hb-ot-hmtx-table.hh

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/*

 * Copyright © 2011,2012  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, Roderick Sheeter

*/

#ifndef HB_OT_HMTX_TABLE_HH

#define HB_OT_HMTX_TABLE_HH

#include "hb-open-type.hh"

#include "hb-ot-maxp-table.hh"

#include "hb-ot-hhea-table.hh"

#include "hb-ot-os2-table.hh"

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

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

#include "hb-ot-metrics.hh"

/*

 * hmtx -- Horizontal Metrics

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

 * vmtx -- Vertical Metrics

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

*/

#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')

#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')

HB_INTERNAL bool

_glyf_get_leading_bearing_with_var_unscaled (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical, int *lsb);

HB_INTERNAL unsigned

_glyf_get_advance_with_var_unscaled (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);

HB_INTERNAL bool

_glyf_get_leading_bearing_without_var_unscaled (hb_face_t *face, hb_codepoint_t gid, bool is_vertical, int *lsb);

namespace OT {

struct LongMetric

  UFWORD	advance; /* Advance width/height. */

  FWORD		sb; /* Leading (left/top) side bearing. */

  public:

  DEFINE_SIZE_STATIC (4);

};

template <typename T/*Data table type*/, typename H/*Header table type*/, typename V/*Var table type*/>

struct hmtxvmtx

  bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const

    TRACE_SANITIZE (this);

    /* We don't check for anything specific here.  The users of the

     * struct do all the hard work... */

    return_trace (true);

  const hb_hashmap_t<hb_codepoint_t, hb_pair_t<unsigned, int>>* get_mtx_map (const hb_subset_plan_t *plan) const

  { return T::is_horizontal ? &plan->hmtx_map : &plan->vmtx_map; }

  bool subset_update_header (hb_subset_context_t *c,

			     unsigned int num_hmetrics,

			     const hb_hashmap_t<hb_codepoint_t, hb_pair_t<unsigned, int>> *mtx_map,

			     const hb_vector_t<unsigned> &bounds_vec) const

    hb_blob_t *src_blob = hb_sanitize_context_t ().reference_table<H> (c->plan->source, H::tableTag);

    hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail (src_blob);

    hb_blob_destroy (src_blob);

    if (unlikely (!dest_blob)) {

      return false;

    unsigned int length;

    H *table = (H *) hb_blob_get_data (dest_blob, &length);

    c->serializer->check_assign (table->numberOfLongMetrics, num_hmetrics, HB_SERIALIZE_ERROR_INT_OVERFLOW);

#ifndef HB_NO_VAR

    if (c->plan->normalized_coords)

      auto &MVAR = *c->plan->source->table.MVAR;

      if (T::is_horizontal)

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_HORIZONTAL_CARET_RISE,   caretSlopeRise);

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_HORIZONTAL_CARET_RUN,    caretSlopeRun);

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_HORIZONTAL_CARET_OFFSET, caretOffset);

      else

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_VERTICAL_CARET_RISE,     caretSlopeRise);

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_VERTICAL_CARET_RUN,      caretSlopeRun);

	HB_ADD_MVAR_VAR (HB_OT_METRICS_TAG_VERTICAL_CARET_OFFSET,   caretOffset);

      bool empty = true;

      int min_lsb = 0x7FFF;

      int min_rsb = 0x7FFF;

      int max_extent = -0x7FFF;

      unsigned max_adv = 0;

      for (const auto _ : *mtx_map)

        hb_codepoint_t gid = _.first;

        unsigned adv = _.second.first;

        int lsb = _.second.second;

        max_adv = hb_max (max_adv, adv);

        if (bounds_vec[gid] != 0xFFFFFFFF)

	  empty = false;

          unsigned bound_width = bounds_vec[gid];

          int rsb = adv - lsb - bound_width;

          int extent = lsb + bound_width;

          min_lsb = hb_min (min_lsb, lsb);

          min_rsb = hb_min (min_rsb, rsb);

          max_extent = hb_max (max_extent, extent);

      table->advanceMax = max_adv;

      if (!empty)

