kc3-lang/harfbuzz/src/hb-ot-glyf-table.hh

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• Hash : 1197bef2
  Author :
  Date : 2019-05-24T10:52:49
  

  [subset] Per code review, use hb_array to avoid duplicated type name
  

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• src/hb-ot-glyf-table.hh

• /*
   * Copyright © 2015  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, Garret Rieger, Roderick Sheeter
   */
  
  #ifndef HB_OT_GLYF_TABLE_HH
  #define HB_OT_GLYF_TABLE_HH
  
  #include "hb-open-type.hh"
  #include "hb-ot-head-table.hh"
  
  namespace OT {
  
  
  /*
   * loca -- Index to Location
   * https://docs.microsoft.com/en-us/typography/opentype/spec/loca
   */
  #define HB_OT_TAG_loca HB_TAG('l','o','c','a')
  
  
  struct loca
  {
    friend struct glyf;
  
    static constexpr hb_tag_t tableTag = HB_OT_TAG_loca;
  
    bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
    {
      TRACE_SANITIZE (this);
      return_trace (true);
    }
  
    protected:
    UnsizedArrayOf<HBUINT8>	dataZ;		/* Location 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. */
  };
  
  
  /*
   * 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
  {
    static constexpr hb_tag_t tableTag = HB_OT_TAG_glyf;
  
    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);
    }
  
    template<typename Iterator,
  	   hb_requires (hb_is_source_of (Iterator, unsigned int))>
    static bool
    _add_loca_and_head (hb_subset_plan_t * plan, Iterator padded_offsets)
    {
      unsigned int max_offset = + padded_offsets | hb_reduce (hb_max, 0);
      unsigned num_offsets = padded_offsets.len () + 1;
      bool use_short_loca = max_offset < 0x1FFFF;
      unsigned entry_size = use_short_loca ? 2 : 4;
      char *loca_prime_data = (char *) calloc (entry_size, num_offsets);
  
      if (unlikely (!loca_prime_data)) return false;
  
      if (use_short_loca)
        _write_loca (padded_offsets, 1, hb_array ((HBUINT16*) loca_prime_data, num_offsets));
      else
        _write_loca (padded_offsets, 0, hb_array ((HBUINT32*) loca_prime_data, num_offsets));
  
      hb_blob_t * loca_blob = hb_blob_create (loca_prime_data,
  					    entry_size * num_offsets,
  					    HB_MEMORY_MODE_WRITABLE,
  					    loca_prime_data,
  					    free);
  
      bool result = plan->add_table (HB_OT_TAG_loca, loca_blob)
  		  && _add_head_and_set_loca_version(plan, use_short_loca);
  
      hb_blob_destroy (loca_blob);
      return result;
    }
  
    template<typename IteratorIn, typename IteratorOut,
  	   hb_requires (hb_is_source_of (IteratorIn, unsigned int)),
  	   hb_requires (hb_is_sink_of (IteratorOut, unsigned))>
    static void
    _write_loca (IteratorIn it, unsigned right_shift, IteratorOut dest)
    {
      unsigned int offset = 0;
      dest << 0;
      + it
      | hb_map ([=, &offset] (unsigned int padded_size) {
        offset += padded_size;
        DEBUG_MSG(SUBSET, nullptr, "loca entry offset %d", offset);
        return offset >> right_shift;
      })
      | hb_sink (dest)
      ;
    }
  
    // requires source of SubsetGlyph complains the identifier isn't declared
    template <typename Iterator>
    bool serialize(hb_serialize_context_t *c,
  		 Iterator it,
  		 const hb_subset_plan_t *plan)
    {
      TRACE_SERIALIZE (this);
  
      + it
      | hb_apply ([=] (const SubsetGlyph& _) { _.serialize (c, plan); })
      ;
  
      return_trace (true);
    }
  
    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);
  
