kc3-lang/harfbuzz/src/hb-ot-var-gvar-table.hh

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• Hash : f159600c
  Author :
  Date : 2025-10-17T21:49:40
  

  Fix a draw fuzzer uninitialized-memory issue (#5615)
  
  Fixes https://oss-fuzz.com/testcase-detail/5714890590584832

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• src/hb-ot-var-gvar-table.hh

• /*
   * 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)));
    }
  
    /* 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); }
  
    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; }
  
    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; }
    const HBUINT16 *get_short_offset_array () const { return (const HBUINT16 *) &offsetZ; }
  
    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 = (apply_to_all && 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 */
  

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