Imported Upstream version 2.3.1
[platform/upstream/harfbuzz.git] / src / hb-ot-layout.cc
index 3ff6fc8..d32be04 100644 (file)
@@ -2,7 +2,7 @@
  * Copyright © 1998-2004  David Turner and Werner Lemberg
  * Copyright © 2006  Behdad Esfahbod
  * Copyright © 2007,2008,2009  Red Hat, Inc.
- * Copyright © 2012  Google, Inc.
+ * Copyright © 2012,2013  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
  * Google Author(s): Behdad Esfahbod
  */
 
-#include "hb-ot-layout-private.hh"
+#include "hb-open-type.hh"
+#include "hb-ot-layout.hh"
+#include "hb-ot-face.hh"
+#include "hb-ot-map.hh"
+#include "hb-map.hh"
 
+#include "hb-ot-kern-table.hh"
+#include "hb-ot-gasp-table.hh" // Just so we compile it; unused otherwise.
 #include "hb-ot-layout-gdef-table.hh"
 #include "hb-ot-layout-gsub-table.hh"
 #include "hb-ot-layout-gpos-table.hh"
+#include "hb-ot-layout-base-table.hh" // Just so we compile it; unused otherwise.
+#include "hb-ot-layout-jstf-table.hh" // Just so we compile it; unused otherwise.
+#include "hb-ot-name-table.hh"
+#include "hb-ot-os2-table.hh"
 
-#include <stdlib.h>
-#include <string.h>
+#include "hb-aat-layout-lcar-table.hh"
+#include "hb-aat-layout-morx-table.hh"
 
 
-HB_SHAPER_DATA_ENSURE_DECLARE(ot, face)
-
-hb_ot_layout_t *
-_hb_ot_layout_create (hb_face_t *face)
-{
-  hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
-  if (unlikely (!layout))
-    return NULL;
-
-  layout->gdef_blob = OT::Sanitizer<OT::GDEF>::sanitize (face->reference_table (HB_OT_TAG_GDEF));
-  layout->gdef = OT::Sanitizer<OT::GDEF>::lock_instance (layout->gdef_blob);
-
-  layout->gsub_blob = OT::Sanitizer<OT::GSUB>::sanitize (face->reference_table (HB_OT_TAG_GSUB));
-  layout->gsub = OT::Sanitizer<OT::GSUB>::lock_instance (layout->gsub_blob);
-
-  layout->gpos_blob = OT::Sanitizer<OT::GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
-  layout->gpos = OT::Sanitizer<OT::GPOS>::lock_instance (layout->gpos_blob);
+/**
+ * SECTION:hb-ot-layout
+ * @title: hb-ot-layout
+ * @short_description: OpenType Layout
+ * @include: hb-ot.h
+ *
+ * Functions for querying OpenType Layout features in the font face.
+ **/
 
-  layout->gsub_lookup_count = layout->gsub->get_lookup_count ();
-  layout->gpos_lookup_count = layout->gpos->get_lookup_count ();
 
-  layout->gsub_digests = (hb_set_digest_t *) calloc (layout->gsub->get_lookup_count (), sizeof (hb_set_digest_t));
-  layout->gpos_digests = (hb_set_digest_t *) calloc (layout->gpos->get_lookup_count (), sizeof (hb_set_digest_t));
+/*
+ * kern
+ */
 
-  if (unlikely ((layout->gsub_lookup_count && !layout->gsub_digests) ||
-               (layout->gpos_lookup_count && !layout->gpos_digests)))
-  {
-    _hb_ot_layout_destroy (layout);
-    return NULL;
-  }
+bool
+hb_ot_layout_has_kerning (hb_face_t *face)
+{
+  return face->table.kern->has_data ();
+}
 
-  for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
-    layout->gsub->get_lookup (i).add_coverage (&layout->gsub_digests[i]);
-  for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
-    layout->gpos->get_lookup (i).add_coverage (&layout->gpos_digests[i]);
+bool
+hb_ot_layout_has_machine_kerning (hb_face_t *face)
+{
+  return face->table.kern->has_state_machine ();
+}
 
-  return layout;
+bool
+hb_ot_layout_has_cross_kerning (hb_face_t *face)
+{
+  return face->table.kern->has_cross_stream ();
 }
 
 void
-_hb_ot_layout_destroy (hb_ot_layout_t *layout)
+hb_ot_layout_kern (const hb_ot_shape_plan_t *plan,
+                  hb_font_t *font,
+                  hb_buffer_t  *buffer)
 {
-  hb_blob_destroy (layout->gdef_blob);
-  hb_blob_destroy (layout->gsub_blob);
-  hb_blob_destroy (layout->gpos_blob);
+  hb_blob_t *blob = font->face->table.kern.get_blob ();
+  const AAT::kern& kern = *blob->as<AAT::kern> ();
 
-  free (layout->gsub_digests);
-  free (layout->gpos_digests);
+  AAT::hb_aat_apply_context_t c (plan, font, buffer, blob);
 
