1 /* 2 * Copyright © 2015 Google, Inc. 3 * 4 * This is part of HarfBuzz, a text shaping library. 5 * 6 * Permission is hereby granted, without written agreement and without 7 * license or royalty fees, to use, copy, modify, and distribute this 8 * software and its documentation for any purpose, provided that the 9 * above copyright notice and the following two paragraphs appear in 10 * all copies of this software. 11 * 12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR 13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES 14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN 15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH 16 * DAMAGE. 17 * 18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, 19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS 21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO 22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. 23 * 24 * Google Author(s): Behdad Esfahbod 25 */ 26 27 #ifndef HB_OT_GLYF_TABLE_HH 28 #define HB_OT_GLYF_TABLE_HH 29 30 #include "hb-open-type.hh" 31 #include "hb-ot-head-table.hh" 32 #include "hb-subset-glyf.hh" 33 34 namespace OT { 35 36 37 /* 38 * loca -- Index to Location 39 * https://docs.microsoft.com/en-us/typography/opentype/spec/loca 40 */ 41 #define HB_OT_TAG_loca HB_TAG('l','o','c','a') 42 43 44 struct loca 45 { 46 friend struct glyf; 47 48 enum { tableTag = HB_OT_TAG_loca }; 49 sanitizeOT::loca50 bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const 51 { 52 TRACE_SANITIZE (this); 53 return_trace (true); 54 } 55 56 protected: 57 UnsizedArrayOf<HBUINT8> dataZ; /* Location data. */ 58 public: 59 DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always 60 * check the size externally, allow Null() object of it by 61 * defining it MIN() instead. */ 62 }; 63 64 65 /* 66 * glyf -- TrueType Glyph Data 67 * https://docs.microsoft.com/en-us/typography/opentype/spec/glyf 68 */ 69 #define HB_OT_TAG_glyf HB_TAG('g','l','y','f') 70 71 72 struct glyf 73 { 74 enum { tableTag = HB_OT_TAG_glyf }; 75 sanitizeOT::glyf76 bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const 77 { 78 TRACE_SANITIZE (this); 79 /* We don't check for anything specific here. The users of the 80 * struct do all the hard work... */ 81 return_trace (true); 82 } 83 subsetOT::glyf84 bool subset (hb_subset_plan_t *plan) const 85 { 86 hb_blob_t *glyf_prime = nullptr; 87 hb_blob_t *loca_prime = nullptr; 88 89 bool success = true; 90 bool use_short_loca = false; 91 if (hb_subset_glyf_and_loca (plan, &use_short_loca, &glyf_prime, &loca_prime)) { 92 success = success && plan->add_table (HB_OT_TAG_glyf, glyf_prime); 93 success = success && plan->add_table (HB_OT_TAG_loca, loca_prime); 94 success = success && _add_head_and_set_loca_version (plan, use_short_loca); 95 } else { 96 success = false; 97 } 98 hb_blob_destroy (loca_prime); 99 hb_blob_destroy (glyf_prime); 100 101 return success; 102 } 103 104 static bool _add_head_and_set_loca_versionOT::glyf105 _add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca) 106 { 107 hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<head> (plan->source); 108 hb_blob_t *head_prime_blob = hb_blob_copy_writable_or_fail (head_blob); 109 hb_blob_destroy (head_blob); 110 111 if (unlikely (!head_prime_blob)) 112 return false; 113 114 head *head_prime = (head *) hb_blob_get_data_writable (head_prime_blob, nullptr); 115 head_prime->indexToLocFormat.set (use_short_loca ? 