public static ClassSequenceRuleTable Load(BigEndianBinaryReader reader, long offset)
{
// ClassSequenceRule
// +----------------------+----------------------------------+------------------------------------------+
// | Type | Name | Description |
// +======================+==================================+==========================================+
// | uint16 | glyphCount | Number of glyphs to be matched |
// +----------------------+----------------------------------+------------------------------------------+
// | uint16 | seqLookupCount | Number of SequenceLookupRecords |
// +----------------------+----------------------------------+------------------------------------------+
// | uint16 | inputSequence[glyphCount - 1] | Sequence of classes to be matched to the |
// | | | input glyph sequence, beginning with the |
// | | | second glyph position |
// +----------------------+----------------------------------+------------------------------------------+
// | SequenceLookupRecord | seqLookupRecords[seqLookupCount] | Array of SequenceLookupRecords |
// +----------------------+----------------------------------+------------------------------------------+
reader.Seek(offset, SeekOrigin.Begin);
ushort glyphCount = reader.ReadUInt16();
ushort seqLookupCount = reader.ReadUInt16();
ushort[] inputSequence = reader.ReadUInt16Array(glyphCount - 1);
SequenceLookupRecord[] seqLookupRecords = SequenceLookupRecord.LoadArray(reader, seqLookupCount);
return(new ClassSequenceRuleTable(inputSequence, seqLookupRecords));
}
internal static SequenceLookupRecord[] LoadSequenceContextFormat3(BigEndianBinaryReader reader, long offset, out CoverageTable[] coverageTables)
{
// https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#sequence-context-format-3-coverage-based-glyph-contexts
// SequenceContextFormat3
// +----------------------+----------------------------------+-------------------------------------------+
// | Type | Name | Description |
// +======================+==================================+===========================================+
// | uint16 | format | Format identifier: format = 3 |
// +----------------------+----------------------------------+-------------------------------------------+
// | uint16 | glyphCount | Number of glyphs in the input sequence |
// +----------------------+----------------------------------+-------------------------------------------+
// | uint16 | seqLookupCount | Number of SequenceLookupRecords |
// +----------------------+----------------------------------+-------------------------------------------+
// | Offset16 | coverageOffsets[glyphCount] | Array of offsets to Coverage tables, from |
// | | | beginning of SequenceContextFormat3 |
// | | | subtable |
// +----------------------+----------------------------------+-------------------------------------------+
// | SequenceLookupRecord | seqLookupRecords[seqLookupCount] | Array of SequenceLookupRecords |
// +----------------------+----------------------------------+-------------------------------------------+
ushort glyphCount = reader.ReadUInt16();
ushort seqLookupCount = reader.ReadUInt16();
ushort[] coverageOffsets = reader.ReadUInt16Array(glyphCount);
SequenceLookupRecord[] seqLookupRecords = SequenceLookupRecord.LoadArray(reader, seqLookupCount);
coverageTables = new CoverageTable[glyphCount];
for (int i = 0; i < coverageTables.Length; i++)
{
coverageTables[i] = CoverageTable.Load(reader, offset + coverageOffsets[i]);
}
return(seqLookupRecords);
}
internal static SequenceLookupRecord[] LoadChainedSequenceContextFormat3(
BigEndianBinaryReader reader,
long offset,
out CoverageTable[] backtrackCoverageTables,
out CoverageTable[] inputCoverageTables,
out CoverageTable[] lookaheadCoverageTables)
{
// https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#chseqctxt3
// ChainedSequenceContextFormat3 1
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | Type | Name | Description |
// +======================+===============================================+================================================================+
// | uint16 | format | Format identifier: format = 3 |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | uint16 | backtrackGlyphCount | Number of glyphs in the backtrack sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | Offset16 | backtrackCoverageOffsets[backtrackGlyphCount] | Array of offsets to coverage tables for the backtrack sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | uint16 | inputGlyphCount | Number of glyphs in the input sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | Offset16 | inputCoverageOffsets[inputGlyphCount] | Array of offsets to coverage tables for the input sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | uint16 | lookaheadGlyphCount | Number of glyphs in the lookahead sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | Offset16 | lookaheadCoverageOffsets[lookaheadGlyphCount] | Array of offsets to coverage tables for the lookahead sequence |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | uint16 | seqLookupCount | Number of SequenceLookupRecords |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
// | SequenceLookupRecord | seqLookupRecords[seqLookupCount] | Array of SequenceLookupRecords |
// +----------------------+-----------------------------------------------+----------------------------------------------------------------+
ushort backtrackGlyphCount = reader.ReadUInt16();
