hb-subset-glyf.cc 6.1 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
/*
 * 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
 */

27
#include "hb-open-type-private.hh"
28
#include "hb-ot-glyf-table.hh"
29
#include "hb-set.h"
30 31
#include "hb-subset-glyf.hh"

32
bool
33 34 35 36
_calculate_glyf_and_loca_prime_size (const OT::glyf::accelerator_t &glyf,
                                     hb_set_t *glyph_ids,
                                     unsigned int *glyf_size /* OUT */,
                                     unsigned int *loca_size /* OUT */)
37 38
{
  unsigned int total = 0;
39
  unsigned int count = 0;
40 41 42
  hb_codepoint_t next_glyph = -1;
  while (hb_set_next(glyph_ids, &next_glyph)) {
    unsigned int start_offset, end_offset;
43
    if (unlikely (!glyf.get_offsets (next_glyph, &start_offset, &end_offset))) {
44 45
      *glyf_size = 0;
      *loca_size = sizeof(OT::HBUINT32);
46 47 48 49
      return false;
    }

    total += end_offset - start_offset;
50
    count++;
51 52
  }

53 54
  *glyf_size = total;
  *loca_size = (count + 1) * sizeof(OT::HBUINT32);
55 56 57 58
  return true;
}

bool
59 60 61 62 63 64 65
_write_glyf_and_loca_prime (const OT::glyf::accelerator_t &glyf,
                            const char                    *glyf_data,
                            const hb_set_t                *glyph_ids,
                            int                            glyf_prime_size,
                            char                          *glyf_prime_data /* OUT */,
                            int                            loca_prime_size,
                            char                          *loca_prime_data /* OUT */)
66
{
67 68
  // TODO(grieger): Handle the missing character glyf and outline.

69
  char *glyf_prime_data_next = glyf_prime_data;
70
  OT::HBUINT32 *loca_prime = (OT::HBUINT32*) loca_prime_data;
71 72

  hb_codepoint_t next_glyph = -1;
73 74
  hb_codepoint_t new_glyph_id = 0;

75
  unsigned int end_offset;
76
  while (hb_set_next(glyph_ids, &next_glyph)) {
77
    unsigned int start_offset;
78
    if (unlikely (!glyf.get_offsets (next_glyph, &start_offset, &end_offset))) {
79 80 81 82 83
      return false;
    }

    int length = end_offset - start_offset;
    memcpy (glyf_prime_data_next, glyf_data + start_offset, length);
84 85
    loca_prime[new_glyph_id].set(start_offset);

86
    glyf_prime_data_next += length;
87
    new_glyph_id++;
88 89
  }

90 91 92 93
  // Add the last loca entry which doesn't correspond to a specific glyph
  // but identifies the end of the last glyphs data.
  loca_prime[new_glyph_id].set(end_offset);

94 95 96
  return true;
}

97
bool
98 99 100 101 102
_hb_subset_glyf_and_loca (const OT::glyf::accelerator_t  &glyf,
                          const char                     *glyf_data,
                          hb_set_t                       *glyphs_to_retain,
                          hb_blob_t                     **glyf_prime /* OUT */,
                          hb_blob_t                     **loca_prime /* OUT */)
103
{
104 105 106
  // TODO(grieger): Sanity check writes to make sure they are in-bounds.
  // TODO(grieger): Sanity check allocation size for the new table.
  // TODO(grieger): Subset loca simultaneously.
107
  // TODO(grieger): Don't fail on bad offsets, just dump them.
108
  // TODO(grieger): Support short loca output.
109
  // TODO(grieger): Add a extra loca entry at the end.
110 111

  unsigned int glyf_prime_size;
112 113 114 115 116
  unsigned int loca_prime_size;
  if (unlikely (!_calculate_glyf_and_loca_prime_size (glyf,
                                                      glyphs_to_retain,
                                                      &glyf_prime_size,
                                                      &loca_prime_size))) {
117 118
    return false;
  }
119

120
  char *glyf_prime_data = (char *) calloc (glyf_prime_size, 1);
121 122 123 124
  char *loca_prime_data = (char *) calloc (loca_prime_size, 1);
  if (unlikely (!_write_glyf_and_loca_prime (glyf, glyf_data, glyphs_to_retain,
                                             glyf_prime_size, glyf_prime_data,
                                             loca_prime_size, loca_prime_data))) {
125 126 127
    free (glyf_prime_data);
    return false;
  }
128

129 130 131 132 133
  *glyf_prime = hb_blob_create (glyf_prime_data,
                                glyf_prime_size,
                                HB_MEMORY_MODE_READONLY,
                                glyf_prime_data,
                                free);
134 135 136 137 138
  *loca_prime = hb_blob_create (loca_prime_data,
                                loca_prime_size,
                                HB_MEMORY_MODE_READONLY,
                                loca_prime_data,
                                free);
139 140
  return true;
}
141 142 143 144 145 146 147 148 149 150

/**
 * hb_subset_glyf:
 * Subsets the glyph table according to a provided plan.
 *
 * Return value: subsetted glyf table.
 *
 * Since: 1.7.5
 **/
bool
151 152 153 154
hb_subset_glyf_and_loca (hb_subset_plan_t *plan,
                         hb_face_t        *face,
                         hb_blob_t       **glyf_prime /* OUT */,
                         hb_blob_t       **loca_prime /* OUT */)
155 156 157 158 159 160
{
  hb_blob_t *glyf_blob = OT::Sanitizer<OT::glyf>().sanitize (face->reference_table (HB_OT_TAG_glyf));
  const char *glyf_data = hb_blob_get_data(glyf_blob, nullptr);

  OT::glyf::accelerator_t glyf;
  glyf.init(face);
161
  bool result = _hb_subset_glyf_and_loca (glyf, glyf_data, plan->glyphs_to_retain, glyf_prime, loca_prime);
162 163
  glyf.fini();

164 165
  // TODO(grieger): Subset loca

166 167
  return result;
}