third_party/ots/src/os2.cc

   1 // Copyright (c) 2009 The Chromium 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 <string>
   6
   7 #include "os2.h"
   8 #include "head.h"
   9
  10 // OS/2 - OS/2 and Windows Metrics
  11 // http://www.microsoft.com/typography/otspec/os2.htm
  12
  13 #define TABLE_NAME "OS/2"
  14
  15 namespace ots {
  16
  17 bool ots_os2_parse(Font *font, const uint8_t *data, size_t length) {
  18   Buffer table(data, length);
  19
  20   OpenTypeOS2 *os2 = new OpenTypeOS2;
  21   font->os2 = os2;
  22
  23   if (!table.ReadU16(&os2->version) ||
  24       !table.ReadS16(&os2->avg_char_width) ||
  25       !table.ReadU16(&os2->weight_class) ||
  26       !table.ReadU16(&os2->width_class) ||
  27       !table.ReadU16(&os2->type) ||
  28       !table.ReadS16(&os2->subscript_x_size) ||
  29       !table.ReadS16(&os2->subscript_y_size) ||
  30       !table.ReadS16(&os2->subscript_x_offset) ||
  31       !table.ReadS16(&os2->subscript_y_offset) ||
  32       !table.ReadS16(&os2->superscript_x_size) ||
  33       !table.ReadS16(&os2->superscript_y_size) ||
  34       !table.ReadS16(&os2->superscript_x_offset) ||
  35       !table.ReadS16(&os2->superscript_y_offset) ||
  36       !table.ReadS16(&os2->strikeout_size) ||
  37       !table.ReadS16(&os2->strikeout_position) ||
  38       !table.ReadS16(&os2->family_class)) {
  39     return OTS_FAILURE_MSG("Error reading basic table elements");
  40   }
  41
  42   if (os2->version > 5) {
  43     return OTS_FAILURE_MSG("Unsupported table version: %u", os2->version);
  44   }
  45
  46   // Follow WPF Font Selection Model's advice.
  47   if (1 <= os2->weight_class && os2->weight_class <= 9) {
  48     OTS_WARNING("Bad usWeightClass: %u, changing it to: %u", os2->weight_class, os2->weight_class * 100);
  49     os2->weight_class *= 100;
  50   }
  51   // Ditto.
  52   if (os2->weight_class > 999) {
  53     OTS_WARNING("Bad usWeightClass: %u, changing it to: %d", os2->weight_class, 999);
  54     os2->weight_class = 999;
  55   }
  56
  57   if (os2->width_class < 1) {
  58     OTS_WARNING("Bad usWidthClass: %u, changing it to: %d", os2->width_class, 1);
  59     os2->width_class = 1;
  60   } else if (os2->width_class > 9) {
  61     OTS_WARNING("Bad usWidthClass: %u, changing it to: %d", os2->width_class, 9);
  62     os2->width_class = 9;
  63   }
  64
  65   // lowest 3 bits of fsType are exclusive.
  66   if (os2->type & 0x2) {
  67     // mask bits 2 & 3.
  68     os2->type &= 0xfff3u;
  69   } else if (os2->type & 0x4) {
  70     // mask bits 1 & 3.
  71     os2->type &= 0xfff4u;
  72   } else if (os2->type & 0x8) {
  73     // mask bits 1 & 2.
  74     os2->type &= 0xfff9u;
  75   }
  76
  77   // mask reserved bits. use only 0..3, 8, 9 bits.
  78   os2->type &= 0x30f;
  79
  80 #define SET_TO_ZERO(a, b)                                     \
  81   if (os2->b < 0) {                                           \
  82     OTS_WARNING("Bad " a ": %d, setting it to zero", os2->b); \
  83     os2->b = 0;                                               \
  84   }
  85
  86   SET_TO_ZERO("ySubscriptXSize", subscript_x_size);
  87   SET_TO_ZERO("ySubscriptYSize", subscript_y_size);
  88   SET_TO_ZERO("ySuperscriptXSize", superscript_x_size);
  89   SET_TO_ZERO("ySuperscriptYSize", superscript_y_size);
  90   SET_TO_ZERO("yStrikeoutSize", strikeout_size);
  91 #undef SET_TO_ZERO
  92
  93   static std::string panose_strings[10] = {
  94     "bFamilyType",
  95     "bSerifStyle",
  96     "bWeight",
  97     "bProportion",
  98     "bContrast",
  99     "bStrokeVariation",
 100     "bArmStyle",
 101     "bLetterform",
 102     "bMidline",
 103     "bXHeight",
 104   };
 105   for (unsigned i = 0; i < 10; ++i) {
 106     if (!table.ReadU8(&os2->panose[i])) {
 107       return OTS_FAILURE_MSG("Error reading PANOSE %s", panose_strings[i].c_str());
 108     }
 109   }
 110
 111   if (!table.ReadU32(&os2->unicode_range_1) ||
 112       !table.ReadU32(&os2->unicode_range_2) ||
 113       !table.ReadU32(&os2->unicode_range_3) ||
 114       !table.ReadU32(&os2->unicode_range_4) ||
 115       !table.ReadU32(&os2->vendor_id) ||
 116       !table.ReadU16(&os2->selection) ||
 117       !table.ReadU16(&os2->first_char_index) ||
 118       !table.ReadU16(&os2->last_char_index) ||
 119       !table.ReadS16(&os2->typo_ascender) ||
 120       !table.ReadS16(&os2->typo_descender) ||
 121       !table.ReadS16(&os2->typo_linegap) ||
 122       !table.ReadU16(&os2->win_ascent) ||
 123       !table.ReadU16(&os2->win_descent)) {
 124     return OTS_FAILURE_MSG("Error reading more basic table fields");
 125   }
 126
 127   // If bit 6 is set, then bits 0 and 5 must be clear.
