/*

 * Copyright © 2019  Adobe Inc.

 * Copyright © 2019  Ebrahim Byagowi

 *

 *  This is part of HarfBuzz, a text shaping library.

 *

 * Permission is hereby granted, without written agreement and without

 * license or royalty fees, to use, copy, modify, and distribute this

 * software and its documentation for any purpose, provided that the

 * above copyright notice and the following two paragraphs appear in

 * all copies of this software.

 *

 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

 * DAMAGE.

 *

 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 *

 * Adobe Author(s): Michiharu Ariza

 */

#ifndef HB_OT_VAR_GVAR_TABLE_HH

#define HB_OT_VAR_GVAR_TABLE_HH

#include "hb-decycler.hh"

#include "hb-open-type.hh"

#include "hb-ot-var-common.hh"

/*

 * gvar -- Glyph Variation Table

 * https://docs.microsoft.com/en-us/typography/opentype/spec/gvar

 */

#define HB_OT_TAG_gvar HB_TAG('g','v','a','r')

#define HB_OT_TAG_GVAR HB_TAG('G','V','A','R')

struct hb_glyf_scratch_t

{

  // glyf

  contour_point_vector_t all_points;

  contour_point_vector_t comp_points;

  hb_decycler_t decycler;

  // gvar

  contour_point_vector_t orig_points;

  hb_vector_t<int> x_deltas;

  hb_vector_t<int> y_deltas;

  contour_point_vector_t deltas;

  hb_vector_t<unsigned int> shared_indices;

  hb_vector_t<unsigned int> private_indices;

};

namespace OT {

template <typename OffsetType>

struct glyph_variations_t

{

  // TODO: Move tuple_variations_t to outside of TupleVariationData

  using tuple_variations_t = typename TupleVariationData<OffsetType>::tuple_variations_t;

  using GlyphVariationData = TupleVariationData<OffsetType>;

  hb_vector_t<tuple_variations_t> glyph_variations;

  hb_vector_t<F2DOT14> compiled_shared_tuples;

  private:

  unsigned shared_tuples_count = 0;

  /* shared coords-> index map after instantiation */

  hb_hashmap_t<const hb_vector_t<F2DOT14>*, unsigned> shared_tuples_idx_map;

  hb_alloc_pool_t pool;

  public:

  unsigned compiled_shared_tuples_count () const

  { return shared_tuples_count; }

  unsigned compiled_byte_size () const

  {

    unsigned byte_size = 0;

    for (const auto& _ : glyph_variations)

      byte_size += _.get_compiled_byte_size ();

    return byte_size;

  }

  bool create_from_glyphs_var_data (unsigned axis_count,

                                    const hb_array_t<const F2DOT14> shared_tuples,

                                    const hb_subset_plan_t *plan,

                                    const hb_hashmap_t<hb_codepoint_t, hb_bytes_t>& new_gid_var_data_map)

  {

    if (unlikely (!glyph_variations.alloc_exact (plan->new_to_old_gid_list.length)))

      return false;

    auto it = hb_iter (plan->new_to_old_gid_list);

    for (auto &_ : it)

    {

      hb_codepoint_t new_gid = _.first;

      contour_point_vector_t *all_contour_points;

      if (!new_gid_var_data_map.has (new_gid) ||

          !plan->new_gid_contour_points_map.has (new_gid, &all_contour_points))

        return false;

      hb_bytes_t var_data = new_gid_var_data_map.get (new_gid);

      const GlyphVariationData* p = reinterpret_cast<const GlyphVariationData*> (var_data.arrayZ);

      typename GlyphVariationData::tuple_iterator_t iterator;

      tuple_variations_t tuple_vars;

      hb_vector_t<unsigned> shared_indices;

      /* in case variation data is empty, push an empty struct into the vector,

       * keep the vector in sync with the new_to_old_gid_list */

      if (!var_data || ! p->has_data () || !all_contour_points->length ||

          !GlyphVariationData::get_tuple_iterator (var_data, axis_count,

                                                   var_data.arrayZ,

                                                   shared_indices, &iterator))

      {

        glyph_variations.push (std::move (tuple_vars));

        continue;

      }

      bool is_composite_glyph = false;

      is_composite_glyph = plan->composite_new_gids.has (new_gid);

      if (!p->decompile_tuple_variations (all_contour_points->length, true /* is_gvar */,

                                          iterator, &(plan->axes_old_index_tag_map),

                                          shared_indices, shared_tuples,

                                          tuple_vars, /* OUT */

            &pool,

                                          is_composite_glyph))

        return false;

      glyph_variations.push (std::move (tuple_vars));

