/*

 * Copyright © 2017  Google, Inc.

 *

 *  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.

 *

 * Google Author(s): Behdad Esfahbod

 */

#ifndef HB_OT_VAR_AVAR_TABLE_HH

#define HB_OT_VAR_AVAR_TABLE_HH

#include "hb-open-type.hh"

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

#include "hb-ot-var-fvar-table.hh"

/*

 * avar -- Axis Variations

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

 */

#define HB_OT_TAG_avar HB_TAG('a','v','a','r')

namespace OT {

/* "Spec": https://github.com/be-fonts/boring-expansion-spec/issues/14 */

struct avarV2Tail

{

  friend struct avar;

  bool sanitize (hb_sanitize_context_t *c,

     const void *base) const

  {

    TRACE_SANITIZE (this);

    return_trace (varIdxMap.sanitize (c, base) &&

      varStore.sanitize (c, base));

  }

  protected:

  Offset32To<DeltaSetIndexMap>  varIdxMap;  /* Offset from the beginning of 'avar' table. */

  Offset32To<ItemVariationStore>  varStore; /* Offset from the beginning of 'avar' table. */

  public:

  DEFINE_SIZE_STATIC (8);

};

struct AxisValueMap

{

  bool sanitize (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    return_trace (c->check_struct (this));

  }

  void set_mapping (float from_coord, float to_coord)

  {

    coords[0].set_float (from_coord);

    coords[1].set_float (to_coord);

  }

  bool is_outside_axis_range (const Triple& axis_range) const

  {

    double from_coord = (double) coords[0].to_float ();

    return !axis_range.contains (from_coord);

  }

  bool must_include () const

  {

    float from_coord = coords[0].to_float ();

    float to_coord = coords[1].to_float ();

    return (from_coord == -1.f && to_coord == -1.f) ||

           (from_coord == 0.f && to_coord == 0.f) ||

           (from_coord == 1.f && to_coord == 1.f);

  }

  void instantiate (const Triple& axis_range,

                    const Triple& unmapped_range,

                    const TripleDistances& triple_distances)

  {

    float from_coord = coords[0].to_float ();

    float to_coord = coords[1].to_float ();

    from_coord = renormalizeValue ((double) from_coord, unmapped_range, triple_distances);

    to_coord = renormalizeValue ((double) to_coord, axis_range, triple_distances);

    coords[0].set_float (from_coord);

    coords[1].set_float (to_coord);

  }

  HB_INTERNAL static int cmp (const void *pa, const void *pb)

  {

    const AxisValueMap *a = (const AxisValueMap *) pa;

    const AxisValueMap *b = (const AxisValueMap *) pb;

    int a_from = a->coords[0].to_int ();

    int b_from = b->coords[0].to_int ();

    if (a_from != b_from)

      return a_from - b_from;

    /* this should never be reached. according to the spec, all of the axis

     * value map records for a given axis must have different fromCoord values

     * */

    int a_to = a->coords[1].to_int ();

    int b_to = b->coords[1].to_int ();

    return a_to - b_to;

  }

  bool serialize (hb_serialize_context_t *c) const

  {

    TRACE_SERIALIZE (this);

    return_trace (c->embed (this));

  }

  public:

  F2DOT14 coords[2];

//   F2DOT14  fromCoord;  /* A normalized coordinate value obtained using

//         * default normalization. */

//   F2DOT14  toCoord;  /* The modified, normalized coordinate value. */

  public:

  DEFINE_SIZE_STATIC (4);

};

struct SegmentMaps : Array16Of<AxisValueMap>

{

  float map_float (float value, unsigned int from_offset = 0, unsigned int to_offset = 1) const

  {

#define fromCoord coords[from_offset].to_float ()

#define toCoord coords[to_offset].to_float ()

    const auto *map = arrayZ;

    /* The following special-cases are not part of OpenType, which requires

     * that at least -1, 0, and +1 must be mapped. But we include these as

     * part of a better error recovery scheme. */

    if (len < 2)

    {

      if (!len)

  return value;

      else /* len == 1*/

  return value - map[0].fromCoord + map[0].toCoord;

    }

    // At least two mappings now.

