[uniscribe] Support feature ranges

As Khaled pointed out, right now setting any features, turns kern
and possibly other features off.

src/hb-uniscribe.cc

@@ -229,7 +229,6 @@ free_uniscribe_funcs (void)
   free (uniscribe_funcs);
 }
 
-
 static hb_uniscribe_shaper_funcs_t *
 hb_uniscribe_shaper_get_funcs (void)
 {
@@ -258,6 +257,39 @@ retry:
 }
 
 
+struct active_feature_t {
+  OPENTYPE_FEATURE_RECORD rec;
+  unsigned int order;
+
+  static int cmp (const active_feature_t *a, const active_feature_t *b) {
+    return a->rec.tagFeature < b->rec.tagFeature ? -1 : a->rec.tagFeature > b->rec.tagFeature ? 1 :
+	   a->order < b->order ? -1 : a->order > b->order ? 1 :
+	   a->rec.lParameter < b->rec.lParameter ? -1 : a->rec.lParameter > b->rec.lParameter ? 1 :
+	   0;
+  }
+  bool operator== (const active_feature_t *f) {
+    return cmp (this, f) == 0;
+  }
+};
+
+struct feature_event_t {
+  unsigned int index;
+  bool start;
+  active_feature_t feature;
+
+  static int cmp (const feature_event_t *a, const feature_event_t *b) {
+    return a->index < b->index ? -1 : a->index > b->index ? 1 :
+	   a->start < b->start ? -1 : a->start > b->start ? 1 :
+	   active_feature_t::cmp (&a->feature, &b->feature);
+  }
+};
+
+struct range_record_t {
+  TEXTRANGE_PROPERTIES props;
+  unsigned int index_first; /* == start */
+  unsigned int index_last;  /* == end - 1 */
+};
+
 HB_SHAPER_DATA_ENSURE_DECLARE(uniscribe, face)
 HB_SHAPER_DATA_ENSURE_DECLARE(uniscribe, font)
 
@@ -567,6 +599,125 @@ _hb_uniscribe_shape (hb_shape_plan_t    *shape_plan,
   hb_uniscribe_shaper_font_data_t *font_data = HB_SHAPER_DATA_GET (font);
   hb_uniscribe_shaper_funcs_t *funcs = face_data->funcs;
 
+  /*
+   * Set up features.
+   */
+  hb_auto_array_t<OPENTYPE_FEATURE_RECORD> feature_records;
+  hb_auto_array_t<range_record_t> range_records;
+  if (num_features)
+  {
+    /* Sort features by start/end events. */
+    hb_auto_array_t<feature_event_t> feature_events;
+    for (unsigned int i = 0; i < num_features; i++)
+    {
+      active_feature_t feature;
+      feature.rec.tagFeature = hb_uint32_swap (features[i].tag);
+      feature.rec.lParameter = features[i].value;
+      feature.order = i;
+
+      feature_event_t *event;
+
+      event = feature_events.push ();
+      if (unlikely (!event))
+	goto fail_features;
+      event->index = features[i].start;
+      event->start = true;
+      event->feature = feature;
+
+      event = feature_events.push ();
+      if (unlikely (!event))
+	goto fail_features;
+      event->index = features[i].end;
+      event->start = false;
+      event->feature = feature;
+    }
+    feature_events.sort ();
+    /* Add a strategic final event. */
+    {
+      active_feature_t feature;
+      feature.rec.tagFeature = 0;
+      feature.rec.lParameter = 0;
+      feature.order = num_features + 1;
+
+      feature_event_t *event = feature_events.push ();
+      if (unlikely (!event))
+	goto fail_features;
+      event->index = 0; /* This value does magic. */
+      event->start = false;
+      event->feature = feature;
+    }
+
+    /* Scan events and save features for each range. */
+    hb_auto_array_t<active_feature_t> active_features;
+    unsigned int last_index = 0;
+    for (unsigned int i = 0; i < feature_events.len; i++)
+    {
+      feature_event_t *event = &feature_events[i];
+
+      if (event->index != last_index)
+      {
+        /* Save a snapshot of active features and the range. */
+	range_record_t *range = range_records.push ();
+	if (unlikely (!range))
+	  goto fail_features;
+
+	unsigned int offset = feature_records.len;
+
+	active_features.sort ();
+	for (unsigned int j = 0; j < active_features.len; j++)
+	{
+	  if (!j || active_features[j].rec.tagFeature != feature_records[feature_records.len - 1].tagFeature)
+	  {
+	    OPENTYPE_FEATURE_RECORD *feature = feature_records.push ();
+	    if (unlikely (!feature))
+	      goto fail_features;
+	    *feature = active_features[j].rec;
+	  }
+	  else
+	  {
+	    /* Overrides value for existing feature. */
+	    feature_records[feature_records.len - 1].lParameter = active_features[j].rec.lParameter;
+	  }
+	}
+
+	/* Will convert to pointer after all is ready, since feature_records.array
+	 * may move as we grow it. */
+	range->props.potfRecords = reinterpret_cast<OPENTYPE_FEATURE_RECORD *> (offset);
+	range->props.cotfRecords = feature_records.len - offset;
+	range->index_first = last_index;
+	range->index_last  = event->index - 1;
+
+	last_index = event->index;
+      }
+
+      if (event->start) {
+        active_feature_t *feature = active_features.push ();
+	if (unlikely (!feature))
+	  goto fail_features;
+	*feature = event->feature;
+      } else {
+        active_feature_t *feature = active_features.find (&event->feature);
+	if (feature)
+	  active_features.remove (feature - active_features.array);
+      }
+    }
+
+    if (!range_records.len) /* No active feature found. */
+      goto fail_features;
+
+    /* Fixup the pointers. */
+    for (unsigned int i = 0; i < range_records.len; i++)
+    {
+      range_record_t *range = &range_records[i];
+      range->props.potfRecords = feature_records.array + reinterpret_cast<unsigned int> (range->props.potfRecords);
+    }
+  }
+  else
+  {
+  fail_features:
+    num_features = 0;
+  }
+
 #define FAIL(...) \
   HB_STMT_START { \
     DEBUG_MSG (UNISCRIBE, NULL, __VA_ARGS__); \
@@ -591,7 +742,8 @@ retry:
 
