public static TupleVariationHeader Read(BinaryReader reader, int axisCount)
{
TupleVariationHeader header = new TupleVariationHeader();
header.variableDataSize = reader.ReadUInt16();
ushort tupleIndex = reader.ReadUInt16();
int flags = (tupleIndex >> 12) & 0xF; //The high 4 bits are flags(see below).
header.flags = flags; //The high 4 bits are flags(see below).
header.indexToSharedTupleRecArray = (ushort)(tupleIndex & 0x0FFF); // The low 12 bits are an index into a shared tuple records array.
if ((flags & ((int)TupleIndexFormat.EMBEDDED_PEAK_TUPLE >> 12)) == ((int)TupleIndexFormat.EMBEDDED_PEAK_TUPLE >> 12))
{
//TODO:...
header.peakTuple = TupleRecord.ReadTupleRecord(reader, axisCount);
}
if ((flags & ((int)TupleIndexFormat.INTERMEDIATE_REGION >> 12)) == ((int)TupleIndexFormat.INTERMEDIATE_REGION >> 12))
{
//TODO:...
header.intermediateStartTuple = TupleRecord.ReadTupleRecord(reader, axisCount);
header.intermediateEndTuple = TupleRecord.ReadTupleRecord(reader, axisCount);
}
return(header);
}
void ReadShareTupleArray(BinaryReader reader, ushort sharedTupleCount)
{
//-------------
//Shared tuples array
//-------------
//The shared tuples array provides a set of variation-space positions
//that can be referenced by variation data for any glyph.
//The shared tuples array follows the GlyphVariationData offsets array
//at the end of the 'gvar' header.
//This data is simply an array of tuple records, each representing a position in the font’s variation space.
//Shared tuples array:
//Type Name Description
//TupleRecord sharedTuples[sharedTupleCount] Array of tuple records shared across all glyph variation data tables.
//Tuple records that are in the shared array or
//that are contained directly within a given glyph variation data table
//use 2.14 values to represent normalized coordinate values.
//See the Common Table Formats chapter for details.
//
//Tuple Records
//https://docs.microsoft.com/en-us/typography/opentype/spec/otvarcommonformats
//The tuple variation store formats make reference to regions within the font’s variation space using tuple records.
//These references identify positions in terms of normalized coordinates, which use F2DOT14 values.
//Tuple record(F2DOT14):
//Type Name Description
//F2DOT14 coordinates[axisCount] Coordinate array specifying a position within the font’s variation space.
// The number of elements must match the axisCount specified in the 'fvar' table.
TupleRecord[] tubleRecords = new TupleRecord[sharedTupleCount];
for (int i = 0; i < sharedTupleCount; ++i)
{
TupleRecord rec = new TupleRecord();
float[] coords = new float[axisCount];
rec.coords = coords;
for (int n = 0; n < axisCount; ++n)
{
coords[n] = reader.ReadF2Dot14();
}
tubleRecords[i] = rec;
}
}
public ushort postScriptNameID;//point to name table, will be resolved later
public void ReadContent(BinaryReader reader, int axisCount, int instanceRecordSize)
{
long expectedEndPos = reader.BaseStream.Position + instanceRecordSize;
subfamilyNameID = reader.ReadUInt16();
flags = reader.ReadUInt16();
float[] coords = new float[axisCount];
for (int i = 0; i < axisCount; ++i)
{
coords[i] = reader.ReadFixed();
}
coordinates = new TupleRecord(coords);
if (reader.BaseStream.Position < expectedEndPos)
{
//optional field
postScriptNameID = reader.ReadUInt16();
}
}