    }

    return !glyph_variations.in_error () && glyph_variations.length == plan->new_to_old_gid_list.length;

  }

  bool instantiate (const hb_subset_plan_t *plan)

  {

    unsigned count = plan->new_to_old_gid_list.length;

    bool iup_optimize = false;

    optimize_scratch_t scratch;

    iup_optimize = plan->flags & HB_SUBSET_FLAGS_OPTIMIZE_IUP_DELTAS;

    for (unsigned i = 0; i < count; i++)

    {

      hb_codepoint_t new_gid = plan->new_to_old_gid_list[i].first;

      contour_point_vector_t *all_points;

      if (!plan->new_gid_contour_points_map.has (new_gid, &all_points))

        return false;

      if (!glyph_variations[i].instantiate (plan->axes_location, plan->axes_triple_distances, scratch, &pool, all_points, iup_optimize))

        return false;

    }

    return true;

  }

  bool compile_bytes (const hb_map_t& axes_index_map,

                      const hb_map_t& axes_old_index_tag_map)

  {

    if (!compile_shared_tuples (axes_index_map, axes_old_index_tag_map))

      return false;

    for (tuple_variations_t& vars: glyph_variations)

      if (!vars.compile_bytes (axes_index_map, axes_old_index_tag_map,

                               true, /* use shared points*/

                               true,

                               &shared_tuples_idx_map,

             &pool))

        return false;

    return true;

  }

  bool compile_shared_tuples (const hb_map_t& axes_index_map,

                              const hb_map_t& axes_old_index_tag_map)

  {

    /* key is pointer to compiled_peak_coords inside each tuple, hashing

     * function will always deref pointers first */

    hb_hashmap_t<const hb_vector_t<F2DOT14>*, unsigned> coords_count_map;

    /* count the num of shared coords */

    for (tuple_variations_t& vars: glyph_variations)

    {

      for (tuple_delta_t& var : vars.tuple_vars)

      {

        if (!var.compile_coords (axes_index_map, axes_old_index_tag_map, &pool))

          return false;

        unsigned *count;

  unsigned hash = hb_hash (&var.compiled_peak_coords);

        if (coords_count_map.has_with_hash (&(var.compiled_peak_coords), hash, &count))

    (*count)++;

        else

          coords_count_map.set_with_hash (&(var.compiled_peak_coords), hash, 1);

      }

    }

    if (!coords_count_map || coords_count_map.in_error ())

      return false;

    /* add only those coords that are used more than once into the vector and sort */

    hb_vector_t<hb_pair_t<const hb_vector_t<F2DOT14>*, unsigned>> shared_coords {

      + hb_iter (coords_count_map)

      | hb_filter ([] (const hb_pair_t<const hb_vector_t<F2DOT14>*, unsigned>& p) { return p.second > 1; })

    };

    if (unlikely (shared_coords.in_error ())) return false;

    /* no shared tuples: no coords are used more than once */

    if (!shared_coords) return true;

    /* sorting based on the coords frequency first (high to low), then compare

     * the coords bytes */

    shared_coords.qsort (_cmp_coords);

    /* build shared_coords->idx map and shared tuples byte array */

    shared_tuples_count = hb_min (0xFFFu + 1, shared_coords.length);

    unsigned len = shared_tuples_count * (shared_coords[0].first->length);

    if (unlikely (!compiled_shared_tuples.alloc (len)))

      return false;

    for (unsigned i = 0; i < shared_tuples_count; i++)

    {

      shared_tuples_idx_map.set (shared_coords[i].first, i);

      /* add a concat() in hb_vector_t? */

      for (auto c : shared_coords[i].first->iter ())

        compiled_shared_tuples.push (c);

    }

    return true;

  }

  static int _cmp_coords (const void *pa, const void *pb)

  {

    const hb_pair_t<hb_vector_t<F2DOT14> *, unsigned> *a = (const hb_pair_t<hb_vector_t<F2DOT14> *, unsigned> *) pa;

    const hb_pair_t<hb_vector_t<F2DOT14> *, unsigned> *b = (const hb_pair_t<hb_vector_t<F2DOT14> *, unsigned> *) pb;

    if (a->second != b->second)

      return b->second - a->second; // high to low

    return b->first->as_array().cmp (a->first->as_array ());

