/// <summary>
/// Reads the Offset and Directory tables. If the FontFileStream represents
/// a TrueType collection, this method will look for the aforementioned
/// tables belonging to <i>fontName</i>.
/// </summary>
/// <remarks>
/// This method can handle a TrueType collection.
/// </remarks>
protected void ReadTableHeaders()
{
// Check for possible TrueType collection
string tag = Encoding.ASCII.GetString(stream.ReadTag());
if (tag == TableNames.Ttcf)
{
// Skip Version field - will be either 1.0 or 2.0
stream.Skip(PrimitiveSizes.ULong);
// Number of fonts in TrueType collection
int numFonts = (int)stream.ReadULong();
bool foundFont = false;
for (int i = 0; i < numFonts && !foundFont; i++)
{
// Offset from beginning of file to a font's subtable
uint directoryOffset = stream.ReadULong();
// Set a restore point since the code below will alter the stream position
stream.SetRestorePoint();
stream.Position = directoryOffset;
header = new TrueTypeHeader();
header.Read(stream);
// To ascertain whether this font is the one we're looking for,
// we must read the 'name' table.
if (!header.Contains(TableNames.Name))
{
throw new Exception("Unable to parse TrueType collection - missing 'head' table.");
}
// If font name is not supplied, select the first font in the colleciton;
// otherwise must have an exact match
NameTable nameTable = (NameTable)GetTable(TableNames.Name);
if (fontName == String.Empty || nameTable.FullName == fontName)
{
foundFont = true;
}
// Stream will now point to the next directory offset
stream.Restore();
}
// We were unable to locate font in collection
if (!foundFont)
{
throw new Exception("Unable to locate font '" + fontName + "' in TrueType collection");
}
}
else
{
stream.Position = 0;
// Read Offset and Directory tables
header = new TrueTypeHeader();
header.Read(stream);
}
}
/// <summary>
/// Reads the contents of the "post" table from the supplied stream
/// at the current position.
/// </summary>
/// <param name="reader"></param>
protected internal override void Read(FontFileReader reader)
{
FontFileStream stream = reader.Stream;
version = stream.ReadFixed();
// The italic angle is stored in the stupid fixed field format.
italicAngle = (float)stream.ReadFixed() / 65536.0f;
underlinePosition = stream.ReadFWord();
underlineThickness = stream.ReadFWord();
fixedPitch = stream.ReadULong();
minMemType42 = stream.ReadULong();
maxMemType42 = stream.ReadULong();
minMemType1 = stream.ReadULong();
maxMemType1 = stream.ReadULong();
}
protected internal void Read(FontFileStream stream) {
// Skip sfnt version (0x00010000 for version 1.0).
stream.Skip(PrimitiveSizes.Fixed);
// Number of tables
int numTables = stream.ReadUShort();
// Skip searchRange, entrySelector and rangeShift entries (3 x ushort)
stream.Skip(PrimitiveSizes.UShort*3);
directoryEntries = new Hashtable(numTables);
for (int i = 0; i < numTables; i++) {
DirectoryEntry entry = new DirectoryEntry(
stream.ReadTag(), // 4-byte identifier.
stream.ReadULong(), // CheckSum for this table.
stream.ReadULong(), // Offset from beginning of TrueType font file.
stream.ReadULong() // Length of this table.
);
directoryEntries.Add(entry.TableName, entry);
}
}
/// <summary>
/// Reads the contents of the "head" table from the current position
/// in the supplied stream.
/// </summary>
/// <param name="reader"></param>
protected internal override void Read(FontFileReader reader)
{
FontFileStream stream = reader.Stream;
versionNo = stream.ReadFixed();
fontRevision = stream.ReadFixed();
checkSumAdjustment = stream.ReadULong();
magicNumber = stream.ReadULong();
flags = stream.ReadUShort();
unitsPermEm = stream.ReadUShort();
// Some fonts have dodgy date offsets that cause AddSeconds to throw an exception
createDate = GetDate(stream.ReadLongDateTime());
updateDate = GetDate(stream.ReadLongDateTime());
xMin = stream.ReadShort();
yMin = stream.ReadShort();
xMax = stream.ReadShort();
yMax = stream.ReadShort();
macStyle = stream.ReadUShort();
lowestRecPPEM = stream.ReadUShort();
fontDirectionHint = stream.ReadShort();
indexToLocFormat = stream.ReadShort();
glyphDataFormat = stream.ReadShort();
}
protected internal void Read(FontFileStream stream)
{
// Skip sfnt version (0x00010000 for version 1.0).
