[pango/font-features-getter: 2/3] fc: Implement get_features for fc fonts

[Matthias Clasen <matthiasc src gnome org>]

commit b0d40c174a1cdebb0ef3fd9b187b6aabf8fc0a20
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Jul 9 23:09:02 2019 -0400

    fc: Implement get_features for fc fonts
    
    We take features out of the FcPattern and
    translate them into harfbuzz features.

 pango/pangofc-font.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)
---
diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index 79fb07c1..fb51b3c6 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -89,7 +89,10 @@ static PangoFontMetrics *    pango_fc_font_get_metrics  (PangoFont        *font,
 static PangoFontMap *        pango_fc_font_get_font_map (PangoFont        *font);
 static PangoFontDescription *pango_fc_font_describe     (PangoFont        *font);
 static PangoFontDescription *pango_fc_font_describe_absolute (PangoFont        *font);
-
+static void                  pango_fc_font_get_features (PangoFont        *font,
+                                                         hb_feature_t     *features,
+                                                         guint             len,
+                                                         guint            *num_features);
 
 #define PANGO_FC_FONT_LOCK_FACE(font)  (PANGO_FC_FONT_GET_CLASS (font)->lock_face (font))
 #define PANGO_FC_FONT_UNLOCK_FACE(font)        (PANGO_FC_FONT_GET_CLASS (font)->unlock_face (font))
@@ -116,6 +119,7 @@ pango_fc_font_class_init (PangoFcFontClass *class)
   font_class->get_coverage = pango_fc_font_get_coverage;
   font_class->get_metrics = pango_fc_font_get_metrics;
   font_class->get_font_map = pango_fc_font_get_font_map;
+  font_class->get_features = pango_fc_font_get_features;
 
   g_object_class_install_property (object_class, PROP_PATTERN,
                                   g_param_spec_pointer ("pattern",
@@ -1086,3 +1090,28 @@ pango_fc_font_get_raw_extents (PangoFcFont    *fcfont,
   PANGO_FC_FONT_UNLOCK_FACE (fcfont);
 }
 
+static void
+pango_fc_font_get_features (PangoFont    *font,
+                            hb_feature_t *features,
+                            guint         len,
+                            guint        *num_features)
+{
+  /* Setup features from fontconfig pattern. */
+  PangoFcFont *fc_font = PANGO_FC_FONT (font);
+  if (fc_font->font_pattern)
+    {
+      char *s;
+      while (*num_features < len &&
+             FcResultMatch == FcPatternGetString (fc_font->font_pattern,
+                                                  PANGO_FC_FONT_FEATURES,
+                                                  *num_features,
+                                                  (FcChar8 **) &s))
+        {
+          gboolean ret = hb_feature_from_string (s, -1, &features[*num_features]);
+          features[*num_features].start = 0;
+          features[*num_features].end   = (unsigned int) -1;
+          if (ret)
+            (*num_features)++;
+        }
+    }
+}