 128   if (os2->selection & 0x40) {
 129     os2->selection &= 0xffdeu;
 130   }
 131
 132   // the settings of bits 0 and 1 must be reflected in the macStyle bits
 133   // in the 'head' table.
 134   if (!font->head) {
 135     return OTS_FAILURE_MSG("Needed head table is missing from the font");
 136   }
 137   if ((os2->selection & 0x1) &&
 138       !(font->head->mac_style & 0x2)) {
 139     OTS_WARNING("adjusting Mac style (italic)");
 140     font->head->mac_style |= 0x2;
 141   }
 142   if ((os2->selection & 0x2) &&
 143       !(font->head->mac_style & 0x4)) {
 144     OTS_WARNING("adjusting Mac style (underscore)");
 145     font->head->mac_style |= 0x4;
 146   }
 147
 148   // While bit 6 on implies that bits 0 and 1 of macStyle are clear,
 149   // the reverse is not true.
 150   if ((os2->selection & 0x40) &&
 151       (font->head->mac_style & 0x3)) {
 152     OTS_WARNING("adjusting Mac style (regular)");
 153     font->head->mac_style &= 0xfffcu;
 154   }
 155
 156   if ((os2->version < 4) &&
 157       (os2->selection & 0x300)) {
 158     // bit 8 and 9 must be unset in OS/2 table versions less than 4.
 159     return OTS_FAILURE_MSG("Version %d incompatible with selection %d", os2->version, os2->selection);
 160   }
 161
 162   // mask reserved bits. use only 0..9 bits.
 163   os2->selection &= 0x3ff;
 164
 165   if (os2->first_char_index > os2->last_char_index) {
 166     return OTS_FAILURE_MSG("first char index %d > last char index %d in os2", os2->first_char_index, os2->last_char_index);
 167   }
 168   if (os2->typo_linegap < 0) {
 169     OTS_WARNING("bad linegap: %d", os2->typo_linegap);
 170     os2->typo_linegap = 0;
 171   }
 172
 173   if (os2->version < 1) {
 174     // http://www.microsoft.com/typography/otspec/os2ver0.htm
 175     return true;
 176   }
 177
 178   if (length < offsetof(OpenTypeOS2, code_page_range_2)) {
 179     OTS_WARNING("bad version number: %u", os2->version);
 180     // Some fonts (e.g., kredit1.ttf and quinquef.ttf) have weird version
 181     // numbers. Fix them.
 182     os2->version = 0;
 183     return true;
 184   }
 185
 186   if (!table.ReadU32(&os2->code_page_range_1) ||
 187       !table.ReadU32(&os2->code_page_range_2)) {
 188     return OTS_FAILURE_MSG("Failed to read codepage ranges");
 189   }
 190
 191   if (os2->version < 2) {
 192     // http://www.microsoft.com/typography/otspec/os2ver1.htm
 193     return true;
 194   }
 195
 196   if (length < offsetof(OpenTypeOS2, max_context)) {
 197     OTS_WARNING("bad version number: %u", os2->version);
 198     // some Japanese fonts (e.g., mona.ttf) have weird version number.
 199     // fix them.
