/// <summary>
/// Create font subset that includes glyphs in the input collection.
/// </summary>
internal byte[] ComputeFontSubset(ICollection <ushort> glyphs)
{
SecurityHelper.DemandUnmanagedCode();
int fileSize = _fileStream.Size;
unsafe
{
void *fontData = _fileStream.Probe(0, fileSize);
// Since we currently don't have a way to subset CFF fonts, just return a copy of the font.
if (_technology == FontTechnology.PostscriptOpenType)
{
byte[] fontCopy = new byte[fileSize];
Marshal.Copy((IntPtr)fontData, fontCopy, 0, fileSize);
return(fontCopy);
}
ushort[] glyphArray;
if (glyphs == null || glyphs.Count == 0)
{
glyphArray = null;
}
else
{
glyphArray = new ushort[glyphs.Count];
glyphs.CopyTo(glyphArray, 0);
}
return(TrueTypeSubsetter.ComputeSubset(fontData, fileSize, SourceUri, _directoryOffset, glyphArray));
}
}
public IndirectReferenceToken WriteFont(IPdfStreamWriter writer, IndirectReferenceToken reservedIndirect = null)
{
var newEncoding = new TrueTypeSubsetEncoding(characterMapping.Keys.ToList());
var subsetBytes = TrueTypeSubsetter.Subset(fontFileBytes.ToArray(), newEncoding);
var embeddedFile = DataCompresser.CompressToStream(subsetBytes);
var fileRef = writer.WriteToken(embeddedFile);
var baseFont = NameToken.Create(font.TableRegister.NameTable.GetPostscriptName());
var postscript = font.TableRegister.PostScriptTable;
var hhead = font.TableRegister.HorizontalHeaderTable;
var bbox = font.TableRegister.HeaderTable.Bounds;
var scaling = 1000m / font.TableRegister.HeaderTable.UnitsPerEm;
var descriptorDictionary = new Dictionary <NameToken, IToken>
{
{ NameToken.Type, NameToken.FontDescriptor },
{ NameToken.FontName, baseFont },
// TODO: get flags TrueTypeEmbedder.java
{ NameToken.Flags, new NumericToken((int)FontDescriptorFlags.Symbolic) },
{ NameToken.FontBbox, GetBoundingBox(bbox, scaling) },
{ NameToken.ItalicAngle, new NumericToken((decimal)postscript.ItalicAngle) },
{ NameToken.Ascent, new NumericToken(Math.Round(hhead.Ascent * scaling, 2)) },
{ NameToken.Descent, new NumericToken(Math.Round(hhead.Descent * scaling, 2)) },
{ NameToken.CapHeight, new NumericToken(90) },
{ NameToken.StemV, new NumericToken(90) },
{ NameToken.FontFile2, fileRef }
};
var os2 = font.TableRegister.Os2Table;
if (os2 == null)
{
throw new InvalidFontFormatException("Embedding TrueType font requires OS/2 table.");
}
if (os2 is Os2Version2To4OpenTypeTable twoPlus)
{
descriptorDictionary[NameToken.CapHeight] = new NumericToken(twoPlus.CapHeight);
descriptorDictionary[NameToken.Xheight] = new NumericToken(twoPlus.XHeight);
}
descriptorDictionary[NameToken.StemV] = new NumericToken(((decimal)bbox.Width) * scaling * 0.13m);
var lastCharacter = 0;
var widths = new List <NumericToken> {
NumericToken.Zero
};
foreach (var kvp in characterMapping)
{
if (kvp.Value > lastCharacter)
{
lastCharacter = kvp.Value;
}
var glyphId = font.WindowsUnicodeCMap.CharacterCodeToGlyphIndex(kvp.Key);
var width = decimal.Round(font.TableRegister.HorizontalMetricsTable.GetAdvanceWidth(glyphId) * scaling, 2);
widths.Add(new NumericToken(width));
}
var descriptor = writer.WriteToken(new DictionaryToken(descriptorDictionary));
var toUnicodeCMap = ToUnicodeCMapBuilder.ConvertToCMapStream(characterMapping);
var toUnicodeStream = DataCompresser.CompressToStream(toUnicodeCMap);
var toUnicode = writer.WriteToken(toUnicodeStream);
var dictionary = new Dictionary <NameToken, IToken>
{
{ NameToken.Type, NameToken.Font },
{ NameToken.Subtype, NameToken.TrueType },
{ NameToken.BaseFont, baseFont },
{ NameToken.FontDescriptor, descriptor },
{ NameToken.FirstChar, new NumericToken(0) },
{ NameToken.LastChar, new NumericToken(lastCharacter) },
{ NameToken.Widths, new ArrayToken(widths) },
{ NameToken.ToUnicode, toUnicode }
};
var token = new DictionaryToken(dictionary);
if (reservedIndirect != null)
{
return(writer.WriteToken(token, reservedIndirect));
}
return(writer.WriteToken(token));
}
