public static void ReadMaxp(DataReader reader, TableRecord[] tables, ref FaceHeader header)
{
SeekToTable(reader, tables, FourCC.Maxp, required: true);
if (reader.ReadInt32BE() != 0x00010000)
throw new InvalidFontException("Font contains an old style maxp table.");
header.GlyphCount = reader.ReadUInt16BE();
if (header.GlyphCount > MaxGlyphs)
throw new InvalidFontException("Font contains too many glyphs.");
// skip maxPoints, maxContours, maxCompositePoints, maxCompositeContours, maxZones
reader.Skip(sizeof(short) * 5);
header.MaxTwilightPoints = reader.ReadUInt16BE();
header.MaxStorageLocations = reader.ReadUInt16BE();
header.MaxFunctionDefs = reader.ReadUInt16BE();
header.MaxInstructionDefs = reader.ReadUInt16BE();
header.MaxStackSize = reader.ReadUInt16BE();
// sanity checking
if (header.MaxTwilightPoints > MaxTwilightPoints || header.MaxStorageLocations > MaxStorageLocations ||
header.MaxFunctionDefs > MaxFunctionDefs || header.MaxInstructionDefs > MaxFunctionDefs ||
header.MaxStackSize > MaxStackSize)
throw new InvalidFontException("Font programs have limits that are larger than built-in sanity checks.");
}
public static TableRecord[] ReadFaceHeader(DataReader reader)
{
var tag = reader.ReadUInt32BE();
//if (tag != TTFv1 && tag != TTFv2 && tag != FourCC.True)
// throw new InvalidFontException("Unknown or unsupported sfnt version.");
var tableCount = reader.ReadUInt16BE();
reader.Skip(6); // skip the rest of the header
// read each font table descriptor
var tables = new TableRecord[tableCount];
for (int i = 0; i < tableCount; i++)
{
tables[i] = new TableRecord {
Tag = reader.ReadUInt32(),
CheckSum = reader.ReadUInt32BE(),
Offset = reader.ReadUInt32BE(),
Length = reader.ReadUInt32BE(),
};
}
return(tables);
}
public unsafe static SbitTable Read(DataReader reader, TableRecord[] tables)
{
if (!SfntTables.SeekToTable(reader, tables, FourCC.Eblc))
return null;
// skip version
var baseOffset = reader.Position;
reader.Skip(sizeof(int));
// load each strike table
var count = reader.ReadInt32BE();
if (count > MaxBitmapStrikes)
throw new InvalidFontException("Too many bitmap strikes in font.");
var sizeTableHeaders = stackalloc BitmapSizeTable[count];
for (int i = 0; i < count; i++)
{
sizeTableHeaders[i].SubTableOffset = reader.ReadUInt32BE();
sizeTableHeaders[i].SubTableSize = reader.ReadUInt32BE();
sizeTableHeaders[i].SubTableCount = reader.ReadUInt32BE();
// skip colorRef, metrics entries, start and end glyph indices
reader.Skip(sizeof(uint) + sizeof(ushort) * 2 + 12 * 2);
sizeTableHeaders[i].PpemX = reader.ReadByte();
sizeTableHeaders[i].PpemY = reader.ReadByte();
sizeTableHeaders[i].BitDepth = reader.ReadByte();
sizeTableHeaders[i].Flags = (BitmapSizeFlags)reader.ReadByte();
}
// read index subtables
var indexSubTables = stackalloc IndexSubTable[count];
for (int i = 0; i < count; i++)
{
reader.Seek(baseOffset + sizeTableHeaders[i].SubTableOffset);
indexSubTables[i] = new IndexSubTable
{
FirstGlyph = reader.ReadUInt16BE(),
LastGlyph = reader.ReadUInt16BE(),
Offset = reader.ReadUInt32BE()
};
}
// read the actual data for each strike table
for (int i = 0; i < count; i++)
{
// read the subtable header
reader.Seek(baseOffset + sizeTableHeaders[i].SubTableOffset + indexSubTables[i].Offset);
var indexFormat = reader.ReadUInt16BE();
var imageFormat = reader.ReadUInt16BE();
var imageDataOffset = reader.ReadUInt32BE();
}
return null;
}
public static void ReadHead(DataReader reader, TableRecord[] tables, out FaceHeader header)
{
SeekToTable(reader, tables, FourCC.Head, required: true);