    /* CoreText is wild...

     * PingFangUI avar needs all this special-casing...

     * So we implement an extended version of the spec here,

     * which is more robust and more likely to be compatible with

     * the wild. */

    unsigned start = 0;

    unsigned end = len;

    if (map[start].fromCoord == -1 && map[start].toCoord == -1 && map[start+1].fromCoord == -1)

      start++;

    if (map[end-1].fromCoord == +1 && map[end-1].toCoord == +1 && map[end-2].fromCoord == +1)

      end--;

    /* Look for exact match first, and do lots of special-casing. */

    unsigned i;

    for (i = start; i < end; i++)

      if (value == map[i].fromCoord)

  break;

    if (i < end)

    {

      // There's at least one exact match. See if there are more.

      unsigned j = i;

      for (; j + 1 < end; j++)

  if (value != map[j + 1].fromCoord)

    break;

      // [i,j] inclusive are all exact matches:

      // If there's only one, return it. This is the only spec-compliant case.

      if (i == j)

  return map[i].toCoord;

      // If there's exactly three, return the middle one.

      if (i + 2 == j)

  return map[i + 1].toCoord;

      // Ignore the middle ones. Return the one mapping closer to 0.

      if (value < 0) return map[j].toCoord;

      if (value > 0) return map[i].toCoord;

      // Mapping 0? CoreText seems confused. It seems to prefer 0 here...

      // So we'll just return the smallest one. lol

      return fabsf (map[i].toCoord) < fabsf (map[j].toCoord) ? map[i].toCoord : map[j].toCoord;

      // Mapping 0? Return one not mapping to 0.

      if (map[i].toCoord == 0)

  return map[j].toCoord;

      else

  return map[i].toCoord;

    }

    /* There's at least two and we're not an exact match. Prepare to lerp. */

    // Find the segment we're in.

    for (i = start; i < end; i++)

      if (value < map[i].fromCoord)

  break;

    if (i == 0)

    {

      // Value before all segments; Shift.

      return value - map[0].fromCoord + map[0].toCoord;

    }

    if (i == end)

    {

      // Value after all segments; Shift.

      return value - map[end - 1].fromCoord + map[end - 1].toCoord;

    }

    // Actually interpolate.

    auto &before = map[i-1];

    auto &after = map[i];

    float denom = after.fromCoord - before.fromCoord; // Can't be zero by now.

    return before.toCoord + ((after.toCoord - before.toCoord) * (value - before.fromCoord)) / denom;

#undef toCoord

#undef fromCoord

  }

  float unmap_float (float value) const { return map_float (value, 1, 0); }

  // TODO Kill this.

  Triple unmap_axis_range (const Triple& axis_range) const

  {

    float unmapped_min = unmap_float (axis_range.minimum);

    float unmapped_middle = unmap_float (axis_range.middle);

    float unmapped_max = unmap_float (axis_range.maximum);

    return Triple{(double) unmapped_min, (double) unmapped_middle, (double) unmapped_max};

  }

  bool subset (hb_subset_context_t *c, hb_tag_t axis_tag,

               hb_vector_t<AxisValueMap> *out_mappings = nullptr) const

  {

    TRACE_SUBSET (this);

    /* This function cannot work on avar2 table (and currently doesn't).

     * We should instead keep the design coords in the shape plan and use

     * those. unmap_axis_range needs to be killed. */

    /* avar mapped normalized axis range. Under avar2, axes_location holds

     * only the self-contained pins for the other tables; avar itself uses

     * the intermediate-space ranges of all restricted axes. */

    const auto &axes_location = c->plan->has_avar2

        ? c->plan->old_intermediates

        : c->plan->axes_location;

    Triple *axis_range;

    if (!axes_location.has (axis_tag, &axis_range))

      return c->serializer->embed (*this);

    TripleDistances *axis_triple_distances;

    if (!c->plan->axes_triple_distances.has (axis_tag, &axis_triple_distances))

      return_trace (false);

    auto *out = c->serializer->start_embed (this);

    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

    Triple unmapped_range = unmap_axis_range (*axis_range);