  }

  template<typename Iterator,

           hb_requires (hb_is_iterator (Iterator))>

  bool serialize_glyph_var_data (hb_serialize_context_t *c,

                                 Iterator it,

                                 bool long_offset,

                                 unsigned num_glyphs,

                                 char* glyph_var_data_offsets /* OUT: glyph var data offsets array */) const

  {

    TRACE_SERIALIZE (this);

    if (long_offset)

    {

      ((HBUINT32 *) glyph_var_data_offsets)[0] = 0;

      glyph_var_data_offsets += 4;

    }

    else

    {

      ((HBUINT16 *) glyph_var_data_offsets)[0] = 0;

      glyph_var_data_offsets += 2;

    }

    unsigned glyph_offset = 0;

    hb_codepoint_t last_gid = 0;

    unsigned idx = 0;

    GlyphVariationData* cur_glyph = c->start_embed<GlyphVariationData> ();

    if (!cur_glyph) return_trace (false);

    for (auto &_ : it)

    {

      hb_codepoint_t gid = _.first;

      if (long_offset)

        for (; last_gid < gid; last_gid++)

          ((HBUINT32 *) glyph_var_data_offsets)[last_gid] = glyph_offset;

      else

        for (; last_gid < gid; last_gid++)

          ((HBUINT16 *) glyph_var_data_offsets)[last_gid] = glyph_offset / 2;

      if (idx >= glyph_variations.length) return_trace (false);

      if (!cur_glyph->serialize (c, true, glyph_variations[idx])) return_trace (false);

      GlyphVariationData* next_glyph = c->start_embed<GlyphVariationData> ();

      glyph_offset += (char *) next_glyph - (char *) cur_glyph;

      if (long_offset)

        ((HBUINT32 *) glyph_var_data_offsets)[gid] = glyph_offset;

      else

        ((HBUINT16 *) glyph_var_data_offsets)[gid] = glyph_offset / 2;

      last_gid++;

      idx++;

      cur_glyph = next_glyph;

    }

    if (long_offset)

      for (; last_gid < num_glyphs; last_gid++)

        ((HBUINT32 *) glyph_var_data_offsets)[last_gid] = glyph_offset;

    else

      for (; last_gid < num_glyphs; last_gid++)

        ((HBUINT16 *) glyph_var_data_offsets)[last_gid] = glyph_offset / 2;

    return_trace (true);

  }

};

template <typename GidOffsetType, unsigned TableTag>

struct gvar_GVAR

{

  static constexpr hb_tag_t tableTag = TableTag;

  using GlyphVariationData = TupleVariationData<GidOffsetType>;

  bool has_data () const { return version.to_int () != 0; }

  bool sanitize_shallow (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    return_trace (c->check_struct (this) &&

      hb_barrier () &&

      (version.major == 1) &&

      sharedTuples.sanitize (c, this, axisCount * sharedTupleCount) &&

      (is_long_offset () ?

         c->check_array (get_long_offset_array (), c->get_num_glyphs () + 1) :

         c->check_array (get_short_offset_array (), c->get_num_glyphs () + 1)));

  }

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned short, 2u>, 1735811442u>::sanitize_shallow(hb_sanitize_context_t*) const

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned int, 3u>, 1196835154u>::sanitize_shallow(hb_sanitize_context_t*) const

  /* GlyphVariationData not sanitized here; must be checked while accessing each glyph variation data */

  bool sanitize (hb_sanitize_context_t *c) const

  { return sanitize_shallow (c); }

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned short, 2u>, 1735811442u>::sanitize(hb_sanitize_context_t*) const

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned int, 3u>, 1196835154u>::sanitize(hb_sanitize_context_t*) const

  bool decompile_glyph_variations (hb_subset_context_t *c,

                                   glyph_variations_t<GidOffsetType>& glyph_vars /* OUT */) const

  {

    hb_hashmap_t<hb_codepoint_t, hb_bytes_t> new_gid_var_data_map;

    auto it = hb_iter (c->plan->new_to_old_gid_list);

    if (it->first == 0 && !(c->plan->flags & HB_SUBSET_FLAGS_NOTDEF_OUTLINE))

    {

      new_gid_var_data_map.set (0, hb_bytes_t ());

      it++;

    }

    for (auto &_ : it)

    {

      hb_codepoint_t new_gid = _.first;

      hb_codepoint_t old_gid = _.second;

      hb_bytes_t var_data_bytes = get_glyph_var_data_bytes (c->source_blob, glyphCountX, old_gid);

      new_gid_var_data_map.set (new_gid, var_data_bytes);