// 'head' table contains global information for the font face
// we only care about a few fields in it
reader.Skip(sizeof(int) * 4); // version, revision, checksum, magic number
header = new FaceHeader
{
Flags = (HeadFlags)reader.ReadUInt16BE(),
UnitsPerEm = reader.ReadUInt16BE()
};
if (header.UnitsPerEm == 0)
throw new InvalidFontException("Invalid 'head' table.");
// skip over created and modified times, bounding box,
// deprecated style bits, direction hints, and size hints
reader.Skip(sizeof(long) * 2 + sizeof(short) * 7);
header.IndexFormat = (IndexFormat)reader.ReadInt16BE();
}
public static TableRecord[] ReadFaceHeader(DataReader reader)
{
var tag = reader.ReadUInt32BE();
if (tag != TTFv1 && tag != TTFv2 && tag != FourCC.True)
throw new InvalidFontException("Unknown or unsupported sfnt version.");
var tableCount = reader.ReadUInt16BE();
reader.Skip(6); // skip the rest of the header
// read each font table descriptor
var tables = new TableRecord[tableCount];
for (int i = 0; i < tableCount; i++)
{
tables[i] = new TableRecord
{
Tag = reader.ReadUInt32(),
CheckSum = reader.ReadUInt32BE(),
Offset = reader.ReadUInt32BE(),
Length = reader.ReadUInt32BE(),
};
}
return tables;
}
public static KerningTable ReadKern(DataReader reader, TableRecord[] tables)
{
// kern table is optional
if (!SfntTables.SeekToTable(reader, tables, FourCC.Kern))
return null;
// skip version
reader.Skip(sizeof(short));
// read each subtable and accumulate kerning values
var tableData = new Dictionary<uint, int>();
var subtableCount = reader.ReadUInt16BE();
for (int i = 0; i < subtableCount; i++)
{
// skip version
var currentOffset = reader.Position;
reader.Skip(sizeof(short));
var length = reader.ReadUInt16BE();
var coverage = reader.ReadUInt16BE();
// we (and Windows) only support Format 0 tables
// only care about tables with horizontal kerning data
var kc = (KernCoverage)coverage;
if ((coverage & FormatMask) == 0 && (kc & KernCoverage.Horizontal) != 0 && (kc & KernCoverage.CrossStream) == 0)
{
// read the number of entries; skip over the rest of the header
var entryCount = reader.ReadUInt16BE();
reader.Skip(sizeof(short) * 3);
var isMin = (kc & KernCoverage.Minimum) != 0;
var isOverride = (kc & KernCoverage.Override) != 0;
// read in each entry and accumulate its kerning data
for (int j = 0; j < entryCount; j++)
{
var left = reader.ReadUInt16BE();
var right = reader.ReadUInt16BE();
var value = reader.ReadInt16BE();
// look up the current value, if we have one; if not, start at zero
int current = 0;
var key = ((uint)left << 16) | right;
tableData.TryGetValue(key, out current);
if (isMin)
{
if (current < value)
tableData[key] = value;
}
else if (isOverride)
tableData[key] = value;
else
tableData[key] = current + value;
}
}
// jump to the next subtable
reader.Seek(currentOffset + length);
}
return new KerningTable(tableData);
}
public static CharacterMap ReadCmap(DataReader reader, TableRecord[] tables)
{
SfntTables.SeekToTable(reader, tables, FourCC.Cmap, required: true);
// skip version
var cmapOffset = reader.Position;
reader.Skip(sizeof(short));
// read all of the subtable headers
var subtableCount = reader.ReadUInt16BE();
var subtableHeaders = new CmapSubtableHeader[subtableCount];
for (int i = 0; i < subtableHeaders.Length; i++)
{
subtableHeaders[i] = new CmapSubtableHeader
{
PlatformID = reader.ReadUInt16BE(),
EncodingID = reader.ReadUInt16BE(),
Offset = reader.ReadUInt32BE()
};
}
// search for a "full" Unicode table first
var chosenSubtableOffset = 0u;
for (int i = 0; i < subtableHeaders.Length; i++)