-  free (layout);
+  kern.apply (&c);
 }
 
-static inline const OT::GDEF&
-_get_gdef (hb_face_t *face)
-{
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GDEF);
-  return *hb_ot_layout_from_face (face)->gdef;
-}
-static inline const OT::GSUB&
-_get_gsub (hb_face_t *face)
+
+/*
+ * GDEF
+ */
+
+bool
+OT::GDEF::is_blacklisted (hb_blob_t *blob,
+                         hb_face_t *face) const
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GSUB);
-  return *hb_ot_layout_from_face (face)->gsub;
+  /* The ugly business of blacklisting individual fonts' tables happen here!
+   * See this thread for why we finally had to bend in and do this:
+   * https://lists.freedesktop.org/archives/harfbuzz/2016-February/005489.html
+   *
+   * In certain versions of Times New Roman Italic and Bold Italic,
+   * ASCII double quotation mark U+0022 has wrong glyph class 3 (mark)
+   * in GDEF.  Many versions of Tahoma have bad GDEF tables that
+   * incorrectly classify some spacing marks such as certain IPA
+   * symbols as glyph class 3. So do older versions of Microsoft
+   * Himalaya, and the version of Cantarell shipped by Ubuntu 16.04.
+   *
+   * Nuke the GDEF tables of to avoid unwanted width-zeroing.
+   *
+   * See https://bugzilla.mozilla.org/show_bug.cgi?id=1279925
+   *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279693
+   *     https://bugzilla.mozilla.org/show_bug.cgi?id=1279875
+   */
+#define ENCODE(x,y,z) (((uint64_t) (x) << 48) | ((uint64_t) (y) << 24) | (uint64_t) (z))
+  switch ENCODE(blob->length,
+               face->table.GSUB->table.get_length (),
+               face->table.GPOS->table.get_length ())
+  {
+    /* sha1sum:c5ee92f0bca4bfb7d06c4d03e8cf9f9cf75d2e8a Windows 7? timesi.ttf */
+    case ENCODE (442, 2874, 42038):
+    /* sha1sum:37fc8c16a0894ab7b749e35579856c73c840867b Windows 7? timesbi.ttf */
+    case ENCODE (430, 2874, 40662):
+    /* sha1sum:19fc45110ea6cd3cdd0a5faca256a3797a069a80 Windows 7 timesi.ttf */
+    case ENCODE (442, 2874, 39116):
+    /* sha1sum:6d2d3c9ed5b7de87bc84eae0df95ee5232ecde26 Windows 7 timesbi.ttf */
+    case ENCODE (430, 2874, 39374):
+    /* sha1sum:8583225a8b49667c077b3525333f84af08c6bcd8 OS X 10.11.3 Times New Roman Italic.ttf */
+    case ENCODE (490, 3046, 41638):
+    /* sha1sum:ec0f5a8751845355b7c3271d11f9918a966cb8c9 OS X 10.11.3 Times New Roman Bold Italic.ttf */
+    case ENCODE (478, 3046, 41902):
+    /* sha1sum:96eda93f7d33e79962451c6c39a6b51ee893ce8c  tahoma.ttf from Windows 8 */
+    case ENCODE (898, 12554, 46470):
+    /* sha1sum:20928dc06014e0cd120b6fc942d0c3b1a46ac2bc  tahomabd.ttf from Windows 8 */
+    case ENCODE (910, 12566, 47732):
+    /* sha1sum:4f95b7e4878f60fa3a39ca269618dfde9721a79e  tahoma.ttf from Windows 8.1 */
+    case ENCODE (928, 23298, 59332):
+    /* sha1sum:6d400781948517c3c0441ba42acb309584b73033  tahomabd.ttf from Windows 8.1 */
+    case ENCODE (940, 23310, 60732):
+    /* tahoma.ttf v6.04 from Windows 8.1 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
+    case ENCODE (964, 23836, 60072):
+    /* tahomabd.ttf v6.04 from Windows 8.1 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
+    case ENCODE (976, 23832, 61456):
+    /* sha1sum:e55fa2dfe957a9f7ec26be516a0e30b0c925f846  tahoma.ttf from Windows 10 */
+    case ENCODE (994, 24474, 60336):
+    /* sha1sum:7199385abb4c2cc81c83a151a7599b6368e92343  tahomabd.ttf from Windows 10 */
+    case ENCODE (1006, 24470, 61740):
+    /* tahoma.ttf v6.91 from Windows 10 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
+    case ENCODE (1006, 24576, 61346):
+    /* tahomabd.ttf v6.91 from Windows 10 x64, see https://bugzilla.mozilla.org/show_bug.cgi?id=1279925 */
+    case ENCODE (1018, 24572, 62828):
+    /* sha1sum:b9c84d820c49850d3d27ec498be93955b82772b5  tahoma.ttf from Windows 10 AU */
+    case ENCODE (1006, 24576, 61352):
+    /* sha1sum:2bdfaab28174bdadd2f3d4200a30a7ae31db79d2  tahomabd.ttf from Windows 10 AU */
+    case ENCODE (1018, 24572, 62834):
+    /* sha1sum:b0d36cf5a2fbe746a3dd277bffc6756a820807a7  Tahoma.ttf from Mac OS X 10.9 */
+    case ENCODE (832, 7324, 47162):
+    /* sha1sum:12fc4538e84d461771b30c18b5eb6bd434e30fba  Tahoma Bold.ttf from Mac OS X 10.9 */
+    case ENCODE (844, 7302, 45474):
+    /* sha1sum:eb8afadd28e9cf963e886b23a30b44ab4fd83acc  himalaya.ttf from Windows 7 */
+    case ENCODE (180, 13054, 7254):
+    /* sha1sum:73da7f025b238a3f737aa1fde22577a6370f77b0  himalaya.ttf from Windows 8 */
+    case ENCODE (192, 12638, 7254):
+    /* sha1sum:6e80fd1c0b059bbee49272401583160dc1e6a427  himalaya.ttf from Windows 8.1 */
+    case ENCODE (192, 12690, 7254):
+    /* 8d9267aea9cd2c852ecfb9f12a6e834bfaeafe44  cantarell-fonts-0.0.21/otf/Cantarell-Regular.otf */
+    /* 983988ff7b47439ab79aeaf9a45bd4a2c5b9d371  cantarell-fonts-0.0.21/otf/Cantarell-Oblique.otf */
+    case ENCODE (188, 248, 3852):
+    /* 2c0c90c6f6087ffbfea76589c93113a9cbb0e75f  cantarell-fonts-0.0.21/otf/Cantarell-Bold.otf */
+    /* 55461f5b853c6da88069ffcdf7f4dd3f8d7e3e6b  cantarell-fonts-0.0.21/otf/Cantarell-Bold-Oblique.otf */
+    case ENCODE (188, 264, 3426):
+    /* d125afa82a77a6475ac0e74e7c207914af84b37a padauk-2.80/Padauk.ttf RHEL 7.2 */
+    case ENCODE (1058, 47032, 11818):
+    /* 0f7b80437227b90a577cc078c0216160ae61b031 padauk-2.80/Padauk-Bold.ttf RHEL 7.2*/
+    case ENCODE (1046, 47030, 12600):
+    /* d3dde9aa0a6b7f8f6a89ef1002e9aaa11b882290 padauk-2.80/Padauk.ttf Ubuntu 16.04 */
+    case ENCODE (1058, 71796, 16770):
+    /* 5f3c98ccccae8a953be2d122c1b3a77fd805093f padauk-2.80/Padauk-Bold.ttf Ubuntu 16.04 */
+    case ENCODE (1046, 71790, 17862):
+    /* 6c93b63b64e8b2c93f5e824e78caca555dc887c7 padauk-2.80/Padauk-book.ttf */
+    case ENCODE (1046, 71788, 17112):
+    /* d89b1664058359b8ec82e35d3531931125991fb9 padauk-2.80/Padauk-bookbold.ttf */
+    case ENCODE (1058, 71794, 17514):
+    /* 824cfd193aaf6234b2b4dc0cf3c6ef576c0d00ef padauk-3.0/Padauk-book.ttf */
+    case ENCODE (1330, 109904, 57938):
+    /* 91fcc10cf15e012d27571e075b3b4dfe31754a8a padauk-3.0/Padauk-bookbold.ttf */
+    case ENCODE (1330, 109904, 58972):
+    /* sha1sum: c26e41d567ed821bed997e937bc0c41435689e85  Padauk.ttf
+     *  "Padauk Regular" "Version 2.5", see https://crbug.com/681813 */
+    case ENCODE (1004, 59092, 14836):
+      return true;
+#undef ENCODE
+  }
+  return false;
 }
-static inline const OT::GPOS&
-_get_gpos (hb_face_t *face)
+
+static void
+_hb_ot_layout_set_glyph_props (hb_font_t *font,
+                              hb_buffer_t *buffer)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GPOS);
-  return *hb_ot_layout_from_face (face)->gpos;
-}
+  _hb_buffer_assert_gsubgpos_vars (buffer);
 
+  const OT::GDEF &gdef = *font->face->table.GDEF->table;
+  unsigned int count = buffer->len;
+  for (unsigned int i = 0; i < count; i++)
+  {
+    _hb_glyph_info_set_glyph_props (&buffer->info[i], gdef.get_glyph_props (buffer->info[i].codepoint));
+    _hb_glyph_info_clear_lig_props (&buffer->info[i]);
+    buffer->info[i].syllable() = 0;
+  }
+}
 
-/*
- * GDEF
- */
+/* Public API */
 
 hb_bool_t
 hb_ot_layout_has_glyph_classes (hb_face_t *face)
 {
-  return _get_gdef (face).has_glyph_classes ();
+  return face->table.GDEF->table->has_glyph_classes ();
 }
 
+/**
+ * hb_ot_layout_get_glyph_class:
+ *
+ * Since: 0.9.7
+ **/
 hb_ot_layout_glyph_class_t
 hb_ot_layout_get_glyph_class (hb_face_t      *face,
                              hb_codepoint_t  glyph)
 {
-  return (hb_ot_layout_glyph_class_t) _get_gdef (face).get_glyph_class (glyph);
+  return (hb_ot_layout_glyph_class_t) face->table.GDEF->table->get_glyph_class (glyph);
 }
 
+/**
+ * hb_ot_layout_get_glyphs_in_class:
+ *
+ * Since: 0.9.7
+ **/
 void
 hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
                                  hb_ot_layout_glyph_class_t  klass,
                                  hb_set_t                   *glyphs /* OUT */)
 {
-  return _get_gdef (face).get_glyphs_in_class (klass, glyphs);
+  return face->table.GDEF->table->get_glyphs_in_class (klass, glyphs);
 }
 
 unsigned int
@@ -142,7 +257,10 @@ hb_ot_layout_get_attach_points (hb_face_t      *face,
                                unsigned int   *point_count /* IN/OUT */,
                                unsigned int   *point_array /* OUT */)
 {
-  return _get_gdef (face).get_attach_points (glyph, start_offset, point_count, point_array);
+  return face->table.GDEF->table->get_attach_points (glyph,
+                                                    start_offset,
+                                                    point_count,
+                                                    point_array);
 }
 
 unsigned int
@@ -151,9 +269,17 @@ hb_ot_layout_get_ligature_carets (hb_font_t      *font,
                                  hb_codepoint_t  glyph,
                                  unsigned int    start_offset,
                                  unsigned int   *caret_count /* IN/OUT */,
-                                 int            *caret_array /* OUT */)
+                                 hb_position_t  *caret_array /* OUT */)
 {
-  return _get_gdef (font->face).get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
+  unsigned int result_caret_count = 0;
+  unsigned int result = font->face->table.GDEF->table->get_lig_carets (font, direction, glyph, start_offset, &result_caret_count, caret_array);
+  if (result)
+  {
+    if (caret_count) *caret_count = result_caret_count;
+  }
+  else
+    result = font->face->table.lcar->get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
+  return result;
 }
 