      // 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
      hb_vector_t<SubsetGlyph> glyphs;
      _populate_subset_glyphs (c->plan, &glyphs);
  
      glyf_prime->serialize (c->serializer, hb_iter (glyphs), c->plan);
  
      auto padded_offsets =
      + hb_iter (glyphs)
      | hb_map (&SubsetGlyph::padded_size)
      ;
  
      return_trace (c->serializer->check_success (_add_loca_and_head (c->plan, padded_offsets)));
    }
  
    template <typename SubsetGlyph>
    void
    _populate_subset_glyphs (const hb_subset_plan_t * plan,
  			   hb_vector_t<SubsetGlyph> * glyphs /* OUT */) const
    {
      OT::glyf::accelerator_t glyf;
      glyf.init (plan->source);
  
      + hb_range (plan->num_output_glyphs ())
      | hb_map ([&] (hb_codepoint_t new_gid) {
        SubsetGlyph subset_glyph;
        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;
  
        subset_glyph.source_glyph = glyf.bytes_for_glyph ((const char *) this, subset_glyph.old_gid);
        if (plan->drop_hints) subset_glyph.drop_hints (glyf);
        else subset_glyph.dest_start = subset_glyph.source_glyph;
  
        return subset_glyph;
      })
      | hb_sink (glyphs)
      ;
  
      glyf.fini();
    }
  
    static void
    _fix_component_gids (const hb_subset_plan_t *plan,
  		       hb_bytes_t glyph)
    {
      OT::glyf::CompositeGlyphHeader::Iterator iterator;
      if (OT::glyf::CompositeGlyphHeader::get_iterator (&glyph,
  						      glyph.length,
  						      &iterator))
      {
        do
        {
  	hb_codepoint_t new_gid;
  	if (!plan->new_gid_for_old_gid (iterator.current->glyphIndex,
  					&new_gid))
  	  continue;
  	((OT::glyf::CompositeGlyphHeader *) iterator.current)->glyphIndex = new_gid;
        } while (iterator.move_to_next ());
      }
    }
  
    static void
    _zero_instruction_length (hb_bytes_t glyph)
    {
      const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (&glyph, 0);
      int16_t num_contours = (int16_t) glyph_header.numberOfContours;
      if (num_contours <= 0) return;  // only for simple glyphs
  
      const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (&glyph, GlyphHeader::static_size + 2 * num_contours);
      (HBUINT16 &) instruction_length = 0;
    }
  
    static bool _remove_composite_instruction_flag (hb_bytes_t glyph)
    {
      const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (&glyph, 0);
      if (glyph_header.numberOfContours >= 0) return true;  // only for composites
  
      /* remove WE_HAVE_INSTRUCTIONS from flags in dest */
      OT::glyf::CompositeGlyphHeader::Iterator composite_it;
      if (unlikely (!OT::glyf::CompositeGlyphHeader::get_iterator (&glyph, glyph.length, &composite_it))) return false;
      const OT::glyf::CompositeGlyphHeader *composite_header;
      do {
        composite_header = composite_it.current;
        OT::HBUINT16 *flags = const_cast<OT::HBUINT16 *> (&composite_header->flags);
        *flags = (uint16_t) *flags & ~OT::glyf::CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS;
      } while (composite_it.move_to_next ());
      return true;
  }
  
    static bool
    _add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca)
    {
      hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<head> (plan->source);
      hb_blob_t *head_prime_blob = hb_blob_copy_writable_or_fail (head_blob);
      hb_blob_destroy (head_blob);
  
      if (unlikely (!head_prime_blob))
        return false;
  
      head *head_prime = (head *) hb_blob_get_data_writable (head_prime_blob, nullptr);
      head_prime->indexToLocFormat = use_short_loca ? 0 : 1;
      bool success = plan->add_table (HB_OT_TAG_head, head_prime_blob);
  
      hb_blob_destroy (head_prime_blob);
      return success;
    }
  
    struct GlyphHeader
    {
      HBINT16		numberOfContours;	/* If the number of contours is
  						 * greater than or equal to zero,
  						 * this is a simple glyph; if negative,
  						 * this is a composite glyph. */
      FWORD		xMin;			/* Minimum x for coordinate data. */
      FWORD		yMin;			/* Minimum y for coordinate data. */
      FWORD		xMax;			/* Maximum x for coordinate data. */
      FWORD		yMax;			/* Maximum y for coordinate data. */
  
