DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (5b81998bb7ab)

VCS Links

Line Code
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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "metrics.h"

#include "head.h"
#include "maxp.h"

// OpenType horizontal and vertical common header format
// http://www.microsoft.com/opentype/otspec/hhea.htm
// http://www.microsoft.com/opentype/otspec/vhea.htm

namespace ots {

bool ParseMetricsHeader(OpenTypeFile *file, Buffer *table,
                        OpenTypeMetricsHeader *header) {
  if (!table->ReadS16(&header->ascent) ||
      !table->ReadS16(&header->descent) ||
      !table->ReadS16(&header->linegap) ||
      !table->ReadU16(&header->adv_width_max) ||
      !table->ReadS16(&header->min_sb1) ||
      !table->ReadS16(&header->min_sb2) ||
      !table->ReadS16(&header->max_extent) ||
      !table->ReadS16(&header->caret_slope_rise) ||
      !table->ReadS16(&header->caret_slope_run) ||
      !table->ReadS16(&header->caret_offset)) {
    return OTS_FAILURE();
  }

  if (header->ascent < 0) {
    OTS_WARNING("bad ascent: %d", header->ascent);
    header->ascent = 0;
  }
  if (header->linegap < 0) {
    OTS_WARNING("bad linegap: %d", header->linegap);
    header->linegap = 0;
  }

  if (!file->head) {
    return OTS_FAILURE();
  }

  // if the font is non-slanted, caret_offset should be zero.
  if (!(file->head->mac_style & 2) &&
      (header->caret_offset != 0)) {
    OTS_WARNING("bad caret offset: %d", header->caret_offset);
    header->caret_offset = 0;
  }

  // skip the reserved bytes
  if (!table->Skip(8)) {
    return OTS_FAILURE();
  }

  int16_t data_format;
  if (!table->ReadS16(&data_format)) {
    return OTS_FAILURE();
  }
  if (data_format) {
    return OTS_FAILURE();
  }

  if (!table->ReadU16(&header->num_metrics)) {
    return OTS_FAILURE();
  }

  if (!file->maxp) {
    return OTS_FAILURE();
  }

  if (header->num_metrics > file->maxp->num_glyphs) {
    return OTS_FAILURE();
  }

  return true;
}

bool SerialiseMetricsHeader(OTSStream *out,
                            const OpenTypeMetricsHeader *header) {
  if (!out->WriteU32(header->version) ||
      !out->WriteS16(header->ascent) ||
      !out->WriteS16(header->descent) ||
      !out->WriteS16(header->linegap) ||
      !out->WriteU16(header->adv_width_max) ||
      !out->WriteS16(header->min_sb1) ||
      !out->WriteS16(header->min_sb2) ||
      !out->WriteS16(header->max_extent) ||
      !out->WriteS16(header->caret_slope_rise) ||
      !out->WriteS16(header->caret_slope_run) ||
      !out->WriteS16(header->caret_offset) ||
      !out->WriteR64(0) ||  // reserved
      !out->WriteS16(0) ||  // metric data format
      !out->WriteU16(header->num_metrics)) {
    return OTS_FAILURE();
  }

  return true;
}

bool ParseMetricsTable(Buffer *table,
                       const uint16_t num_glyphs,
                       const OpenTypeMetricsHeader *header,
                       OpenTypeMetricsTable *metrics) {
  // |num_metrics| is a uint16_t, so it's bounded < 65536. This limits that
  // amount of memory that we'll allocate for this to a sane amount.
  const unsigned num_metrics = header->num_metrics;

  if (num_metrics > num_glyphs) {
    return OTS_FAILURE();
  }
  if (!num_metrics) {
    return OTS_FAILURE();
  }
  const unsigned num_sbs = num_glyphs - num_metrics;

  metrics->entries.reserve(num_metrics);
  for (unsigned i = 0; i < num_metrics; ++i) {
    uint16_t adv = 0;
    int16_t sb = 0;
    if (!table->ReadU16(&adv) || !table->ReadS16(&sb)) {
      return OTS_FAILURE();
    }

    // Since so many fonts don't have proper value on |adv| and |sb|,
    // we should not call ots_failure() here. For example, about 20% of fonts
    // in http://www.princexml.com/fonts/ (200+ fonts) fails these tests.
    if (adv > header->adv_width_max) {
      OTS_WARNING("bad adv: %u > %u", adv, header->adv_width_max);
      adv = header->adv_width_max;
    }

    if (sb < header->min_sb1) {
      OTS_WARNING("bad sb: %d < %d", sb, header->min_sb1);
      sb = header->min_sb1;
    }

    metrics->entries.push_back(std::make_pair(adv, sb));
  }

  metrics->sbs.reserve(num_sbs);
  for (unsigned i = 0; i < num_sbs; ++i) {
    int16_t sb;
    if (!table->ReadS16(&sb)) {
      // Some Japanese fonts (e.g., mona.ttf) fail this test.
      return OTS_FAILURE();
    }

    if (sb < header->min_sb1) {
      // The same as above. Three fonts in http://www.fontsquirrel.com/fontface
      // (e.g., Notice2Std.otf) have weird lsb values.
      OTS_WARNING("bad lsb: %d < %d", sb, header->min_sb1);
      sb = header->min_sb1;
    }

    metrics->sbs.push_back(sb);
  }

  return true;
}

bool SerialiseMetricsTable(OTSStream *out,
                           const OpenTypeMetricsTable *metrics) {
  for (unsigned i = 0; i < metrics->entries.size(); ++i) {
    if (!out->WriteU16(metrics->entries[i].first) ||
        !out->WriteS16(metrics->entries[i].second)) {
      return OTS_FAILURE();
    }
  }

  for (unsigned i = 0; i < metrics->sbs.size(); ++i) {
    if (!out->WriteS16(metrics->sbs[i])) {
      return OTS_FAILURE();
    }
  }

  return true;
}

}  // namespace ots