 
@@ -161,14 +287,46 @@ hb_ot_layout_get_ligature_carets (hb_font_t      *font,
  * GSUB/GPOS
  */
 
+bool
+OT::GSUB::is_blacklisted (hb_blob_t *blob HB_UNUSED,
+                         hb_face_t *face) const
+{
+  /* Mac OS X prefers morx over GSUB.  It also ships with various Indic fonts,
+   * all by 'MUTF' foundry (Tamil MN, Tamil Sangam MN, etc.), that have broken
+   * GSUB/GPOS tables.  Some have GSUB with zero scripts, those are ignored by
+   * our morx/GSUB preference code.  But if GSUB has non-zero scripts, we tend
+   * to prefer it over morx because we want to be consistent with other OpenType
+   * shapers.
+   *
+   * To work around broken Indic Mac system fonts, we ignore GSUB table if
+   * OS/2 VendorId is 'MUTF' and font has morx table as well.
+   *
+   * https://github.com/harfbuzz/harfbuzz/issues/1410
+   * https://github.com/harfbuzz/harfbuzz/issues/1348
+   * https://github.com/harfbuzz/harfbuzz/issues/1391
+   */
+  if (unlikely (face->table.OS2->achVendID == HB_TAG ('M','U','T','F') &&
+               face->table.morx->has_data ()))
+    return true;
+
+  return false;
+}
+
+bool
+OT::GPOS::is_blacklisted (hb_blob_t *blob HB_UNUSED,
+                         hb_face_t *face HB_UNUSED) const
+{
+  return false;
+}
+
 static const OT::GSUBGPOS&
 get_gsubgpos_table (hb_face_t *face,
                    hb_tag_t   table_tag)
 {
   switch (table_tag) {
-    case HB_OT_TAG_GSUB: return _get_gsub (face);
-    case HB_OT_TAG_GPOS: return _get_gpos (face);
-    default:             return OT::Null(OT::GSUBGPOS);
+    case HB_OT_TAG_GSUB: return *face->table.GSUB->table;
+    case HB_OT_TAG_GPOS: return *face->table.GPOS->table;
+    default:             return Null(OT::GSUBGPOS);
   }
 }
 
@@ -178,7 +336,7 @@ hb_ot_layout_table_get_script_tags (hb_face_t    *face,
                                    hb_tag_t      table_tag,
                                    unsigned int  start_offset,
                                    unsigned int *script_count /* IN/OUT */,
-                                   hb_tag_t     *script_tags /* OUT */)
+                                   hb_tag_t     *script_tags  /* OUT */)
 {
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
 
@@ -193,7 +351,7 @@ hb_ot_layout_table_find_script (hb_face_t    *face,
                                hb_tag_t      script_tag,
                                unsigned int *script_index)
 {
-  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
+  static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX), "");
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
 
   if (g.find_script_index (script_tag, script_index))
@@ -224,17 +382,36 @@ hb_ot_layout_table_choose_script (hb_face_t      *face,
                                  unsigned int   *script_index,
                                  hb_tag_t       *chosen_script)
 {
-  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
+  const hb_tag_t *t;
+  for (t = script_tags; *t; t++);
+  return hb_ot_layout_table_select_script (face, table_tag, t - script_tags, script_tags, script_index, chosen_script);
+}
+
+/**
+ * hb_ot_layout_table_select_script:
+ *
+ * Since: 2.0.0
+ **/
+hb_bool_t
+hb_ot_layout_table_select_script (hb_face_t      *face,
+                                 hb_tag_t        table_tag,
+                                 unsigned int    script_count,
+                                 const hb_tag_t *script_tags,
+                                 unsigned int   *script_index  /* OUT */,
+                                 hb_tag_t       *chosen_script /* OUT */)
+{
+  static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX), "");
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  unsigned int i;
 
-  while (*script_tags)
+  for (i = 0; i < script_count; i++)
   {
-    if (g.find_script_index (*script_tags, script_index)) {
+    if (g.find_script_index (script_tags[i], script_index))
+    {
       if (chosen_script)
-        *chosen_script = *script_tags;
+        *chosen_script = script_tags[i];
       return true;
     }
-    script_tags++;
   }
 
   /* try finding 'DFLT' */
@@ -270,13 +447,35 @@ hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
                                     hb_tag_t      table_tag,
                                     unsigned int  start_offset,
                                     unsigned int *feature_count /* IN/OUT */,
-                                    hb_tag_t     *feature_tags /* OUT */)
+                                    hb_tag_t     *feature_tags  /* OUT */)
 {
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
 
   return g.get_feature_tags (start_offset, feature_count, feature_tags);
 }
 
+bool
+hb_ot_layout_table_find_feature (hb_face_t    *face,
+                                hb_tag_t      table_tag,
+                                hb_tag_t      feature_tag,
+                                unsigned int *feature_index)
+{
+  static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX), "");
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+
+  unsigned int num_features = g.get_feature_count ();
+  for (unsigned int i = 0; i < num_features; i++)
+  {
+    if (feature_tag == g.get_feature_tag (i)) {
+      if (feature_index) *feature_index = i;
+      return true;
+    }
+  }
+
+  if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
+  return false;
+}
+
 
 unsigned int
 hb_ot_layout_script_get_language_tags (hb_face_t    *face,
@@ -284,7 +483,7 @@ hb_ot_layout_script_get_language_tags (hb_face_t    *face,
                                       unsigned int  script_index,
                                       unsigned int  start_offset,
                                       unsigned int *language_count /* IN/OUT */,
-                                      hb_tag_t     *language_tags /* OUT */)
+                                      hb_tag_t     *language_tags  /* OUT */)
 {
   const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
 
@@ -298,13 +497,38 @@ hb_ot_layout_script_find_language (hb_face_t    *face,
                                   hb_tag_t      language_tag,
                                   unsigned int *language_index)
 {
-  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
+  return hb_ot_layout_script_select_language (face,
+                                             table_tag,
+                                             script_index,
+                                             1,
+                                             &language_tag,
+                                             language_index);
+}
+
+/**
+ * hb_ot_layout_script_select_language:
+ *
+ * Since: 2.0.0
+ **/
+hb_bool_t
+hb_ot_layout_script_select_language (hb_face_t      *face,
+                                    hb_tag_t        table_tag,
+                                    unsigned int    script_index,
+                                    unsigned int    language_count,
+                                    const hb_tag_t *language_tags,
+                                    unsigned int   *language_index /* OUT */)
+{
+  static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX), "");
   const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
+  unsigned int i;
 
-  if (s.find_lang_sys_index (language_tag, language_index))
-    return true;
+  for (i = 0; i < language_count; i++)
+  {
+    if (s.find_lang_sys_index (language_tags[i], language_index))
+      return true;
+  }
 
-  /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
+  /* try finding 'dflt' */
   if (s.find_lang_sys_index (HB_OT_TAG_DEFAULT_LANGUAGE, language_index))
     return false;
 