    /* create a vector of retained mappings and sort */

    hb_vector_t<AxisValueMap> value_mappings;

    for (const auto& _ : as_array ())

    {

      if (_.is_outside_axis_range (unmapped_range))

        continue;

      AxisValueMap mapping;

      mapping = _;

      mapping.instantiate (*axis_range, unmapped_range, *axis_triple_distances);

      /* (-1, -1), (0, 0), (1, 1) mappings will be added later, so avoid

       * duplicates here */

      if (mapping.must_include ())

        continue;

      value_mappings.push (mapping);

    }

    AxisValueMap m;

    m.set_mapping (-1.f, -1.f);

    value_mappings.push (m);

    m.set_mapping (0.f, 0.f);

    value_mappings.push (m);

    m.set_mapping (1.f, 1.f);

    value_mappings.push (m);

    value_mappings.qsort ();

    if (unlikely (value_mappings.in_error ()))

      return_trace (false);

    for (const auto& _ : value_mappings)

    {

      if (!_.serialize (c->serializer))

        return_trace (false);

    }

    if (!c->serializer->check_assign (out->len, value_mappings.length, HB_SERIALIZE_ERROR_INT_OVERFLOW))

      return_trace (false);

    /* Hand the instantiated mappings to the caller; avar2 offset

     * compensation needs them to locate the new mapping's kinks. */

    if (out_mappings)

      *out_mappings = std::move (value_mappings);

    return_trace (true);

  }

  public:

  DEFINE_SIZE_ARRAY (2, *this);

};

/* One knot of the avar2 offset-compensation function

 * offset(z) = inv_renorm(z) - z, in new intermediate space. */

struct avar2_offset_knot_t

{

  double z;

  double offset;

};

/* Insert a knot keeping the vector sorted by z; first insertion wins on

 * duplicate z. */

static inline void

_avar2_add_knot (hb_vector_t<avar2_offset_knot_t> &knots, double z, double offset)

{

  unsigned i = 0;

  while (i < knots.length && knots.arrayZ[i].z < z) i++;

  if (i < knots.length && knots.arrayZ[i].z == z) return;

  knots.push (avar2_offset_knot_t {0.0, 0.0});

  if (unlikely (knots.in_error ())) return;

  for (unsigned j = knots.length - 1; j > i; j--)

    knots.arrayZ[j] = knots.arrayZ[j - 1];

  knots.arrayZ[i] = avar2_offset_knot_t {z, offset};

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_add_knot(hb_vector_t<OT::avar2_offset_knot_t, false>&, double, double)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_add_knot(hb_vector_t<OT::avar2_offset_knot_t, false>&, double, double)

/* Piecewise-linear evaluation over the sorted knots. Inputs are always

 * within [-1, +1] and anchor knots at -1/0/+1 always exist. */

static inline double

_avar2_eval_offset (const hb_vector_t<avar2_offset_knot_t> &knots, double z)

{

  unsigned len = knots.length;

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

  {

    if (z == knots.arrayZ[i].z) return knots.arrayZ[i].offset;

    if (z < knots.arrayZ[i].z)

    {

      if (!i) return knots.arrayZ[0].offset;

      const auto &before = knots.arrayZ[i - 1];

      const auto &after = knots.arrayZ[i];

      double denom = after.z - before.z;

      return before.offset + (after.offset - before.offset) * (z - before.z) / denom;

    }

  }

  return len ? knots.arrayZ[len - 1].offset : 0.0;

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_eval_offset(hb_vector_t<OT::avar2_offset_knot_t, false> const&, double)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_eval_offset(hb_vector_t<OT::avar2_offset_knot_t, false> const&, double)

/* Piecewise-linear evaluation over instantiated avar v1 mappings, as

 * produced by SegmentMaps::subset (sorted, with -1/0/+1 anchors).

 * Matches SegmentMaps::map_float for such well-formed mappings. */

static inline double

_avar2_map_new_mapping (const hb_vector_t<AxisValueMap> &mappings, double v)

{

  unsigned len = mappings.length;

  if (!len) return v;

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

  {

    double from = (double) mappings.arrayZ[i].coords[0].to_float ();

    if (v == from) return (double) mappings.arrayZ[i].coords[1].to_float ();

    if (v < from)

    {

      double to = (double) mappings.arrayZ[i].coords[1].to_float ();

      if (!i) return v - from + to;

      double prev_from = (double) mappings.arrayZ[i - 1].coords[0].to_float ();

      double prev_to = (double) mappings.arrayZ[i - 1].coords[1].to_float ();

      double denom = from - prev_from;

      if (denom == 0.0) return prev_to;

      return prev_to + (to - prev_to) * (v - prev_from) / denom;

    }

  }

  return v - (double) mappings.arrayZ[len - 1].coords[0].to_float ()

           + (double) mappings.arrayZ[len - 1].coords[1].to_float ();

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_map_new_mapping(hb_vector_t<OT::AxisValueMap, false> const&, double)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_map_new_mapping(hb_vector_t<OT::AxisValueMap, false> const&, double)

/* Plain (non-avar) fvar-style normalization of a user value against a

 * user-space (min, default, max) triple. */

static inline double

_avar2_normalize_value (double v, double min, double def, double max)

{

  v = hb_clamp (v, min, max);

  if (v == def) return 0.0;

  if (v < def) return def == min ? 0.0 : (v - def) / (def - min);

  return def == max ? 0.0 : (v - def) / (max - def);

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_normalize_value(double, double, double, double)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_normalize_value(double, double, double, double)

/* Inverse of the above: map a normalized value back to user space. */

static inline double

_avar2_denormalize_value (double v, double min, double def, double max)

{

  if (v == 0.0) return def;

  return v < 0.0 ? def + v * (def - min) : def + v * (max - def);

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_denormalize_value(double, double, double, double)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_denormalize_value(double, double, double, double)

/* Estimate the residual offset-compensation error for one restricted axis:

 * the max |old-avar1-final - (new-avar1 + offset)| over the retained user

 * range, in F2Dot14 units. offset(z) is the piecewise-linear function

 * through the knots. The residual is dominated by F2Dot14 requantization of

 * a steep retained avar v1 segment (e.g. a moved default compressing part

 * of the axis into a narrow z band); offset compensation cannot remove it.

 * Used only to pick the better knot set and decide whether to warn, so a

 * coarse uniform sample suffices. */

static inline unsigned

_avar2_estimate_offset_error (const SegmentMaps &old_seg,

                              const hb_vector_t<AxisValueMap> &new_mapping,

                              double old_min, double old_def, double old_max,

                              double new_min, double new_def, double new_max,

                              const hb_vector_t<avar2_offset_knot_t> &knots)

{

  unsigned max_err = 0;

  constexpr unsigned samples = 257;

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

  {

    double u = new_min + (new_max - new_min) * i / (samples - 1);

    double n_old = _avar2_normalize_value (u, old_min, old_def, old_max);

    double old_final = (double) old_seg.map_float ((float) n_old);

    double n_new = _avar2_normalize_value (u, new_min, new_def, new_max);

    double z = _avar2_map_new_mapping (new_mapping, n_new);

    double new_final = z + _avar2_eval_offset (knots, z);

    int err = abs ((int) roundf ((float) (old_final * 16384.0)) -

                   (int) roundf ((float) (new_final * 16384.0)));

    if ((unsigned) err > max_err) max_err = err;

  }

  return max_err;

}

Unexecuted instantiation: hb-font.cc:OT::_avar2_estimate_offset_error(OT::SegmentMaps const&, hb_vector_t<OT::AxisValueMap, false> const&, double, double, double, double, double, double, hb_vector_t<OT::avar2_offset_knot_t, false> const&)

Unexecuted instantiation: hb-ot-var.cc:OT::_avar2_estimate_offset_error(OT::SegmentMaps const&, hb_vector_t<OT::AxisValueMap, false> const&, double, double, double, double, double, double, hb_vector_t<OT::avar2_offset_knot_t, false> const&)

struct avar

{

  static constexpr hb_tag_t tableTag = HB_OT_TAG_avar;

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

  const SegmentMaps* get_segment_maps () const

  { return &firstAxisSegmentMaps; }

  unsigned get_axis_count () const

  { return axisCount; }

  bool sanitize (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    if (!(version.sanitize (c) &&

    hb_barrier () &&

    (version.major == 1

#ifndef HB_NO_AVAR2

     || version.major == 2

#endif

     ) &&

    c->check_struct (this)))

      return_trace (false);

    const SegmentMaps *map = &firstAxisSegmentMaps;

    unsigned int count = axisCount;

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

    {

      if (unlikely (!map->sanitize (c)))

  return_trace (false);

      map = &StructAfter<SegmentMaps> (*map);

    }

#ifndef HB_NO_AVAR2

    if (version.major < 2)

      return_trace (true);

    hb_barrier ();

    const auto &v2 = * (const avarV2Tail *) map;

    if (unlikely (!v2.sanitize (c, this)))

      return_trace (false);

#endif

    return_trace (true);

  }

  void map_coords_16_16 (int *coords, unsigned int coords_length) const

  {

    unsigned int count = hb_min (coords_length, axisCount);

    const SegmentMaps *map = &firstAxisSegmentMaps;

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

    {

      coords[i] = roundf (map->map_float (coords[i] / 65536.f) * 65536.f);

      map = &StructAfter<SegmentMaps> (*map);

    }

#ifndef HB_NO_AVAR2

    if (version.major < 2)

      return;

    hb_barrier ();

    for (; count < axisCount; count++)

      map = &StructAfter<SegmentMaps> (*map);

    const auto &v2 = * (const avarV2Tail *) map;

    const auto &varidx_map = this+v2.varIdxMap;

    const auto &var_store = this+v2.varStore;

    auto *var_store_cache = var_store.create_cache ();

    hb_vector_t<int> coords_2_14;

    coords_2_14.resize (coords_length);

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

      coords_2_14[i] = roundf (coords[i] / 4.f); // 16.16 -> 2.14

    hb_vector_t<int> out;

    out.alloc (coords_length);

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

    {

      int v = coords[i];

      uint32_t varidx = varidx_map.map (i);

      float delta = var_store.get_delta (varidx, coords_2_14.arrayZ, coords_2_14.length, var_store_cache);

      /* Apply the delta unclamped and clamp only the result to [-1, +1],

       * matching fontTools. Since inputs and results are in [-1, +1],

       * deltas beyond ±2 are equivalent to ±2; clamp to that range only

       * to keep the float->int conversion safe. */

      float d = hb_clamp (delta * 4, -(float) (1<<17), +(float) (1<<17)); // 2.14 -> 16.16

      v += (int) roundf (d);

      v = hb_clamp (v, -(1<<16), +(1<<16));

      out.push (v);

    }

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

      coords[i] = out[i];

    OT::ItemVariationStore::destroy_cache (var_store_cache);

#endif

  }

  bool has_v2_data () const { return version.major > 1; }

  /* Resolve the avar2 VarStore and VarIdxMap, for the subset planner. */

  bool get_v2_store_and_map (const ItemVariationStore **store,

                             const DeltaSetIndexMap **varidx_map) const

  {

#ifndef HB_NO_AVAR2

    if (version.major < 2) return false;

    const SegmentMaps *map = &firstAxisSegmentMaps;

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

      map = &StructAfter<SegmentMaps> (*map);

    const auto &v2 = * (const avarV2Tail *) map;

    *store = &(this+v2.varStore);

    *varidx_map = &(this+v2.varIdxMap);

    return true;

#else

    return false;

#endif

  }

  // axis normalization is done in 2.14 here

  // TODO: deprecate this API once fonttools is updated to use 16.16 normalization

  bool map_coords_2_14 (float *coords, unsigned int coords_length,

      bool v1_only = false) const

  {

    hb_vector_t<int> coords_2_14;

    if (!v1_only && !coords_2_14.resize (coords_length)) return false;

    unsigned int count = hb_min (coords_length, axisCount);

    const SegmentMaps *map = &firstAxisSegmentMaps;

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

    {

      int v = roundf (map->map_float (coords[i]) * 16384.f);

      if (!v1_only)

  coords_2_14[i] = v;

      coords[i] = v / 16384.f;

      map = &StructAfter<SegmentMaps> (*map);

    }

    if (v1_only)

      return true;

#ifndef HB_NO_AVAR2

    if (version.major < 2)

      return true;

    hb_barrier ();

    for (; count < axisCount; count++)

      map = &StructAfter<SegmentMaps> (*map);

    const auto &v2 = * (const avarV2Tail *) map;

    const auto &varidx_map = this+v2.varIdxMap;

    const auto &var_store = this+v2.varStore;

    auto *var_store_cache = var_store.create_cache ();

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

    {

      int v = coords_2_14[i];

      uint32_t varidx = varidx_map.map (i);

      float delta = var_store.get_delta (varidx, coords_2_14.arrayZ, coords_2_14.length, var_store_cache);

      /* As above: apply the delta unclamped (±2 covers every useful case)

       * and clamp the result to [-1, +1], matching fontTools. */

      v += (int) hb_clamp (roundf (delta), -(float) (1<<15), +(float) (1<<15));

      v = hb_clamp (v, -(1<<14), +(1<<14));

      coords[i] = v / 16384.f;

    }

    OT::ItemVariationStore::destroy_cache (var_store_cache);

    return true;

#else

    return version.major < 2;

#endif

  }

  bool subset (hb_subset_context_t *c) const

  {

    TRACE_SUBSET (this);

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

    if (!retained_axis_count) //all axes are pinned/dropped

      return_trace (false);

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

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

    out->version.major = c->plan->has_avar2 ? 2 : 1;

    out->version.minor = 0;

    if (!c->serializer->check_assign (out->axisCount, retained_axis_count, HB_SERIALIZE_ERROR_INT_OVERFLOW))

      return_trace (false);

    /* For avar2, keep the instantiated v1 mappings around; offset

     * compensation needs them to locate the new mappings' kinks. */

    hb_vector_t<hb_vector_t<AxisValueMap>> new_mappings;

    if (c->plan->has_avar2 && !new_mappings.resize (axisCount))

      return_trace (false);

    const hb_map_t& axes_index_map = c->plan->axes_index_map;

    const SegmentMaps *map = &firstAxisSegmentMaps;

    unsigned count = axisCount;

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

    {

      if (axes_index_map.has (i))

      {

        hb_tag_t *axis_tag;

        if (!c->plan->axes_old_index_tag_map.has (i, &axis_tag))

          return_trace (false);

        Triple *axis_location;

        if (c->plan->has_avar2 &&

            c->plan->user_axes_location.has (*axis_tag, &axis_location) &&

            axis_location->is_point ())

        {

          /* Pinned axis in avar2 mode: serialize identity segment map

           * {-1->-1, 0->0, 1->1}. The axis is kept in fvar as hidden,

           * so avar needs a segment map entry for it. */

          auto *identity_map = c->serializer->start_embed<SegmentMaps> ();

          if (unlikely (!c->serializer->extend_min (identity_map)))

            return_trace (false);

          AxisValueMap m;

          m.set_mapping (-1.f, -1.f);

          if (!m.serialize (c->serializer)) return_trace (false);

          m.set_mapping (0.f, 0.f);

          if (!m.serialize (c->serializer)) return_trace (false);

          m.set_mapping (1.f, 1.f);

          if (!m.serialize (c->serializer)) return_trace (false);

          if (!c->serializer->check_assign (identity_map->len, 3u,

                                            HB_SERIALIZE_ERROR_INT_OVERFLOW))

            return_trace (false);

        }

        else

        {

          /* Restricted or free axis: use standard SegmentMaps::subset() */

          if (!map->subset (c, *axis_tag,

                            c->plan->has_avar2 ? &new_mappings[i] : nullptr))

            return_trace (false);

        }

      }

      map = &StructAfter<SegmentMaps> (*map);

    }

    if (c->plan->has_avar2)

      return_trace (_subset_avar2 (c, new_mappings));

    return_trace (true);

