileHeader.Height, this.metadata);
Buffer2D<TPixel> pixels = image.GetRootFramePixelBuffer();
if (this.fileHeader.ImageType == TgaImageType.ColorMapped)
{
if (palette is null)
{
TgaThrowHelper.ThrowImageFormatException("Tga image is missing a color palette");
}
this.ReadPaletted(this.fileHeader.Width, this.fileHeader.Height, pixels, palette, colorMapPixelSizeInBytes);
return image;
}
switch (this.fileHeader.PixelDepth)
{
case 8:
@ -85,7 +123,7 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
else
{
this.ReadMonoChrome(pixels);
this.ReadMonoChrome(this.fileHeader.Width, this.fileHeader.Height, pixels);
}
break;
@ -98,7 +136,7 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
else
{
this.ReadBgra16(pixels);
this.ReadBgra16(this.fileHeader.Width, this.fileHeader.Height, pixels);
}
break;
@ -110,7 +148,7 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
else
{
this.ReadBgr24(pixels);
this.ReadBgr24(this.fileHeader.Width, this.fileHeader.Height, pixels);
}
break;
@ -122,7 +160,7 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
else
{
this.ReadBgra32(pixels);
this.ReadBgra32(this.fileHeader.Width, this.fileHeader.Height, pixels);
}
break;
@ -140,41 +178,99 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
}
private void ReadMonoChrome<TPixel>(Buffer2D<TPixel> pixels)
private void ReadPaletted<TPixel>(int width, int height, Buffer2D<TPixel> pixels, byte[] palette, int pixelSizeInBytes)
where TPixel : struct, IPixel<TPixel>
{
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(this.fileHeader.Width, 1, 0))
using (IManagedByteBuffer row = this.memoryAllocator.AllocateManagedByteBuffer(width, AllocationOptions.Clean))
{
for (int y = 0; y < this.fileHeader.Height; y++)
TPixel color = default;
Span<byte> rowSpan = row.GetSpan();
for (int y = 0; y < height; y++)
{
this.currentStream.Read(row);
Span<TPixel> pixelSpan = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
Span<TPixel> pixelRow = pixels.GetRowSpan(height - y - 1);
switch (pixelSizeInBytes)
{
case 1:
for (int x = 0; x < width; x++)
{
int colorIndex = rowSpan[x];
color.FromGray8(Unsafe.As<byte, Gray8>(ref palette[colorIndex]));
pixelRow[x] = color;
}
break;
case 2:
for (int x = 0; x < width; x++)
{
int colorIndex = rowSpan[x];
color.FromBgra5551(Unsafe.As<byte, Bgra5551>(ref palette[colorIndex * pixelSizeInBytes]));
pixelRow[x] = color;
}
break;
case 3:
for (int x = 0; x < width; x++)
{
int colorIndex = rowSpan[x];
color.FromBgr24(Unsafe.As<byte, Bgr24>(ref palette[colorIndex * pixelSizeInBytes]));
pixelRow[x] = color;
}
break;
case 4:
for (int x = 0; x < width; x++)
{
int colorIndex = rowSpan[x];
color.FromBgra32(Unsafe.As<byte, Bgra32>(ref palette[colorIndex * pixelSizeInBytes]));
pixelRow[x] = color;
}
break;
}
}
}
}
private void ReadMonoChrome<TPixel>(int width, int height, Buffer2D<TPixel> pixels)
where TPixel : struct, IPixel<TPixel>
{
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(width, 1, 0))
{
for (int y = 0; y < height; y++)
{
this.currentStream.Read(row);
Span<TPixel> pixelSpan = pixels.GetRowSpan(height - y - 1);
PixelOperations<TPixel>.Instance.FromGray8Bytes(
this.configuration,
row.GetSpan(),
pixelSpan,
this.fileHeader.Width);
width);
}
}
}
private void ReadBgra16<TPixel>(Buffer2D<TPixel> pixels)
private void ReadBgra16<TPixel>(int width, int height, Buffer2D<TPixel> pixels)
where TPixel : struct, IPixel<TPixel>
{
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(this.fileHeader.Width, 2, 0))
using (IMemoryOwner<Bgra5551> bgraRow = this.memoryAllocator.Allocate<Bgra5551>(this.fileHeader.Width))
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(width, 2, 0))
using (IMemoryOwner<Bgra5551> bgraRow = this.memoryAllocator.Allocate<Bgra5551>(width))
{
Span<Bgra5551> bgraRowSpan = bgraRow.GetSpan();
long currentPosition = this.currentStream.Position;
for (int y = 0; y < this.fileHeader.Height; y++)
{
this.currentStream.Read(row);
Span<TPixel> pixelSpan = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
Span<TPixel> pixelSpan = pixels.GetRowSpan(height - y - 1);
PixelOperations<TPixel>.Instance.FromBgra5551Bytes(
this.configuration,
row.GetSpan(),
pixelSpan,
this.fileHeader.Width);
width);
}
// We need to set each alpha component value to fully opaque.
@ -182,38 +278,38 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
}
private void ReadBgr24<TPixel>(Buffer2D<TPixel> pixels)
private void ReadBgr24<TPixel>(int width, int height, Buffer2D<TPixel> pixels)
where TPixel : struct, IPixel<TPixel>
{
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(this.fileHeader.Width, 3, 0))
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(width, 3, 0))
{
for (int y = 0; y < this.fileHeader.Height; y++)
for (int y = 0; y < height; y++)
{
this.currentStream.Read(row);
Span<TPixel> pixelSpan = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
Span<TPixel> pixelSpan = pixels.GetRowSpan(height - y - 1);
PixelOperations<TPixel>.Instance.FromBgr24Bytes(
this.configuration,
row.GetSpan(),
pixelSpan,
this.fileHeader.Width);
width);
}
}
}
private void ReadBgra32<TPixel>(Buffer2D<TPixel> pixels)
private void ReadBgra32<TPixel>(int width, int height, Buffer2D<TPixel> pixels)
where TPixel : struct, IPixel<TPixel>
{
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(this.fileHeader.Width, 4, 0))
using (IManagedByteBuffer row = this.memoryAllocator.AllocatePaddedPixelRowBuffer(width, 4, 0))
{
for (int y = 0; y < this.fileHeader.Height; y++)
for (int y = 0; y < height; y++)
{
this.currentStream.Read(row);
Span<TPixel> pixelSpan = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
Span<TPixel> pixelSpan = pixels.GetRowSpan(height - y - 1);
PixelOperations<TPixel>.Instance.FromBgra32Bytes(
this.configuration,
row.GetSpan(),
pixelSpan,
this.fileHeader.Width);
width);
}
}
}

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