kc3-lang/harfbuzz/src/OT/Layout/GSUB/SingleSubstFormat2.hh

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• Hash : 7327006d
  Author :
  Date : 2023-03-07T21:06:01
  

  [GSUB] Support SingleSubst in get_glyph_alternates
  
  Fixes https://github.com/harfbuzz/harfbuzz/discussions/4146
  

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• src/OT/Layout/GSUB/SingleSubstFormat2.hh

• #ifndef OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH
  #define OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH
  
  #include "Common.hh"
  
  namespace OT {
  namespace Layout {
  namespace GSUB_impl {
  
  template <typename Types>
  struct SingleSubstFormat2_4
  {
    protected:
    HBUINT16      format;                 /* Format identifier--format = 2 */
    typename Types::template OffsetTo<Coverage>
                  coverage;               /* Offset to Coverage table--from
                                           * beginning of Substitution table */
    Array16Of<typename Types::HBGlyphID>
                  substitute;             /* Array of substitute
                                           * GlyphIDs--ordered by Coverage Index */
  
    public:
    DEFINE_SIZE_ARRAY (4 + Types::size, substitute);
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (coverage.sanitize (c, this) && substitute.sanitize (c));
    }
  
    bool intersects (const hb_set_t *glyphs) const
    { return (this+coverage).intersects (glyphs); }
  
    bool may_have_non_1to1 () const
    { return false; }
  
    void closure (hb_closure_context_t *c) const
    {
      auto &cov = this+coverage;
      auto &glyph_set = c->parent_active_glyphs ();
  
      if (substitute.len > glyph_set.get_population () * 4)
      {
        for (auto g : glyph_set)
        {
  	unsigned i = cov.get_coverage (g);
  	if (i == NOT_COVERED || i >= substitute.len)
  	  continue;
  	c->output->add (substitute.arrayZ[i]);
        }
  
        return;
      }
  
      + hb_zip (cov, substitute)
      | hb_filter (glyph_set, hb_first)
      | hb_map (hb_second)
      | hb_sink (c->output)
      ;
    }
  
    void closure_lookups (hb_closure_lookups_context_t *c) const {}
  
    void collect_glyphs (hb_collect_glyphs_context_t *c) const
    {
      if (unlikely (!(this+coverage).collect_coverage (c->input))) return;
      + hb_zip (this+coverage, substitute)
      | hb_map (hb_second)
      | hb_sink (c->output)
      ;
    }
  
    const Coverage &get_coverage () const { return this+coverage; }
  
    bool would_apply (hb_would_apply_context_t *c) const
    { return c->len == 1 && (this+coverage).get_coverage (c->glyphs[0]) != NOT_COVERED; }
  
    unsigned
    get_glyph_alternates (hb_codepoint_t  glyph_id,
                          unsigned        start_offset,
                          unsigned       *alternate_count  /* IN/OUT.  May be NULL. */,
                          hb_codepoint_t *alternate_glyphs /* OUT.     May be NULL. */) const
    {
      unsigned int index = (this+coverage).get_coverage (glyph_id);
      if (likely (index == NOT_COVERED))
      {
        if (alternate_count)
          *alternate_count = 0;
        return 0;
      }
  
      if (alternate_count && *alternate_count)
      {
        glyph_id = substitute[index];
  
        *alternate_glyphs = glyph_id;
        *alternate_count = 1;
      }
  
      return 1;
    }
  
    bool apply (hb_ot_apply_context_t *c) const
    {
      TRACE_APPLY (this);
      unsigned int index = (this+coverage).get_coverage (c->buffer->cur().codepoint);
      if (likely (index == NOT_COVERED)) return_trace (false);
  
      if (unlikely (index >= substitute.len)) return_trace (false);
  
      if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
      {
        c->buffer->sync_so_far ();
        c->buffer->message (c->font,
  			  "replacing glyph at %u (single substitution)",
  			  c->buffer->idx);
      }
  
      c->replace_glyph (substitute[index]);
  
      if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
      {
        c->buffer->message (c->font,
  			  "replaced glyph at %u (single substitution)",
  			  c->buffer->idx - 1u);
      }
  
      return_trace (true);
    }
  
    template<typename Iterator,
             hb_requires (hb_is_sorted_source_of (Iterator,
                                                  hb_codepoint_pair_t))>
    bool serialize (hb_serialize_context_t *c,
                    Iterator it)
    {
      TRACE_SERIALIZE (this);
      auto substitutes =
        + it
        | hb_map (hb_second)
        ;
      auto glyphs =
        + it
        | hb_map_retains_sorting (hb_first)
        ;
      if (unlikely (!c->extend_min (this))) return_trace (false);
      if (unlikely (!substitute.serialize (c, substitutes))) return_trace (false);
      if (unlikely (!coverage.serialize_serialize (c, glyphs))) return_trace (false);
      return_trace (true);
    }
  
    bool subset (hb_subset_context_t *c) const
    {
      TRACE_SUBSET (this);
      const hb_set_t &glyphset = *c->plan->glyphset_gsub ();
      const hb_map_t &glyph_map = *c->plan->glyph_map;
  
      auto it =
      + hb_zip (this+coverage, substitute)
      | hb_filter (glyphset, hb_first)
      | hb_filter (glyphset, hb_second)
      | hb_map_retains_sorting ([&] (hb_pair_t<hb_codepoint_t, const typename Types::HBGlyphID &> p) -> hb_codepoint_pair_t
                                { return hb_pair (glyph_map[p.first], glyph_map[p.second]); })
      ;
  
      bool ret = bool (it);
      SingleSubst_serialize (c->serializer, it);
      return_trace (ret);
    }
  };
  
  }
  }
  }
  
  #endif /* OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH */
  

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