[pango/small-caps: 1/2] fc: Implement PANGO_VARIANT_SMALL_CAPS

[Matthias Clasen <matthiasc src gnome org>]

commit 64b7b2c8d91577b56282bc65551090bd005f4ca1
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Nov 5 20:48:40 2021 -0400

    fc: Implement PANGO_VARIANT_SMALL_CAPS
    
    Arrange for PANGO_VARIANT_SMALL_CAPS to be translated
    into the OpenType feature smcp=1 and back. This makes
    small caps survive a roundtrip from font description
    to font and back.

 pango/pangofc-fontmap.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
---
diff --git a/pango/pangofc-fontmap.c b/pango/pangofc-fontmap.c
index 1d67485a..113142fd 100644
--- a/pango/pangofc-fontmap.c
+++ b/pango/pangofc-fontmap.c
@@ -1854,6 +1854,7 @@ pango_fc_make_pattern (const  PangoFontDescription *description,
   int slant;
   double weight;
   PangoGravity gravity;
+  PangoVariant variant;
   char **families;
   int i;
   int width;
@@ -1864,6 +1865,7 @@ pango_fc_make_pattern (const  PangoFontDescription *description,
   width = pango_fc_convert_width_to_fc (pango_font_description_get_stretch (description));
 
   gravity = pango_font_description_get_gravity (description);
+  variant = pango_font_description_get_variant (description);
 
   /* The reason for passing in FC_SIZE as well as FC_PIXEL_SIZE is
    * to work around a bug in libgnomeprint where it doesn't look
@@ -1913,6 +1915,9 @@ pango_fc_make_pattern (const  PangoFontDescription *description,
   if (prgname)
     FcPatternAddString (pattern, PANGO_FC_PRGNAME, (FcChar8*) prgname);
 
+  if (variant == PANGO_VARIANT_SMALL_CAPS)
+    FcPatternAddString (pattern, PANGO_FC_FONT_FEATURES, (FcChar8*) "smcp=1");
+
   return pattern;
 }
 
@@ -2787,6 +2792,22 @@ pango_fc_font_description_from_pattern (FcPattern *pattern, gboolean include_siz
 
   pango_font_description_set_variant (desc, PANGO_VARIANT_NORMAL);
 
+  for (int i = 0; i < 32; i++)
+    {
+      const char *s;
+
+      if (FcPatternGetString (pattern, PANGO_FC_FONT_FEATURES, i, (FcChar8 **)&s) == FcResultMatch)
+        {
+          if (strcmp (s, "smcp=1") == 0)
+            {
+              pango_font_description_set_variant (desc, PANGO_VARIANT_SMALL_CAPS);
+              break;
+            }
+        }
+      else
+        break;
+    }
+
   if (include_size && FcPatternGetDouble (pattern, FC_SIZE, 0, &size) == FcResultMatch)
     {
       FcMatrix *fc_matrix;