    }

    if (new_gid_var_data_map.in_error ()) return false;

    hb_array_t<const F2DOT14> shared_tuples = (this+sharedTuples).as_array ((unsigned) sharedTupleCount * (unsigned) axisCount);

    return glyph_vars.create_from_glyphs_var_data (axisCount, shared_tuples, c->plan, new_gid_var_data_map);

  }

  template<typename Iterator,

           hb_requires (hb_is_iterator (Iterator))>

  bool serialize (hb_serialize_context_t *c,

                  const glyph_variations_t<GidOffsetType>& glyph_vars,

                  Iterator it,

                  unsigned axis_count,

                  unsigned num_glyphs,

                  bool force_long_offsets) const

  {

    TRACE_SERIALIZE (this);

    gvar_GVAR *out = c->allocate_min<gvar_GVAR> ();

    if (unlikely (!out)) return_trace (false);

    out->version.major = 1;

    out->version.minor = 0;

    out->axisCount = axis_count;

    out->glyphCountX = hb_min (0xFFFFu, num_glyphs);

    unsigned glyph_var_data_size = glyph_vars.compiled_byte_size ();

    /* According to the spec: If the short format (Offset16) is used for offsets,

     * the value stored is the offset divided by 2, so the maximum data size should

     * be 2 * 0xFFFFu, which is 0x1FFFEu */

    bool long_offset = glyph_var_data_size > 0x1FFFEu || force_long_offsets;

    out->flags = long_offset ? 1 : 0;

    HBUINT8 *glyph_var_data_offsets = c->allocate_size<HBUINT8> ((long_offset ? 4 : 2) * (num_glyphs + 1), false);

    if (!glyph_var_data_offsets) return_trace (false);

    /* shared tuples */

    unsigned shared_tuple_count = glyph_vars.compiled_shared_tuples_count ();

    out->sharedTupleCount = shared_tuple_count;

    if (!shared_tuple_count)

      out->sharedTuples = 0;

    else

    {

      hb_array_t<const F2DOT14> shared_tuples = glyph_vars.compiled_shared_tuples.as_array ().copy (c);

      if (!shared_tuples.arrayZ) return_trace (false);

      out->sharedTuples = (const char *) shared_tuples.arrayZ - (char *) out;

    }

    char *glyph_var_data = c->start_embed<char> ();

    if (!glyph_var_data) return_trace (false);

    out->dataZ = glyph_var_data - (char *) out;

    return_trace (glyph_vars.serialize_glyph_var_data (c, it, long_offset, num_glyphs,

                                                       (char *) glyph_var_data_offsets));

  }

  bool instantiate (hb_subset_context_t *c) const

  {

    TRACE_SUBSET (this);

    glyph_variations_t<GidOffsetType> glyph_vars;

    if (!decompile_glyph_variations (c, glyph_vars))

      return_trace (false);

    if (!glyph_vars.instantiate (c->plan)) return_trace (false);

    if (!glyph_vars.compile_bytes (c->plan->axes_index_map, c->plan->axes_old_index_tag_map))

      return_trace (false);

    unsigned axis_count = c->plan->axes_index_map.get_population ();

    unsigned num_glyphs = c->plan->num_output_glyphs ();

    auto it = hb_iter (c->plan->new_to_old_gid_list);

    bool force_long_offsets = false;

#ifdef HB_EXPERIMENTAL_API

    force_long_offsets = c->plan->flags & HB_SUBSET_FLAGS_IFTB_REQUIREMENTS;

#endif

    return_trace (serialize (c->serializer, glyph_vars, it, axis_count, num_glyphs, force_long_offsets));

  }

  bool subset (hb_subset_context_t *c) const

  {

    TRACE_SUBSET (this);

    if (c->plan->all_axes_pinned)

      return_trace (false);

    if (c->plan->normalized_coords)

      return_trace (instantiate (c));

    unsigned glyph_count = version.to_int () ? c->plan->source->get_num_glyphs () : 0;

    gvar_GVAR *out = c->serializer->allocate_min<gvar_GVAR> ();

    if (unlikely (!out)) return_trace (false);

    out->version.major = 1;

    out->version.minor = 0;

    out->axisCount = axisCount;

    out->sharedTupleCount = sharedTupleCount;

    unsigned int num_glyphs = c->plan->num_output_glyphs ();

    out->glyphCountX = hb_min (0xFFFFu, num_glyphs);

    auto it = hb_iter (c->plan->new_to_old_gid_list);

    if (it->first == 0 && !(c->plan->flags & HB_SUBSET_FLAGS_NOTDEF_OUTLINE))

      it++;

    unsigned int subset_data_size = 0;

    for (auto &_ : it)