ushort[] backtrackCoverageOffsets = reader.ReadUInt16Array(backtrackGlyphCount);
ushort inputGlyphCount = reader.ReadUInt16();
ushort[] inputCoverageOffsets = reader.ReadUInt16Array(inputGlyphCount);
ushort lookaheadGlyphCount = reader.ReadUInt16();
ushort[] lookaheadCoverageOffsets = reader.ReadUInt16Array(lookaheadGlyphCount);
ushort seqLookupCount = reader.ReadUInt16();
SequenceLookupRecord[] seqLookupRecords = SequenceLookupRecord.LoadArray(reader, seqLookupCount);
backtrackCoverageTables = CoverageTable.LoadArray(reader, offset, backtrackCoverageOffsets);
inputCoverageTables = CoverageTable.LoadArray(reader, offset, inputCoverageOffsets);
lookaheadCoverageTables = CoverageTable.LoadArray(reader, offset, lookaheadCoverageOffsets);
return(seqLookupRecords);
}
public static ChainedClassSequenceRuleTable Load(BigEndianBinaryReader reader, long offset)
{
// ChainedClassSequenceRule
// +----------------------+----------------------------------------+--------------------------------------------+
// | Type | Name | Description |
// +======================+========================================+============================================+
// | uint16 | backtrackGlyphCount | Number of glyphs in the backtrack |
// | | | sequence |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | backtrackSequence[backtrackGlyphCount] | Array of backtrack-sequence classes |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | inputGlyphCount | Total number of glyphs in the input |
// | | | sequence |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | inputSequence[inputGlyphCount - 1] | Array of input sequence classes, beginning |
// | | | with the second glyph position |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | lookaheadGlyphCount | Number of glyphs in the lookahead |
// | | | sequence |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | lookaheadSequence[lookaheadGlyphCount] | Array of lookahead-sequence classes |
// +----------------------+----------------------------------------+--------------------------------------------+
// | uint16 | seqLookupCount | Number of SequenceLookupRecords |
// +----------------------+----------------------------------------+--------------------------------------------+
// | SequenceLookupRecord | seqLookupRecords[seqLookupCount] | Array of SequenceLookupRecords |
// +----------------------+----------------------------------------+--------------------------------------------+
reader.Seek(offset, SeekOrigin.Begin);
ushort backtrackGlyphCount = reader.ReadUInt16();
ushort[] backtrackSequence = reader.ReadUInt16Array(backtrackGlyphCount);
ushort inputGlyphCount = reader.ReadUInt16();
ushort[] inputSequence = reader.ReadUInt16Array(inputGlyphCount - 1);
ushort lookaheadGlyphCount = reader.ReadUInt16();
ushort[] lookaheadSequence = reader.ReadUInt16Array(lookaheadGlyphCount);
ushort seqLookupCount = reader.ReadUInt16();
SequenceLookupRecord[] seqLookupRecords = SequenceLookupRecord.LoadArray(reader, seqLookupCount);
return(new ChainedClassSequenceRuleTable(backtrackSequence, inputSequence, lookaheadSequence, seqLookupRecords));
}
public static SequenceLookupRecord[] LoadArray(BigEndianBinaryReader reader, int count)
{
// +--------+-----------------+---------------------------------------------------+
// | Type | Name | Description |
// +========+=================+===================================================+
// | uint16 | SequenceIndex | Index into current glyph sequence-first glyph = 0 |
// +--------+-----------------+---------------------------------------------------+
// | uint16 | LookupListIndex | Lookup to apply to that position-zero-based. |
// +--------+-----------------+---------------------------------------------------+
var records = new SequenceLookupRecord[count];
for (int i = 0; i < records.Length; i++)
{
records[i] = new SequenceLookupRecord(reader.ReadUInt16(), reader.ReadUInt16());
}
return(records);
}
public static SequenceRuleTable Load(BigEndianBinaryReader reader, long offset)
{
// +----------------------+----------------------------------+---------------------------------------------------------+
// | Type | Name | Description |
// +======================+==================================+=========================================================+
// | uint16 | glyphCount | Number of glyphs in the input glyph sequence |
// +----------------------+----------------------------------+---------------------------------------------------------+
// | uint16 | seqLookupCount | Number of SequenceLookupRecords |
// +----------------------+----------------------------------+---------------------------------------------------------+
// | uint16 | inputSequence[glyphCount - 1] | Array of input glyph IDs—starting with the second glyph |
// +----------------------+----------------------------------+---------------------------------------------------------+
// | SequenceLookupRecord | seqLookupRecords[seqLookupCount] | Array of Sequence lookup records |
// +----------------------+----------------------------------+---------------------------------------------------------+
reader.Seek(offset, SeekOrigin.Begin);
ushort glyphCount = reader.ReadUInt16();
ushort seqLookupCount = reader.ReadUInt16();
ushort[] inputSequence = reader.ReadUInt16Array(glyphCount - 1);
SequenceLookupRecord[] seqLookupRecords = SequenceLookupRecord.LoadArray(reader, seqLookupCount);
return(new SequenceRuleTable(inputSequence, seqLookupRecords));
}
