ちょっとだけharfbuzz(3)

さて、タイ語などではMicrosoftの仕様書にあったように、ccmpなどがデフォルトで発動していた。これってharfbuzzではどこで処理しているのだろう？ということで見てみた。

[hb-ot-shape.cc]

static hb_tag_t common_features[] = {
  HB_TAG('c','c','m','p'),
  HB_TAG('l','o','c','l'),
  HB_TAG('m','a','r','k'),
  HB_TAG('m','k','m','k'),
  HB_TAG('r','l','i','g'),
};

...

static void
hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
                  const hb_segment_properties_t  *props,
                  const hb_feature_t             *user_features,
                  unsigned int                    num_user_features)
{
  hb_ot_map_builder_t *map = &planner->map;

  switch (props->direction) {
    case HB_DIRECTION_LTR:
      map->add_global_bool_feature (HB_TAG ('l','t','r','a'));
      map->add_global_bool_feature (HB_TAG ('l','t','r','m'));
      break;
    case HB_DIRECTION_RTL:
      map->add_global_bool_feature (HB_TAG ('r','t','l','a'));
      map->add_feature (HB_TAG ('r','t','l','m'), 1, F_NONE);
      break;
    case HB_DIRECTION_TTB:
    case HB_DIRECTION_BTT:
    case HB_DIRECTION_INVALID:
    default:
      break;
  }

  map->add_feature (HB_TAG ('f','r','a','c'), 1, F_NONE);
  map->add_feature (HB_TAG ('n','u','m','r'), 1, F_NONE);
  map->add_feature (HB_TAG ('d','n','o','m'), 1, F_NONE);

  if (planner->shaper->collect_features)
    planner->shaper->collect_features (planner);

  for (unsigned int i = 0; i < ARRAY_LENGTH (common_features); i++)
    map->add_global_bool_feature (common_features[i]);

たぶんここだ。