    {

      hb_codepoint_t old_gid = _.second;

      subset_data_size += get_glyph_var_data_bytes (c->source_blob, glyph_count, old_gid).length;

    }

    /* According to the spec: If the short format (Offset16) is used for offsets,

     * the value stored is the offset divided by 2, so the maximum data size should

     * be 2 * 0xFFFFu, which is 0x1FFFEu */

    bool long_offset = subset_data_size > 0x1FFFEu;

#ifdef HB_EXPERIMENTAL_API

    long_offset = long_offset || (c->plan->flags & HB_SUBSET_FLAGS_IFTB_REQUIREMENTS);

#endif

    out->flags = long_offset ? 1 : 0;

    HBUINT8 *subset_offsets = c->serializer->allocate_size<HBUINT8> ((long_offset ? 4 : 2) * (num_glyphs + 1), false);

    if (!subset_offsets) return_trace (false);

    /* shared tuples */

    if (!sharedTupleCount || !sharedTuples)

      out->sharedTuples = 0;

    else

    {

      unsigned int shared_tuple_size = F2DOT14::static_size * axisCount * sharedTupleCount;

      F2DOT14 *tuples = c->serializer->allocate_size<F2DOT14> (shared_tuple_size);

      if (!tuples) return_trace (false);

      out->sharedTuples = (char *) tuples - (char *) out;

      hb_memcpy (tuples, this+sharedTuples, shared_tuple_size);

    }

    /* This ordering relative to the shared tuples array, which puts the glyphVariationData

       last in the table, is required when HB_SUBSET_FLAGS_IFTB_REQUIREMENTS is set */

    char *subset_data = c->serializer->allocate_size<char> (subset_data_size, false);

    if (!subset_data) return_trace (false);

    out->dataZ = subset_data - (char *) out;

    if (long_offset)

    {

      ((HBUINT32 *) subset_offsets)[0] = 0;

      subset_offsets += 4;

    }

    else

    {

      ((HBUINT16 *) subset_offsets)[0] = 0;

      subset_offsets += 2;

    }

    unsigned int glyph_offset = 0;

    hb_codepoint_t last = 0;

    it = hb_iter (c->plan->new_to_old_gid_list);

    if (it->first == 0 && !(c->plan->flags & HB_SUBSET_FLAGS_NOTDEF_OUTLINE))

      it++;

    for (auto &_ : it)

    {

      hb_codepoint_t gid = _.first;

      hb_codepoint_t old_gid = _.second;

      if (long_offset)

  for (; last < gid; last++)

    ((HBUINT32 *) subset_offsets)[last] = glyph_offset;

      else

  for (; last < gid; last++)

    ((HBUINT16 *) subset_offsets)[last] = glyph_offset / 2;

      hb_bytes_t var_data_bytes = get_glyph_var_data_bytes (c->source_blob,

                  glyph_count,

                  old_gid);

      hb_memcpy (subset_data, var_data_bytes.arrayZ, var_data_bytes.length);

      subset_data += var_data_bytes.length;

      glyph_offset += var_data_bytes.length;

      if (long_offset)

  ((HBUINT32 *) subset_offsets)[gid] = glyph_offset;

      else

  ((HBUINT16 *) subset_offsets)[gid] = glyph_offset / 2;

      last++; // Skip over gid

    }

    if (long_offset)

      for (; last < num_glyphs; last++)

  ((HBUINT32 *) subset_offsets)[last] = glyph_offset;

    else

      for (; last < num_glyphs; last++)

  ((HBUINT16 *) subset_offsets)[last] = glyph_offset / 2;

    return_trace (true);

  }

  protected:

  const hb_bytes_t get_glyph_var_data_bytes (hb_blob_t *blob,

               unsigned glyph_count,

               hb_codepoint_t glyph) const

  {

    unsigned start_offset = get_offset (glyph_count, glyph);

    unsigned end_offset = get_offset (glyph_count, glyph+1);

    if (unlikely (end_offset < start_offset)) return hb_bytes_t ();

    unsigned length = end_offset - start_offset;

    hb_bytes_t var_data = blob->as_bytes ().sub_array (((unsigned) dataZ) + start_offset, length);

    return likely (var_data.length >= GlyphVariationData::min_size) ? var_data : hb_bytes_t ();

  }

  bool is_long_offset () const { return flags & 1; }

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned short, 2u>, 1735811442u>::is_long_offset() const