0 : 1); 116 bool success = plan->add_table (HB_OT_TAG_head, head_prime_blob); 117 118 hb_blob_destroy (head_prime_blob); 119 return success; 120 } 121 122 struct GlyphHeader 123 { 124 HBINT16 numberOfContours; /* If the number of contours is 125 * greater than or equal to zero, 126 * this is a simple glyph; if negative, 127 * this is a composite glyph. */ 128 FWORD xMin; /* Minimum x for coordinate data. */ 129 FWORD yMin; /* Minimum y for coordinate data. */ 130 FWORD xMax; /* Maximum x for coordinate data. */ 131 FWORD yMax; /* Maximum y for coordinate data. */ 132 133 DEFINE_SIZE_STATIC (10); 134 }; 135 136 struct CompositeGlyphHeader 137 { 138 enum composite_glyph_flag_t { 139 ARG_1_AND_2_ARE_WORDS = 0x0001, 140 ARGS_ARE_XY_VALUES = 0x0002, 141 ROUND_XY_TO_GRID = 0x0004, 142 WE_HAVE_A_SCALE = 0x0008, 143 MORE_COMPONENTS = 0x0020, 144 WE_HAVE_AN_X_AND_Y_SCALE = 0x0040, 145 WE_HAVE_A_TWO_BY_TWO = 0x0080, 146 WE_HAVE_INSTRUCTIONS = 0x0100, 147 USE_MY_METRICS = 0x0200, 148 OVERLAP_COMPOUND = 0x0400, 149 SCALED_COMPONENT_OFFSET = 0x0800, 150 UNSCALED_COMPONENT_OFFSET = 0x1000 151 }; 152 153 HBUINT16 flags; 154 GlyphID glyphIndex; 155 get_sizeOT::glyf::CompositeGlyphHeader156 unsigned int get_size () const 157 { 158 unsigned int size = min_size; 159 // arg1 and 2 are int16 160 if (flags & ARG_1_AND_2_ARE_WORDS) size += 4; 161 // arg1 and 2 are int8 162 else size += 2; 163 164 // One x 16 bit (scale) 165 if (flags & WE_HAVE_A_SCALE) size += 2; 166 // Two x 16 bit (xscale, yscale) 167 else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) size += 4; 168 // Four x 16 bit (xscale, scale01, scale10, yscale) 169 else if (flags & WE_HAVE_A_TWO_BY_TWO) size += 8; 170 171 return size; 172 } 173 174 struct Iterator 175 { 176 const char *glyph_start; 177 const char *glyph_end; 178 const CompositeGlyphHeader *current; 179 move_to_nextOT::glyf::CompositeGlyphHeader::Iterator180 bool move_to_next () 181 { 182 if (current->flags & CompositeGlyphHeader::MORE_COMPONENTS) 183 { 184 const CompositeGlyphHeader *possible = 185 &StructAfter<CompositeGlyphHeader, CompositeGlyphHeader> (*current); 186 if (!in_range (possible)) 187 return false; 188 current = possible; 189 return true; 190 } 191 return false; 192 } 193 in_rangeOT::glyf::CompositeGlyphHeader::Iterator194 bool in_range (const CompositeGlyphHeader *composite) const 195 { 196 return (const char *) composite >= glyph_start 197 && ((const char *) composite + CompositeGlyphHeader::min_size) <= glyph_end 198 && ((const char *) composite + composite->get_size ()) <= glyph_end; 199 } 200 }; 201 get_iteratorOT::glyf::CompositeGlyphHeader202 static bool get_iterator (const char * glyph_data, 203 unsigned int length, 204 CompositeGlyphHeader::Iterator *iterator /* OUT */) 205 { 206 if (length < GlyphHeader::static_size) 207 return false; /* Empty glyph; zero extents. */ 208 209 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph_data, 0); 210 if (glyph_header.numberOfContours < 0) 211 { 212 const CompositeGlyphHeader *possible = 213 &StructAfter<CompositeGlyphHeader, GlyphHeader> (glyph_header); 214 215 iterator->glyph_start = glyph_data; 216 iterator->glyph_end = (const char *) glyph_data + length; 217 if (!iterator->in_range (possible)) 218 return false; 219 iterator->current = possible; 220 return true; 221 } 222 223 return false; 224 } 225 226 DEFINE_SIZE_MIN (4); 227 }; 228 229 struct accelerator_t 230 { initOT::glyf::accelerator_t231 void init (hb_face_t *face) 232 { 233 memset (this, 0, sizeof (accelerator_t)); 234 235 const OT::head &head = *face->table.head; 236 if (head.indexToLocFormat > 1 || head.glyphDataFormat != 0) 237 /* Unknown format. Leave num_glyphs=0, that takes care of disabling us. */ 238 return; 239 short_offset = 0 == head.indexToLocFormat; 240 241 loca_table = hb_sanitize_context_t ().reference_table<loca> (face); 242 glyf_table = hb_sanitize_context_t ().reference_table<glyf> (face); 243 244 num_glyphs = MAX (1u, loca_table.get_length () / (short_offset ? 2 : 4)) - 1; 245 } 246 finiOT::glyf::accelerator_t247 void fini () 248 { 249 loca_table.destroy (); 250 glyf_table.destroy (); 251 } 252 253 /* 254 * Returns true if the referenced glyph is a valid glyph and a composite glyph. 255 * If true is returned a pointer to the composite glyph will be written into 256 * composite. 257 */ get_compositeOT::glyf::accelerator_t258 bool get_composite (hb_codepoint_t glyph, 259 CompositeGlyphHeader::Iterator *composite /* OUT */) const 260 { 261 if (unlikely (!num_glyphs)) 262 return false; 263 264 unsigned int start_offset, end_offset; 265 if (!get_offsets (glyph, &start_offset, &end_offset)) 266 return false; /* glyph not found */ 267 268 return CompositeGlyphHeader::get_iterator ((const char *) this->glyf_table + start_offset, 269 end_offset - start_offset, 270 composite); 271 } 272 273 enum simple_glyph_flag_t { 274 FLAG_ON_CURVE = 0x01, 275 FLAG_X_SHORT = 0x02, 276 FLAG_Y_SHORT = 0x04, 277 FLAG_REPEAT = 0x08, 278 FLAG_X_SAME = 0x10, 279 FLAG_Y_SAME = 0x20, 280 FLAG_RESERVED1 = 0x40, 281 FLAG_RESERVED2 = 0x80 282 }; 283 284 /* based on FontTools _g_l_y_f.py::trim */ remove_paddingOT::glyf::accelerator_t285 bool remove_padding (unsigned int start_offset, 286 unsigned int *end_offset) const 287 { 288 if (*end_offset - start_offset < GlyphHeader::static_size) return true; 289 290 const char *glyph = ((const char *) glyf_table) + start_offset; 291 const char * const glyph_end = glyph + (*end_offset - start_offset); 292 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph, 0); 293 int16_t num_contours = (int16_t) glyph_header.numberOfContours; 294 295 if (num_contours < 0) 296 /* Trimming for composites not implemented. 297 * If removing hints it falls out of that. */ 298 return true; 299 else if (num_contours > 0) 300 { 301 /* simple glyph w/contours, possibly trimmable */ 302 glyph += GlyphHeader::static_size + 2 * num_contours; 303 304 if (unlikely (glyph + 2 >= glyph_end)) return false; 305 uint16_t nCoordinates = (uint16_t) StructAtOffset<HBUINT16> (glyph - 2, 0) + 1; 306 uint16_t nInstructions = (uint16_t) StructAtOffset<HBUINT16> (glyph, 0); 307 308 glyph += 2 + nInstructions; 309 if (unlikely (glyph + 2 >= glyph_end)) return false; 310 311 unsigned int coordBytes = 0; 312 unsigned int coordsWithFlags = 0; 313 while (glyph < glyph_end) 314 { 315 uint8_t flag = (uint8_t) *glyph; 316 glyph++; 317 318 unsigned int repeat = 1; 319 if (flag & FLAG_REPEAT) 320 { 321 if (glyph >= glyph_end) 322 { 323 DEBUG_MSG(SUBSET, nullptr, "Bad flag"); 324 return false; 325 } 326 repeat = ((uint8_t) *glyph) + 1; 327 glyph++; 328 } 329 330 unsigned int xBytes, yBytes; 331 xBytes = yBytes = 0; 332 if (flag & FLAG_X_SHORT) xBytes = 1; 333 else if ((flag & FLAG_X_SAME) == 0) xBytes = 2; 334 335 if (flag & FLAG_Y_SHORT) yBytes = 1; 336 else if ((flag & FLAG_Y_SAME) == 0) yBytes = 2; 337 338 coordBytes += (xBytes + yBytes) * repeat; 339 coordsWithFlags += repeat; 340 if (coordsWithFlags >= nCoordinates) 341 break; 342 } 343 344 if (coordsWithFlags != nCoordinates) 345 { 346 DEBUG_MSG(SUBSET, nullptr, "Expect %d coords to have flags, got flags for %d", nCoordinates, coordsWithFlags); 347 return false; 348 } 349 glyph += coordBytes; 350 351 if (glyph < glyph_end) 352 *end_offset -= glyph_end - glyph; 353 } 354 return true; 355 } 356 get_offsetsOT::glyf::accelerator_t357 bool get_offsets (hb_codepoint_t glyph, 358 unsigned int *start_offset /* OUT */, 359 unsigned int *end_offset /* OUT */) const 360 { 361 if (unlikely (glyph >= num_glyphs)) 362 return false; 363 364 if (short_offset) 365 { 366 const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ.arrayZ; 367 *start_offset = 2 * offsets[glyph]; 368 *end_offset = 2 * offsets[glyph + 1]; 369 } 370 else 371 { 372 const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ.arrayZ; 