 200     os2->version = 1;
 201     return true;
 202   }
 203
 204   if (!table.ReadS16(&os2->x_height) ||
 205       !table.ReadS16(&os2->cap_height) ||
 206       !table.ReadU16(&os2->default_char) ||
 207       !table.ReadU16(&os2->break_char) ||
 208       !table.ReadU16(&os2->max_context)) {
 209     return OTS_FAILURE_MSG("Failed to read version 2-specific fields");
 210   }
 211
 212   if (os2->x_height < 0) {
 213     OTS_WARNING("bad x_height: %d", os2->x_height);
 214     os2->x_height = 0;
 215   }
 216   if (os2->cap_height < 0) {
 217     OTS_WARNING("bad cap_height: %d", os2->cap_height);
 218     os2->cap_height = 0;
 219   }
 220
 221   if (os2->version < 5) {
 222     // http://www.microsoft.com/typography/otspec/os2ver4.htm
 223     return true;
 224   }
 225
 226   if (!table.ReadU16(&os2->lower_optical_pointsize) ||
 227       !table.ReadU16(&os2->upper_optical_pointsize)) {
 228     return OTS_FAILURE_MSG("Failed to read version 5-specific fields");
 229   }
 230
 231   if (os2->lower_optical_pointsize > 0xFFFE) {
 232     OTS_WARNING("'usLowerOpticalPointSize' is bigger than 0xFFFE: %d", os2->lower_optical_pointsize);
 233     os2->lower_optical_pointsize = 0xFFFE;
 234   }
 235
 236   if (os2->upper_optical_pointsize < 2) {
 237     OTS_WARNING("'usUpperOpticalPointSize' is lower than 2: %d", os2->upper_optical_pointsize);
 238     os2->upper_optical_pointsize = 2;
 239   }
 240
 241   return true;
 242 }
 243
 244 bool ots_os2_should_serialise(Font *font) {
 245   return font->os2 != NULL;
 246 }
 247
 248 bool ots_os2_serialise(OTSStream *out, Font *font) {
 249   const OpenTypeOS2 *os2 = font->os2;
 250
 251   if (!out->WriteU16(os2->version) ||
 252       !out->WriteS16(os2->avg_char_width) ||
 253       !out->WriteU16(os2->weight_class) ||
 254       !out->WriteU16(os2->width_class) ||
 255       !out->WriteU16(os2->type) ||
 256       !out->WriteS16(os2->subscript_x_size) ||
 257       !out->WriteS16(os2->subscript_y_size) ||
 258       !out->WriteS16(os2->subscript_x_offset) ||
 259       !out->WriteS16(os2->subscript_y_offset) ||
 260       !out->WriteS16(os2->superscript_x_size) ||
 261       !out->WriteS16(os2->superscript_y_size) ||
 262       !out->WriteS16(os2->superscript_x_offset) ||
 263       !out->WriteS16(os2->superscript_y_offset) ||
 264       !out->WriteS16(os2->strikeout_size) ||
 265       !out->WriteS16(os2->strikeout_position) ||
 266       !out->WriteS16(os2->family_class)) {
 267     return OTS_FAILURE_MSG("Failed to write basic OS2 information");
 268   }
 269
 270   for (unsigned i = 0; i < 10; ++i) {
 271     if (!out->Write(&os2->panose[i], 1)) {
 272       return OTS_FAILURE_MSG("Failed to write os2 panose information");
 273     }
 274   }
 275
 276   if (!out->WriteU32(os2->unicode_range_1) ||
 277       !out->WriteU32(os2->unicode_range_2) ||
 278       !out->WriteU32(os2->unicode_range_3) ||
 279       !out->WriteU32(os2->unicode_range_4) ||
 280       !out->WriteU32(os2->vendor_id) ||
 281       !out->WriteU16(os2->selection) ||
 282       !out->WriteU16(os2->first_char_index) ||
 283       !out->WriteU16(os2->last_char_index) ||
 284       !out->WriteS16(os2->typo_ascender) ||
 285       !out->WriteS16(os2->typo_descender) ||
 286       !out->WriteS16(os2->typo_linegap) ||
 287       !out->WriteU16(os2->win_ascent) ||
 288       !out->WriteU16(os2->win_descent)) {
 289     return OTS_FAILURE_MSG("Failed to write version 1-specific fields");
 290   }
 291
 292   if (os2->version < 1) {
 293     return true;
 294   }
 295
 296   if (!out->WriteU32(os2->code_page_range_1) ||
 297       !out->WriteU32(os2->code_page_range_2)) {
 298     return OTS_FAILURE_MSG("Failed to write codepage ranges");
 299   }
 300
 301   if (os2->version < 2) {
 302     return true;
 303   }
 304
 305   if (!out->WriteS16(os2->x_height) ||
 306       !out->WriteS16(os2->cap_height) ||
 307       !out->WriteU16(os2->default_char) ||
 308       !out->WriteU16(os2->break_char) ||
 309       !out->WriteU16(os2->max_context)) {
 310     return OTS_FAILURE_MSG("Failed to write version 2-specific fields");
 311   }
 312
 313   if (os2->version < 5) {
 314     return true;
 315   }
 316
 317   if (!out->WriteU16(os2->lower_optical_pointsize) ||
 318       !out->WriteU16(os2->upper_optical_pointsize)) {
 319     return OTS_FAILURE_MSG("Failed to write version 5-specific fields");
 320   }
 321
 322   return true;
 323 }
 324
 325 void ots_os2_reuse(Font *font, Font *other) {
 326   font->os2 = other->os2;
 327   font->os2_reused = true;
 328 }
 329
 330 void ots_os2_free(Font *font) {
 331   delete font->os2;
 332 }
 333
 334 }  // namespace ots
 335
 336 #undef TABLE_NAME