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vcl: embed fonts with CFF table as OpenType fonts

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Instead of converting the CFF table to Type1 font, embed the full font
as OpenType (SFNT with CFF table).

Also for such fonts, add an /Encoding dictionary with /Differences array
to the PDF font dictionary, mapping character codes to CFF glyph names,
which seems to be needed by some PDF viewers.

Change-Id: I3dc51dfbcb9cc996c9253d858d166ac9612aede7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/203441
Tested-by: Jenkins
Reviewed-by: Khaled Hosny <khaled@libreoffice.org>
This commit is contained in:
Khaled Hosny
2026-04-12 22:33:34 +02:00
committed by Khaled Hosny
parent 6c88e551e3
commit d9a6a3f7f0
3 changed files with 51 additions and 27 deletions
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vcl/inc/fontsubset.hxx
+3
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@@ -25,6 +25,8 @@
#include <vcl/dllapi.h>
#include <vector>
// Translate units from TT to PS (standard 1/1000)
inline int XUnits(int nUPEM, int n) { return (n * 1000) / nUPEM; }
@@ -50,6 +52,7 @@ public: // TODO: make subsetter results private and provide accessor methods ins
int m_nCapHeight = 0;
tools::Rectangle m_aFontBBox;
FontType m_nFontType = FontType::NO_FONT; ///< font-type of subset result
std::vector<OString> m_aGlyphNames; ///< glyph names for CFF encoding
};
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
vcl/source/font/PhysicalFontFace.cxx
+20 -25
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@@ -548,13 +548,28 @@ bool PhysicalFontFace::CreateFontSubset(std::vector<sal_uInt8>& rOutBuffer,
hb_blob_t* pCFFBlob = hb_face_reference_table(pSubsetFace, HB_TAG('C', 'F', 'F', ' '));
comphelper::ScopeGuard aCFFBlobGuard([&]() { hb_blob_destroy(pCFFBlob); });
if (pCFFBlob == hb_blob_get_empty())
{
// This is not a font with CFF table, so we will create a TTF font subset.
rInfo.m_nFontType = FontType::SFNT_TTF;
else
{
rInfo.m_nFontType = FontType::SFNT_CFF;
// HarfBuzz creates a Unicode cmap, but we need a fake cmap based on pEncoding,
// so we use face builder construct a new face based in the subset table,
// and create a new cmap table and add it to the new face.
// Get glyph names from the subset CFF charset, needed for building
// the PDF Encoding dictionary that maps character codes to glyph names.
rInfo.m_aGlyphNames.resize(nGlyphCount);
for (int i = 0; i < nGlyphCount; ++i)
{
char aName[64];
if (hb_font_get_glyph_name(pSubsetFont, pEncoding[i], aName, sizeof(aName)))
rInfo.m_aGlyphNames[i] = OString(aName);
else
rInfo.m_aGlyphNames[i] = ".notdef"_ostr;
}
}
// HarfBuzz creates a Unicode cmap, but we need a fake cmap based on pEncoding,
// so we use face builder to construct a new face based on the subset tables,
// and create a new cmap table and add it to the new face.
{
hb_face_t* pBuilderFace = hb_face_builder_create();
comphelper::ScopeGuard aBuilderFaceGuard([&]() { hb_face_destroy(pBuilderFace); });
unsigned int nSubsetTableCount = hb_face_get_table_tags(pSubsetFace, 0, nullptr, nullptr);
@@ -611,26 +626,6 @@ bool PhysicalFontFace::CreateFontSubset(std::vector<sal_uInt8>& rOutBuffer,
rOutBuffer.assign(reinterpret_cast<const sal_uInt8*>(pSubsetData),
reinterpret_cast<const sal_uInt8*>(pSubsetData) + nSubsetLength);
}
else
{
// Ideally we should be outputting a CFF (Type1C) font here, but I couldn’t get it to work.
// So we oconvert it to Type1 font instead.
// TODO: simplify CreateCFFfontSubset() to only do the conversion, since we already
// have the subsetted font.
rInfo.m_nFontType = FontType::TYPE1_PFB;
unsigned int nCffLen;
const char* pCffData = hb_blob_get_data(pCFFBlob, &nCffLen);
if (!pCffData || !nCffLen)
return false;
if (!ConvertCFFfontToType1(reinterpret_cast<const unsigned char*>(pCffData), nCffLen,
rOutBuffer, rInfo))
{
SAL_WARN("vcl.fonts.cff", "Failed to convert CFF data to Type 1 font");
return false;
}
}
return true;
}
vcl/source/pdf/pdfwriter_impl.cxx
+28 -2
View File
@@ -2040,6 +2040,7 @@ sal_Int32 PDFWriterImpl::emitFontDescriptor( const vcl::font::PhysicalFontFace*
aLine.append( '2' );
break;
case FontType::CFF_FONT:
case FontType::SFNT_CFF:
aLine.append( "3" );
break;
case FontType::TYPE1_PFB:
@@ -2131,9 +2132,23 @@ bool PDFWriterImpl::emitFonts()
if (!writeBufferBytes(aBuffer.data(), aBuffer.size()))
return false;
}
else if( aSubsetInfo.m_nFontType == FontType::SFNT_CFF )
{
aLine.append("/Length1 "
+ OString::number(aBuffer.size())
+ "/Subtype/OpenType>>\n"
"stream\n" );
if ( !writeBuffer( aLine ) ) return false;
if ( osl::File::E_None != m_aFile.getPos(nStartPos) ) return false;
// copy font file
beginCompression();
checkAndEnableStreamEncryption( nFontStream );
if (!writeBufferBytes(aBuffer.data(), aBuffer.size()))
return false;
}
else if( aSubsetInfo.m_nFontType & FontType::CFF_FONT)
{
// CFF subset is embedded as an SFNT font (same as TrueType)
aLine.append("/Subtype/Type1C>>\nstream\n");
if ( !writeBuffer( aLine ) ) return false;
if ( osl::File::E_None != m_aFile.getPos(nStartPos) ) return false;
@@ -2204,7 +2219,7 @@ bool PDFWriterImpl::emitFonts()
if ( !updateObject( nFontObject ) ) return false;
aLine.setLength( 0 );
aLine.append( OString::number(nFontObject) + " 0 obj\n" );
aLine.append( (aSubsetInfo.m_nFontType & (FontType::TYPE1_PFB | FontType::CFF_FONT)) ?
aLine.append( (aSubsetInfo.m_nFontType & (FontType::SFNT_CFF | FontType::TYPE1_PFB | FontType::CFF_FONT)) ?
"<</Type/Font/Subtype/Type1/BaseFont/" :
"<</Type/Font/Subtype/TrueType/BaseFont/" );
appendSubsetName( s_subset.m_nFontID, aSubsetInfo.m_aPSName, aLine );
@@ -2229,6 +2244,17 @@ bool PDFWriterImpl::emitFonts()
+ OString::number( nToUnicodeStream )
+ " 0 R\n" );
}
if( aSubsetInfo.m_nFontType == FontType::SFNT_CFF
&& !aSubsetInfo.m_aGlyphNames.empty() )
{
aLine.append( "/Encoding<</Type/Encoding/Differences[" );
for (size_t i = 0; i < aSubsetInfo.m_aGlyphNames.size(); i++)
{
aLine.append( OString::number(sal_Int32(i))
+ "/" + aSubsetInfo.m_aGlyphNames[i] + " " );
}
aLine.append( "]>>\n" );
}
aLine.append( ">>\n"
"endobj\n\n" );
if ( !writeBuffer( aLine ) ) return false;