harfbuzz/src/hb-subset-plan.hh

/*
 * Copyright © 2018  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, Roderick Sheeter
 */

#ifndef HB_SUBSET_PLAN_HH
#define HB_SUBSET_PLAN_HH

#include "hb.hh"

#include "hb-subset.h"
#include "hb-subset-input.hh"

#include "hb-map.hh"
#include "hb-set.hh"

struct hb_subset_plan_t
{
  hb_object_header_t header;

  bool drop_hints : 1;
  bool drop_layout : 1;
  bool desubroutinize : 1;

  // For each cp that we'd like to retain maps to the corresponding gid.
  hb_set_t *unicodes;

  // The glyph subset
  hb_map_t *codepoint_to_glyph;

  // Old -> New glyph id mapping
  hb_map_t *glyph_map;
  hb_map_t *reverse_glyph_map;

  // Plan is only good for a specific source/dest so keep them with it
  hb_face_t *source;
  hb_face_t *dest;

  unsigned int _num_output_glyphs;
  hb_set_t *_glyphset;

 public:

  /*
   * The set of input glyph ids which will be retained in the subset.
   */
  inline const hb_set_t *
  glyphset () const
  {
    return _glyphset;
  }

  /*
   * The total number of output glyphs in the final subset.
   */
  inline unsigned int
  num_output_glyphs () const
  {
    return _num_output_glyphs;
  }

  /*
   * Given an output gid , returns true if that glyph id is an empty
   * glyph (ie. it's a gid that we are dropping all data for).
   */
  inline bool is_empty_glyph (hb_codepoint_t gid) const
  {
    return !_glyphset->has (gid);
  }

  inline bool new_gid_for_codepoint (hb_codepoint_t codepoint,
                                     hb_codepoint_t *new_gid) const
  {
    hb_codepoint_t old_gid = codepoint_to_glyph->get (codepoint);
    if (old_gid == HB_MAP_VALUE_INVALID)
      return false;

    return new_gid_for_old_gid (old_gid, new_gid);
  }

  inline bool new_gid_for_old_gid (hb_codepoint_t old_gid,
                                   hb_codepoint_t *new_gid) const
  {
    hb_codepoint_t gid = glyph_map->get (old_gid);
    if (gid == HB_MAP_VALUE_INVALID)
      return false;

    *new_gid = gid;
    return true;
  }

  inline bool old_gid_for_new_gid (hb_codepoint_t  new_gid,
                                   hb_codepoint_t *old_gid) const
  {
    hb_codepoint_t gid = reverse_glyph_map->get (new_gid);
    if (gid == HB_MAP_VALUE_INVALID)
      return false;

    *old_gid = gid;
    return true;
  }

  inline bool
  add_table (hb_tag_t tag,
	     hb_blob_t *contents)
  {
    hb_blob_t *source_blob = source->reference_table (tag);
    DEBUG_MSG(SUBSET, nullptr, "add table %c%c%c%c, dest %d bytes, source %d bytes",
	      HB_UNTAG(tag),
	      hb_blob_get_length (contents),
	      hb_blob_get_length (source_blob));
    hb_blob_destroy (source_blob);
    return hb_face_builder_add_table (dest, tag, contents);
  }
};

typedef struct hb_subset_plan_t hb_subset_plan_t;

HB_INTERNAL hb_subset_plan_t *
hb_subset_plan_create (hb_face_t           *face,
                       hb_subset_input_t   *input);

HB_INTERNAL void
hb_subset_plan_destroy (hb_subset_plan_t *plan);

#endif /* HB_SUBSET_PLAN_HH */