{
var platform = subtableHeaders[i].PlatformID;
var encoding = subtableHeaders[i].EncodingID;
if ((platform == PlatformID.Microsoft && encoding == WindowsEncoding.UnicodeFull) ||
(platform == PlatformID.Unicode && encoding == UnicodeEncoding.Unicode32))
{
chosenSubtableOffset = subtableHeaders[i].Offset;
break;
}
}
// if no full unicode table, just grab the first
// one that supports any flavor of Unicode
if (chosenSubtableOffset == 0)
{
for (int i = 0; i < subtableHeaders.Length; i++)
{
var platform = subtableHeaders[i].PlatformID;
var encoding = subtableHeaders[i].EncodingID;
if ((platform == PlatformID.Microsoft && encoding == WindowsEncoding.UnicodeBmp) ||
platform == PlatformID.Unicode)
{
chosenSubtableOffset = subtableHeaders[i].Offset;
break;
}
}
}
// no unicode support at all is an error
if (chosenSubtableOffset == 0)
throw new Exception("Font does not support Unicode.");
// jump to our chosen table and find out what format it's in
reader.Seek(cmapOffset + chosenSubtableOffset);
var format = reader.ReadUInt16BE();
switch (format)
{
case 4: return ReadCmapFormat4(reader);
default: throw new Exception("Unsupported cmap format.");
}
}
public static bool SeekToTable(DataReader reader, TableRecord[] tables, FourCC tag, bool required = false)
{
// check if we have the desired table and that it's not empty
var index = FindTable(tables, tag);
if (index == -1 || tables[index].Length == 0)
{
if (required)
//throw new InvalidFontException($"Missing or empty '{tag}' table.");
throw new InvalidFontException(string.Format(
"Missing or empty '{0}' table.", tag));
return false;
}
// seek to the appropriate offset
reader.Seek(tables[index].Offset);
return true;
}
public static byte[] ReadProgram(DataReader reader, TableRecord[] tables, FourCC tag)
{
var index = FindTable(tables, tag);
if (index == -1)
return null;
reader.Seek(tables[index].Offset);
return reader.ReadBytes((int)tables[index].Length);
}
public static int FindTable(TableRecord[] tables, FourCC tag)
{
var index = -1;
for (int i = 0; i < tables.Length; i++)
{
if (tables[i].Tag == tag)
{
index = i;
break;
}
}
return index;
}
public static FUnit[] ReadCvt(DataReader reader, TableRecord[] tables)
{
var index = FindTable(tables, FourCC.Cvt);
if (index == -1)
return null;
reader.Seek(tables[index].Offset);
var results = new FUnit[tables[index].Length / sizeof(short)];
for (int i = 0; i < results.Length; i++)
results[i] = (FUnit)reader.ReadInt16BE();
return results;
}
public unsafe static NameData ReadNames(DataReader reader, TableRecord[] tables)
{
if (!SeekToTable(reader, tables, FourCC.Name))
return default(NameData);
// read header
var currentOffset = reader.Position;
var format = reader.ReadUInt16BE();
var count = reader.ReadUInt16BE();
var dataOffset = currentOffset + reader.ReadUInt16BE();
// read name records, filtering out non-Unicode and platforms we don't know about
var stringData = stackalloc StringData[count];
var stringDataCount = 0;
for (int i = 0; i < count; i++)
{
var platform = reader.ReadUInt16BE();
var encoding = reader.ReadUInt16BE();
var language = reader.ReadUInt16BE();
var name = reader.ReadUInt16BE();
var length = reader.ReadUInt16BE();
var offset = reader.ReadUInt16BE();
// we only support Unicode strings
if (platform == PlatformID.Microsoft)
{
if (encoding != WindowsEncoding.UnicodeBmp && encoding != WindowsEncoding.UnicodeFull)
continue;
if (language != CultureInfo.CurrentCulture.LCID)
continue;
}
else if (platform != PlatformID.Unicode)
continue;
stringData[stringDataCount++] = new StringData
