gfx/ots/src/head.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 "head.h"
   6
   7 #include <cstring>
   8
   9 // head - Font Header
  10 // http://www.microsoft.com/typography/otspec/head.htm
  11
  12 namespace ots {
  13
  14 bool OpenTypeHEAD::Parse(const uint8_t *data, size_t length) {
  15   Buffer table(data, length);
  16
  17   uint32_t version = 0;
  18   if (!table.ReadU32(&version) ||
  19       !table.ReadU32(&this->revision)) {
  20     return Error("Failed to read table header");
  21   }
  22
  23   if (version >> 16 != 1) {
  24     return Error("Unsupported majorVersion: %d", version >> 16);
  25   }
  26
  27   // Skip the checksum adjustment
  28   if (!table.Skip(4)) {
  29     return Error("Failed to read checksum");
  30   }
  31
  32   uint32_t magic;
  33   if (!table.ReadU32(&magic) || magic != 0x5F0F3CF5) {
  34     return Error("Failed to read or incorrect magicNumber");
  35   }
  36
  37   if (!table.ReadU16(&this->flags)) {
  38     return Error("Failed to read flags");
  39   }
  40
  41   // We allow bits 0..4, 11..13
  42   this->flags &= 0x381f;
  43
  44   if (!table.ReadU16(&this->upem)) {
  45     return Error("Failed to read unitsPerEm");
  46   }
  47
  48   // upem must be in range
  49   if (this->upem < 16 ||
  50       this->upem > 16384) {
  51     return Error("unitsPerEm on in the range [16, 16384]: %d", this->upem);
  52   }
  53
  54   if (!table.ReadR64(&this->created) ||
  55       !table.ReadR64(&this->modified)) {
  56     return Error("Can't read font dates");
  57   }
  58
  59   if (!table.ReadS16(&this->xmin) ||
  60       !table.ReadS16(&this->ymin) ||
  61       !table.ReadS16(&this->xmax) ||
  62       !table.ReadS16(&this->ymax)) {
  63     return Error("Failed to read font bounding box");
  64   }
  65
  66   if (this->xmin > this->xmax) {
  67     return Error("Bad x dimension in the font bounding box (%d, %d)",
  68                   this->xmin, this->xmax);
  69   }
  70   if (this->ymin > this->ymax) {
  71     return Error("Bad y dimension in the font bounding box (%d, %d)",
  72                   this->ymin, this->ymax);
  73   }
  74
  75   if (!table.ReadU16(&this->mac_style)) {
  76     return Error("Failed to read macStyle");
  77   }
  78
  79   // We allow bits 0..6
  80   this->mac_style &= 0x7f;
  81
  82   if (!table.ReadU16(&this->min_ppem)) {
  83     return Error("Failed to read lowestRecPPEM");
  84   }
  85
  86   // We don't care about the font direction hint
  87   if (!table.Skip(2)) {
  88     return Error("Failed to read fontDirectionHint");
  89   }
  90
  91   if (!table.ReadS16(&this->index_to_loc_format)) {
  92     return Error("Failed to read indexToLocFormat");
  93   }
  94   if (this->index_to_loc_format < 0 ||
  95       this->index_to_loc_format > 1) {
  96     return Error("Bad indexToLocFormat %d", this->index_to_loc_format);
  97   }
  98
  99   int16_t glyph_data_format;
 100   if (!table.ReadS16(&glyph_data_format) ||
 101       glyph_data_format) {
 102     return Error("Failed to read or bad glyphDataFormat");
 103   }
 104
 105   return true;
 106 }
 107
 108 bool OpenTypeHEAD::Serialize(OTSStream *out) {
 109   if (!out->WriteU32(0x00010000) ||
 110       !out->WriteU32(this->revision) ||
 111       !out->WriteU32(0) ||  // check sum not filled in yet
 112       !out->WriteU32(0x5F0F3CF5) ||
 113       !out->WriteU16(this->flags) ||
 114       !out->WriteU16(this->upem) ||
 115       !out->WriteR64(this->created) ||
 116       !out->WriteR64(this->modified) ||
 117       !out->WriteS16(this->xmin) ||
 118       !out->WriteS16(this->ymin) ||
 119       !out->WriteS16(this->xmax) ||
 120       !out->WriteS16(this->ymax) ||
 121       !out->WriteU16(this->mac_style) ||
 122       !out->WriteU16(this->min_ppem) ||
 123       !out->WriteS16(2) ||
 124       !out->WriteS16(this->index_to_loc_format) ||
 125       !out->WriteS16(0)) {
 126     return Error("Failed to write table");
 127   }
 128
 129   return true;
 130 }
 131
 132 }  // namespace