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned int, 3u>, 1196835154u>::is_long_offset() const

  unsigned get_offset (unsigned glyph_count, unsigned i) const

  {

    if (unlikely (i > glyph_count)) return 0;

    hb_barrier ();

    return is_long_offset () ? get_long_offset_array ()[i] : get_short_offset_array ()[i] * 2;

  }

  const HBUINT32 * get_long_offset_array () const { return (const HBUINT32 *) &offsetZ; }

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned short, 2u>, 1735811442u>::get_long_offset_array() const

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned int, 3u>, 1196835154u>::get_long_offset_array() const

  const HBUINT16 *get_short_offset_array () const { return (const HBUINT16 *) &offsetZ; }

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned short, 2u>, 1735811442u>::get_short_offset_array() const

Unexecuted instantiation: OT::gvar_GVAR<OT::NumType<true, unsigned int, 3u>, 1196835154u>::get_short_offset_array() const

  public:

  struct accelerator_t

  {

    hb_scalar_cache_t *create_cache () const

    {

      return hb_scalar_cache_t::create (table->sharedTupleCount);

    }

    static void destroy_cache (hb_scalar_cache_t *cache)

    {

      hb_scalar_cache_t::destroy (cache);

    }

    bool has_data () const { return table->has_data (); }

    accelerator_t (hb_face_t *face)

    {

      table = hb_sanitize_context_t ().reference_table<gvar_GVAR> (face);

      /* If sanitize failed, set glyphCount to 0. */

      glyphCount = table->version.to_int () ? face->get_num_glyphs () : 0;

    }

    ~accelerator_t () { table.destroy (); }

    private:

    static float infer_delta (const hb_array_t<contour_point_t> points,

            const hb_array_t<contour_point_t> deltas,

            unsigned int target, unsigned int prev, unsigned int next,

            float contour_point_t::*m)

    {

      float target_val = points.arrayZ[target].*m;

      float prev_val = points.arrayZ[prev].*m;

      float next_val = points.arrayZ[next].*m;

      float prev_delta =  deltas.arrayZ[prev].*m;

      float next_delta =  deltas.arrayZ[next].*m;

      if (prev_val == next_val)

  return (prev_delta == next_delta) ? prev_delta : 0.f;

      else if (target_val <= hb_min (prev_val, next_val))

  return (prev_val < next_val) ? prev_delta : next_delta;

      else if (target_val >= hb_max (prev_val, next_val))

  return (prev_val > next_val) ? prev_delta : next_delta;

      /* linear interpolation */

      float r = (target_val - prev_val) / (next_val - prev_val);

      return prev_delta + r * (next_delta - prev_delta);

    }

    static unsigned int next_index (unsigned int i, unsigned int start, unsigned int end)

    { return (i >= end) ? start : (i + 1); }

    public:

    bool apply_deltas_to_points (hb_codepoint_t glyph,

         hb_array_t<const int> coords,

         const hb_array_t<contour_point_t> points,

         hb_glyf_scratch_t &scratch,

         hb_scalar_cache_t *gvar_cache = nullptr,

         bool phantom_only = false) const

    {

      if (unlikely (glyph >= glyphCount)) return true;

      hb_bytes_t var_data_bytes = table->get_glyph_var_data_bytes (table.get_blob (), glyphCount, glyph);

      if (!var_data_bytes.as<GlyphVariationData> ()->has_data ()) return true;

      auto &shared_indices = scratch.shared_indices;

      shared_indices.clear ();

      typename GlyphVariationData::tuple_iterator_t iterator;

      if (!GlyphVariationData::get_tuple_iterator (var_data_bytes, table->axisCount,

               var_data_bytes.arrayZ,

               shared_indices, &iterator))

  return true; /* so isn't applied at all */

      /* Save original points for inferred delta calculation */

      auto &orig_points_vec = scratch.orig_points;

      orig_points_vec.clear (); // Populated lazily

      auto orig_points = orig_points_vec.as_array ();

      /* flag is used to indicate referenced point */

      auto &deltas_vec = scratch.deltas;

      deltas_vec.clear (); // Populated lazily

      auto deltas = deltas_vec.as_array ();

      unsigned num_coords = table->axisCount;

      hb_array_t<const F2DOT14> shared_tuples = (table+table->sharedTuples).as_array (table->sharedTupleCount * num_coords);

      auto &private_indices = scratch.private_indices;

      auto &x_deltas = scratch.x_deltas;

      auto &y_deltas = scratch.y_deltas;

      unsigned count = points.length;

      bool flush = false;

      do

      {

  float scalar = iterator.current_tuple->calculate_scalar (coords, num_coords, shared_tuples,

                 gvar_cache);

  if (scalar == 0.f) continue;

  const HBUINT8 *p = iterator.get_serialized_data ();

  unsigned int length = iterator.current_tuple->get_data_size ();

  if (unlikely (!iterator.var_data_bytes.check_range (p, length)))

    return false;

  if (!deltas)