@@ -319,9 +543,33 @@ hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
                                                  unsigned int  language_index,
                                                  unsigned int *feature_index)
 {
-  const OT::LangSys &l = get_gsubgpos_table (face, table_tag).get_script (script_index).get_lang_sys (language_index);
+  return hb_ot_layout_language_get_required_feature (face,
+                                                    table_tag,
+                                                    script_index,
+                                                    language_index,
+                                                    feature_index,
+                                                    nullptr);
+}
+
+/**
+ * hb_ot_layout_language_get_required_feature:
+ *
+ * Since: 0.9.30
+ **/
+hb_bool_t
+hb_ot_layout_language_get_required_feature (hb_face_t    *face,
+                                           hb_tag_t      table_tag,
+                                           unsigned int  script_index,
+                                           unsigned int  language_index,
+                                           unsigned int *feature_index,
+                                           hb_tag_t     *feature_tag)
+{
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 
-  if (feature_index) *feature_index = l.get_required_feature_index ();
+  unsigned int index = l.get_required_feature_index ();
+  if (feature_index) *feature_index = index;
+  if (feature_tag) *feature_tag = g.get_feature_tag (index);
 
   return l.has_required_feature ();
 }
@@ -332,7 +580,7 @@ hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
                                           unsigned int  script_index,
                                           unsigned int  language_index,
                                           unsigned int  start_offset,
-                                          unsigned int *feature_count /* IN/OUT */,
+                                          unsigned int *feature_count   /* IN/OUT */,
                                           unsigned int *feature_indexes /* OUT */)
 {
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
@@ -348,12 +596,12 @@ hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
                                        unsigned int  language_index,
                                        unsigned int  start_offset,
                                        unsigned int *feature_count /* IN/OUT */,
-                                       hb_tag_t     *feature_tags /* OUT */)
+                                       hb_tag_t     *feature_tags  /* OUT */)
 {
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 
-  ASSERT_STATIC (sizeof (unsigned int) == sizeof (hb_tag_t));
+  static_assert ((sizeof (unsigned int) == sizeof (hb_tag_t)), "");
   unsigned int ret = l.get_feature_indexes (start_offset, feature_count, (unsigned int *) feature_tags);
 
   if (feature_tags) {
@@ -374,7 +622,7 @@ hb_ot_layout_language_find_feature (hb_face_t    *face,
                                    hb_tag_t      feature_tag,
                                    unsigned int *feature_index)
 {
-  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
+  static_assert ((OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX), "");
   const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 
@@ -392,210 +640,246 @@ hb_ot_layout_language_find_feature (hb_face_t    *face,
   return false;
 }
 
+/**
+ * hb_ot_layout_feature_get_lookups:
+ *
+ * Since: 0.9.7
+ **/
 unsigned int
 hb_ot_layout_feature_get_lookups (hb_face_t    *face,
                                  hb_tag_t      table_tag,
                                  unsigned int  feature_index,
                                  unsigned int  start_offset,
-                                 unsigned int *lookup_count /* IN/OUT */,
+                                 unsigned int *lookup_count   /* IN/OUT */,
                                  unsigned int *lookup_indexes /* OUT */)
 {
-  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
-  const OT::Feature &f = g.get_feature (feature_index);
+  return hb_ot_layout_feature_with_variations_get_lookups (face,
+                                                          table_tag,
+                                                          feature_index,
+                                                          HB_OT_LAYOUT_NO_VARIATIONS_INDEX,
+                                                          start_offset,
+                                                          lookup_count,
+                                                          lookup_indexes);
+}
 
-  return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
+/**
+ * hb_ot_layout_table_get_lookup_count:
+ *
+ * Since: 0.9.22
+ **/
+unsigned int
+hb_ot_layout_table_get_lookup_count (hb_face_t    *face,
+                                    hb_tag_t      table_tag)
+{
+  return get_gsubgpos_table (face, table_tag).get_lookup_count ();
 }
 
-static void
-_hb_ot_layout_collect_lookups_lookups (hb_face_t      *face,
-                                      hb_tag_t        table_tag,
-                                      unsigned int    feature_index,
-                                      hb_set_t       *lookup_indexes /* OUT */)
+
+struct hb_collect_features_context_t
 {
-  unsigned int lookup_indices[32];
-  unsigned int offset, len;
+  hb_collect_features_context_t (hb_face_t       *face,
+                                hb_tag_t         table_tag,
+                                hb_set_t        *feature_indexes_)
+    : g (get_gsubgpos_table (face, table_tag)),
+      feature_indexes (feature_indexes_),
+      script_count(0),langsys_count(0) {}
+
+  bool visited (const OT::Script &s)
+  {
+    /* We might have Null() object here.  Don't want to involve
+     * that in the memoize.  So, detect empty objects and return. */
+    if (unlikely (!s.has_default_lang_sys () &&
+                 !s.get_lang_sys_count ()))
+      return true;
+
+    if (script_count++ > HB_MAX_SCRIPTS)
+      return true;
+
+    return visited (s, visited_script);
+  }
+  bool visited (const OT::LangSys &l)
+  {
+    /* We might have Null() object here.  Don't want to involve
+     * that in the memoize.  So, detect empty objects and return. */
+    if (unlikely (!l.has_required_feature () &&
+                 !l.get_feature_count ()))
+      return true;
 
-  offset = 0;
-  do {
-    len = ARRAY_LENGTH (lookup_indices);
-    hb_ot_layout_feature_get_lookups (face,
-                                     table_tag,
-                                     feature_index,
-                                     offset, &len,
-                                     lookup_indices);
+    if (langsys_count++ > HB_MAX_LANGSYS)
+      return true;
 
-    for (unsigned int i = 0; i < len; i++)
-      lookup_indexes->add (lookup_indices[i]);
+    return visited (l, visited_langsys);
+  }
 
-    offset += len;
-  } while (len == ARRAY_LENGTH (lookup_indices));
-}
+  private:
+  template <typename T>
+  bool visited (const T &p, hb_set_t &visited_set)
+  {
+    hb_codepoint_t delta = (hb_codepoint_t) ((uintptr_t) &p - (uintptr_t) &g);
+     if (visited_set.has (delta))
+      return true;
+
+    visited_set.add (delta);
+    return false;
+  }
+
+  public:
+  const OT::GSUBGPOS &g;
+  hb_set_t           *feature_indexes;
+
+  private:
+  hb_set_t visited_script;
+  hb_set_t visited_langsys;
+  unsigned int script_count;
+  unsigned int langsys_count;
+};
 
 static void
-_hb_ot_layout_collect_lookups_features (hb_face_t      *face,
-                                       hb_tag_t        table_tag,
-                                       unsigned int    script_index,
-                                       unsigned int    language_index,
-                                       const hb_tag_t *features,
-                                       hb_set_t       *lookup_indexes /* OUT */)
-{
-  unsigned int required_feature_index;
-  if (hb_ot_layout_language_get_required_feature_index (face,
-                                                       table_tag,
-                                                       script_index,
-                                                       language_index,
-                                                       &required_feature_index))
-    _hb_ot_layout_collect_lookups_lookups (face,
-                                          table_tag,
-                                          required_feature_index,
-                                          lookup_indexes);
+langsys_collect_features (hb_collect_features_context_t *c,
+                         const OT::LangSys  &l,
+                         const hb_tag_t     *features)
+{
+  if (c->visited (l)) return;
 
   if (!features)
   {
-    /* All features */
-    unsigned int feature_indices[32];
-    unsigned int offset, len;
-
-    offset = 0;
-    do {
-      len = ARRAY_LENGTH (feature_indices);
-      hb_ot_layout_language_get_feature_indexes (face,
-                                                table_tag,
-                                                script_index,
-                                                language_index,
-                                                offset, &len,
-                                                feature_indices);
-
-      for (unsigned int i = 0; i < len; i++)
-       _hb_ot_layout_collect_lookups_lookups (face,
-                                              table_tag,
-                                              feature_indices[i],
-                                              lookup_indexes);
-
-      offset += len;
-    } while (len == ARRAY_LENGTH (feature_indices));
+    /* All features. */
+    if (l.has_required_feature ())
+      c->feature_indexes->add (l.get_required_feature_index ());
+
+    l.add_feature_indexes_to (c->feature_indexes);
   }
   else
   {
+    /* Ugh. Any faster way? */
     for (; *features; features++)
     {
-      unsigned int feature_index;
-      if (hb_ot_layout_language_find_feature (face,
-                                             table_tag,
-                                             script_index,
-                                             language_index,
-                                             *features,
-                                             &feature_index))
-        _hb_ot_layout_collect_lookups_lookups (face,
-                                              table_tag,
-                                              feature_index,
-                                              lookup_indexes);
+      hb_tag_t feature_tag = *features;
+      unsigned int num_features = l.get_feature_count ();
+      for (unsigned int i = 0; i < num_features; i++)
+      {
+       unsigned int feature_index = l.get_feature_index (i);
+
+       if (feature_tag == c->g.get_feature_tag (feature_index))
+       {
+         c->feature_indexes->add (feature_index);
+         break;
+       }
+      }
     }
   }
 }
 
