FcFileScan - scan a font file
#include <fontconfig/fontconfig.h>
FcBool FcFileScan (FcFontSet *set, FcStrSet *dirs, FcFileCache *cache, FcBlanks *blanks, const FcChar8 *file, FcBool force);
Scans a single file and adds all fonts found to set. If force is
  FcTrue, then the file is scanned even if associated information is found in
  cache. If file is a directory, it is added to dirs.
  Whether fonts are found depends on fontconfig policy as well as the current
  configuration. Internally, fontconfig will ignore BDF and PCF fonts which are
  not in Unicode (or the effectively equivalent ISO Latin-1) encoding as those
  are not usable by Unicode-based applications. The configuration can ignore
  fonts based on filename or contents of the font file itself. Returns FcFalse
  if any of the fonts cannot be added (due to allocation failure). Otherwise
  returns FcTrue.