fc: Ignore more unsupported font formats

FontConfig uses FreeType’s FT_Get_X11_Font_Format() to get the font
format. From the list of font formats it supports, only “TrueType” and
“CFF” are supported by HarfBuzz. We now check explicitly for supported
formats and reject anything else:
https://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/include/freetype/internal/services/svfntfmt.h#n36

FreeType, however, seems to use “CFF” for both OpenType fonts with CFF
table (.otf) and bare CFF fonts (.cff), but the later are not supported
by HarfBuzz although they rather rare (outside of PDF files, which
shouldn’t be rendered with Pango), so it should be OK.

1 files changed, 17 insertions, 4 deletions

diff --git a/pango/pangofc-fontmap.c b/pango/pangofc-fontmap.c
index bddd5410..d0a01115 100644
--- a/pango/pangofc-fontmap.c
+++ b/pango/pangofc-fontmap.c
@@ -895,6 +895,20 @@ pango_fc_fontset_get_key (PangoFcFontset *fontset)
   return fontset->key;
 }
 
+static gboolean
+pango_fc_is_supported_font_format (const char *fontformat)
+{
+  /* harfbuzz supports only SFNT fonts. */
+  /* FIXME: "CFF" is used for both CFF in OpenType and bare CFF files, but
+   * HarfBuzz does not support the later and FontConfig does not seem
+   * to have a way to tell them apart.
+   */
+  if (g_ascii_strcasecmp (fontformat, "TrueType") == 0 ||
+      g_ascii_strcasecmp (fontformat, "CFF") == 0)
+    return TRUE;
+  return FALSE;
+}
+
 static PangoFont *
 pango_fc_fontset_load_next_font (PangoFcFontset *fontset,
                                  gboolean       *has_more)
@@ -925,8 +939,7 @@ pango_fc_fontset_load_next_font (PangoFcFontset *fontset,
 
   res = FcPatternGetString (font_pattern, FC_FONTFORMAT, 0, (FcChar8 **)(void*)&s);
   g_assert (res == FcResultMatch);
-  /* harfbuzz does not support these */
-  if (strcmp (s, "Type 1") == 0 || strcmp (s, "PCF") == 0)
+  if (!pango_fc_is_supported_font_format (s))
     font = NULL;
   else
     font = pango_fc_font_map_new_font (fontset->key->fontmap,
@@ -1394,8 +1407,8 @@ pango_fc_font_map_list_families (PangoFontMap      *fontmap,
 
 	  res = FcPatternGetString (fontset->fonts[i], FC_FONTFORMAT, 0, (FcChar8 **)(void*)&s);
 	  g_assert (res == FcResultMatch);
-          if (strcmp (s, "Type 1") == 0 || strcmp (s, "PCF") == 0)
-            continue; /* harfbuzz does not support these */
+          if (!pango_fc_is_supported_font_format (s))
+            continue;
 
 	  res = FcPatternGetString (fontset->fonts[i], FC_FAMILY, 0, (FcChar8 **)(void*)&s);
 	  g_assert (res == FcResultMatch);