private unsafe FamilyCollection.CachedCharacterMetrics *LookupMetrics(int unicodeScalar)
{
if (unicodeScalar >= 0 && unicodeScalar <= FontFamilyMap.LastUnicodeScalar)
{
int pageTableOffset = _deviceFont->OffsetToCharacterMap;
int *pageTable = (int *)CheckedPointer.Probe(
pageTableOffset,
CharacterMetricsDictionary.PageCount * sizeof(int)
);
int i = pageTable[unicodeScalar >> CharacterMetricsDictionary.PageShift];
if (i != 0)
{
int *page = (int *)CheckedPointer.Probe(
pageTableOffset + (i * sizeof(int)),
CharacterMetricsDictionary.PageSize * sizeof(int)
);
int offset = page[unicodeScalar & CharacterMetricsDictionary.PageMask];
if (offset != 0)
{
return((FamilyCollection.CachedCharacterMetrics *)CheckedPointer.Probe(
offset,
sizeof(FamilyCollection.CachedCharacterMetrics)
));
}
}
}
return(null);
}
private static int ReadOpenTypeLong(CheckedPointer pointer)
{
unsafe
{
byte *readBuffer = (byte *)pointer.Probe(0, 4);
int result = (int)((((((readBuffer[0] << 8) + readBuffer[1]) << 8) + readBuffer[2]) << 8) + readBuffer[3]);
return(result);
}
}
/// <summary>
/// The follwoing APIs extract OpenType variable types from OpenType font
/// files. OpenType variables are stored big-endian, and the type are named
/// as follows:
/// Byte - signed 8 bit
/// UShort - unsigned 16 bit
/// Short - signed 16 bit
/// ULong - unsigned 32 bit
/// Long - signed 32 bit
/// </summary>
private static ushort ReadOpenTypeUShort(CheckedPointer pointer)
{
unsafe
{
byte * readBuffer = (byte *)pointer.Probe(0, 2);
ushort result = (ushort)((readBuffer[0] << 8) + readBuffer[1]);
return(result);
}
}
internal DeviceFont(CachedFontFamily cachedFamily, CheckedPointer deviceFont)
{
unsafe
{
_cachedFamily = cachedFamily;
_deviceFont = (FamilyCollection.CachedDeviceFont *)deviceFont.Probe(0, sizeof(FamilyCollection.CachedDeviceFont));
_sizeInBytes = deviceFont.Size;
}
}
internal TrueTypeFontDriver(UnmanagedMemoryStream unmanagedMemoryStream, Uri sourceUri)
{
_sourceUri = sourceUri;
_unmanagedMemoryStream = unmanagedMemoryStream;
_fileStream = new CheckedPointer(unmanagedMemoryStream);
try
{
CheckedPointer seekPosition = _fileStream;
TrueTypeTags typeTag = (TrueTypeTags)ReadOpenTypeLong(seekPosition);
seekPosition += 4;
if (typeTag == TrueTypeTags.TTC_TTCF)
{
// this is a TTC file, we need to decode the ttc header
_technology = FontTechnology.TrueTypeCollection;
seekPosition += 4; // skip version
_numFaces = ReadOpenTypeLong(seekPosition);
}
else if (typeTag == TrueTypeTags.OTTO)
{
_technology = FontTechnology.PostscriptOpenType;
_numFaces = 1;
}
else
{
_technology = FontTechnology.TrueType;
_numFaces = 1;
}
}
catch (ArgumentOutOfRangeException e)
{
// convert exceptions from CheckedPointer to FileFormatException
throw new FileFormatException(SourceUri, e);
}
}
internal TrueTypeFontDriver(UnmanagedMemoryStream unmanagedMemoryStream, Uri sourceUri)
{
_sourceUri = sourceUri;
_unmanagedMemoryStream = unmanagedMemoryStream;
_fileStream = new CheckedPointer(unmanagedMemoryStream);
try
{
CheckedPointer seekPosition = _fileStream;
TrueTypeTags typeTag = (TrueTypeTags)ReadOpenTypeLong(seekPosition);
seekPosition += 4;
if (typeTag == TrueTypeTags.TTC_TTCF)
{
// this is a TTC file, we need to decode the ttc header
_technology = FontTechnology.TrueTypeCollection;
seekPosition += 4; // skip version
_numFaces = ReadOpenTypeLong(seekPosition);
