tor-browser

hb-ot-var-gvar-table.hh (31954B)

---

/*
* 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 */