public static BmpInfo Load(
ImageBinReader s, ReadState ri, ArrayPool <byte>?bytePool = null)
{
// TODO: optimize by pulling out some branching from loops
bytePool ??= ArrayPool <byte> .Shared;
var info = ParseHeader(s, ri) ??
throw new StbImageReadException(ErrorCode.UnknownHeader);
ri.OutComponents = ri.Components;
ri.OutDepth = Math.Max(ri.Depth, 8);
ri.StateReady();
int psize = 0;
if (info.headerSize == 12)
{
if (info.bitsPerPixel < 24)
{
psize = (info.offset - 14 - 24) / 3;
}
}
else
{
if (info.bitsPerPixel < 16)
{
psize = (info.offset - 14 - info.headerSize) >> 2;
}
}
int easy = 0;
if (info.bitsPerPixel == 32)
{
if (info.mb == 0xffu << 0 &&
info.mg == 0xffu << 8 &&
info.mr == 0xffu << 16 &&
info.ma == 0xffu << 24)
{
easy = 2;
}
}
else if (info.bitsPerPixel == 24)
{
easy = 1;
}
bool flipRows = (ri.Orientation & ImageOrientation.BottomToTop) == ImageOrientation.BottomToTop;
int rowByteSize = ri.Width * ri.OutComponents;
var rowBuffer = bytePool.Rent(rowByteSize);
try
{
if (info.bitsPerPixel < 16)
{
if ((psize == 0) || (psize > 256))
{
throw new StbImageReadException(ErrorCode.InvalidPLTE);
}
// TODO: output palette
Span <byte> palette = stackalloc byte[256 * 4];
for (int x = 0; x < psize; ++x)
{
palette[x * 4 + 2] = s.ReadByte();
palette[x * 4 + 1] = s.ReadByte();
palette[x * 4 + 0] = s.ReadByte();
palette[x * 4 + 3] = info.headerSize == 12
? (byte)255
: s.ReadByte();
}
s.Skip(
info.offset - 14 - info.headerSize -
psize * (info.headerSize == 12 ? 3 : 4));
int width;
if (info.bitsPerPixel == 4)
{
width = (ri.Width + 1) / 2;
}
else if (info.bitsPerPixel == 8)
{
width = ri.Width;
}
else
{
throw new StbImageReadException(ErrorCode.BadBitsPerPixel);
}
int pad = (-width) & 3;
for (int y = 0; y < ri.Height; ++y)
{
for (int x = 0, z = 0; x < ri.Width; x += 2)
{
void WriteFromPalette(int comp, Span <byte> palette)
{
rowBuffer[z + 0] = palette[0];
rowBuffer[z + 1] = palette[1];
rowBuffer[z + 2] = palette[2];
if (comp == 4)
{
rowBuffer[z + 3] = palette[3];
}
z += comp;
}
int v2 = 0;
int v1 = s.ReadByte();
if (info.bitsPerPixel == 4)
{
v2 = v1 & 15;
v1 >>= 4;
}
WriteFromPalette(ri.OutComponents, palette[(v1 * 4)..]);
public static TgaInfo ParseHeader(ImageBinReader reader, ReadState state)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
if (state == null)
{
throw new ArgumentNullException(nameof(state));
}
Span <byte> tmp = stackalloc byte[HeaderSize];
if (!reader.TryReadBytes(tmp))
{
throw new EndOfStreamException();
}
bool test = TestCore(tmp, out var info);
if (info.colormap_type == 1)
{
if (info.image_type != 1 &&
info.image_type != 9)
{
throw new StbImageReadException(ErrorCode.BadImageType);
}
info.palette_start = reader.ReadInt16LE();
info.palette_len = reader.ReadInt16LE();
info.palette_bpp = reader.ReadByte();
if (info.palette_bpp != 8 &&
info.palette_bpp != 15 &&
info.palette_bpp != 16 &&
info.palette_bpp != 24 &&
info.palette_bpp != 32)
{
throw new StbImageReadException(ErrorCode.BadPalette);
}
}
else
{
if (info.image_type != 2 &&
info.image_type != 3 &&
info.image_type != 10 &&
info.image_type != 11)
{
throw new StbImageReadException(ErrorCode.BadImageType);
}
reader.Skip(5);
// 16bit: Color Map Origin
// 16bit: Color Map Length
// 8bit: Color Map Entry Size
}
Debug.Assert(test); // Prior checks should throw if test was unsucessful.
info.x_origin = reader.ReadInt16LE();
info.y_origin = reader.ReadInt16LE();
state.Width = reader.ReadUInt16LE();
if (state.Width < 1)
{
throw new StbImageReadException(ErrorCode.ZeroWidth);
}
state.Height = reader.ReadUInt16LE();
if (state.Height < 1)
{
throw new StbImageReadException(ErrorCode.ZeroHeight);
}
info.bits_per_pixel = reader.ReadByte();
info.inverted = reader.ReadByte();
info.inverted = 1 - ((info.inverted >> 5) & 1);
// use the number of bits from the palette if paletted
if (info.palette_bpp != 0)
{
if (info.bits_per_pixel != 8 &&
info.bits_per_pixel != 16)
{
throw new StbImageReadException(ErrorCode.BadBitsPerPixel);
}
state.Components = GetComponentCount(
info.palette_bpp, false, out state.Depth);
}
else
{
state.Components = GetComponentCount(
info.bits_per_pixel, info.image_type == 3, out state.Depth);
}
if (state.Components == 0)
{
throw new StbImageReadException(ErrorCode.BadComponentCount);
}
state.OutComponents = state.Components;
state.OutDepth = state.Depth;
state.Orientation =
ImageOrientation.LeftToRight |
(info.inverted != 0 ? ImageOrientation.BottomToTop : ImageOrientation.TopToBottom);
state.StateReady();
return(info);
}