 static void
-_hb_ot_layout_collect_lookups_languages (hb_face_t      *face,
-                                        hb_tag_t        table_tag,
-                                        unsigned int    script_index,
-                                        const hb_tag_t *languages,
-                                        const hb_tag_t *features,
-                                        hb_set_t       *lookup_indexes /* OUT */)
-{
-  _hb_ot_layout_collect_lookups_features (face,
-                                         table_tag,
-                                         script_index,
-                                         HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
-                                         features,
-                                         lookup_indexes);
+script_collect_features (hb_collect_features_context_t *c,
+                        const OT::Script   &s,
+                        const hb_tag_t *languages,
+                        const hb_tag_t *features)
+{
+  if (c->visited (s)) return;
 
   if (!languages)
   {
-    /* All languages */
-    unsigned int count = hb_ot_layout_script_get_language_tags (face,
-                                                               table_tag,
-                                                               script_index,
-                                                               0, NULL, NULL);
+    /* All languages. */
+    if (s.has_default_lang_sys ())
+      langsys_collect_features (c,
+                               s.get_default_lang_sys (),
+                               features);
+
+    unsigned int count = s.get_lang_sys_count ();
     for (unsigned int language_index = 0; language_index < count; language_index++)
-      _hb_ot_layout_collect_lookups_features (face,
-                                             table_tag,
-                                             script_index,
-                                             language_index,
-                                             features,
-                                             lookup_indexes);
+      langsys_collect_features (c,
+                               s.get_lang_sys (language_index),
+                               features);
   }
   else
   {
     for (; *languages; languages++)
     {
       unsigned int language_index;
-      if (hb_ot_layout_script_find_language (face,
-                                            table_tag,
-                                            script_index,
-                                            *languages,
-                                            &language_index))
-        _hb_ot_layout_collect_lookups_features (face,
-                                               table_tag,
-                                               script_index,
-                                               language_index,
-                                               features,
-                                               lookup_indexes);
+      if (s.find_lang_sys_index (*languages, &language_index))
+       langsys_collect_features (c,
+                                 s.get_lang_sys (language_index),
+                                 features);
     }
   }
 }
 
+/**
+ * hb_ot_layout_collect_features:
+ *
+ * Since: 1.8.5
+ **/
 void
-hb_ot_layout_collect_lookups (hb_face_t      *face,
-                             hb_tag_t        table_tag,
-                             const hb_tag_t *scripts,
-                             const hb_tag_t *languages,
-                             const hb_tag_t *features,
-                             hb_set_t       *lookup_indexes /* OUT */)
+hb_ot_layout_collect_features (hb_face_t      *face,
+                               hb_tag_t        table_tag,
+                               const hb_tag_t *scripts,
+                               const hb_tag_t *languages,
+                               const hb_tag_t *features,
+                               hb_set_t       *feature_indexes /* OUT */)
 {
+  hb_collect_features_context_t c (face, table_tag, feature_indexes);
   if (!scripts)
   {
-    /* All scripts */
-    unsigned int count = hb_ot_layout_table_get_script_tags (face,
-                                                            table_tag,
-                                                            0, NULL, NULL);
+    /* All scripts. */
+    unsigned int count = c.g.get_script_count ();
     for (unsigned int script_index = 0; script_index < count; script_index++)
-      _hb_ot_layout_collect_lookups_languages (face,
-                                              table_tag,
-                                              script_index,
-                                              languages,
-                                              features,
-                                              lookup_indexes);
+      script_collect_features (&c,
+                              c.g.get_script (script_index),
+                              languages,
+                              features);
   }
   else
   {
     for (; *scripts; scripts++)
     {
       unsigned int script_index;
-      if (hb_ot_layout_table_find_script (face,
-                                         table_tag,
-                                         *scripts,
-                                         &script_index))
-        _hb_ot_layout_collect_lookups_languages (face,
-                                                table_tag,
-                                                script_index,
-                                                languages,
-                                                features,
-                                                lookup_indexes);
+      if (c.g.find_script_index (*scripts, &script_index))
+       script_collect_features (&c,
+                                c.g.get_script (script_index),
+                                languages,
+                                features);
     }
   }
 }
 
+/**
+ * hb_ot_layout_collect_lookups:
+ *
+ * Since: 0.9.8
+ **/
+void
+hb_ot_layout_collect_lookups (hb_face_t      *face,
+                             hb_tag_t        table_tag,
+                             const hb_tag_t *scripts,
+                             const hb_tag_t *languages,
+                             const hb_tag_t *features,
+                             hb_set_t       *lookup_indexes /* OUT */)
+{
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+
+  hb_set_t feature_indexes;
+  hb_ot_layout_collect_features (face, table_tag, scripts, languages, features, &feature_indexes);
+
+  for (hb_codepoint_t feature_index = HB_SET_VALUE_INVALID;
+       hb_set_next (&feature_indexes, &feature_index);)
+    g.get_feature (feature_index).add_lookup_indexes_to (lookup_indexes);
+}
+
+/**
+ * hb_ot_layout_lookup_collect_glyphs:
+ *
+ * Since: 0.9.7
+ **/
 void
 hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
                                    hb_tag_t      table_tag,
                                    unsigned int  lookup_index,
-                                   hb_set_t     *glyphs_before, /* OUT. May be NULL */
-                                   hb_set_t     *glyphs_input,  /* OUT. May be NULL */
-                                   hb_set_t     *glyphs_after,  /* OUT. May be NULL */
-                                   hb_set_t     *glyphs_output  /* OUT. May be NULL */)
+                                   hb_set_t     *glyphs_before, /* OUT.  May be NULL */
+                                   hb_set_t     *glyphs_input,  /* OUT.  May be NULL */
+                                   hb_set_t     *glyphs_after,  /* OUT.  May be NULL */
+                                   hb_set_t     *glyphs_output  /* OUT.  May be NULL */)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return;
-
   OT::hb_collect_glyphs_context_t c (face,
                                     glyphs_before,
                                     glyphs_input,
@@ -606,20 +890,52 @@ hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
   {
     case HB_OT_TAG_GSUB:
     {
-      const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
-      l.collect_glyphs_lookup (&c);
+      const OT::SubstLookup& l = face->table.GSUB->table->get_lookup (lookup_index);
+      l.collect_glyphs (&c);
       return;
     }
     case HB_OT_TAG_GPOS:
     {
-      const OT::PosLookup& l = hb_ot_layout_from_face (face)->gpos->get_lookup (lookup_index);
-      l.collect_glyphs_lookup (&c);
+      const OT::PosLookup& l = face->table.GPOS->table->get_lookup (lookup_index);
+      l.collect_glyphs (&c);
       return;
     }
   }
 }
 
 
+/* Variations support */
+
+hb_bool_t
+hb_ot_layout_table_find_feature_variations (hb_face_t    *face,
+                                           hb_tag_t      table_tag,
+                                           const int    *coords,
+                                           unsigned int  num_coords,
+                                           unsigned int *variations_index /* out */)
+{
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+
+  return g.find_variations_index (coords, num_coords, variations_index);
+}
+
+unsigned int
+hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
+                                                 hb_tag_t      table_tag,
+                                                 unsigned int  feature_index,
+                                                 unsigned int  variations_index,
+                                                 unsigned int  start_offset,
+                                                 unsigned int *lookup_count /* IN/OUT */,
+                                                 unsigned int *lookup_indexes /* OUT */)
+{
+  static_assert ((OT::FeatureVariations::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_VARIATIONS_INDEX), "");
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+
+  const OT::Feature &f = g.get_feature_variation (feature_index, variations_index);
+
+  return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
+}
+
+
 /*
  * OT::GSUB
  */
@@ -627,9 +943,14 @@ hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
 hb_bool_t
 hb_ot_layout_has_substitution (hb_face_t *face)
 {
-  return &_get_gsub (face) != &OT::Null(OT::GSUB);
+  return face->table.GSUB->table->has_data ();
 }
 
