Touch up new API

New API:
+hb_ot_layout_feature_get_name_ids()
+hb_ot_layout_feature_get_characters()

src/hb-ot-layout.cc

@@ -1121,7 +1121,6 @@ hb_ot_layout_get_size_params (hb_face_t    *face,
  * @face: #hb_face_t to work upon
  * @table_tag:
  * @feature_index:
- * @feature_tag: ssXX and cvXX tag
  * @label_id: (out) (allow-none): The ‘name’ table name ID that specifies a string
  *            for a user-interface label for this feature. (May be NULL.)
  * @tooltip_id: (out) (allow-none): The ‘name’ table name ID that specifies a string
@@ -1134,7 +1133,10 @@ hb_ot_layout_get_size_params (hb_face_t    *face,
  *                  strings for user-interface labels for the feature
  *                  parameters. (Must be zero if numParameters is zero.)
  *
- * Return value: true if could find any feature with the tag, false otherwise
+ * Fetches name indices from feature parameters for "Stylistic Set" ('ssXX') or
+ * "Character Variant" ('cvXX') features.
+ *
+ * Return value: true if data found, false otherwise
  *
  * Since: REPLACEME
  **/
@@ -1142,16 +1144,15 @@ hb_bool_t
 hb_ot_layout_feature_get_name_ids (hb_face_t      *face,
 				   hb_tag_t        table_tag,
 				   unsigned int    feature_index,
-				   hb_tag_t        feature_tag,
 				   hb_name_id_t   *label_id,             /* OUT.  May be NULL */
 				   hb_name_id_t   *tooltip_id,           /* OUT.  May be NULL */
 				   hb_name_id_t   *sample_id,            /* OUT.  May be NULL */
 				   unsigned int   *num_named_parameters, /* OUT.  May be NULL */
 				   hb_name_id_t   *first_param_id        /* OUT.  May be NULL */)
 {
-  static_assert ((OT::FeatureVariations::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_VARIATIONS_INDEX), "");
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
 
+  hb_tag_t feature_tag = g.get_feature_tag (feature_index);
   const OT::Feature &f = g.get_feature (feature_index);
 
   const OT::FeatureParams &feature_params = f.get_feature_params ();
@@ -1195,7 +1196,6 @@ hb_ot_layout_feature_get_name_ids (hb_face_t      *face,
 /**
  * hb_ot_layout_feature_get_characters::
  * @face: #hb_face_t to work upon
- * @feature_tag: cvXX tag
  * @table_tag:
  * @feature_index:
  * @start_offset: In case the resulting char_count was equal to its input value, there
@@ -1208,6 +1208,9 @@ hb_ot_layout_feature_get_name_ids (hb_face_t      *face,
  * @characters: (out) (allow-none): A buffer pointer. The Unicode Scalar Value
  *              of the characters for which this feature provides glyph variants.
  *
+ * Fetches characters listed by designer under feature parameters for "Character
+ * Variant" ("cvXX") features.
+ *
  * Return value: Number of total sample characters in the cvXX feature.
  *
  * Since: REPLACEME
@@ -1216,14 +1219,13 @@ unsigned int
 hb_ot_layout_feature_get_characters (hb_face_t      *face,
 				     hb_tag_t        table_tag,
 				     unsigned int    feature_index,
-				     hb_tag_t        feature_tag,
 				     unsigned int    start_offset,
 				     unsigned int   *char_count, /* IN/OUT.  May be NULL */
 				     hb_codepoint_t *characters  /* OUT.     May be NULL */)
 {
-  static_assert ((OT::FeatureVariations::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_VARIATIONS_INDEX), "");
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
 
+  hb_tag_t feature_tag = g.get_feature_tag (feature_index);
   const OT::Feature &f = g.get_feature (feature_index);
 
   const OT::FeatureParams &feature_params = f.get_feature_params ();

src/hb-ot-layout.h

@@ -335,7 +335,6 @@ HB_EXTERN hb_bool_t
 hb_ot_layout_feature_get_name_ids (hb_face_t      *face,
 				   hb_tag_t        table_tag,
 				   unsigned int    feature_index,
-				   hb_tag_t        feature_tag,
 				   hb_name_id_t   *label_id             /* OUT.  May be NULL */,
 				   hb_name_id_t   *tooltip_id           /* OUT.  May be NULL */,
 				   hb_name_id_t   *sample_id            /* OUT.  May be NULL */,
@@ -347,7 +346,6 @@ HB_EXTERN unsigned int
 hb_ot_layout_feature_get_characters (hb_face_t      *face,
 				     hb_tag_t        table_tag,
 				     unsigned int    feature_index,
-				     hb_tag_t        feature_tag,
 				     unsigned int    start_offset,
 				     unsigned int   *char_count    /* IN/OUT.  May be NULL */,
 				     hb_codepoint_t *characters    /* OUT.     May be NULL */);

test/api/test-ot-nameid.c

@@ -53,10 +53,14 @@ main (int argc, char **argv)
   font = hb_font_create (face);
 
   hb_tag_t cv01 = HB_TAG ('c','v','0','1');
-  unsigned int feature_index = 0;
+  unsigned int feature_index;
-  // FIXME: See why below doesn't work
+  if (!hb_ot_layout_language_find_feature (face,
-  // if (!hb_ot_layout_language_find_feature (face, HB_OT_TAG_GSUB, 0, 0, cv01, &feature_index))
+					   HB_OT_TAG_GSUB,
-  //   g_error ("Failed to find feature index");
+					   0,
+					   HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
+					   cv01,
+					   &feature_index))
+     g_error ("Failed to find feature index");
 
   hb_name_id_t label_id;
   hb_name_id_t tooltip_id;
@@ -64,7 +68,7 @@ main (int argc, char **argv)
   unsigned int num_named_parameters;
   hb_name_id_t first_param_id;
   if (!hb_ot_layout_feature_get_name_ids (face, HB_OT_TAG_GSUB, feature_index,
-					  cv01, &label_id, &tooltip_id, &sample_id,
+					  &label_id, &tooltip_id, &sample_id,
 					  &num_named_parameters, &first_param_id))
     g_error ("Failed to get name ids");
 
@@ -79,7 +83,7 @@ main (int argc, char **argv)
 
   unsigned int all_chars;
   all_chars = hb_ot_layout_feature_get_characters (face, HB_OT_TAG_GSUB, feature_index,
-						   cv01, 0, &char_count, characters);
+						   0, &char_count, characters);
 
   g_assert (all_chars == 2);
   g_assert (char_count == 2);