   WCHAR *pchars = (WCHAR *) scratch;
   unsigned int chars_len = 0;
-  for (unsigned int i = 0; i < buffer->len; i++) {
+  for (unsigned int i = 0; i < buffer->len; i++)
+  {
     hb_codepoint_t c = buffer->info[i].codepoint;
     buffer->info[i].utf16_index() = chars_len;
     if (likely (c < 0x10000))
@@ -608,6 +760,20 @@ retry:
   ALLOCATE_ARRAY (WORD, log_clusters, chars_len);
   ALLOCATE_ARRAY (SCRIPT_CHARPROP, char_props, chars_len);
 
+  if (num_features)
+  {
+    /* Need log_clusters to assign features. */
+    chars_len = 0;
+    for (unsigned int i = 0; i < buffer->len; i++)
+    {
+      hb_codepoint_t c = buffer->info[i].codepoint;
+      unsigned int cluster = buffer->info[i].cluster;
+      log_clusters[chars_len++] = cluster;
+      if (c >= 0x10000 && c < 0x110000)
+	log_clusters[chars_len++] = cluster; /* Surrogates. */
+    }
+  }
+
   /* On Windows, we don't care about alignment...*/
   unsigned int glyphs_size = scratch_size / (sizeof (WORD) +
 					     sizeof (SCRIPT_GLYPHPROP) +
@@ -659,30 +825,9 @@ retry:
 
 #undef MAX_ITEMS
 
-  hb_auto_array_t<OPENTYPE_FEATURE_RECORD> feature_records;
-  hb_auto_array_t<TEXTRANGE_PROPERTIES> range_records;
+  OPENTYPE_TAG language_tag = hb_uint32_swap (hb_ot_tag_from_language (buffer->props.language));
   hb_auto_array_t<TEXTRANGE_PROPERTIES*> range_properties;
   hb_auto_array_t<int> range_char_counts;
-  if (num_features)
-  {
-    for (unsigned int i = 0; i < num_features; i++)
-    {
-      OPENTYPE_FEATURE_RECORD *record = feature_records.push ();
-      if (likely (record))
-      {
-	record->tagFeature = hb_uint32_swap (features[i].tag);
-	record->lParameter = features[i].value;
-      }
-    }
-    TEXTRANGE_PROPERTIES *range_record = range_records.push ();
-    if (likely (range_record))
-    {
-      range_record->potfRecords = feature_records.array;
-      range_record->cotfRecords = feature_records.len;
-    }
-  }
-
-  OPENTYPE_TAG language_tag = hb_uint32_swap (hb_ot_tag_from_language (buffer->props.language));
 
   unsigned int glyphs_offset = 0;
   unsigned int glyphs_len;
@@ -695,18 +840,39 @@ retry:
 
     if (num_features)
     {
-      /* XXX We currently ignore feature ranges and apply all features to all characters.
-       * Also, turning off a previously turned-on feature doesn't work.  We have to do
-       * that part ourselves and pass the active features down to Uniscribe. */
-
-      range_char_counts.shrink (0);
       range_properties.shrink (0);
+      range_char_counts.shrink (0);
 
-      range_char_counts.push (); /* Can't fail. */
-      range_properties.push (); /* Can't fail. */
+      range_record_t *last_range = &range_records[0];
 
-      range_char_counts.array[0] = item_chars_len;
-      range_properties.array[0] = range_records.array;
+      for (unsigned int k = chars_offset; k < chars_offset + item_chars_len; k++)
+      {
+	range_record_t *range = last_range;
+	while (log_clusters[k] < range->index_first)
+	  range--;
+	while (log_clusters[k] > range->index_last)
+	  range++;
+	if (!range_properties.len ||
+	    &range->props != range_properties[range_properties.len - 1])
+	{
+	  TEXTRANGE_PROPERTIES **props = range_properties.push ();
+	  int *c = range_char_counts.push ();
+	  if (unlikely (!props || !c))
+	  {
+	    range_properties.shrink (0);
+	    range_char_counts.shrink (0);
+	    break;
+	  }
+	  *props = &range->props;
+	  *c = 1;
+	}
+	else
+	{
+	  range_char_counts[range_char_counts.len - 1]++;
+	}
+
+	last_range = range;
+      }
     }
 
   retry_shape: