chromium/third_party/harfbuzz-ng/src/src/hb-repacker.hh

/*
 * Copyright © 2020  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
 */

#ifndef HB_REPACKER_HH
#define HB_REPACKER_HH

#include "hb-open-type.hh"
#include "hb-map.hh"
#include "hb-vector.hh"
#include "graph/graph.hh"
#include "graph/gsubgpos-graph.hh"
#include "graph/serialize.hh"

graph_t;

/*
 * For a detailed writeup on the overflow resolution algorithm see:
 * docs/repacker.md
 */

struct lookup_size_t
{ … };

static inline
bool _presplit_subtables_if_needed (graph::gsubgpos_graph_context_t& ext_context)
{ … }

/*
 * Analyze the lookups in a GSUB/GPOS table and decide if any should be promoted
 * to extension lookups.
 */
static inline
bool _promote_extensions_if_needed (graph::gsubgpos_graph_context_t& ext_context)
{ … }

static inline
bool _try_isolating_subgraphs (const hb_vector_t<graph::overflow_record_t>& overflows,
                               graph_t& sorted_graph)
{ … }

static inline
bool _resolve_shared_overflow(const hb_vector_t<graph::overflow_record_t>& overflows,
                              int overflow_index,
                              graph_t& sorted_graph)
{ … }

static inline
bool _process_overflows (const hb_vector_t<graph::overflow_record_t>& overflows,
                         hb_set_t& priority_bumped_parents,
                         graph_t& sorted_graph)
{ … }

inline bool
hb_resolve_graph_overflows (hb_tag_t table_tag,
                            unsigned max_rounds ,
                            bool always_recalculate_extensions,
                            graph_t& sorted_graph /* IN/OUT */)
{ … }

/*
 * Attempts to modify the topological sorting of the provided object graph to
 * eliminate offset overflows in the links between objects of the graph. If a
 * non-overflowing ordering is found the updated graph is serialized it into the
 * provided serialization context.
 *
 * If necessary the structure of the graph may be modified in ways that do not
 * affect the functionality of the graph. For example shared objects may be
 * duplicated.
 *
 * For a detailed writeup describing how the algorithm operates see:
 * docs/repacker.md
 */
template<typename T>
inline hb_blob_t*
hb_resolve_overflows (const T& packed,
                      hb_tag_t table_tag,
                      unsigned max_rounds = 32,
                      bool recalculate_extensions = false) { … }

#endif /* HB_REPACKER_HH */