{
Name = name,
Offset = offset,
Length = length
};
}
// find strings we care about and extract them from the blob
var nameData = new NameData();
for (int i = 0; i < stringDataCount; i++)
{
var data = stringData[i];
switch (data.Name)
{
case NameID.FamilyName: nameData.FamilyName = ExtractString(reader, dataOffset, data); break;
case NameID.SubfamilyName: nameData.SubfamilyName = ExtractString(reader, dataOffset, data); break;
case NameID.UniqueID: nameData.UniqueID = ExtractString(reader, dataOffset, data); break;
case NameID.FullName: nameData.FullName = ExtractString(reader, dataOffset, data); break;
case NameID.Version: nameData.Version = ExtractString(reader, dataOffset, data); break;
case NameID.Description: nameData.Description = ExtractString(reader, dataOffset, data); break;
case NameID.TypographicFamilyName: nameData.TypographicFamilyName = ExtractString(reader, dataOffset, data); break;
case NameID.TypographicSubfamilyName: nameData.TypographicSubfamilyName = ExtractString(reader, dataOffset, data); break;
}
}
return nameData;
}
public static void ReadLoca(DataReader reader, TableRecord[] tables, IndexFormat format, uint* table, int count)
{
SeekToTable(reader, tables, FourCC.Loca, required: true);
if (format == IndexFormat.Short)
{
// values are ushort, divided by 2, so we need to shift back
for (int i = 0; i < count; i++)
*table++ = (uint)(reader.ReadUInt16BE() << 1);
}
else
{
for (int i = 0; i < count; i++)
*table++ = reader.ReadUInt32BE();
}
}
public static void ReadPost(DataReader reader, TableRecord[] tables, ref FaceHeader header)
{
if (!SeekToTable(reader, tables, FourCC.Post))
return;
// skip over version and italicAngle
reader.Skip(sizeof(int) * 2);
header.UnderlinePosition = reader.ReadInt16BE();
header.UnderlineThickness = reader.ReadInt16BE();
header.IsFixedPitch = reader.ReadUInt32BE() != 0;
}
public static OS2Data ReadOS2(DataReader reader, TableRecord[] tables)
{
SeekToTable(reader, tables, FourCC.OS_2, required: true);
// skip over version, xAvgCharWidth
reader.Skip(sizeof(short) * 2);
var result = new OS2Data
{
Weight = (FontWeight)reader.ReadUInt16BE(),
Stretch = (FontStretch)reader.ReadUInt16BE()
};
// skip over fsType, ySubscriptXSize, ySubscriptYSize, ySubscriptXOffset, ySubscriptYOffset,
// ySuperscriptXSize, ySuperscriptYSize, ySuperscriptXOffset, ySuperscriptXOffset
reader.Skip(sizeof(short) * 9);
result.StrikeoutSize = reader.ReadInt16BE();
result.StrikeoutPosition = reader.ReadInt16BE();
// skip over sFamilyClass, panose[10], ulUnicodeRange1-4, achVendID[4]
reader.Skip(sizeof(short) + sizeof(int) * 4 + 14);
// check various style flags
var fsSelection = (FsSelectionFlags)reader.ReadUInt16BE();
result.Style = (fsSelection & FsSelectionFlags.Italic) != 0 ? FontStyle.Italic :
(fsSelection & FsSelectionFlags.Bold) != 0 ? FontStyle.Bold :
(fsSelection & FsSelectionFlags.Oblique) != 0 ? FontStyle.Oblique :
FontStyle.Regular;
result.IsWWSFont = (fsSelection & FsSelectionFlags.WWS) != 0;
result.UseTypographicMetrics = (fsSelection & FsSelectionFlags.UseTypoMetrics) != 0;
// skip over usFirstCharIndex, usLastCharIndex
reader.Skip(sizeof(short) * 2);
result.TypographicAscender = reader.ReadInt16BE();
result.TypographicDescender = reader.ReadInt16BE();
result.TypographicLineGap = reader.ReadInt16BE();
result.WinAscent = reader.ReadUInt16BE();
result.WinDescent = reader.ReadUInt16BE();
// skip over ulCodePageRange1-2
reader.Skip(sizeof(int) * 2);
result.XHeight = reader.ReadInt16BE();
result.CapHeight = reader.ReadInt16BE();
return result;
}