+/**
+ * hb_ot_layout_lookup_would_substitute:
+ *
+ * Since: 0.9.7
+ **/
 hb_bool_t
 hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
                                      unsigned int          lookup_index,
@@ -637,62 +958,136 @@ hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
                                      unsigned int          glyphs_length,
                                      hb_bool_t             zero_context)
 {
-  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
-  return hb_ot_layout_lookup_would_substitute_fast (face, lookup_index, glyphs, glyphs_length, zero_context);
+  return hb_ot_layout_lookup_would_substitute_fast (face,
+                                                   lookup_index,
+                                                   glyphs, glyphs_length,
+                                                   zero_context);
 }
 
-hb_bool_t
+bool
 hb_ot_layout_lookup_would_substitute_fast (hb_face_t            *face,
                                           unsigned int          lookup_index,
                                           const hb_codepoint_t *glyphs,
                                           unsigned int          glyphs_length,
-                                          hb_bool_t             zero_context)
+                                          bool                  zero_context)
 {
-  if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
-  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context);
+  if (unlikely (lookup_index >= face->table.GSUB->lookup_count)) return false;
+  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, (bool) zero_context);
 
-  const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
+  const OT::SubstLookup& l = face->table.GSUB->table->get_lookup (lookup_index);
 
-  return l.would_apply (&c, &hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
+  return l.would_apply (&c, &face->table.GSUB->accels[lookup_index]);
 }
 
 void
-hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
+hb_ot_layout_substitute_start (hb_font_t    *font,
+                              hb_buffer_t  *buffer)
 {
-  OT::GSUB::substitute_start (font, buffer);
+_hb_ot_layout_set_glyph_props (font, buffer);
 }
 
-hb_bool_t
-hb_ot_layout_substitute_lookup (hb_font_t    *font,
-                               hb_buffer_t  *buffer,
-                               unsigned int  lookup_index,
-                               hb_mask_t     mask)
+void
+hb_ot_layout_delete_glyphs_inplace (hb_buffer_t *buffer,
+                                   bool (*filter) (const hb_glyph_info_t *info))
 {
-  if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gsub_lookup_count)) return false;
+  /* Merge clusters and delete filtered glyphs.
+   * NOTE! We can't use out-buffer as we have positioning data. */
+  unsigned int j = 0;
+  unsigned int count = buffer->len;
+  hb_glyph_info_t *info = buffer->info;
+  hb_glyph_position_t *pos = buffer->pos;
+  for (unsigned int i = 0; i < count; i++)
+  {
+    if (filter (&info[i]))
+    {
+      /* Merge clusters.
+       * Same logic as buffer->delete_glyph(), but for in-place removal. */
 
-  OT::hb_apply_context_t c (font, buffer, mask);
+      unsigned int cluster = info[i].cluster;
+      if (i + 1 < count && cluster == info[i + 1].cluster)
+       continue; /* Cluster survives; do nothing. */
 
-  const OT::SubstLookup& l = hb_ot_layout_from_face (font->face)->gsub->get_lookup (lookup_index);
+      if (j)
+      {
+       /* Merge cluster backward. */
+       if (cluster < info[j - 1].cluster)
+       {
+         unsigned int mask = info[i].mask;
+         unsigned int old_cluster = info[j - 1].cluster;
+         for (unsigned k = j; k && info[k - 1].cluster == old_cluster; k--)
+           buffer->set_cluster (info[k - 1], cluster, mask);
+       }
+       continue;
+      }
 
-  return l.apply_string (&c, &hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
-}
+      if (i + 1 < count)
+       buffer->merge_clusters (i, i + 2); /* Merge cluster forward. */
 
-void
-hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
-{
-  OT::GSUB::substitute_finish (font, buffer);
+      continue;
+    }
+
+    if (j != i)
+    {
+      info[j] = info[i];
+      pos[j] = pos[i];
+    }
+    j++;
+  }
+  buffer->len = j;
 }
 
+/**
+ * hb_ot_layout_lookup_substitute_closure:
+ *
+ * Since: 0.9.7
+ **/
 void
 hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
                                        unsigned int  lookup_index,
                                        hb_set_t     *glyphs)
 {
-  OT::hb_closure_context_t c (face, glyphs);
+  hb_map_t done_lookups;
+  OT::hb_closure_context_t c (face, glyphs, &done_lookups);
 
-  const OT::SubstLookup& l = _get_gsub (face).get_lookup (lookup_index);
+  const OT::SubstLookup& l = face->table.GSUB->table->get_lookup (lookup_index);
+
+  l.closure (&c, lookup_index);
+}
+
+/**
+ * hb_ot_layout_lookups_substitute_closure:
+ *
+ * Compute the transitive closure of glyphs needed for all of the
+ * provided lookups.
+ *
+ * Since: 1.8.1
+ **/
+void
+hb_ot_layout_lookups_substitute_closure (hb_face_t      *face,
+                                         const hb_set_t *lookups,
+                                         hb_set_t       *glyphs)
+{
+  hb_map_t done_lookups;
+  OT::hb_closure_context_t c (face, glyphs, &done_lookups);
+  const OT::GSUB& gsub = *face->table.GSUB->table;
 
-  l.closure (&c);
+  unsigned int iteration_count = 0;
+  unsigned int glyphs_length;
+  do
+  {
+    glyphs_length = glyphs->get_population ();
+    if (lookups != nullptr)
+    {
+      for (hb_codepoint_t lookup_index = HB_SET_VALUE_INVALID; hb_set_next (lookups, &lookup_index);)
+        gsub.get_lookup (lookup_index).closure (&c, lookup_index);
+    }
+    else
+    {
+      for (unsigned int i = 0; i < gsub.get_lookup_count (); i++)
+        gsub.get_lookup (i).closure (&c, i);
+    }
+  } while (iteration_count++ <= HB_CLOSURE_MAX_STAGES &&
+          glyphs_length != glyphs->get_population ());
 }
 
 /*
@@ -702,7 +1097,7 @@ hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
 hb_bool_t
 hb_ot_layout_has_positioning (hb_face_t *face)
 {
-  return &_get_gpos (face) != &OT::Null(OT::GPOS);
+  return face->table.GPOS->table->has_data ();
 }
 
 void
@@ -711,36 +1106,32 @@ hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
   OT::GPOS::position_start (font, buffer);
 }
 
-hb_bool_t
-hb_ot_layout_position_lookup (hb_font_t    *font,
-                             hb_buffer_t  *buffer,
-                             unsigned int  lookup_index,
-                             hb_mask_t     mask)
+void
+hb_ot_layout_position_finish_advances (hb_font_t *font, hb_buffer_t *buffer)
 {
-  if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gpos_lookup_count)) return false;
-
-  OT::hb_apply_context_t c (font, buffer, mask);
-
-  const OT::PosLookup& l = hb_ot_layout_from_face (font->face)->gpos->get_lookup (lookup_index);
-
-  return l.apply_string (&c, &hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
+  OT::GPOS::position_finish_advances (font, buffer);
 }
 
 void
-hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer, hb_bool_t zero_width_attached_marks)
+hb_ot_layout_position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer)
 {
-  OT::GPOS::position_finish (font, buffer, zero_width_attached_marks);
+  OT::GPOS::position_finish_offsets (font, buffer);
 }
 