        table->minLeadingBearing = min_lsb;

        table->minTrailingBearing = min_rsb;

        table->maxExtent = max_extent;

      if (T::is_horizontal)

        const auto &OS2 = *c->plan->source->table.OS2;

        if (OS2.has_data () &&

            table->ascender == OS2.sTypoAscender &&

            table->descender == OS2.sTypoDescender &&

            table->lineGap == OS2.sTypoLineGap)

          table->ascender = static_cast<int> (roundf (OS2.sTypoAscender +

                                                      MVAR.get_var (HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER,

                                                                    c->plan->normalized_coords.arrayZ,

                                                                    c->plan->normalized_coords.length)));

          table->descender = static_cast<int> (roundf (OS2.sTypoDescender +

                                                       MVAR.get_var (HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER,

                                                                     c->plan->normalized_coords.arrayZ,

                                                                     c->plan->normalized_coords.length)));

          table->lineGap = static_cast<int> (roundf (OS2.sTypoLineGap +

                                                     MVAR.get_var (HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP,

                                                                   c->plan->normalized_coords.arrayZ,

                                                                   c->plan->normalized_coords.length)));

#endif

    bool result = c->plan->add_table (H::tableTag, dest_blob);

    hb_blob_destroy (dest_blob);

    return result;

  template<typename Iterator,

	   hb_requires (hb_is_iterator (Iterator))>

  void serialize (hb_serialize_context_t *c,

		  Iterator it,

		  const hb_vector_t<hb_codepoint_pair_t> new_to_old_gid_list,

		  unsigned num_long_metrics,

                  unsigned total_num_metrics)

    LongMetric* long_metrics = c->allocate_size<LongMetric> (num_long_metrics * LongMetric::static_size);

    FWORD* short_metrics = c->allocate_size<FWORD> ((total_num_metrics - num_long_metrics) * FWORD::static_size);

    if (!long_metrics || !short_metrics) return;

    short_metrics -= num_long_metrics;

    for (auto _ : new_to_old_gid_list)

      hb_codepoint_t gid = _.first;

      auto mtx = *it++;

      if (gid < num_long_metrics)

	LongMetric& lm = long_metrics[gid];

	lm.advance = mtx.first;

	lm.sb = mtx.second;

      // TODO(beyond-64k): This assumes that maxp.numGlyphs is 0xFFFF.

      else if (gid < 0x10000u)

        short_metrics[gid] = mtx.second;

      else

        ((UFWORD*) short_metrics)[gid] = mtx.first;

  bool subset (hb_subset_context_t *c) const

    TRACE_SUBSET (this);

    auto *table_prime = c->serializer->start_embed <T> ();

    accelerator_t _mtx (c->plan->source);

    unsigned num_long_metrics;

    const hb_hashmap_t<hb_codepoint_t, hb_pair_t<unsigned, int>> *mtx_map = get_mtx_map (c->plan);

      /* Determine num_long_metrics to encode. */

      auto& plan = c->plan;

      // TODO Don't consider retaingid holes here.

      num_long_metrics = hb_min (plan->num_output_glyphs (), 0xFFFFu);

      unsigned int last_advance = get_new_gid_advance_unscaled (plan, mtx_map, num_long_metrics - 1, _mtx);

      while (num_long_metrics > 1 &&

	     last_advance == get_new_gid_advance_unscaled (plan, mtx_map, num_long_metrics - 2, _mtx))

	num_long_metrics--;

    auto it =

    + hb_iter (c->plan->new_to_old_gid_list)

    | hb_map ([c, &_mtx, mtx_map] (hb_codepoint_pair_t _)

		hb_codepoint_t new_gid = _.first;

		hb_codepoint_t old_gid = _.second;

		hb_pair_t<unsigned, int> *v = nullptr;

		if (!mtx_map->has (new_gid, &v))

		  int lsb = 0;

		  if (!_mtx.get_leading_bearing_without_var_unscaled (old_gid, &lsb))

		    (void) _glyf_get_leading_bearing_without_var_unscaled (c->plan->source, old_gid, !T::is_horizontal, &lsb);

		  return hb_pair (_mtx.get_advance_without_var_unscaled (old_gid), +lsb);

		return *v;