373 374 *start_offset = offsets[glyph]; 375 *end_offset = offsets[glyph + 1]; 376 } 377 378 if (*start_offset > *end_offset || *end_offset > glyf_table.get_length ()) 379 return false; 380 381 return true; 382 } 383 get_instruction_offsetsOT::glyf::accelerator_t384 bool get_instruction_offsets (unsigned int start_offset, 385 unsigned int end_offset, 386 unsigned int *instruction_start /* OUT */, 387 unsigned int *instruction_end /* OUT */) const 388 { 389 if (end_offset - start_offset < GlyphHeader::static_size) 390 { 391 *instruction_start = 0; 392 *instruction_end = 0; 393 return true; /* Empty glyph; no instructions. */ 394 } 395 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset); 396 int16_t num_contours = (int16_t) glyph_header.numberOfContours; 397 if (num_contours < 0) 398 { 399 CompositeGlyphHeader::Iterator composite_it; 400 if (unlikely (!CompositeGlyphHeader::get_iterator ( 401 (const char*) this->glyf_table + start_offset, 402 end_offset - start_offset, &composite_it))) return false; 403 const CompositeGlyphHeader *last; 404 do { 405 last = composite_it.current; 406 } while (composite_it.move_to_next ()); 407 408 if ((uint16_t) last->flags & CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS) 409 *instruction_start = ((char *) last - (char *) glyf_table->dataZ.arrayZ) + last->get_size (); 410 else 411 *instruction_start = end_offset; 412 *instruction_end = end_offset; 413 if (unlikely (*instruction_start > *instruction_end)) 414 { 415 DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside [%d, %d]", *instruction_start, start_offset, end_offset); 416 return false; 417 } 418 } 419 else 420 { 421 unsigned int instruction_length_offset = start_offset + GlyphHeader::static_size + 2 * num_contours; 422 if (unlikely (instruction_length_offset + 2 > end_offset)) 423 { 424 DEBUG_MSG(SUBSET, nullptr, "Glyph size is too short, missing field instructionLength."); 425 return false; 426 } 427 428 const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (glyf_table, instruction_length_offset); 429 unsigned int start = instruction_length_offset + 2; 430 unsigned int end = start + (uint16_t) instruction_length; 431 if (unlikely (end > end_offset)) // Out of bounds of the current glyph 432 { 433 DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries."); 434 return false; 435 } 436 437 *instruction_start = start; 438 *instruction_end = end; 439 } 440 return true; 441 } 442 get_extentsOT::glyf::accelerator_t443 bool get_extents (hb_codepoint_t glyph, hb_glyph_extents_t *extents) const 444 { 445 unsigned int start_offset, end_offset; 446 if (!get_offsets (glyph, &start_offset, &end_offset)) 447 return false; 448 449 if (end_offset - start_offset < GlyphHeader::static_size) 450 return true; /* Empty glyph; zero extents. */ 451 452 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset); 453 454 extents->x_bearing = MIN (glyph_header.xMin, glyph_header.xMax); 455 extents->y_bearing = MAX (glyph_header.yMin, glyph_header.yMax); 456 extents->width = MAX (glyph_header.xMin, glyph_header.xMax) - extents->x_bearing; 457 extents->height = MIN (glyph_header.yMin, glyph_header.yMax) - extents->y_bearing; 458 459 return true; 460 } 461 462 private: 463 bool short_offset; 464 unsigned int num_glyphs; 465 hb_blob_ptr_t<loca> loca_table; 466 hb_blob_ptr_t<glyf> glyf_table; 467 }; 468 469 protected: 470 UnsizedArrayOf<HBUINT8> dataZ; /* Glyphs data. */ 471 public: 472 DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always 473 * check the size externally, allow Null() object of it by 474 * defining it MIN() instead. */ 475 }; 476 477 struct glyf_accelerator_t : glyf::accelerator_t {}; 478 479 } /* namespace OT */ 480 481 482 #endif /* HB_OT_GLYF_TABLE_HH */ 483