+/**
+ * hb_ot_layout_get_size_params:
+ *
+ * Since: 0.9.10
+ **/
 hb_bool_t
-hb_ot_layout_get_size_params (hb_face_t    *face,
-                             unsigned int *design_size,       /* OUT.  May be NULL */
-                             unsigned int *subfamily_id,      /* OUT.  May be NULL */
-                             unsigned int *subfamily_name_id, /* OUT.  May be NULL */
-                             unsigned int *range_start,       /* OUT.  May be NULL */
-                             unsigned int *range_end          /* OUT.  May be NULL */)
-{
-  const OT::GPOS &gpos = _get_gpos (face);
+hb_ot_layout_get_size_params (hb_face_t       *face,
+                             unsigned int    *design_size,       /* OUT.  May be NULL */
+                             unsigned int    *subfamily_id,      /* OUT.  May be NULL */
+                             hb_ot_name_id_t *subfamily_name_id, /* OUT.  May be NULL */
+                             unsigned int    *range_start,       /* OUT.  May be NULL */
+                             unsigned int    *range_end          /* OUT.  May be NULL */)
+{
+  const OT::GPOS &gpos = *face->table.GPOS->table;
   const hb_tag_t tag = HB_TAG ('s','i','z','e');
 
   unsigned int num_features = gpos.get_feature_count ();
@@ -753,26 +1144,388 @@ hb_ot_layout_get_size_params (hb_face_t    *face,
 
       if (params.designSize)
       {
-#define PARAM(a, A) if (a) *a = params.A
-       PARAM (design_size, designSize);
-       PARAM (subfamily_id, subfamilyID);
-       PARAM (subfamily_name_id, subfamilyNameID);
-       PARAM (range_start, rangeStart);
-       PARAM (range_end, rangeEnd);
-#undef PARAM
+       if (design_size) *design_size = params.designSize;
+       if (subfamily_id) *subfamily_id = params.subfamilyID;
+       if (subfamily_name_id) *subfamily_name_id = params.subfamilyNameID;
+       if (range_start) *range_start = params.rangeStart;
+       if (range_end) *range_end = params.rangeEnd;
 
        return true;
       }
     }
   }
 
-#define PARAM(a, A) if (a) *a = 0
-  PARAM (design_size, designSize);
-  PARAM (subfamily_id, subfamilyID);
-  PARAM (subfamily_name_id, subfamilyNameID);
-  PARAM (range_start, rangeStart);
-  PARAM (range_end, rangeEnd);
-#undef PARAM
+  if (design_size) *design_size = 0;
+  if (subfamily_id) *subfamily_id = 0;
+  if (subfamily_name_id) *subfamily_name_id = HB_OT_NAME_ID_INVALID;
+  if (range_start) *range_start = 0;
+  if (range_end) *range_end = 0;
+
+  return false;
+}
+
+/**
+ * hb_ot_layout_feature_get_name_ids:
+ * @face: #hb_face_t to work upon
+ * @table_tag: table tag to query, "GSUB" or "GPOS".
+ * @feature_index: index of feature to query.
+ * @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
+ *              that an application can use for tooltip text for this
+ *              feature. (May be NULL.)
+ * @sample_id: (out) (allow-none): The ‘name’ table name ID that specifies sample text
+ *             that illustrates the effect of this feature. (May be NULL.)
+ * @num_named_parameters: (out) (allow-none):  Number of named parameters. (May be zero.)
+ * @first_param_id: (out) (allow-none): The first ‘name’ table name ID used to specify
+ *                  strings for user-interface labels for the feature
+ *                  parameters. (Must be zero if numParameters is zero.)
+ *
+ * Fetches name indices from feature parameters for "Stylistic Set" ('ssXX') or
+ * "Character Variant" ('cvXX') features.
+ *
+ * Return value: true if data found, false otherwise
+ *
+ * Since: 2.0.0
+ **/
+hb_bool_t
+hb_ot_layout_feature_get_name_ids (hb_face_t       *face,
+                                  hb_tag_t         table_tag,
+                                  unsigned int     feature_index,
+                                  hb_ot_name_id_t *label_id,             /* OUT.  May be NULL */
+                                  hb_ot_name_id_t *tooltip_id,           /* OUT.  May be NULL */
+                                  hb_ot_name_id_t *sample_id,            /* OUT.  May be NULL */
+                                  unsigned int    *num_named_parameters, /* OUT.  May be NULL */
+                                  hb_ot_name_id_t *first_param_id        /* OUT.  May be NULL */)
+{
+  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 ();
+  if (&feature_params != &Null (OT::FeatureParams))
+  {
+    const OT::FeatureParamsStylisticSet& ss_params =
+      feature_params.get_stylistic_set_params (feature_tag);
+    if (&ss_params != &Null (OT::FeatureParamsStylisticSet)) /* ssXX */
+    {
+      if (label_id) *label_id = ss_params.uiNameID;
+      // ssXX features don't have the rest
+      if (tooltip_id) *tooltip_id = HB_OT_NAME_ID_INVALID;
+      if (sample_id) *sample_id = HB_OT_NAME_ID_INVALID;
+      if (num_named_parameters) *num_named_parameters = 0;
+      if (first_param_id) *first_param_id = HB_OT_NAME_ID_INVALID;
+      return true;
+    }
+    const OT::FeatureParamsCharacterVariants& cv_params =
+      feature_params.get_character_variants_params (feature_tag);
+    if (&cv_params != &Null (OT::FeatureParamsCharacterVariants)) /* cvXX */
+    {
+      if (label_id) *label_id = cv_params.featUILableNameID;
+      if (tooltip_id) *tooltip_id = cv_params.featUITooltipTextNameID;
+      if (sample_id) *sample_id = cv_params.sampleTextNameID;
+      if (num_named_parameters) *num_named_parameters = cv_params.numNamedParameters;
+      if (first_param_id) *first_param_id = cv_params.firstParamUILabelNameID;
+      return true;
+    }
+  }
 