})

    table_prime->serialize (c->serializer,

it,

			    c->plan->new_to_old_gid_list,

			    num_long_metrics,

			    c->plan->num_output_glyphs ());

    if (unlikely (c->serializer->in_error ()))

      return_trace (false);

    // Amend header num hmetrics

    if (unlikely (!subset_update_header (c, num_long_metrics, mtx_map,

                                         T::is_horizontal ? c->plan->bounds_width_vec : c->plan->bounds_height_vec)))

      return_trace (false);

    return_trace (true);

  struct accelerator_t

    friend struct hmtxvmtx;

    accelerator_t (hb_face_t *face)

      table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);

      var_table = hb_sanitize_context_t ().reference_table<V> (face, T::variationsTag);

      default_advance = T::is_horizontal ? hb_face_get_upem (face) / 2 : hb_face_get_upem (face);

      /* Populate count variables and sort them out as we go */

      unsigned int len = table.get_length ();

      if (len & 1)

        len--;

      num_long_metrics = T::is_horizontal ?

			 face->table.hhea->numberOfLongMetrics :

#ifndef HB_NO_VERTICAL

			 face->table.vhea->numberOfLongMetrics

#else

#endif

      if (unlikely (num_long_metrics * 4 > len))

	num_long_metrics = len / 4;

      len -= num_long_metrics * 4;

      num_bearings = face->table.maxp->get_num_glyphs ();

      if (unlikely (num_bearings < num_long_metrics))

        num_bearings = num_long_metrics;

      if (unlikely ((num_bearings - num_long_metrics) * 2 > len))

        num_bearings = num_long_metrics + len / 2;

      len -= (num_bearings - num_long_metrics) * 2;

      /* We MUST set num_bearings to zero if num_long_metrics is zero.

       * Our get_advance() depends on that. */

      if (unlikely (!num_long_metrics))

	num_bearings = num_long_metrics = 0;

      num_advances = num_bearings + len / 2;

      num_glyphs = face->get_num_glyphs ();

      if (num_glyphs < num_advances)

        num_glyphs = num_advances;

    ~accelerator_t ()

      table.destroy ();

      var_table.destroy ();

    bool has_data () const { return (bool) num_bearings; }

    bool get_leading_bearing_without_var_unscaled (hb_codepoint_t glyph,

						   int *lsb) const

      if (glyph < num_long_metrics)

	*lsb = table->longMetricZ[glyph].sb;

	return true;

      if (unlikely (glyph >= num_bearings))

	return false;

      const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_long_metrics];

      *lsb = bearings[glyph - num_long_metrics];

      return true;

    bool get_leading_bearing_with_var_unscaled (hb_font_t *font,

						hb_codepoint_t glyph,

						int *lsb) const

      if (!font->num_coords)

	return get_leading_bearing_without_var_unscaled (glyph, lsb);

#ifndef HB_NO_VAR

      float delta;

      if (var_table->get_lsb_delta_unscaled (glyph, font->coords, font->num_coords, &delta) &&

	  get_leading_bearing_without_var_unscaled (glyph, lsb))

	*lsb += roundf (delta);

	return true;

      return _glyf_get_leading_bearing_with_var_unscaled (font, glyph, T::tableTag == HB_OT_TAG_vmtx, lsb);

#else

      return false;

#endif

    unsigned int get_advance_without_var_unscaled (hb_codepoint_t glyph) const

      /* OpenType case. */

      if (glyph < num_bearings)

	return table->longMetricZ[hb_min (glyph, (uint32_t) num_long_metrics - 1)].advance;

      /* If num_advances is zero, it means we don't have the metrics table

       * for this direction: return default advance.  Otherwise, there's a

       * well-defined answer. */

      if (unlikely (!num_advances))

	return default_advance;

#ifdef HB_NO_BEYOND_64K

      return 0;

#endif

      if (unlikely (glyph >= num_glyphs))

        return 0;

      /* num_bearings <= glyph < num_glyphs;