  }

  private:

  struct avar2_index_map_plan_t

  {

    bool init (const hb_vector_t<uint32_t> &varidx_mapping,

         const hb_map_t &axes_index_map,

         unsigned axis_count)

    {

      if (!output_map.alloc (axes_index_map.get_population ()))

  return false;

      bool has_no_variation = false;

      unsigned max_outer = 0, max_inner = 0;

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

      {

  if (!axes_index_map.has (i)) continue;

  uint32_t varidx = varidx_mapping[i];

  output_map.push (varidx);

  if (varidx == HB_OT_LAYOUT_NO_VARIATIONS_INDEX)

  {

    has_no_variation = true;

    continue;

  }

  max_outer = hb_max (max_outer, varidx >> 16);

  max_inner = hb_max (max_inner, varidx & 0xFFFF);

      }

      if (output_map.in_error () ||

    output_map.length != axes_index_map.get_population ())

  return false;

      if (has_no_variation)

      {

  width = 4;

  inner_bit_count = 16;

      }

      else

      {

  inner_bit_count = hb_max (1u, hb_bit_storage (max_inner));

  unsigned outer_bit_count = hb_max (1u, hb_bit_storage (max_outer));

  width = hb_clamp ((inner_bit_count + outer_bit_count + 7) / 8, 1u, 4u);

  if (inner_bit_count + outer_bit_count > width * 8)

    inner_bit_count = width * 8 - outer_bit_count;

      }

      return true;

    }

    unsigned get_inner_bit_count () const { return inner_bit_count; }

    unsigned get_width () const { return width; }

    hb_array_t<const uint32_t> get_output_map () const { return output_map.as_array (); }

    unsigned inner_bit_count = 1;

    unsigned width = 1;

    hb_vector_t<uint32_t> output_map;

  };

  bool _subset_avar2 (hb_subset_context_t *c,

                      const hb_vector_t<hb_vector_t<AxisValueMap>> &new_mappings) const

  {

#if defined (HB_NO_VAR) || defined (HB_NO_AVAR2)

    /* Not reachable: the plan never sets has_avar2 in these configurations. */

    return false;

#else

    /* 1. Locate original avar2 data, keeping per-axis old segment maps */

    hb_vector_t<const SegmentMaps *> old_seg_maps;

    if (!old_seg_maps.alloc (axisCount)) return false;

    const SegmentMaps *map = &firstAxisSegmentMaps;

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

    {

      old_seg_maps.push (map);

      map = &StructAfter<SegmentMaps> (*map);

    }

    const auto &v2 = * (const avarV2Tail *) map;

    const auto &varidx_map = this+v2.varIdxMap;

    const auto &var_store = this+v2.varStore;

    auto fvar_axes = c->plan->source->table.fvar->get_axes ();

    /* 2. Compute default deltas by evaluating VarStore at old defaults */

    hb_vector_t<int> default_coords;

    if (!default_coords.resize (axisCount)) return false;

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

    {

      hb_tag_t *axis_tag;

      if (c->plan->axes_old_index_tag_map.has (i, &axis_tag) &&

          c->plan->old_intermediates.has (*axis_tag))

      {

        float d_i = (float) c->plan->old_intermediates.get (*axis_tag).middle;

        default_coords[i] = roundf (d_i * 16384.f);

      }

      else

        default_coords[i] = 0;

    }

    auto *store_cache = var_store.create_cache ();

    hb_vector_t<float> default_deltas;

    if (!default_deltas.resize (axisCount)) {

      ItemVariationStore::destroy_cache (store_cache);

      return false;

    }

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

    {

      uint32_t varidx = varidx_map.map (i);

      if (varidx == HB_OT_LAYOUT_NO_VARIATIONS_INDEX)

        default_deltas[i] = 0.f;

      else

        default_deltas[i] = var_store.get_delta (varidx, default_coords.arrayZ,

                                                  default_coords.length, store_cache);

    }

    ItemVariationStore::destroy_cache (store_cache);

    /* 3. Rebase IVS regions */

    item_variations_t item_vars;

    if (!item_vars.create_from_item_varstore (var_store, c->plan->axes_old_index_tag_map))

      return false;

    if (!item_vars.instantiate_tuple_vars (c->plan->old_intermediates,

                                           c->plan->axes_triple_distances,

                                           false))

      return false;

    /* 4. Self-contained pinned axes (whose final coordinate is constant over

     * the retained box) were detected at plan time

     * (_compute_avar2_reachable_ranges) and removed from axes_index_map.

