tor-browser

coverage-graph.hh (6711B)

---

/*
* Copyright © 2022  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): Garret Rieger
*/

#include "graph.hh"
#include "../OT/Layout/Common/Coverage.hh"

#ifndef GRAPH_COVERAGE_GRAPH_HH
#define GRAPH_COVERAGE_GRAPH_HH

namespace graph {

static bool sanitize (
 const OT::Layout::Common::CoverageFormat1_3<OT::Layout::SmallTypes>* thiz,
 graph_t::vertex_t& vertex
) {
 int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
 constexpr unsigned min_size = OT::Layout::Common::CoverageFormat1_3<OT::Layout::SmallTypes>::min_size;
 if (vertex_len < min_size) return false;
 hb_barrier ();
 return vertex_len >= min_size + thiz->glyphArray.get_size () - thiz->glyphArray.len.get_size ();
}

static bool sanitize (
 const OT::Layout::Common::CoverageFormat2_4<OT::Layout::SmallTypes>* thiz,
 graph_t::vertex_t& vertex
) {
 int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
 constexpr unsigned min_size = OT::Layout::Common::CoverageFormat2_4<OT::Layout::SmallTypes>::min_size;
 if (vertex_len < min_size) return false;
 hb_barrier ();
 return vertex_len >= min_size + thiz->rangeRecord.get_size () - thiz->rangeRecord.len.get_size ();
}

struct Coverage : public OT::Layout::Common::Coverage
{
 static Coverage* clone_coverage (gsubgpos_graph_context_t& c,
                                  unsigned coverage_id,
                                  unsigned new_parent_id,
                                  unsigned link_position,
                                  unsigned start, unsigned end)

 {
   unsigned coverage_size = c.graph.vertices_[coverage_id].table_size ();
   auto& coverage_v = c.graph.vertices_[coverage_id];
   Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
   if (!coverage_table || !coverage_table->sanitize (coverage_v))
     return nullptr;

   auto new_coverage =
       + hb_zip (coverage_table->iter (), hb_range ())
       | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
         return p.second >= start && p.second < end;
       })
       | hb_map_retains_sorting (hb_first)
       ;

   return add_coverage (c, new_parent_id, link_position, new_coverage, coverage_size);
 }

 template<typename It>
 static Coverage* add_coverage (gsubgpos_graph_context_t& c,
                                unsigned parent_id,
                                unsigned link_position,
                                It glyphs,
                                unsigned max_size)
 {
   unsigned coverage_prime_id = c.graph.new_node (nullptr, nullptr);
   auto& coverage_prime_vertex = c.graph.vertices_[coverage_prime_id];
   if (!make_coverage (c, glyphs, coverage_prime_id, max_size))
     return nullptr;

   auto* coverage_link = c.graph.vertices_[parent_id].obj.real_links.push ();
   coverage_link->width = SmallTypes::size;
   coverage_link->objidx = coverage_prime_id;
   coverage_link->position = link_position;
   coverage_prime_vertex.add_parent (parent_id, false);

   return (Coverage*) coverage_prime_vertex.obj.head;
 }

 // Filter an existing coverage table to glyphs at indices [start, end) and replace it with the filtered version.
 static bool filter_coverage (gsubgpos_graph_context_t& c,
                              unsigned existing_coverage,
                              unsigned start, unsigned end) {
   unsigned coverage_size = c.graph.vertices_[existing_coverage].table_size ();
   auto& coverage_v = c.graph.vertices_[existing_coverage];
   Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
   if (!coverage_table || !coverage_table->sanitize (coverage_v))
     return false;

   auto new_coverage =
       + hb_zip (coverage_table->iter (), hb_range ())
       | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
         return p.second >= start && p.second < end;
       })
       | hb_map_retains_sorting (hb_first)
       ;

   return make_coverage (c, new_coverage, existing_coverage, coverage_size * 2 + 100);
 }

 // Replace the coverage table at dest obj with one covering 'glyphs'.
 template<typename It>
 static bool make_coverage (gsubgpos_graph_context_t& c,
                            It glyphs,
                            unsigned dest_obj,
                            unsigned max_size)
 {
   char* buffer = (char*) hb_calloc (1, max_size);
   hb_serialize_context_t serializer (buffer, max_size);
   OT::Layout::Common::Coverage_serialize (&serializer, glyphs);
   serializer.end_serialize ();
   if (serializer.in_error ())
   {
     hb_free (buffer);
     return false;
   }

   hb_bytes_t coverage_copy = serializer.copy_bytes ();
   if (!coverage_copy.arrayZ) return false;
   // Give ownership to the context, it will cleanup the buffer.
   if (!c.add_buffer ((char *) coverage_copy.arrayZ))
   {
     hb_free ((char *) coverage_copy.arrayZ);
     return false;
   }

   auto& obj = c.graph.vertices_[dest_obj].obj;
   obj.head = (char *) coverage_copy.arrayZ;
   obj.tail = obj.head + coverage_copy.length;

   hb_free (buffer);
   return true;
 }

 bool sanitize (graph_t::vertex_t& vertex) const
 {
   int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
   if (vertex_len < OT::Layout::Common::Coverage::min_size) return false;
   hb_barrier ();
   switch (u.format.v)
   {
   case 1: return graph::sanitize ((const OT::Layout::Common::CoverageFormat1_3<OT::Layout::SmallTypes>*) this, vertex);
   case 2: return graph::sanitize ((const OT::Layout::Common::CoverageFormat2_4<OT::Layout::SmallTypes>*) this, vertex);
#ifndef HB_NO_BEYOND_64K
   // Not currently supported
   case 3:
   case 4:
#endif
   default: return false;
   }
 }
};


}

#endif  // GRAPH_COVERAGE_GRAPH_HH