}
else if (typeTag == TrueTypeTags.OTTO)
{
_technology = FontTechnology.PostscriptOpenType;
_numFaces = 1;
}
else
{
_technology = FontTechnology.TrueType;
_numFaces = 1;
}
}
catch (ArgumentOutOfRangeException e)
{
// convert exceptions from CheckedPointer to FileFormatException
throw new FileFormatException(SourceUri, e);
}
}
private static int ReadOpenTypeLong(CheckedPointer pointer)
{
unsafe
{
byte * readBuffer = (byte *)pointer.Probe(0, 4);
int result = (int)((((((readBuffer[0] << 8) + readBuffer[1]) << 8) + readBuffer[2]) << 8) + readBuffer[3]);
return result;
}
}
private static ushort ReadOpenTypeUShort(CheckedPointer pointer)
{
unsafe
{
byte * readBuffer = (byte *)pointer.Probe(0, 2);
ushort result = (ushort)((readBuffer[0] << 8) + readBuffer[1]);
return result;
}
}
internal void SetFace(int faceIndex)
{
if (_technology == FontTechnology.TrueTypeCollection)
{
if (faceIndex < 0 || faceIndex >= _numFaces)
{
throw new ArgumentOutOfRangeException("faceIndex");
}
}
else
{
if (faceIndex != 0)
{
throw new ArgumentOutOfRangeException("faceIndex", SR.Get(SRID.FaceIndexValidOnlyForTTC));
}
}
try
{
CheckedPointer seekPosition = _fileStream + 4;
if (_technology == FontTechnology.TrueTypeCollection)
{
// this is a TTC file, we need to decode the ttc header
// skip version, num faces, OffsetTable array
seekPosition += (4 + 4 + 4 * faceIndex);
_directoryOffset = ReadOpenTypeLong(seekPosition);
seekPosition = _fileStream + (_directoryOffset + 4);
// 4 means that we skip the version number
}
_faceIndex = faceIndex;
int numTables = ReadOpenTypeUShort(seekPosition);
seekPosition += 2;
// quick check for malformed fonts, see if numTables is too large
// file size should be >= sizeof(offset table) + numTables * (sizeof(directory entry) + minimum table size (4))
long minimumFileSize = (4 + 2 + 2 + 2 + 2) + numTables * (4 + 4 + 4 + 4 + 4);
if (_fileStream.Size < minimumFileSize)
{
throw new FileFormatException(SourceUri);
}
_tableDirectory = new DirectoryEntry[numTables];
// skip searchRange, entrySelector and rangeShift
seekPosition += 6;
// I can't use foreach here because C# disallows modifying the current value
for (int i = 0; i < _tableDirectory.Length; ++i)
{
_tableDirectory[i].tag = (TrueTypeTags)ReadOpenTypeLong(seekPosition);
seekPosition += 8; // skip checksum
int offset = ReadOpenTypeLong(seekPosition);
seekPosition += 4;
int length = ReadOpenTypeLong(seekPosition);
seekPosition += 4;
_tableDirectory[i].pointer = _fileStream.CheckedProbe(offset, length);
}
}
catch (ArgumentOutOfRangeException e)
{
// convert exceptions from CheckedPointer to FileFormatException
throw new FileFormatException(SourceUri, e);
}
}
internal unsafe CheckedUShortPointer(ushort * pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(ushort));
}
internal unsafe CheckedIntPointer(int * pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(int));
}
internal unsafe CheckedCharPointer(char * pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(char));
}
internal unsafe CheckedUShortPointer(ushort *pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(ushort));
}
internal unsafe CheckedIntPointer(int *pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(int));
}
internal unsafe CheckedCharPointer(char *pointer, int length)
{
_checkedPointer = new CheckedPointer(pointer, length * sizeof(char));
}