      DEFINE_SIZE_STATIC (10);
    };
  
    struct CompositeGlyphHeader
    {
      enum composite_glyph_flag_t {
        ARG_1_AND_2_ARE_WORDS =      0x0001,
        ARGS_ARE_XY_VALUES =         0x0002,
        ROUND_XY_TO_GRID =           0x0004,
        WE_HAVE_A_SCALE =            0x0008,
        MORE_COMPONENTS =            0x0020,
        WE_HAVE_AN_X_AND_Y_SCALE =   0x0040,
        WE_HAVE_A_TWO_BY_TWO =       0x0080,
        WE_HAVE_INSTRUCTIONS =       0x0100,
        USE_MY_METRICS =             0x0200,
        OVERLAP_COMPOUND =           0x0400,
        SCALED_COMPONENT_OFFSET =    0x0800,
        UNSCALED_COMPONENT_OFFSET =  0x1000
      };
  
      HBUINT16 flags;
      GlyphID  glyphIndex;
  
      unsigned int get_size () const
      {
        unsigned int size = min_size;
        // arg1 and 2 are int16
        if (flags & ARG_1_AND_2_ARE_WORDS) size += 4;
        // arg1 and 2 are int8
        else size += 2;
  
        // One x 16 bit (scale)
        if (flags & WE_HAVE_A_SCALE) size += 2;
        // Two x 16 bit (xscale, yscale)
        else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) size += 4;
        // Four x 16 bit (xscale, scale01, scale10, yscale)
        else if (flags & WE_HAVE_A_TWO_BY_TWO) size += 8;
  
        return size;
      }
  
      // TODO rewrite using new iterator framework if possible
      struct Iterator
      {
        const char *glyph_start;
        const char *glyph_end;
        const CompositeGlyphHeader *current;
  
        bool move_to_next ()
        {
  	if (current->flags & CompositeGlyphHeader::MORE_COMPONENTS)
  	{
  	  const CompositeGlyphHeader *possible =
  	    &StructAfter<CompositeGlyphHeader, CompositeGlyphHeader> (*current);
  	  if (!in_range (possible))
  	    return false;
  	  current = possible;
  	  return true;
  	}
  	return false;
        }
  
        bool in_range (const CompositeGlyphHeader *composite) const
        {
  	return (const char *) composite >= glyph_start
  	  && ((const char *) composite + CompositeGlyphHeader::min_size) <= glyph_end
  	  && ((const char *) composite + composite->get_size ()) <= glyph_end;
        }
      };
  
      static bool get_iterator (const char * glyph_data,
  			      unsigned int length,
  			      CompositeGlyphHeader::Iterator *iterator /* OUT */)
      {
        if (length < GlyphHeader::static_size)
  	return false; /* Empty glyph; zero extents. */
  
        const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph_data, 0);
        if (glyph_header.numberOfContours < 0)
        {
  	const CompositeGlyphHeader *possible =
  	  &StructAfter<CompositeGlyphHeader, GlyphHeader> (glyph_header);
  
  	iterator->glyph_start = glyph_data;
  	iterator->glyph_end = (const char *) glyph_data + length;
  	if (!iterator->in_range (possible))
  	  return false;
  	iterator->current = possible;
  	return true;
        }
  
        return false;
      }
  
      DEFINE_SIZE_MIN (4);
    };
  
    struct accelerator_t
    {
      void init (hb_face_t *face)
      {
        memset (this, 0, sizeof (accelerator_t));
  
        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 = hb_sanitize_context_t ().reference_table<loca> (face);
        glyf_table = hb_sanitize_context_t ().reference_table<glyf> (face);
  
        num_glyphs = hb_max (1u, loca_table.get_length () / (short_offset ? 2 : 4)) - 1;
      }
  
      void fini ()
      {
        loca_table.destroy ();
        glyf_table.destroy ();
      }
  
