/// <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);
}
}
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);
}
}
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);
}
}
