internal TiffFieldReader(TiffFileContentReader reader, TiffOperationContext context, bool leaveOpen = false)
{
_reader = reader;
_context = context;
_leaveOpen = leaveOpen;
_reverseEndianNeeded = BitConverter.IsLittleEndian != context.IsLittleEndian;
}
internal TiffImageFileDirectoryEntry(TiffOperationContext context, TiffTag tag, TiffFieldType type, long valueCount, ReadOnlySpan <byte> valueData)
{
Tag = tag;
Type = type;
ValueCount = valueCount;
if (context.ByteCountOfValueOffsetField == 4)
{
uint offset32 = MemoryMarshal.Read <uint>(valueData);
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
offset32 = BinaryPrimitives.ReverseEndianness(offset32);
}
ValueOffset = (long)(ulong)offset32;
}
else if (context.ByteCountOfValueOffsetField == 8)
{
ulong offset64 = MemoryMarshal.Read <ulong>(valueData);
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
offset64 = BinaryPrimitives.ReverseEndianness(offset64);
}
ValueOffset = (long)offset64;
}
else
{
ValueOffset = 0;
}
}
/// <summary>
/// Restore the ValueOffset field into original bytes in the TIFF stream.
/// </summary>
/// <param name="context">Parameters of how the TIFF file should be parsed.</param>
/// <param name="destination">The destination buffer.</param>
public void RestoreRawOffsetBytes(TiffOperationContext context, Span <byte> destination)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
if (destination.Length < context.ByteCountOfValueOffsetField)
{
throw new ArgumentException($"Destination requires at least {context.ByteCountOfValueOffsetField} bytes.", nameof(destination));
}
if (context.ByteCountOfValueOffsetField == 4)
{
uint valueOffset32 = (uint)ValueOffset;
MemoryMarshal.Write(destination, ref valueOffset32);
}
else
{
ulong valueOffset64 = (ulong)ValueOffset;
MemoryMarshal.Write(destination, ref valueOffset64);
}
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
destination.Slice(0, context.ByteCountOfValueOffsetField).Reverse();
}
}
internal static bool TryParse(TiffOperationContext context, ReadOnlySpan <byte> data, out TiffImageFileDirectoryEntry entry)
{
if (data.Length < 12)
{
entry = default;
return(false);
}
ushort tag;
short type;
tag = MemoryMarshal.Read <ushort>(data);
type = MemoryMarshal.Read <short>(data.Slice(2));
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
tag = BinaryPrimitives.ReverseEndianness(tag);
type = BinaryPrimitives.ReverseEndianness(type);
}
data = data.Slice(4);
if (context.ByteCountOfValueOffsetField == 4)
{
uint count32 = MemoryMarshal.Read <uint>(data);
uint offset32 = MemoryMarshal.Read <uint>(data.Slice(4));
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
count32 = BinaryPrimitives.ReverseEndianness(count32);
offset32 = BinaryPrimitives.ReverseEndianness(offset32);
}
entry = new TiffImageFileDirectoryEntry((TiffTag)tag, (TiffFieldType)type, (long)(ulong)count32, (long)(ulong)offset32);
return(true);
}
else if (context.ByteCountOfValueOffsetField == 8)
{
if (data.Length < 16)
{
entry = default;
return(false);
}
ulong count64 = MemoryMarshal.Read <ulong>(data);
ulong offset64 = MemoryMarshal.Read <ulong>(data.Slice(8));
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
count64 = BinaryPrimitives.ReverseEndianness(count64);
offset64 = BinaryPrimitives.ReverseEndianness(offset64);
}
entry = new TiffImageFileDirectoryEntry((TiffTag)tag, (TiffFieldType)type, (long)count64, (long)offset64);
return(true);
}
else
{
entry = default;
return(false);
}
}
internal int Write(TiffOperationContext context, Span <byte> destination)
{
if (destination.Length < 12)
{
throw new ArgumentException("Destination too short.", nameof(destination));
}
ushort tag = (ushort)Tag, type = (ushort)Type;
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
tag = BinaryPrimitives.ReverseEndianness(tag);
type = BinaryPrimitives.ReverseEndianness(type);
}
MemoryMarshal.Write(destination, ref tag);
MemoryMarshal.Write(destination.Slice(2), ref type);
destination = destination.Slice(4);
if (context.ByteCountOfValueOffsetField == 4)
{
uint count32 = (uint)ValueCount, offset32 = (uint)ValueOffset;
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
count32 = BinaryPrimitives.ReverseEndianness(count32);
offset32 = BinaryPrimitives.ReverseEndianness(offset32);
}
MemoryMarshal.Write(destination, ref count32);
MemoryMarshal.Write(destination.Slice(4), ref offset32);
return(12);
}
else if (context.ByteCountOfValueOffsetField == 8)
{
if (destination.Length < 16)
{
throw new ArgumentException("Destination too short.", nameof(destination));
}
ulong count64 = (ulong)ValueCount, offset64 = (ulong)ValueOffset;
if (context.IsLittleEndian != BitConverter.IsLittleEndian)
{
count64 = BinaryPrimitives.ReverseEndianness(count64);
offset64 = BinaryPrimitives.ReverseEndianness(offset64);
}
MemoryMarshal.Write(destination, ref count64);
MemoryMarshal.Write(destination.Slice(8), ref offset64);
return(20);
}
else
{
throw new NotSupportedException();
}
}
internal bool TryDetermineInlined(TiffOperationContext context, out bool isInlined)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
if (!TryDetermineValueLength(out long bytesLength))
{
isInlined = false;
return(false);
}
isInlined = bytesLength <= context.ByteCountOfValueOffsetField;
return(true);
}