[Subtitles] Show font family name's to subtitle fonts list

src/stream/FFmpegStream.cpp

@@ -2142,11 +2142,16 @@ DemuxStream* FFmpegStream::AddStream(int streamIdx)
           }
           else
           {
-            // Note: libass only supports a single font directory to look for additional fonts
-            // (c.f. ass_set_fonts_dir). To support both user defined fonts (those placed in
-            // special://home/media/Fonts/) and fonts extracted by the demuxer, make it extract
-            // fonts to the user directory with a known, easy to identify, prefix (tmp.font.*).
-            fileName += "tmp.font." + FilenameUtils::MakeLegalFileName(nameTag->value, LEGAL_WIN32_COMPAT);
+            // Note: Libass only supports a single additional font directory,
+            // currently set for user fonts (c.f. ass_set_fonts_dir) therefore
+            // we will also use this folder to store fonts extracted by the
+            // demuxer. The extracted fonts will have a prefix in the filename
+            // for easy identification.
+            //! @todo: this font file management system on disk could be completely
+            //! removed, by sending font data to the subtitle renderer and
+            //! using libass ass_add_font to add the fonts directly in memory.
+            fileName += FilenameUtils::TEMP_FONT_FILENAME_PREFIX +
+                        FilenameUtils::MakeLegalFileName(nameTag->value, LEGAL_WIN32_COMPAT);
             kodi::vfs::CFile file;
             if (pStream->codecpar->extradata && file.OpenFileForWrite(fileName))
             {

src/utils/FilenameUtils.h

@@ -15,6 +15,9 @@ namespace ffmpegdirect
   static const int LEGAL_WIN32_COMPAT = 1;
   static const int LEGAL_FATX = 2;
 
+  // Prefix used to store temporary font files in the user fonts folder
+  constexpr const char* TEMP_FONT_FILENAME_PREFIX = "tmp.font.";
+
   class FilenameUtils
   {
   public:
@@ -24,6 +27,6 @@ namespace ffmpegdirect
 #else
     static std::string MakeLegalFileName(const std::string &strFile, int LegalType=LEGAL_NONE);
     static std::string MakeLegalPath(const std::string &strPath, int LegalType=LEGAL_NONE);
-#endif      
+#endif
   };
 } //namespace ffmpegdirect