Related: rhbz#1690732 FC_INDEX doesn't mean exactly what it used to mean

its been repurposed to hold font face variation information too

Change-Id: I5d667d79a49337e7ade1e1697ca2fc9cb8c00f1c
Reviewed-on: https://gerrit.libreoffice.org/69474
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

vcl/unx/generic/fontmanager/fontconfig.cxx

@@ -467,6 +467,17 @@ static void lcl_FcFontSetRemove(FcFontSet* pFSet, int i)
     memmove(pFSet->fonts + i, pFSet->fonts + i + 1, nTail*sizeof(FcPattern*));
 }
 
+namespace
+{
+    // for variable fonts, FC_INDEX has been changed such that the lower half is now the
+    // index of the font within the collection, and the upper half has been repurposed
+    // as the index within the variations
+    unsigned int GetCollectionIndex(unsigned int nCollectionEntryId)
+    {
+        return nCollectionEntryId & 0xFFFF;
+    }
+}
+
 void PrintFontManager::countFontconfigFonts( std::unordered_map<OString, int>& o_rVisitedPaths )
 {
     int nFonts = 0;
@@ -487,7 +498,7 @@ void PrintFontManager::countFontconfigFonts( std::unordered_map<OString, int>& o
             int weight = 0;
             int width = 0;
             int spacing = 0;
-            int nCollectionEntry = -1;
+            int nCollectionEntryId = -1;
             FcBool outline = false;
 
             FcResult eFileRes         = FcPatternGetString(pFSet->fonts[i], FC_FILE, 0, &file);
@@ -500,7 +511,7 @@ void PrintFontManager::countFontconfigFonts( std::unordered_map<OString, int>& o
             FcResult eWidthRes        = FcPatternGetInteger(pFSet->fonts[i], FC_WIDTH, 0, &width);
             FcResult eSpacRes         = FcPatternGetInteger(pFSet->fonts[i], FC_SPACING, 0, &spacing);
             FcResult eOutRes          = FcPatternGetBool(pFSet->fonts[i], FC_OUTLINE, 0, &outline);
-            FcResult eIndexRes        = FcPatternGetInteger(pFSet->fonts[i], FC_INDEX, 0, &nCollectionEntry);
+            FcResult eIndexRes        = FcPatternGetInteger(pFSet->fonts[i], FC_INDEX, 0, &nCollectionEntryId);
             FcResult eFormatRes       = FcPatternGetString(pFSet->fonts[i], FC_FONTFORMAT, 0, &format);
 
             if( eFileRes != FcResultMatch || eFamilyRes != FcResultMatch || eOutRes != FcResultMatch )
@@ -565,8 +576,9 @@ void PrintFontManager::countFontconfigFonts( std::unordered_map<OString, int>& o
             else // more than one font
             {
                 // a collection entry, get the correct index
-                if( eIndexRes == FcResultMatch && nCollectionEntry != -1 )
+                if( eIndexRes == FcResultMatch && nCollectionEntryId != -1 )
                 {
+                    int nCollectionEntry = GetCollectionIndex(nCollectionEntryId);
                     for (auto & font : aFonts)
                     {
                         if( font->m_nCollectionEntry == nCollectionEntry )
@@ -583,14 +595,14 @@ void PrintFontManager::countFontconfigFonts( std::unordered_map<OString, int>& o
                     // additional entries will be created in the cache
                     // if this is a new index (that is if the loop above
                     // ran to the end of the list)
-                    xUpdate->m_nCollectionEntry = nCollectionEntry;
+                    xUpdate->m_nCollectionEntry = GetCollectionIndex(nCollectionEntryId);
                 }
                 else
                 {
                     SAL_INFO(
                         "vcl.fonts",
                         "multiple fonts for file, but no index in fontconfig pattern ! (index res ="
-                        << eIndexRes << " collection entry = " << nCollectionEntry
+                        << eIndexRes << " collection entry = " << nCollectionEntryId
                         << "; file will not be used");
                     // we have found more than one font in this file
                     // but fontconfig will not tell us which index is meant
@@ -933,16 +945,16 @@ void PrintFontManager::Substitute(FontSelectPattern &rPattern, OUString& rMissin
             //extract the closest match
             FcChar8* file = nullptr;
             FcResult eFileRes = FcPatternGetString(pSet->fonts[0], FC_FILE, 0, &file);
-            int nCollectionEntry = 0;
-            FcResult eIndexRes = FcPatternGetInteger(pSet->fonts[0], FC_INDEX, 0, &nCollectionEntry);
+            int nCollectionEntryId = 0;
+            FcResult eIndexRes = FcPatternGetInteger(pSet->fonts[0], FC_INDEX, 0, &nCollectionEntryId);
             if (eIndexRes != FcResultMatch)
-                nCollectionEntry = 0;
+                nCollectionEntryId = 0;
             if( eFileRes == FcResultMatch )
             {
                 OString aDir, aBase, aOrgPath( reinterpret_cast<char*>(file) );
                 splitPath( aOrgPath, aDir, aBase );
                 int nDirID = getDirectoryAtom( aDir );
-                fontID aFont = findFontFileID( nDirID, aBase, nCollectionEntry );
+                fontID aFont = findFontFileID( nDirID, aBase, GetCollectionIndex(nCollectionEntryId) );
                 if( aFont > 0 )
                 {
                     FastPrintFontInfo aInfo;