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Add decoding of 32 bit RLE

pull/1026/head
Brian Popow 7 years ago
parent
f6cce786ea
commit
f69048fdcc
1 changed files with 75 additions and 25 deletions
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  1. 100
      src/ImageSharp/Formats/Tga/TgaDecoderCore.cs

100
src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
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@ -94,7 +94,15 @@ namespace SixLabors.ImageSharp.Formats.Tga
break;
case 32:
this.ReadBgra32(pixels);
if (this.fileHeader.ImageType.IsRunLengthEncoded())
{
this.ReadRle32(pixels, this.fileHeader.Width, this.fileHeader.Height);
}
else
{
this.ReadBgra32(pixels);
}
break;
default:
@ -196,7 +204,7 @@ namespace SixLabors.ImageSharp.Formats.Tga
using (IMemoryOwner<byte> buffer = this.memoryAllocator.Allocate<byte>(width * height * 3, AllocationOptions.Clean))
{
Span<byte> bufferSpan = buffer.GetSpan();
this.UncompressRle24(width, bufferSpan);
this.UncompressRle24(width, height, bufferSpan);
for (int y = 0; y < height; y++)
{
Span<TPixel> pixelRow = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
@ -210,54 +218,38 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
}
private void UncompressRle24(int w, Span<byte> buffer)
private void UncompressRle24(int width, int height, Span<byte> buffer)
{
int uncompressedPixels = 0;
#if NETCOREAPP2_1
Span<byte> pixel = stackalloc byte[3];
#else
var pixel = new byte[3];
#endif
int totalPixels = this.fileHeader.Height * this.fileHeader.Width;
int totalPixels = width * height;
while (uncompressedPixels < totalPixels)
{
byte runLengthByte = (byte)this.currentStream.ReadByte();
// The high bit of the run length value is always 1, to indicate that this is a run-length encoded packet.
// The high bit of a run length packet is set to 1.
int highBit = runLengthByte >> 7;
if (highBit == 1)
{
int runLength = runLengthByte & 127;
if (runLength == 0)
{
// TgaThrowHelper.ThrowImageFormatException("invalid run length of zero");
}
this.currentStream.Read(pixel, 0, 3);
int bufferIdx = uncompressedPixels * 3;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
buffer[bufferIdx++] = pixel[0];
buffer[bufferIdx++] = pixel[1];
buffer[bufferIdx++] = pixel[2];
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
bufferIdx += 3;
}
}
else
{
// Non-run-length encoded packet.
int runLength = runLengthByte;
if (runLength == 0)
{
// TgaThrowHelper.ThrowImageFormatException("invalid run length of zero");
}
int bufferIdx = uncompressedPixels * 3;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
this.currentStream.Read(pixel, 0, 3);
buffer[bufferIdx++] = pixel[0];
buffer[bufferIdx++] = pixel[1];
buffer[bufferIdx++] = pixel[2];
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
bufferIdx += 3;
}
}
}
@ -281,6 +273,64 @@ namespace SixLabors.ImageSharp.Formats.Tga
}
}
private void ReadRle32<TPixel>(Buffer2D<TPixel> pixels, int width, int height)
where TPixel : struct, IPixel<TPixel>
{
TPixel color = default;
using (IMemoryOwner<byte> buffer = this.memoryAllocator.Allocate<byte>(width * height * 4, AllocationOptions.Clean))
{
Span<byte> bufferSpan = buffer.GetSpan();
this.UncompressRle32(width, height, bufferSpan);
for (int y = 0; y < height; y++)
{
Span<TPixel> pixelRow = pixels.GetRowSpan(this.fileHeader.Height - y - 1);
for (int x = 0; x < width; x++)
{
int idx = (y * width * 4) + (x * 4);
color.FromBgra32(Unsafe.As<byte, Bgra32>(ref bufferSpan[idx]));
pixelRow[x] = color;
}
}
}
}
private void UncompressRle32(int width, int height, Span<byte> buffer)
{
int uncompressedPixels = 0;
var pixel = new byte[4];
int totalPixels = width * height;
while (uncompressedPixels < totalPixels)
{
byte runLengthByte = (byte)this.currentStream.ReadByte();
// The high bit of a run length packet is set to 1.
int highBit = runLengthByte >> 7;
if (highBit == 1)
{
int runLength = runLengthByte & 127;
this.currentStream.Read(pixel, 0, 4);
int bufferIdx = uncompressedPixels * 4;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
bufferIdx += 4;
}
}
else
{
// Non-run-length encoded packet.
int runLength = runLengthByte;
int bufferIdx = uncompressedPixels * 4;
for (int i = 0; i < runLength + 1; i++, uncompressedPixels++)
{
this.currentStream.Read(pixel, 0, 4);
pixel.AsSpan().CopyTo(buffer.Slice(bufferIdx));
bufferIdx += 4;
}
}
}
}
/// <summary>
/// Reads the raw image information from the specified stream.
/// </summary>

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