     * They are skipped below; their constant contribution is baked into the

     * other variation tables by standard instancing at the plan's

     * axes_location/normalized_coords. */

    /* 5. Build per-axis varIdx mapping (may create new VarDatas) */

    hb_vector_t<uint32_t> new_varidx_mapping;

    if (!new_varidx_mapping.resize (axisCount)) return false;

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

      new_varidx_mapping[i] = varidx_map.map (i);

    /* 5.5. Privatize shared varIdx delta rows before adding offset

     * compensation. avar2's VarIdxMap may map several fvar axes to the SAME

     * IVS delta row. Writing one axis's offset-compensation deltas into a

     * shared row would corrupt every other axis that reads that row. So give

     * each offset-receiving axis whose row is shared its own private copy of

     * the row (identical contents, preserving the rebased deltas), then

     * repoint its varIdx. Sharers keep the clean row; the varstore

     * optimization pass re-merges identical rows afterwards. */

    hb_hashmap_t<uint32_t, unsigned> varidx_ref_count;

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

    {

      if (!c->plan->axes_index_map.has (i)) continue; /* self-contained: dropped */

      uint32_t varidx = new_varidx_mapping[i];

      if (varidx == HB_OT_LAYOUT_NO_VARIATIONS_INDEX) continue;

      unsigned *count;

      if (varidx_ref_count.has (varidx, &count))

        (*count)++;

      else if (!varidx_ref_count.set (varidx, 1))

        return false;

    }

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

    {

      hb_tag_t *axis_tag_ptr;

      if (!c->plan->axes_old_index_tag_map.has (i, &axis_tag_ptr))

        return false;

      /* Only axes that will receive offset compensation (restricted or

       * pinned) can contaminate a shared row. */

      if (!c->plan->axes_index_map.has (i) ||

          !c->plan->user_axes_location.has (*axis_tag_ptr))

        continue;

      uint32_t varidx = new_varidx_mapping[i];

      if (varidx == HB_OT_LAYOUT_NO_VARIATIONS_INDEX)

        continue; /* gets a fresh, private VarData in the offset loop below */

      unsigned *count;

      if (!varidx_ref_count.has (varidx, &count) || *count <= 1)

        continue; /* sole owner: safe to write offsets in place */

      unsigned outer = varidx >> 16;

      unsigned new_inner = item_vars.duplicate_row (outer, varidx & 0xFFFF);

      if (unlikely (new_inner == (unsigned) -1)) return false;

      new_varidx_mapping[i] = (outer << 16) | new_inner;

      (*count)--;

    }

    /* 6. Add offset compensation tuples.

     * Track processed (outer,inner) pairs to avoid adding duplicate biases

     * when multiple axes share the same varIdx. */

    hb_set_t processed_varidxes;

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

    {

      hb_tag_t *axis_tag_ptr;

      if (!c->plan->axes_old_index_tag_map.has (i, &axis_tag_ptr))

        return false;

      hb_tag_t axis_tag = *axis_tag_ptr;

      /* Self-contained pinned axes are removed from fvar/avar; their

       * contribution is baked into the variation tables instead. */

      if (!c->plan->axes_index_map.has (i))

        continue;

      Triple *new_user;

      if (c->plan->user_axes_location.has (axis_tag, &new_user))

      {

        /* This axis is being restricted or pinned */

        Triple *old_int;

        if (!c->plan->old_intermediates.has (axis_tag, &old_int))

          return false;

        float a_i = (float) old_int->minimum;

        float d_i = (float) old_int->middle;

        float b_i = (float) old_int->maximum;

        int d_int = roundf (d_i * 16384.f);

        bool is_pinned = new_user->is_point ();

        uint32_t varidx = new_varidx_mapping[i];