  {

    if (unlikely (!deltas_vec.resize_dirty  (count))) return false;

    deltas = deltas_vec.as_array ();

    hb_memset (deltas.arrayZ + (phantom_only ? count - 4 : 0), 0,

         (phantom_only ? 4 : count) * sizeof (deltas[0]));

  }

  const HBUINT8 *end = p + length;

  bool has_private_points = iterator.current_tuple->has_private_points ();

  if (has_private_points &&

      !GlyphVariationData::decompile_points (p, private_indices, end))

    return false;

  const hb_array_t<unsigned int> &indices = has_private_points ? private_indices : shared_indices;

  bool apply_to_all = (indices.length == 0);

  unsigned num_deltas = apply_to_all ? points.length : indices.length;

  unsigned start_deltas = (phantom_only && num_deltas >= 4 ? num_deltas - 4 : 0);

  if (unlikely (!x_deltas.resize_dirty  (num_deltas))) return false;

  if (unlikely (!GlyphVariationData::decompile_deltas (p, x_deltas, end, false, start_deltas))) return false;

  if (unlikely (!y_deltas.resize_dirty  (num_deltas))) return false;

  if (unlikely (!GlyphVariationData::decompile_deltas (p, y_deltas, end, false, start_deltas))) return false;

  if (!apply_to_all)

  {

    if (!orig_points && !phantom_only)

    {

      orig_points_vec.extend (points);

      if (unlikely (orig_points_vec.in_error ())) return false;

      orig_points = orig_points_vec.as_array ();

    }

    if (flush)

    {

      for (unsigned int i = phantom_only ? count - 4 : 0; i < count; i++)

        points.arrayZ[i].translate (deltas.arrayZ[i]);

      flush = false;

    }

    hb_memset (deltas.arrayZ + (phantom_only ? count - 4 : 0), 0,

         (phantom_only ? 4 : count) * sizeof (deltas[0]));

  }

  if (HB_OPTIMIZE_SIZE_VAL)

  {

    for (unsigned int i = 0; i < num_deltas; i++)

    {

      unsigned int pt_index;

      if (apply_to_all)

        pt_index = i;

      else

      {

        pt_index = indices[i];

        if (unlikely (pt_index >= deltas.length)) continue;

      }

      if (phantom_only && pt_index < count - 4) continue;

      auto &delta = deltas.arrayZ[pt_index];

      delta.flag = 1; /* this point is referenced, i.e., explicit deltas specified */

      delta.add_delta (x_deltas.arrayZ[i] * scalar,

           y_deltas.arrayZ[i] * scalar);

    }

  }

  else

  {

    /* Ouch. Four cases... for optimization. */

    if (scalar != 1.0f)

    {

      if (apply_to_all)

        for (unsigned int i = phantom_only ? count - 4 : 0; i < count; i++)

        {

    auto &delta = deltas.arrayZ[i];

    delta.add_delta (x_deltas.arrayZ[i] * scalar,

         y_deltas.arrayZ[i] * scalar);

        }

      else

        for (unsigned int i = 0; i < num_deltas; i++)

        {

    unsigned int pt_index = indices[i];

    if (unlikely (pt_index >= deltas.length)) continue;

    if (phantom_only && pt_index < count - 4) continue;

    auto &delta = deltas.arrayZ[pt_index];

    delta.flag = 1; /* this point is referenced, i.e., explicit deltas specified */

    delta.add_delta (x_deltas.arrayZ[i] * scalar,

         y_deltas.arrayZ[i] * scalar);

        }

    }

    else

    {

      if (apply_to_all)

        for (unsigned int i = phantom_only ? count - 4 : 0; i < count; i++)

        {

    auto &delta = deltas.arrayZ[i];

    delta.add_delta (x_deltas.arrayZ[i],

         y_deltas.arrayZ[i]);

        }

      else

        for (unsigned int i = 0; i < num_deltas; i++)

        {

    unsigned int pt_index = indices[i];

    if (unlikely (pt_index >= deltas.length)) continue;

    if (phantom_only && pt_index < count - 4) continue;

    auto &delta = deltas.arrayZ[pt_index];

    delta.flag = 1; /* this point is referenced, i.e., explicit deltas specified */

    delta.add_delta (x_deltas.arrayZ[i],

         y_deltas.arrayZ[i]);