      /*
       * Returns true if the referenced glyph is a valid glyph and a composite glyph.
       * If true is returned a pointer to the composite glyph will be written into
       * composite.
       */
      bool get_composite (hb_codepoint_t glyph,
  			CompositeGlyphHeader::Iterator *composite /* OUT */) const
      {
        if (unlikely (!num_glyphs))
  	return false;
  
        unsigned int start_offset, end_offset;
        if (!get_offsets (glyph, &start_offset, &end_offset))
  	return false; /* glyph not found */
  
        return CompositeGlyphHeader::get_iterator ((const char *) this->glyf_table + start_offset,
  						 end_offset - start_offset,
  						 composite);
      }
  
      enum simple_glyph_flag_t {
        FLAG_ON_CURVE = 0x01,
        FLAG_X_SHORT = 0x02,
        FLAG_Y_SHORT = 0x04,
        FLAG_REPEAT = 0x08,
        FLAG_X_SAME = 0x10,
        FLAG_Y_SAME = 0x20,
        FLAG_RESERVED1 = 0x40,
        FLAG_RESERVED2 = 0x80
      };
  
      /* based on FontTools _g_l_y_f.py::trim */
      bool remove_padding (unsigned int start_offset,
  			 unsigned int *end_offset) const
      {
        if (*end_offset - start_offset < GlyphHeader::static_size) return true;
  
        const char *glyph = ((const char *) glyf_table) + start_offset;
        const char * const glyph_end = glyph + (*end_offset - start_offset);
        const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph, 0);
        int16_t num_contours = (int16_t) glyph_header.numberOfContours;
  
        if (num_contours < 0)
  	/* Trimming for composites not implemented.
  	 * If removing hints it falls out of that. */
  	return true;
        else if (num_contours > 0)
        {
  	/* simple glyph w/contours, possibly trimmable */
  	glyph += GlyphHeader::static_size + 2 * num_contours;
  
  	if (unlikely (glyph + 2 >= glyph_end)) return false;
  	uint16_t nCoordinates = (uint16_t) StructAtOffset<HBUINT16> (glyph - 2, 0) + 1;
  	uint16_t nInstructions = (uint16_t) StructAtOffset<HBUINT16> (glyph, 0);
  
  	glyph += 2 + nInstructions;
  	if (unlikely (glyph + 2 >= glyph_end)) return false;
  
  	unsigned int coordBytes = 0;
  	unsigned int coordsWithFlags = 0;
  	while (glyph < glyph_end)
  	{
  	  uint8_t flag = (uint8_t) *glyph;
  	  glyph++;
  
  	  unsigned int repeat = 1;
  	  if (flag & FLAG_REPEAT)
  	  {
  	    if (glyph >= glyph_end)
  	    {
  	      DEBUG_MSG(SUBSET, nullptr, "Bad flag");
  	      return false;
  	    }
  	    repeat = ((uint8_t) *glyph) + 1;
  	    glyph++;
  	  }
  
  	  unsigned int xBytes, yBytes;
  	  xBytes = yBytes = 0;
  	  if (flag & FLAG_X_SHORT) xBytes = 1;
  	  else if ((flag & FLAG_X_SAME) == 0) xBytes = 2;
  
  	  if (flag & FLAG_Y_SHORT) yBytes = 1;
  	  else if ((flag & FLAG_Y_SAME) == 0) yBytes = 2;
  
  	  coordBytes += (xBytes + yBytes) * repeat;
  	  coordsWithFlags += repeat;
  	  if (coordsWithFlags >= nCoordinates)
  	    break;
  	}
  
  	if (coordsWithFlags != nCoordinates)
  	{
  	  DEBUG_MSG(SUBSET, nullptr, "Expect %d coords to have flags, got flags for %d", nCoordinates, coordsWithFlags);
  	  return false;
  	}
  	glyph += coordBytes;
  