+  if (label_id) *label_id = HB_OT_NAME_ID_INVALID;
+  if (tooltip_id) *tooltip_id = HB_OT_NAME_ID_INVALID;
+  if (sample_id) *sample_id = HB_OT_NAME_ID_INVALID;
+  if (num_named_parameters) *num_named_parameters = 0;
+  if (first_param_id) *first_param_id = HB_OT_NAME_ID_INVALID;
   return false;
 }
+
+/**
+ * hb_ot_layout_feature_get_characters:
+ * @face: #hb_face_t to work upon
+ * @table_tag: table tag to query, "GSUB" or "GPOS".
+ * @feature_index: index of feature to query.
+ * @start_offset: In case the resulting char_count was equal to its input value, there
+ *                is a chance there were more characters on the tag so this API can be
+ *                called with an offset till resulting char_count gets to a number
+ *                lower than input buffer (or consider using just a bigger buffer for
+ *                one shot copying).
+ * @char_count: (inout) (allow-none): The count of characters for which this feature
+ *              provides glyph variants. (May be zero.)
+ * @characters: (out caller-allocates) (array length=char_count): A buffer pointer. The Unicode codepoints
+ *              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: 2.0.0
+ **/
+unsigned int
+hb_ot_layout_feature_get_characters (hb_face_t      *face,
+                                    hb_tag_t        table_tag,
+                                    unsigned int    feature_index,
+                                    unsigned int    start_offset,
+                                    unsigned int   *char_count, /* IN/OUT.  May be NULL */
+                                    hb_codepoint_t *characters  /* OUT.     May be NULL */)
+{
+  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 ();
+
+  const OT::FeatureParamsCharacterVariants& cv_params =
+    feature_params.get_character_variants_params(feature_tag);
+
+  unsigned int len = 0;
+  if (char_count && characters && start_offset < cv_params.characters.len)
+  {
+    len = MIN (cv_params.characters.len - start_offset, *char_count);
+    for (unsigned int i = 0; i < len; ++i)
+      characters[i] = cv_params.characters[start_offset + i];
+  }
+  if (char_count) *char_count = len;
+  return cv_params.characters.len;
+}
+
+
+/*
+ * Parts of different types are implemented here such that they have direct
+ * access to GSUB/GPOS lookups.
+ */
+
+
+struct GSUBProxy
+{
+  static constexpr unsigned table_index = 0u;
+  static constexpr bool inplace = false;
+  typedef OT::SubstLookup Lookup;
+
+  GSUBProxy (hb_face_t *face) :
+    table (*face->table.GSUB->table),
+    accels (face->table.GSUB->accels) {}
+
+  const OT::GSUB &table;
+  const OT::hb_ot_layout_lookup_accelerator_t *accels;
+};
+
+struct GPOSProxy
+{
+  static constexpr unsigned table_index = 1u;
+  static constexpr bool inplace = true;
+  typedef OT::PosLookup Lookup;
+
+  GPOSProxy (hb_face_t *face) :
+    table (*face->table.GPOS->table),
+    accels (face->table.GPOS->accels) {}
+
+  const OT::GPOS &table;
+  const OT::hb_ot_layout_lookup_accelerator_t *accels;
+};
+
+
+static inline bool
+apply_forward (OT::hb_ot_apply_context_t *c,
+              const OT::hb_ot_layout_lookup_accelerator_t &accel)
+{
+  bool ret = false;
+  hb_buffer_t *buffer = c->buffer;
+  while (buffer->idx < buffer->len && buffer->successful)
+  {
+    bool applied = false;
+    if (accel.may_have (buffer->cur().codepoint) &&
+       (buffer->cur().mask & c->lookup_mask) &&
+       c->check_glyph_property (&buffer->cur(), c->lookup_props))
+     {
+       applied = accel.apply (c);
+     }
+
+    if (applied)
+      ret = true;
+    else
+      buffer->next_glyph ();
+  }
+  return ret;
+}
+
+static inline bool
+apply_backward (OT::hb_ot_apply_context_t *c,
+              const OT::hb_ot_layout_lookup_accelerator_t &accel)
+{
+  bool ret = false;
+  hb_buffer_t *buffer = c->buffer;
+  do
+  {
+    if (accel.may_have (buffer->cur().codepoint) &&
+       (buffer->cur().mask & c->lookup_mask) &&
+       c->check_glyph_property (&buffer->cur(), c->lookup_props))
+     ret |= accel.apply (c);
+
+    /* The reverse lookup doesn't "advance" cursor (for good reason). */
+    buffer->idx--;
+
+  }
+  while ((int) buffer->idx >= 0);
+  return ret;
+}
+
+template <typename Proxy>
+static inline void
+apply_string (OT::hb_ot_apply_context_t *c,
+             const typename Proxy::Lookup &lookup,
+             const OT::hb_ot_layout_lookup_accelerator_t &accel)
+{
+  hb_buffer_t *buffer = c->buffer;
+
+  if (unlikely (!buffer->len || !c->lookup_mask))
+    return;
+
+  c->set_lookup_props (lookup.get_props ());
+
+  if (likely (!lookup.is_reverse ()))
+  {
+    /* in/out forward substitution/positioning */
+    if (Proxy::table_index == 0u)
+      buffer->clear_output ();
+    buffer->idx = 0;
+
+    bool ret;
+    ret = apply_forward (c, accel);
+    if (ret)
+    {
+      if (!Proxy::inplace)
+       buffer->swap_buffers ();
+      else
+       assert (!buffer->has_separate_output ());
+    }
+  }
+  else
+  {
+    /* in-place backward substitution/positioning */
+    if (Proxy::table_index == 0u)
+      buffer->remove_output ();
+    buffer->idx = buffer->len - 1;
+
+    apply_backward (c, accel);
+  }
+}
+
+template <typename Proxy>
+inline void hb_ot_map_t::apply (const Proxy &proxy,
+                               const hb_ot_shape_plan_t *plan,
+                               hb_font_t *font,
+                               hb_buffer_t *buffer) const
+{
+  const unsigned int table_index = proxy.table_index;
+  unsigned int i = 0;
+  OT::hb_ot_apply_context_t c (table_index, font, buffer);
+  c.set_recurse_func (Proxy::Lookup::apply_recurse_func);
+
+  for (unsigned int stage_index = 0; stage_index < stages[table_index].length; stage_index++) {
+    const stage_map_t *stage = &stages[table_index][stage_index];
+    for (; i < stage->last_lookup; i++)
+    {
+      unsigned int lookup_index = lookups[table_index][i].index;
+      if (!buffer->message (font, "start lookup %d", lookup_index)) continue;
+      c.set_lookup_index (lookup_index);
+      c.set_lookup_mask (lookups[table_index][i].mask);
+      c.set_auto_zwj (lookups[table_index][i].auto_zwj);
+      c.set_auto_zwnj (lookups[table_index][i].auto_zwnj);
+      if (lookups[table_index][i].random)
+      {
+       c.set_random (true);
+       buffer->unsafe_to_break_all ();
+      }
+      apply_string<Proxy> (&c,
+                          proxy.table.get_lookup (lookup_index),
+                          proxy.accels[lookup_index]);
+      (void) buffer->message (font, "end lookup %d", lookup_index);
+    }
+
+    if (stage->pause_func)
+    {
+      buffer->clear_output ();
+      stage->pause_func (plan, font, buffer);
+    }
+  }
+}
+
+void hb_ot_map_t::substitute (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
+{
+  GSUBProxy proxy (font->face);
+  apply (proxy, plan, font, buffer);
+}
+
+void hb_ot_map_t::position (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
+{
+  GPOSProxy proxy (font->face);
+  apply (proxy, plan, font, buffer);
+}
+
+void
+hb_ot_layout_substitute_lookup (OT::hb_ot_apply_context_t *c,
+                               const OT::SubstLookup &lookup,
+                               const OT::hb_ot_layout_lookup_accelerator_t &accel)
+{
+  apply_string<GSUBProxy> (c, lookup, accel);
+}
+
+#if 0
+static const OT::BASE& _get_base (hb_face_t *face)
+{
+  return *face->table.BASE;
+}
+
+hb_bool_t
+hb_ot_layout_get_baseline (hb_font_t               *font,
+                          hb_ot_layout_baseline_t  baseline,
+                          hb_direction_t           direction,
+                          hb_tag_t                 script_tag,
+                          hb_tag_t                 language_tag,
+                          hb_position_t           *coord        /* OUT.  May be NULL. */)
+{
+  const OT::BASE &base = _get_base (font->face);
+  bool result = base.get_baseline (font, baseline, direction, script_tag,
+                                  language_tag, coord);
+
+  /* TODO: Simulate https://docs.microsoft.com/en-us/typography/opentype/spec/baselinetags#ideographic-em-box */
+  if (!result && coord) *coord = 0;
+
+  if (coord) *coord = font->em_scale_dir (*coord, direction);
+
+  return result;
+}
+
+/* To be moved to public header */
+/*
+ * BASE
+ */
+
+/**
+ * hb_ot_layout_baseline_t:
+ *
+ * https://docs.microsoft.com/en-us/typography/opentype/spec/baselinetags
+ *
+ * Since: DONTREPLACEME
+ */
+typedef enum {
+  HB_OT_LAYOUT_BASELINE_HANG = HB_TAG('h','a','n','g'),
+  HB_OT_LAYOUT_BASELINE_ICFB = HB_TAG('i','c','f','b'),
+  HB_OT_LAYOUT_BASELINE_ICFT = HB_TAG('i','c','f','t'),
+  HB_OT_LAYOUT_BASELINE_IDEO = HB_TAG('i','d','e','o'),
+  HB_OT_LAYOUT_BASELINE_IDTB = HB_TAG('i','d','t','b'),
+  HB_OT_LAYOUT_BASELINE_MATH = HB_TAG('m','a','t','h'),
+  HB_OT_LAYOUT_BASELINE_ROMN = HB_TAG('r','o','m','n')
+} hb_ot_layout_baseline_t;
+
+HB_EXTERN hb_bool_t
+hb_ot_layout_get_baseline (hb_font_t               *font,
+                          hb_ot_layout_baseline_t  baseline,
+                          hb_direction_t           direction,
+                          hb_tag_t                 script_tag,
+                          hb_tag_t                 language_tag,
+                          hb_position_t           *coord        /* OUT.  May be NULL. */);
+
+#endif