The Tor Browser: gfx/ots/src/kern.cc@6474c204b198 (annotated)

gfx/ots/src/kern.cc@6474c204b198 (annotated)

gfx/ots/src/kern.cc

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2009 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 "kern.h"
 // kern - Kerning
 // http://www.microsoft.com/typography/otspec/kern.htm
 #define TABLE_NAME "kern"
 #define DROP_THIS_TABLE \
   do { \
     delete file->kern; \
     file->kern = 0; \
     OTS_FAILURE_MSG("Table discarded"); \
   } while (0)
 namespace ots {
 bool ots_kern_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   Buffer table(data, length);
   OpenTypeKERN *kern = new OpenTypeKERN;
   file->kern = kern;
   uint16_t num_tables = 0;
   if (!table.ReadU16(&kern->version) ||
       !table.ReadU16(&num_tables)) {
     return OTS_FAILURE_MSG("Failed to read kern header");
   }
   if (kern->version > 0) {
     DROP_THIS_TABLE;
     return true;
   }
   if (num_tables == 0) {
     OTS_WARNING("num_tables is zero");
     DROP_THIS_TABLE;
     return true;
   }
   kern->subtables.reserve(num_tables);
   for (unsigned i = 0; i < num_tables; ++i) {
     OpenTypeKERNFormat0 subtable;
     uint16_t sub_length = 0;
     if (!table.ReadU16(&subtable.version) ||
         !table.ReadU16(&sub_length)) {
       return OTS_FAILURE_MSG("Failed to read kern subtable %d header", i);
     }
     if (subtable.version > 0) {
       OTS_WARNING("Bad subtable version: %d", subtable.version);
       continue;
     }
     const size_t current_offset = table.offset();
     if (current_offset - 4 + sub_length > length) {
       return OTS_FAILURE_MSG("Bad kern subtable %d offset %ld", i, current_offset);
     }
     if (!table.ReadU16(&subtable.coverage)) {
       return OTS_FAILURE_MSG("Cailed to read kern subtable %d coverage", i);
     }
     if (!(subtable.coverage & 0x1)) {
       OTS_WARNING(
           "We don't support vertical data as the renderer doesn't support it.");
       continue;
     }
     if (subtable.coverage & 0xF0) {
       OTS_WARNING("Reserved fields should zero-filled.");
       DROP_THIS_TABLE;
       return true;
     }
     const uint32_t format = (subtable.coverage & 0xFF00) >> 8;
     if (format != 0) {
       OTS_WARNING("Format %d is not supported.", format);
       continue;
     }
     // Parse the format 0 field.
     uint16_t num_pairs = 0;
     if (!table.ReadU16(&num_pairs) ||
         !table.ReadU16(&subtable.search_range) ||
         !table.ReadU16(&subtable.entry_selector) ||
         !table.ReadU16(&subtable.range_shift)) {
       return OTS_FAILURE_MSG("Failed to read kern subtable %d format 0 fields", i);
     }
     if (!num_pairs) {
       OTS_WARNING("Zero length subtable is found.");
       DROP_THIS_TABLE;
       return true;
     }
     // Sanity checks for search_range, entry_selector, and range_shift. See the
     // comment in ots.cc for details.
     const size_t kFormat0PairSize = 6;  // left, right, and value. 2 bytes each.
     if (num_pairs > (65536 / kFormat0PairSize)) {
       // Some fonts (e.g. calibri.ttf, pykes_peak_zero.ttf) have pairs >= 10923.
       OTS_WARNING("Too large subtable.");
       DROP_THIS_TABLE;
       return true;
     }
     unsigned max_pow2 = 0;
     while (1u << (max_pow2 + 1) <= num_pairs) {
       ++max_pow2;
     }
     const uint16_t expected_search_range = (1u << max_pow2) * kFormat0PairSize;
     if (subtable.search_range != expected_search_range) {
       OTS_WARNING("bad search range");
       subtable.search_range = expected_search_range;
     }
     if (subtable.entry_selector != max_pow2) {
       return OTS_FAILURE_MSG("Bad subtable %d entry selector %d", i, subtable.entry_selector);
     }
     const uint32_t expected_range_shift
         = kFormat0PairSize * num_pairs - subtable.search_range;
     if (subtable.range_shift != expected_range_shift) {
       OTS_WARNING("bad range shift");
       subtable.range_shift = expected_range_shift;
     }
     // Read kerning pairs.
     subtable.pairs.reserve(num_pairs);
     uint32_t last_pair = 0;
     for (unsigned j = 0; j < num_pairs; ++j) {
       OpenTypeKERNFormat0Pair kerning_pair;
       if (!table.ReadU16(&kerning_pair.left) ||
           !table.ReadU16(&kerning_pair.right) ||
           !table.ReadS16(&kerning_pair.value)) {
         return OTS_FAILURE_MSG("Failed to read subtable %d kerning pair %d", i, j);
       }
       const uint32_t current_pair
           = (kerning_pair.left << 16) + kerning_pair.right;
       if (j != 0 && current_pair <= last_pair) {
         OTS_WARNING("Kerning pairs are not sorted.");
         // Many free fonts don't follow this rule, so we don't call OTS_FAILURE
         // in order to support these fonts.
         DROP_THIS_TABLE;
         return true;
       }
       last_pair = current_pair;
       subtable.pairs.push_back(kerning_pair);
     }
     kern->subtables.push_back(subtable);
   }
   if (!kern->subtables.size()) {
     OTS_WARNING("All subtables are removed.");
     DROP_THIS_TABLE;
     return true;
   }
   return true;
 }
 bool ots_kern_should_serialise(OpenTypeFile *file) {
   if (!file->glyf) return false;  // this table is not for CFF fonts.
   return file->kern != NULL;
 }
 bool ots_kern_serialise(OTSStream *out, OpenTypeFile *file) {
   const OpenTypeKERN *kern = file->kern;
   if (!out->WriteU16(kern->version) ||
       !out->WriteU16(kern->subtables.size())) {
     return OTS_FAILURE_MSG("Can't write kern table header");
   }
   for (unsigned i = 0; i < kern->subtables.size(); ++i) {
     const uint16_t length = 14 + (6 * kern->subtables[i].pairs.size());
     if (!out->WriteU16(kern->subtables[i].version) ||
         !out->WriteU16(length) ||
         !out->WriteU16(kern->subtables[i].coverage) ||
         !out->WriteU16(kern->subtables[i].pairs.size()) ||
         !out->WriteU16(kern->subtables[i].search_range) ||
         !out->WriteU16(kern->subtables[i].entry_selector) ||
         !out->WriteU16(kern->subtables[i].range_shift)) {
       return OTS_FAILURE_MSG("Failed to write kern subtable %d", i);
     }
     for (unsigned j = 0; j < kern->subtables[i].pairs.size(); ++j) {
       if (!out->WriteU16(kern->subtables[i].pairs[j].left) ||
           !out->WriteU16(kern->subtables[i].pairs[j].right) ||
           !out->WriteS16(kern->subtables[i].pairs[j].value)) {
         return OTS_FAILURE_MSG("Failed to write kern pair %d for subtable %d", j, i);
       }
     }
   }
   return true;
 }
 void ots_kern_free(OpenTypeFile *file) {
   delete file->kern;
 }
 }  // namespace ots

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gfx/ots/src/kern.cc@6474c204b198 (annotated)

gfx/ots/src/kern.cc