[pango] Make CoreText backend more robust against broken fonts

[Kristian Rietveld <kristian src gnome org>]

commit 38ada127bfb53911ecd64ced26fd23ec67138b43
Author: Kristian Rietveld <kris lanedo com>
Date:   Sat Jan 28 10:34:52 2012 +0100

    Make CoreText backend more robust against broken fonts
    
    Patch written in collaboration with Michael Natterer.
    
    Some CTFontDescriptors apparently do not have a style name or font
    family name set. This patch makes the code take such corner cases into
    account. The font family problem only appears to occur on Snow Leopard
    systems, we try to fall back on the font name (postscript name), if that
    fails, we fall back on a default fallback.
    
    In some cases a coverage is also not set. (This seems to happen when we
    cannot map a broken font back to a correct font descriptor). In such
    cases we simply return an empty PangoCoverage, which will likely cause
    the engine to fallback on a different font.

 pango/pangocoretext-fontmap.c |   71 ++++++++++++++++++++++++++++++++++------
 pango/pangocoretext.c         |    4 ++
 2 files changed, 64 insertions(+), 11 deletions(-)
---
diff --git a/pango/pangocoretext-fontmap.c b/pango/pangocoretext-fontmap.c
index 511380d..687c340 100644
--- a/pango/pangocoretext-fontmap.c
+++ b/pango/pangocoretext-fontmap.c
@@ -167,12 +167,63 @@ gchar_from_cf_string (CFStringRef str)
 }
 
 static char *
+ct_font_descriptor_get_family_name (CTFontDescriptorRef desc)
+{
+  CFStringRef cf_str;
+  char *buffer;
+
+  cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontFamilyNameAttribute);
+  if (!cf_str)
+    {
+      int i;
+
+      /* No font family name is set, try to retrieve font name and deduce
+       * the family name from that instead.
+       */
+      cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontNameAttribute);
+      if (!cf_str)
+        {
+          /* This font is likely broken, return a default family name ... */
+          return g_strdup ("Sans");
+        }
+
+      buffer = gchar_from_cf_string (cf_str);
+      CFRelease (cf_str);
+
+      for (i = 0; i < strlen (buffer); i++)
+        if (buffer[i] == '-')
+          break;
+
+      if (i < strlen (buffer))
+        {
+          char *ret;
+
+          ret = g_strndup (buffer, i);
+          g_free (buffer);
+
+          return ret;
+        }
+      else
+        return buffer;
+    }
+  /* else */
+
+  buffer = gchar_from_cf_string (cf_str);
+  CFRelease (cf_str);
+
+  return buffer;
+}
+
+static char *
 ct_font_descriptor_get_style_name (CTFontDescriptorRef desc)
 {
   CFStringRef cf_str;
   char *buffer;
 
   cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontStyleNameAttribute);
+  if (!cf_str)
+    return NULL;
+
   buffer = gchar_from_cf_string (cf_str);
   CFRelease (cf_str);
 
@@ -271,6 +322,9 @@ ct_font_descriptor_get_weight (CTFontDescriptorRef desc)
 static inline gboolean
 pango_core_text_style_name_is_oblique (const char *style_name)
 {
+  if (!style_name)
+    return FALSE;
+
   return g_strrstr (style_name, "Oblique") != NULL;
 }
 
@@ -278,25 +332,20 @@ PangoFontDescription *
 _pango_core_text_font_description_from_ct_font_descriptor (CTFontDescriptorRef desc)
 {
   SInt64 font_traits;
-  char *buffer;
+  char *family_name;
   char *style_name;
-  CFStringRef cf_str;
   PangoFontDescription *font_desc;
 
   font_desc = pango_font_description_new ();
 
   /* Family name */
 
-  /* FIXME: Should we actually retrieve the family name from the list of families
-   * in a font map?
+  /* FIXME: Should we actually retrieve the family name from the list of
+   * families in a font map?
    */
-  cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontFamilyNameAttribute);
-  buffer = gchar_from_cf_string (cf_str);
-
-  pango_font_description_set_family (font_desc, buffer);
-
-  g_free (buffer);
-  CFRelease (cf_str);
+  family_name = ct_font_descriptor_get_family_name (desc);
+  pango_font_description_set_family (font_desc, family_name);
+  g_free (family_name);
 
   /* Weight */
   pango_font_description_set_weight (font_desc,
diff --git a/pango/pangocoretext.c b/pango/pangocoretext.c
index 5023e93..ee74393 100644
--- a/pango/pangocoretext.c
+++ b/pango/pangocoretext.c
@@ -80,6 +80,10 @@ ct_font_descriptor_get_coverage (CTFontDescriptorRef desc)
   coverage = pango_coverage_new ();
 
   charset = CTFontDescriptorCopyAttribute (desc, kCTFontCharacterSetAttribute);
+  if (!charset)
+    /* Return an empty coverage */
+    return coverage;
+
   bitmap = CFCharacterSetCreateBitmapRepresentation (kCFAllocatorDefault,
                                                      charset);