gfx/ots/src/ltsh.cc

   1 // Copyright (c) 2009-2017 The OTS Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ltsh.h"
   6
   7 #include "maxp.h"
   8
   9 // LTSH - Linear Threshold
  10 // http://www.microsoft.com/typography/otspec/ltsh.htm
  11
  12 namespace ots {
  13
  14 bool OpenTypeLTSH::Parse(const uint8_t *data, size_t length) {
  15   Buffer table(data, length);
  16
  17   OpenTypeMAXP *maxp = static_cast<OpenTypeMAXP*>(
  18       GetFont()->GetTypedTable(OTS_TAG_MAXP));
  19   if (!maxp) {
  20     return Error("Required maxp table is missing");
  21   }
  22
  23   uint16_t num_glyphs = 0;
  24   if (!table.ReadU16(&this->version) ||
  25       !table.ReadU16(&num_glyphs)) {
  26     return Error("Failed to read table header");
  27   }
  28
  29   if (this->version != 0) {
  30     return Drop("Unsupported version: %u", this->version);
  31   }
  32
  33   if (num_glyphs != maxp->num_glyphs) {
  34     return Drop("Bad numGlyphs: %u", num_glyphs);
  35   }
  36
  37   this->ypels.reserve(num_glyphs);
  38   for (unsigned i = 0; i < num_glyphs; ++i) {
  39     uint8_t pel = 0;
  40     if (!table.ReadU8(&pel)) {
  41       return Error("Failed to read pixels for glyph %d", i);
  42     }
  43     this->ypels.push_back(pel);
  44   }
  45
  46   return true;
  47 }
  48
  49 bool OpenTypeLTSH::Serialize(OTSStream *out) {
  50   const uint16_t num_ypels = static_cast<uint16_t>(this->ypels.size());
  51   if (num_ypels != this->ypels.size() ||
  52       !out->WriteU16(this->version) ||
  53       !out->WriteU16(num_ypels)) {
  54     return Error("Failed to write table header");
  55   }
  56   for (uint16_t i = 0; i < num_ypels; ++i) {
  57     if (!out->Write(&(this->ypels[i]), 1)) {
  58       return Error("Failed to write pixel size for glyph %d", i);
  59     }
  60   }
  61
  62   return true;
  63 }
  64
  65 bool OpenTypeLTSH::ShouldSerialize() {
  66   return Table::ShouldSerialize() &&
  67          // this table is not for CFF fonts.
  68          GetFont()->GetTable(OTS_TAG_GLYF) != NULL;
  69 }
  70
  71 }  // namespace ots