/******************
* protected methods
*/
protected static OffsetTable ReadOffsetTable(OTFile file, uint filepos)
{
// read the Offset Table from the file
const int SIZEOF_OFFSETTABLE = 12;
OffsetTable ot = null;
// read the offset table
MBOBuffer buf = file.ReadPaddedBuffer(filepos, SIZEOF_OFFSETTABLE);
if (buf != null)
{
if (OTFile.IsValidSfntVersion(buf.GetUint(0)))
{
ot = new OffsetTable(buf);
}
}
// now read the directory entries
if (ot != null)
{
const int SIZEOF_DIRECTORYENTRY = 16;
for (int i = 0; i < ot.numTables; i++)
{
uint dirFilePos = (uint)(filepos + SIZEOF_OFFSETTABLE + i * SIZEOF_DIRECTORYENTRY);
MBOBuffer DirEntBuf = file.ReadPaddedBuffer(dirFilePos, SIZEOF_DIRECTORYENTRY);
if (DirEntBuf != null)
{
DirectoryEntry de = new DirectoryEntry(DirEntBuf);
ot.DirectoryEntries.Add(de);
}
else
{
Debug.Assert(false);
break;
}
}
}
return(ot);
}
// Offset relative to subtable start
// Return value is relative to subtable start
static public uint MaxOffset( MBOBuffer b,
uint subtableOffset,
uint offset )
{
uint nRec = b.GetUint( subtableOffset + offset );
return
offset + 4 + ( nRec * UVSMapping.BYTES_PER_RECORD ) - 1;
}
public void Populate( MBOBuffer b,
uint subtableOffset,
uint offset )
{
uint o = subtableOffset + offset;
mappings = new List<UVSMapping>();
numUVSMappings = b.GetUint( o );
o += 4;
for ( uint i = 0; i < numUVSMappings; i++ ) {
UVSMapping r = new UVSMapping();
r.Populate( b, o );
mappings.Add( r );
o += UVSMapping.BYTES_PER_RECORD;
}
}
// Offset relative to subtable start
// Return value is relative to subtable start
static public uint MaxOffset( MBOBuffer b,
uint subtableOffset,
uint offset )
{
uint nRec = b.GetUint( subtableOffset + offset );
return
offset + 4 +
( nRec * UnicodeValueRange.BYTES_PER_RECORD )
- 1;
}
// Offset is relative to start of subtable
public void Populate( MBOBuffer b,
uint subtableOffset,
uint offset )
{
uint o = subtableOffset + offset;
numUnicodeValueRanges = b.GetUint( o );
ranges = new List<UnicodeValueRange>();
o += 4;
for ( uint i = 0; i < numUnicodeValueRanges; i++ ) {
UnicodeValueRange r = new UnicodeValueRange();
r.Populate( b, o );
ranges.Add( r );
o += UnicodeValueRange.BYTES_PER_RECORD;
}
}
/************************
* public static methods
*/
public static TTCHeader ReadTTCHeader(OTFile file)
{
TTCHeader ttc = null;
const int SIZEOF_FIRSTTHREEFIELDS = 12;
const int SIZEOF_UINT = 4;
// read the first three fields of the TTC Header
// starting at the beginning of the file
MBOBuffer buf = file.ReadPaddedBuffer(0, SIZEOF_FIRSTTHREEFIELDS);
OTTag tag = null;
uint version = 0;
uint DirectoryCount = 0;
if (buf != null)
{
tag = new OTTag(buf.GetBuffer());
version = buf.GetUint(4);
DirectoryCount = buf.GetUint(8);
}
// if the tag and the version and the dir count seem correct then
// allocate a TTCHeader object and try to read the rest of the header
if ((string)tag == "ttcf" &&
(version == 0x00010000 || version == 0x00020000) &&
12 + DirectoryCount * SIZEOF_UINT < file.GetFileLength())
{
ttc = new TTCHeader();
ttc.TTCTag = tag;
ttc.version = version;
ttc.DirectoryCount = DirectoryCount;
// Directory offsets
buf = file.ReadPaddedBuffer(SIZEOF_FIRSTTHREEFIELDS, DirectoryCount * SIZEOF_UINT);
if (buf != null)
{
for (uint i = 0; i < ttc.DirectoryCount; i++)
{
uint offset = buf.GetUint(i * SIZEOF_UINT);
ttc.DirectoryOffsets.Add(offset);
}
}
// only read Dsig fields if version 2.0 and last buffer was successfully read
if ((version == 0x00010000 || version == 0x00020000) && buf != null)
{
uint filepos = SIZEOF_FIRSTTHREEFIELDS + DirectoryCount * SIZEOF_UINT;
buf = file.ReadPaddedBuffer(filepos, 3 * SIZEOF_UINT);
if (buf != null)
{
// DsigTag
ttc.DsigTag = new OTTag(buf.GetBuffer());
if ((version == 0x00010000) && ((string)ttc.DsigTag != "DSIG"))
{
// failed v1 trial - reset & bail
ttc.DsigTag = null;
return(ttc);
}
// DsigLength
ttc.DsigLength = buf.GetUint(4);
// DsigOffset
ttc.DsigOffset = buf.GetUint(8);
}
}
}
return(ttc);
}