stream.Skip(PrimitiveSizes.Fixed);
// Number of tables
int numTables = stream.ReadUShort();
// Skip searchRange, entrySelector and rangeShift entries (3 x ushort)
stream.Skip(PrimitiveSizes.UShort * 3);
directoryEntries = new Hashtable(numTables);
for (int i = 0; i < numTables; i++)
{
DirectoryEntry entry = new DirectoryEntry(
stream.ReadTag(), // 4-byte identifier.
stream.ReadULong(), // CheckSum for this table.
stream.ReadULong(), // Offset from beginning of TrueType font file.
stream.ReadULong() // Length of this table.
);
directoryEntries.Add(entry.TableName, entry);
}
}
/// <summary>
/// Calculates the checksum of a <see cref="FontTable"/>.
/// </summary>
/// <remarks>
/// The supplied <i>stream</i> must be positioned at the beginning of
/// the table.
/// </remarks>
/// <param name="length"></param>
/// <returns></returns>
private uint CalculateCheckSum(long length)
{
long numBytes = length + (length % 4);
uint checkSum = 0;
for (long i = 0; i < numBytes; i += PrimitiveSizes.ULong)
{
checkSum += stream.ReadULong();
if (checkSum > 0xFFFFFFFF)
{
checkSum = checkSum - 0xFFFFFFFF;
}
}
return(checkSum);
}
/// <summary>
/// Reads the contents of the "os/2" table from the supplied stream
/// at the current position.
/// </summary>
/// <param name="reader"></param>
protected internal override void Read(FontFileReader reader)
{
FontFileStream stream = reader.Stream;
version = stream.ReadUShort();
avgCharWidth = stream.ReadShort();
usWeightClass = stream.ReadUShort();
usWidthClass = stream.ReadUShort();
// According to the OpenType spec, bit 0 must be zero.
fsType = (ushort)(stream.ReadUShort() & ~1);
subscriptXSize = stream.ReadShort();
subscriptYSize = stream.ReadShort();
subscriptXOffset = stream.ReadShort();
subscriptYOffset = stream.ReadShort();
superscriptXSize = stream.ReadShort();
superscriptYSize = stream.ReadShort();
superscriptXOffset = stream.ReadShort();
superscriptYOffset = stream.ReadShort();
strikeoutSize = stream.ReadShort();
strikeoutPosition = stream.ReadShort();
short familyClass = stream.ReadShort();
classID = (byte)(familyClass >> 8);
subclassID = (byte)(familyClass & 255);
stream.Read(panose, 0, panose.Length);
unicodeRange1 = stream.ReadULong();
unicodeRange2 = stream.ReadULong();
unicodeRange3 = stream.ReadULong();
unicodeRange4 = stream.ReadULong();
vendorID[0] = stream.ReadChar();
vendorID[1] = stream.ReadChar();
vendorID[2] = stream.ReadChar();
vendorID[3] = stream.ReadChar();
fsSelection = stream.ReadUShort();
usFirstCharIndex = stream.ReadUShort();
usLastCharIndex = stream.ReadUShort();
typoAscender = stream.ReadShort();
typoDescender = stream.ReadShort();
typoLineGap = stream.ReadShort();
usWinAscent = stream.ReadUShort();
usWinDescent = stream.ReadUShort();
codePageRange1 = stream.ReadULong();
codePageRange2 = stream.ReadULong();
sxHeight = stream.ReadShort();
sCapHeight = stream.ReadShort();
usDefaultChar = stream.ReadUShort();
usBreakChar = stream.ReadUShort();
usMaxContext = stream.ReadUShort();
}
/// <summary>
/// Reads the contents of the "loca" table from the supplied stream
/// at the current position.
/// </summary>
/// <param name="reader"></param>
protected internal override void Read(FontFileReader reader)
{
FontFileStream stream = reader.Stream;
// Glyph offsets can be stored in either short of long format
bool isShortFormat = reader.GetHeaderTable().IsShortFormat;
// Number of glyphs including extra entry
int glyphCount = reader.GetMaximumProfileTable().GlyphCount + 1;
offsets = new ArrayList(glyphCount);
for (int i = 0; i < glyphCount; i++)
{
offsets.Insert(i, (isShortFormat) ? (uint)(stream.ReadUShort() << 1) : stream.ReadULong());
}
}