  	if (glyph < glyph_end)
  	  *end_offset -= glyph_end - glyph;
        }
        return true;
      }
  
      bool get_offsets (hb_codepoint_t  glyph,
  		      unsigned int   *start_offset /* OUT */,
  		      unsigned int   *end_offset   /* OUT */) const
      {
        if (unlikely (glyph >= num_glyphs))
  	return false;
  
        if (short_offset)
        {
  	const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ.arrayZ;
  	*start_offset = 2 * offsets[glyph];
  	*end_offset   = 2 * offsets[glyph + 1];
        }
        else
        {
  	const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ.arrayZ;
  
  	*start_offset = offsets[glyph];
  	*end_offset   = offsets[glyph + 1];
        }
  
        if (*start_offset > *end_offset || *end_offset > glyf_table.get_length ())
  	return false;
  
        return true;
      }
  
      bool get_instruction_length (hb_bytes_t glyph,
  				 unsigned int * length /* OUT */) const
      {
        /* Empty glyph; no instructions. */
        if (glyph.length < GlyphHeader::static_size)
        {
  	*length = 0;
  	// only 0 byte glyphs are healthy when missing GlyphHeader
  	return glyph.length == 0;
        }
        const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (&glyph, 0);
        int16_t num_contours = (int16_t) glyph_header.numberOfContours;
        if (num_contours < 0)
        {
  	unsigned int start = glyph.length;
  	unsigned int end = glyph.length;
  	unsigned int glyph_offset = &glyph - glyf_table;
  	CompositeGlyphHeader::Iterator composite_it;
  	if (unlikely (!CompositeGlyphHeader::get_iterator (&glyph, glyph.length, &composite_it))) return false;
  	const CompositeGlyphHeader *last;
  	do {
  	  last = composite_it.current;
  	} while (composite_it.move_to_next ());
  
  	if ((uint16_t) last->flags & CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS)
  	  start = ((char *) last - (char *) glyf_table->dataZ.arrayZ) + last->get_size () - glyph_offset;
  	if (unlikely (start > end))
  	{
  	  DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside %d byte buffer", start, glyph.length);
  	  return false;
  	}
  	*length = end - start;
        }
        else
        {
  	unsigned int instruction_length_offset = GlyphHeader::static_size + 2 * num_contours;
  	if (unlikely (instruction_length_offset + 2 > glyph.length))
  	{
  	  DEBUG_MSG(SUBSET, nullptr, "Glyph size is too short, missing field instructionLength.");
  	  return false;
  	}
  
  	const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (&glyph, instruction_length_offset);
  	if (unlikely (instruction_length_offset + instruction_length > glyph.length)) // Out of bounds of the current glyph
  	{
  	  DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries.");
  	  return false;
  	}
  	*length = (uint16_t) instruction_length;
        }
        return true;
      }
  
      bool get_extents (hb_codepoint_t glyph, hb_glyph_extents_t *extents) const
      {
        unsigned int start_offset, end_offset;
        if (!get_offsets (glyph, &start_offset, &end_offset))
  	return false;
  
        if (end_offset - start_offset < GlyphHeader::static_size)
  	return true; /* Empty glyph; zero extents. */
  
        const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
  
        extents->x_bearing = hb_min (glyph_header.xMin, glyph_header.xMax);
        extents->y_bearing = hb_max (glyph_header.yMin, glyph_header.yMax);
        extents->width     = hb_max (glyph_header.xMin, glyph_header.xMax) - extents->x_bearing;
        extents->height    = hb_min (glyph_header.yMin, glyph_header.yMax) - extents->y_bearing;
  