       * num_bearings <= num_advances */

      if (num_bearings == num_advances)

        return get_advance_without_var_unscaled (num_bearings - 1);

      const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_long_metrics];

      const UFWORD *advances = (const UFWORD *) &bearings[num_bearings - num_long_metrics];

      return advances[hb_min (glyph - num_bearings, num_advances - num_bearings - 1)];

    unsigned get_advance_with_var_unscaled (hb_codepoint_t  glyph,

					    hb_font_t      *font,

					    ItemVariationStore::cache_t *store_cache = nullptr) const

      unsigned int advance = get_advance_without_var_unscaled (glyph);

#ifndef HB_NO_VAR

      if (unlikely (glyph >= num_bearings) || !font->num_coords)

	return advance;

      if (var_table.get_length ())

	return advance + roundf (var_table->get_advance_delta_unscaled (glyph,

									font->coords, font->num_coords,

									store_cache));

      unsigned glyf_advance = _glyf_get_advance_with_var_unscaled (font, glyph, T::tableTag == HB_OT_TAG_vmtx);

      return glyf_advance ? glyf_advance : advance;

#else

      return advance;

#endif

    protected:

    // 0 <= num_long_metrics <= num_bearings <= num_advances <= num_glyphs

    unsigned num_long_metrics;

    unsigned num_bearings;

    unsigned num_advances;

    unsigned num_glyphs;

    unsigned int default_advance;

    public:

    hb_blob_ptr_t<hmtxvmtx> table;

    hb_blob_ptr_t<V> var_table;

};

  /* get advance: when no variations, call get_advance_without_var_unscaled.

   * when there're variations, get advance value from mtx_map in subset_plan*/

  unsigned get_new_gid_advance_unscaled (const hb_subset_plan_t *plan,

                                         const hb_hashmap_t<hb_codepoint_t, hb_pair_t<unsigned, int>> *mtx_map,

                                         unsigned new_gid,

                                         const accelerator_t &_mtx) const

    if (mtx_map->is_empty ())

      hb_codepoint_t old_gid = 0;

      return plan->old_gid_for_new_gid (new_gid, &old_gid) ?

             _mtx.get_advance_without_var_unscaled (old_gid) : 0;

    return mtx_map->get (new_gid).first;

  protected:

  UnsizedArrayOf<LongMetric>

		longMetricZ;	/* Paired advance width and leading

				 * bearing values for each glyph. The

				 * value numOfHMetrics comes from

				 * the 'hhea' table. If the font is

				 * monospaced, only one entry need

				 * be in the array, but that entry is

				 * required. The last entry applies to

				 * all subsequent glyphs. */

/*UnsizedArrayOf<FWORD>	leadingBearingX;*/

				/* Here the advance is assumed

				 * to be the same as the advance

				 * for the last entry above. The

				 * number of entries in this array is

				 * derived from numGlyphs (from 'maxp'

				 * table) minus numberOfLongMetrics.

				 * This generally is used with a run

				 * of monospaced glyphs (e.g., Kanji

				 * fonts or Courier fonts). Only one

				 * run is allowed and it must be at

				 * the end. This allows a monospaced

				 * font to vary the side bearing

				 * values for each glyph. */

/*UnsizedArrayOf<UFWORD>advancesX;*/

				/* TODO Document. */

  public:

  DEFINE_SIZE_ARRAY (0, longMetricZ);

};

struct hmtx : hmtxvmtx<hmtx, hhea, HVAR> {

  static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;

  static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;

  static constexpr bool is_horizontal = true;

};

struct vmtx : hmtxvmtx<vmtx, vhea, VVAR> {

  static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;

  static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;

  static constexpr bool is_horizontal = false;

};

struct hmtx_accelerator_t : hmtx::accelerator_t {

  hmtx_accelerator_t (hb_face_t *face) : hmtx::accelerator_t (face) {}

};

struct vmtx_accelerator_t : vmtx::accelerator_t {

  vmtx_accelerator_t (hb_face_t *face) : vmtx::accelerator_t (face) {}

};

} /* namespace OT */

#endif /* HB_OT_HMTX_TABLE_HH */