glyf.hh

#ifndef OT_GLYF_GLYF_HH
#define OT_GLYF_GLYF_HH


#include "../../hb-open-type.hh"
#include "../../hb-ot-head-table.hh"
#include "../../hb-ot-hmtx-table.hh"
#include "../../hb-ot-var-gvar-table.hh"
#include "../../hb-draw.hh"

#include "glyf-helpers.hh"
#include "Glyph.hh"
#include "SubsetGlyph.hh"
#include "loca.hh"
#include "path-builder.hh"


namespace OT {


/*
 * glyf -- TrueType Glyph Data
 * https://docs.microsoft.com/en-us/typography/opentype/spec/glyf
 */
#define HB_OT_TAG_glyf HB_TAG('g','l','y','f')


struct glyf
{
  friend struct glyf_accelerator_t;

  static constexpr hb_tag_t tableTag = HB_OT_TAG_glyf;

  bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
  {
    TRACE_SANITIZE (this);
    /* Runtime checks as eager sanitizing each glyph is costy */
    return_trace (true);
  }

  /* requires source of SubsetGlyph complains the identifier isn't declared */
  template <typename Iterator>
  bool serialize (hb_serialize_context_t *c,
                  Iterator it,
                  bool use_short_loca,
                  const hb_subset_plan_t *plan)
  {
    TRACE_SERIALIZE (this);
    unsigned init_len = c->length ();
    for (const auto &_ : it) _.serialize (c, use_short_loca, plan);

    /* As a special case when all glyph in the font are empty, add a zero byte
     * to the table, so that OTS doesn’t reject it, and to make the table work
     * on Windows as well.
     * See https://github.com/khaledhosny/ots/issues/52 */
    if (init_len == c->length ())
    {
      HBUINT8 empty_byte;
      empty_byte = 0;
      c->copy (empty_byte);
    }
    return_trace (true);
  }

  /* Byte region(s) per glyph to output
     unpadded, hints removed if so requested
     If we fail to process a glyph we produce an empty (0-length) glyph */
  bool subset (hb_subset_context_t *c) const
  {
    TRACE_SUBSET (this);

    glyf *glyf_prime = c->serializer->start_embed <glyf> ();
    if (unlikely (!c->serializer->check_success (glyf_prime))) return_trace (false);

    hb_vector_t<glyf_impl::SubsetGlyph> glyphs;
    _populate_subset_glyphs (c->plan, &glyphs);

    auto padded_offsets =
    + hb_iter (glyphs)
    | hb_map (&glyf_impl::SubsetGlyph::padded_size)
    ;

    unsigned max_offset = + padded_offsets | hb_reduce (hb_add, 0);
    bool use_short_loca = max_offset < 0x1FFFF;


    glyf_prime->serialize (c->serializer, hb_iter (glyphs), use_short_loca, c->plan);
    if (!use_short_loca) {
      padded_offsets =
          + hb_iter (glyphs)
          | hb_map (&glyf_impl::SubsetGlyph::length)
          ;
    }


    if (unlikely (c->serializer->in_error ())) return_trace (false);
    return_trace (c->serializer->check_success (glyf_impl::_add_loca_and_head (c->plan,
                                                                               padded_offsets,
                                                                               use_short_loca)));
  }

  void
  _populate_subset_glyphs (const hb_subset_plan_t   *plan,
                           hb_vector_t<glyf_impl::SubsetGlyph> *glyphs /* OUT */) const;

  protected:
  UnsizedArrayOf<HBUINT8>
                dataZ;  /* Glyphs data. */
  public:
  DEFINE_SIZE_MIN (0);  /* In reality, this is UNBOUNDED() type; but since we always
                         * check the size externally, allow Null() object of it by
                         * defining it _MIN instead. */
};

struct glyf_accelerator_t
{
  glyf_accelerator_t (hb_face_t *face)
  {
    short_offset = false;
    num_glyphs = 0;
    loca_table = nullptr;
    glyf_table = nullptr;
#ifndef HB_NO_VAR
    gvar = nullptr;
#endif
    hmtx = nullptr;
#ifndef HB_NO_VERTICAL
    vmtx = nullptr;
#endif
    const OT::head &head = *face->table.head;
    if (head.indexToLocFormat > 1 || head.glyphDataFormat > 0)
      /* Unknown format.  Leave num_glyphs=0, that takes care of disabling us. */
      return;
    short_offset = 0 == head.indexToLocFormat;

    loca_table = face->table.loca.get_blob (); // Needs no destruct!
    glyf_table = hb_sanitize_context_t ().reference_table<glyf> (face);
#ifndef HB_NO_VAR
    gvar = face->table.gvar;
#endif
    hmtx = face->table.hmtx;
#ifndef HB_NO_VERTICAL
    vmtx = face->table.vmtx;
#endif

    num_glyphs = hb_max (1u, loca_table.get_length () / (short_offset ? 2 : 4)) - 1;
    num_glyphs = hb_min (num_glyphs, face->get_num_glyphs ());
  }
  ~glyf_accelerator_t ()
  {
    glyf_table.destroy ();
  }

  bool has_data () const { return num_glyphs; }

  protected:
  template<typename T>
  bool get_points (hb_font_t *font, hb_codepoint_t gid, T consumer) const
  {
    if (gid >= num_glyphs) return false;

    /* Making this allocfree is not that easy
       https://github.com/harfbuzz/harfbuzz/issues/2095
       mostly because of gvar handling in VF fonts,
       perhaps a separate path for non-VF fonts can be considered */
    contour_point_vector_t all_points;

    bool phantom_only = !consumer.is_consuming_contour_points ();
    if (unlikely (!glyph_for_gid (gid).get_points (font, *this, all_points, phantom_only)))
      return false;

    if (consumer.is_consuming_contour_points ())
    {
      unsigned count = all_points.length;
      assert (count >= glyf_impl::PHANTOM_COUNT);
      count -= glyf_impl::PHANTOM_COUNT;
      for (unsigned point_index = 0; point_index < count; point_index++)
        consumer.consume_point (all_points[point_index]);
      consumer.points_end ();
    }

    /* Where to write phantoms, nullptr if not requested */
    contour_point_t *phantoms = consumer.get_phantoms_sink ();
    if (phantoms)
      for (unsigned i = 0; i < glyf_impl::PHANTOM_COUNT; ++i)
        phantoms[i] = all_points[all_points.length - glyf_impl::PHANTOM_COUNT + i];

    return true;
  }

#ifndef HB_NO_VAR
  struct points_aggregator_t
  {
    hb_font_t *font;
    hb_glyph_extents_t *extents;
    contour_point_t *phantoms;

    struct contour_bounds_t
    {
      contour_bounds_t () { min_x = min_y = FLT_MAX; max_x = max_y = -FLT_MAX; }

      void add (const contour_point_t &p)
      {
        min_x = hb_min (min_x, p.x);
        min_y = hb_min (min_y, p.y);
        max_x = hb_max (max_x, p.x);
        max_y = hb_max (max_y, p.y);
      }

      bool empty () const { return (min_x >= max_x) || (min_y >= max_y); }

      void get_extents (hb_font_t *font, hb_glyph_extents_t *extents)
      {
        if (unlikely (empty ()))
        {
          extents->width = 0;
          extents->x_bearing = 0;
          extents->height = 0;
          extents->y_bearing = 0;
          return;
        }
        extents->x_bearing = font->em_scalef_x (min_x);
        extents->width = font->em_scalef_x (max_x) - extents->x_bearing;
        extents->y_bearing = font->em_scalef_y (max_y);
        extents->height = font->em_scalef_y (min_y) - extents->y_bearing;
      }

      protected:
      float min_x, min_y, max_x, max_y;
    } bounds;

    points_aggregator_t (hb_font_t *font_, hb_glyph_extents_t *extents_, contour_point_t *phantoms_)
    {
      font = font_;
      extents = extents_;
      phantoms = phantoms_;
      if (extents) bounds = contour_bounds_t ();
    }

    void consume_point (const contour_point_t &point) { bounds.add (point); }
    void points_end () { bounds.get_extents (font, extents); }

    bool is_consuming_contour_points () { return extents; }
    contour_point_t *get_phantoms_sink () { return phantoms; }
  };

  public:
  unsigned
  get_advance_var (hb_font_t *font, hb_codepoint_t gid, bool is_vertical) const
  {
    if (unlikely (gid >= num_glyphs)) return 0;

    bool success = false;

    contour_point_t phantoms[glyf_impl::PHANTOM_COUNT];
    if (likely (font->num_coords == gvar->get_axis_count ()))
      success = get_points (font, gid, points_aggregator_t (font, nullptr, phantoms));

    if (unlikely (!success))
      return
#ifndef HB_NO_VERTICAL
        is_vertical ? vmtx->get_advance (gid) :
#endif
        hmtx->get_advance (gid);

    float result = is_vertical
                 ? phantoms[glyf_impl::PHANTOM_TOP].y - phantoms[glyf_impl::PHANTOM_BOTTOM].y
                 : phantoms[glyf_impl::PHANTOM_RIGHT].x - phantoms[glyf_impl::PHANTOM_LEFT].x;
    return hb_clamp (roundf (result), 0.f, (float) UINT_MAX / 2);
  }

  int get_side_bearing_var (hb_font_t *font, hb_codepoint_t gid, bool is_vertical) const
  {
    if (unlikely (gid >= num_glyphs)) return 0;

    hb_glyph_extents_t extents;

    contour_point_t phantoms[glyf_impl::PHANTOM_COUNT];
    if (unlikely (!get_points (font, gid, points_aggregator_t (font, &extents, phantoms))))
      return
#ifndef HB_NO_VERTICAL
        is_vertical ? vmtx->get_side_bearing (gid) :
#endif
        hmtx->get_side_bearing (gid);

    return is_vertical
         ? ceilf (phantoms[glyf_impl::PHANTOM_TOP].y) - extents.y_bearing
         : floorf (phantoms[glyf_impl::PHANTOM_LEFT].x);
  }
#endif

  public:
  bool get_extents (hb_font_t *font, hb_codepoint_t gid, hb_glyph_extents_t *extents) const
  {
    if (unlikely (gid >= num_glyphs)) return false;

#ifndef HB_NO_VAR
    if (font->num_coords)
      return get_points (font, gid, points_aggregator_t (font, extents, nullptr));
#endif
    return glyph_for_gid (gid).get_extents (font, *this, extents);
  }

  const glyf_impl::Glyph
  glyph_for_gid (hb_codepoint_t gid, bool needs_padding_removal = false) const
  {
    if (unlikely (gid >= num_glyphs)) return glyf_impl::Glyph ();

    unsigned int start_offset, end_offset;

    if (short_offset)
    {
      const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ.arrayZ;
      start_offset = 2 * offsets[gid];
      end_offset   = 2 * offsets[gid + 1];
    }
    else
    {
      const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ.arrayZ;
      start_offset = offsets[gid];
      end_offset   = offsets[gid + 1];
    }

    if (unlikely (start_offset > end_offset || end_offset > glyf_table.get_length ()))
      return glyf_impl::Glyph ();

    glyf_impl::Glyph glyph (hb_bytes_t ((const char *) this->glyf_table + start_offset,
                             end_offset - start_offset), gid);
    return needs_padding_removal ? glyf_impl::Glyph (glyph.trim_padding (), gid) : glyph;
  }

  bool
  get_path (hb_font_t *font, hb_codepoint_t gid, hb_draw_session_t &draw_session) const
  { return get_points (font, gid, glyf_impl::path_builder_t (font, draw_session)); }

#ifndef HB_NO_VAR
  const gvar_accelerator_t *gvar;
#endif
  const hmtx_accelerator_t *hmtx;
#ifndef HB_NO_VERTICAL
  const vmtx_accelerator_t *vmtx;
#endif

  private:
  bool short_offset;
  unsigned int num_glyphs;
  hb_blob_ptr_t<loca> loca_table;
  hb_blob_ptr_t<glyf> glyf_table;
};


inline void
glyf::_populate_subset_glyphs (const hb_subset_plan_t   *plan,
                               hb_vector_t<glyf_impl::SubsetGlyph> *glyphs /* OUT */) const
{
  OT::glyf_accelerator_t glyf (plan->source);

  + hb_range (plan->num_output_glyphs ())
  | hb_map ([&] (hb_codepoint_t new_gid)
        {
          glyf_impl::SubsetGlyph subset_glyph = {0};
          subset_glyph.new_gid = new_gid;

          /* should never fail: all old gids should be mapped */
          if (!plan->old_gid_for_new_gid (new_gid, &subset_glyph.old_gid))
            return subset_glyph;

          if (new_gid == 0 &&
              !(plan->flags & HB_SUBSET_FLAGS_NOTDEF_OUTLINE))
            subset_glyph.source_glyph = glyf_impl::Glyph ();
          else
            subset_glyph.source_glyph = glyf.glyph_for_gid (subset_glyph.old_gid, true);
          if (plan->flags & HB_SUBSET_FLAGS_NO_HINTING)
            subset_glyph.drop_hints_bytes ();
          else
            subset_glyph.dest_start = subset_glyph.source_glyph.get_bytes ();
          return subset_glyph;
        })
  | hb_sink (glyphs)
  ;
}



} /* namespace OT */


#endif /* OT_GLYF_GLYF_HH */