        return true;
      }
  
    hb_bytes_t bytes_for_glyph (const char * glyf, hb_codepoint_t gid)
    {
      unsigned int start_offset, end_offset;
      if (unlikely (!(get_offsets (gid, &start_offset, &end_offset) &&
        remove_padding (start_offset, &end_offset))))
      {
        DEBUG_MSG(SUBSET, nullptr, "Unable to get offset or remove padding for %d", gid);
        return hb_bytes_t ();
      }
      hb_bytes_t glyph = hb_bytes_t (glyf + start_offset, end_offset - start_offset);
      if (glyph.length == 0) return glyph;
      if (unlikely (glyph.length < GlyphHeader::static_size))
      {
        DEBUG_MSG(SUBSET, nullptr, "Glyph size smaller than minimum header %d", gid);
        return hb_bytes_t ();
      }
      return glyph;
    }
  
      private:
      bool short_offset;
      unsigned int num_glyphs;
      hb_blob_ptr_t<loca> loca_table;
      hb_blob_ptr_t<glyf> glyf_table;
    };
  
  
    struct SubsetGlyph
    {
      hb_codepoint_t new_gid;
      hb_codepoint_t old_gid;
      hb_bytes_t source_glyph;
      hb_bytes_t dest_start;  // region of source_glyph to copy first
      hb_bytes_t dest_end;    // region of source_glyph to copy second
  
  
    bool serialize (hb_serialize_context_t *c,
  		  const hb_subset_plan_t *plan) const
    {
      TRACE_SERIALIZE (this);
  
      hb_bytes_t dest_glyph = dest_start.copy(c);
      dest_glyph = hb_bytes_t (&dest_glyph, dest_glyph.length + dest_end.copy(c).length);
      unsigned int pad_length = padding ();
      DEBUG_MSG(SUBSET, nullptr, "serialize %d byte glyph, width %d pad %d", dest_glyph.length, dest_glyph.length  + pad_length, pad_length);
  
      HBUINT8 pad;
      pad = 0;
      while (pad_length > 0)
      {
        c->embed(pad);
        pad_length--;
      }
  
      if (dest_glyph.length)
      {
        _fix_component_gids (plan, dest_glyph);
        if (plan->drop_hints)
        {
  	_zero_instruction_length (dest_glyph);
  	c->check_success (_remove_composite_instruction_flag (dest_glyph));
        }
      }
  
      return_trace (true);
    }
  
      void drop_hints (const OT::glyf::accelerator_t& glyf)
      {
        if (source_glyph.length == 0) return;
  
        unsigned int instruction_length = 0;
        if (!glyf.get_instruction_length (source_glyph, &instruction_length))
        {
  	 DEBUG_MSG(SUBSET, nullptr, "Unable to read instruction length for new_gid %d", new_gid);
  	return ;
        }
  
        const GlyphHeader& header = StructAtOffset<GlyphHeader> (&source_glyph, 0);
        int16_t num_contours = (int16_t) header.numberOfContours;
        DEBUG_MSG(SUBSET, nullptr, "new_gid %d (%d contours) drop %d instruction bytes from %d byte source glyph", new_gid, num_contours, instruction_length, source_glyph.length);
        if (num_contours < 0)
        {
  	// composite, just chop instructions off the end
  	dest_start = hb_bytes_t (&source_glyph, source_glyph.length - instruction_length);
        }
        else
        {
  	// simple glyph
  	dest_start = hb_bytes_t (&source_glyph, GlyphHeader::static_size + 2 * header.numberOfContours + 2);
  	dest_end = hb_bytes_t (&source_glyph + dest_start.length + instruction_length,
  			       source_glyph.length - dest_start.length - instruction_length);
  DEBUG_MSG(SUBSET, nullptr, "source_len %d start len %d instruction_len %d end len %d", source_glyph.length, dest_start.length, instruction_length, dest_end.length);
        }
      }
  
      unsigned int length () const
      {
        return dest_start.length + dest_end.length;
      }
  
      // pad to 2 to ensure 2-byte loca will be ok
      unsigned int padding () const
      {
        return length () % 2;
      }
  
      unsigned int padded_size () const
      {
        return length () + padding ();
      }
    };
  
    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 {};
  
  } /* namespace OT */
  
  
  #endif /* HB_OT_GLYF_TABLE_HH */
  

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