        }

    }

  }

  /* infer deltas for unreferenced points */

  if (!apply_to_all && !phantom_only)

  {

    unsigned start_point = 0;

    unsigned end_point = 0;

    while (true)

    {

      while (end_point < count && !points.arrayZ[end_point].is_end_point)

        end_point++;

      if (unlikely (end_point == count)) break;

      /* Check the number of unreferenced points in a contour. If no unref points or no ref points, nothing to do. */

      unsigned unref_count = 0;

      for (unsigned i = start_point; i < end_point + 1; i++)

        unref_count += deltas.arrayZ[i].flag;

      unref_count = (end_point - start_point + 1) - unref_count;

      unsigned j = start_point;

      if (unref_count == 0 || unref_count > end_point - start_point)

        goto no_more_gaps;

      for (;;)

      {

        /* Locate the next gap of unreferenced points between two referenced points prev and next.

         * Note that a gap may wrap around at left (start_point) and/or at right (end_point).

         */

        unsigned int prev, next, i;

        for (;;)

        {

    i = j;

    j = next_index (i, start_point, end_point);

    if (deltas.arrayZ[i].flag && !deltas.arrayZ[j].flag) break;

        }

        prev = j = i;

        for (;;)

        {

    i = j;

    j = next_index (i, start_point, end_point);

    if (!deltas.arrayZ[i].flag && deltas.arrayZ[j].flag) break;

        }

        next = j;

        /* Infer deltas for all unref points in the gap between prev and next */

        i = prev;

        for (;;)

        {

    i = next_index (i, start_point, end_point);

    if (i == next) break;

    deltas.arrayZ[i].x = infer_delta (orig_points, deltas, i, prev, next, &contour_point_t::x);

    deltas.arrayZ[i].y = infer_delta (orig_points, deltas, i, prev, next, &contour_point_t::y);

    if (--unref_count == 0) goto no_more_gaps;

        }

      }

    no_more_gaps:

      start_point = end_point = end_point + 1;

    }

  }

  flush = true;

      } while (iterator.move_to_next ());

      if (flush)

      {

  for (unsigned int i = phantom_only ? count - 4 : 0; i < count; i++)

    points.arrayZ[i].translate (deltas.arrayZ[i]);

      }

      return true;

    }

    unsigned int get_axis_count () const { return table->axisCount; }

    private:

    hb_blob_ptr_t<gvar_GVAR> table;

    unsigned glyphCount;

  };

  protected:

  FixedVersion<>version;  /* Version number of the glyph variations table

         * Set to 0x00010000u. */

  HBUINT16  axisCount;  /* The number of variation axes for this font. This must be

         * the same number as axisCount in the 'fvar' table. */

  HBUINT16  sharedTupleCount;

        /* The number of shared tuple records. Shared tuple records

         * can be referenced within glyph variation data tables for

         * multiple glyphs, as opposed to other tuple records stored

         * directly within a glyph variation data table. */

  NNOffset32To<UnsizedArrayOf<F2DOT14>>

    sharedTuples; /* Offset from the start of this table to the shared tuple records.

         * Array of tuple records shared across all glyph variation data tables. */

  GidOffsetType glyphCountX;  /* The number of glyphs in this font. This must match the number of

         * glyphs stored elsewhere in the font. */

  HBUINT16  flags;    /* Bit-field that gives the format of the offset array that follows.

         * If bit 0 is clear, the offsets are uint16; if bit 0 is set, the

         * offsets are uint32. */

  Offset32To<GlyphVariationData>

    dataZ;    /* Offset from the start of this table to the array of

         * GlyphVariationData tables. */

  UnsizedArrayOf<HBUINT8>

    offsetZ;  /* Offsets from the start of the GlyphVariationData array

         * to each GlyphVariationData table. */

  public:

  DEFINE_SIZE_ARRAY (20, offsetZ);

};

using gvar = gvar_GVAR<HBUINT16, HB_OT_TAG_gvar>;

using GVAR = gvar_GVAR<HBUINT24, HB_OT_TAG_GVAR>;

struct gvar_accelerator_t : gvar::accelerator_t {

  gvar_accelerator_t (hb_face_t *face) : gvar::accelerator_t (face) {}

};

struct GVAR_accelerator_t : GVAR::accelerator_t {

  GVAR_accelerator_t (hb_face_t *face) : GVAR::accelerator_t (face) {}

};

} /* namespace OT */

#endif /* HB_OT_VAR_GVAR_TABLE_HH */