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-private.hh"
31 #include "hb-ot-head-table.hh"
32 #include "hb-subset-glyf.hh"
33 #include "hb-subset-plan.hh"
34 #include "hb-subset-private.hh"
35
36 namespace OT {
37
38
39 /*
40 * loca -- Index to Location
41 * https://docs.microsoft.com/en-us/typography/opentype/spec/loca
42 */
43 #define HB_OT_TAG_loca HB_TAG('l','o','c','a')
44
45
46 struct loca
47 {
48 friend struct glyf;
49
50 static const hb_tag_t tableTag = HB_OT_TAG_loca;
51
52 inline bool sanitize (hb_sanitize_context_t *c) const
53 {
54 TRACE_SANITIZE (this);
55 return_trace (true);
56 }
57
58 protected:
59 HBUINT8 dataZ[VAR]; /* Location data. */
60 DEFINE_SIZE_ARRAY (0, dataZ);
61 };
62
63
64 /*
65 * glyf -- TrueType Glyph Data
66 * https://docs.microsoft.com/en-us/typography/opentype/spec/glyf
67 */
68 #define HB_OT_TAG_glyf HB_TAG('g','l','y','f')
69
70
71 struct glyf
72 {
73 static const hb_tag_t tableTag = HB_OT_TAG_glyf;
74
75 inline bool sanitize (hb_sanitize_context_t *c) const
76 {
77 TRACE_SANITIZE (this);
78 /* We don't check for anything specific here. The users of the
79 * struct do all the hard work... */
80 return_trace (true);
81 }
82
83 inline bool subset (hb_subset_plan_t *plan) const
84 {
85 hb_blob_t *glyf_prime = nullptr;
86 hb_blob_t *loca_prime = nullptr;
87
88 bool success = true;
89 bool use_short_loca = false;
90 if (hb_subset_glyf_and_loca (plan, &use_short_loca, &glyf_prime, &loca_prime)) {
91 success = success && plan->add_table (HB_OT_TAG_glyf, glyf_prime);
92 success = success && plan->add_table (HB_OT_TAG_loca, loca_prime);
93 success = success && _add_head_and_set_loca_version (plan, use_short_loca);
94 } else {
95 success = false;
96 }
97 hb_blob_destroy (loca_prime);
98 hb_blob_destroy (glyf_prime);
99
100 return success;
101 }
102
103 static bool
104 _add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca)
105 {
106 hb_blob_t *head_blob = OT::Sanitizer<OT::head>().sanitize (hb_face_reference_table (plan->source, HB_OT_TAG_head));
107 hb_blob_t *head_prime_blob = hb_blob_copy_writable_or_fail (head_blob);
108 hb_blob_destroy (head_blob);
109
110 if (unlikely (!head_prime_blob))
111 return false;
112
113 OT::head *head_prime = (OT::head *) hb_blob_get_data_writable (head_prime_blob, nullptr);
114 head_prime->indexToLocFormat.set (use_short_loca ? 0 : 1);
115 bool success = plan->add_table (HB_OT_TAG_head, head_prime_blob);
116
117 hb_blob_destroy (head_prime_blob);
118 return success;
119 }
120
121 struct GlyphHeader
122 {
123 HBINT16 numberOfContours; /* If the number of contours is
124 * greater than or equal to zero,
125 * this is a simple glyph; if negative,
126 * this is a composite glyph. */
127 FWORD xMin; /* Minimum x for coordinate data. */
128 FWORD yMin; /* Minimum y for coordinate data. */
129 FWORD xMax; /* Maximum x for coordinate data. */
130 FWORD yMax; /* Maximum y for coordinate data. */
131
132 DEFINE_SIZE_STATIC (10);
133 };
134
135 struct CompositeGlyphHeader
136 {
137 enum composite_glyph_flag_t {
138 ARG_1_AND_2_ARE_WORDS = 0x0001,
139 ARGS_ARE_XY_VALUES = 0x0002,
140 ROUND_XY_TO_GRID = 0x0004,
141 WE_HAVE_A_SCALE = 0x0008,
142 MORE_COMPONENTS = 0x0020,
143 WE_HAVE_AN_X_AND_Y_SCALE = 0x0040,
144 WE_HAVE_A_TWO_BY_TWO = 0x0080,
145 WE_HAVE_INSTRUCTIONS = 0x0100,
146 USE_MY_METRICS = 0x0200,
147 OVERLAP_COMPOUND = 0x0400,
148 SCALED_COMPONENT_OFFSET = 0x0800,
149 UNSCALED_COMPONENT_OFFSET = 0x1000
150 };
151
152 HBUINT16 flags;
153 HBUINT16 glyphIndex;
154
155 inline unsigned int get_size (void) const
156 {
157 unsigned int size = min_size;
158 if (flags & ARG_1_AND_2_ARE_WORDS) {
159 // arg1 and 2 are int16
160 size += 4;
161 } else {
162 // arg1 and 2 are int8
163 size += 2;
164 }
165 if (flags & WE_HAVE_A_SCALE) {
166 // One x 16 bit (scale)
167 size += 2;
168 } else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) {
169 // Two x 16 bit (xscale, yscale)
170 size += 4;
171 } else if (flags & WE_HAVE_A_TWO_BY_TWO) {
172 // Four x 16 bit (xscale, scale01, scale10, yscale)
173 size += 8;
174 }
175 return size;
176 }
177
178 struct Iterator
179 {
180 const char *glyph_start;
181 const char *glyph_end;
182 const CompositeGlyphHeader *current;
183
184 inline bool move_to_next ()
185 {
186 if (current->flags & CompositeGlyphHeader::MORE_COMPONENTS)
187 {
188 const CompositeGlyphHeader *possible =
189 &StructAfter<CompositeGlyphHeader, CompositeGlyphHeader> (*current);
190 if (!in_range (possible))
191 return false;
192 current = possible;
193 return true;
194 }
195 return false;
196 }
197
198 inline bool in_range (const CompositeGlyphHeader *composite) const
199 {
200 return (const char *) composite >= glyph_start
201 && ((const char *) composite + CompositeGlyphHeader::min_size) <= glyph_end
202 && ((const char *) composite + composite->get_size()) <= glyph_end;
203 }
204 };
205
206 static inline bool get_iterator (const char * glyph_data,
207 unsigned int length,
208 CompositeGlyphHeader::Iterator *iterator /* OUT */)
209 {
210 if (length < GlyphHeader::static_size)
211 return false; /* Empty glyph; zero extents. */
212
213 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph_data, 0);
214 if (glyph_header.numberOfContours < 0)
215 {
216 const CompositeGlyphHeader *possible =
217 &StructAfter<CompositeGlyphHeader, GlyphHeader> (glyph_header);
218
219 iterator->glyph_start = glyph_data;
220 iterator->glyph_end = (const char *) glyph_data + length;
221 if (!iterator->in_range (possible))
222 return false;
223 iterator->current = possible;
224 return true;
225 }
226
227 return false;
228 }
229
230 DEFINE_SIZE_MIN (4);
231 };
232
233 struct accelerator_t
234 {
235 inline void init (hb_face_t *face)
236 {
237 memset (this, 0, sizeof (accelerator_t));
238
239 hb_blob_t *head_blob = Sanitizer<head>().sanitize (face->reference_table (HB_OT_TAG_head));
240 const head *head_table = head_blob->as<head> ();
241 if (head_table == &Null(head) || (unsigned int) head_table->indexToLocFormat > 1 || head_table->glyphDataFormat != 0)
242 {
243 /* head table is not present, or in an unknown format. Leave num_glyphs=0, that takes care of disabling us. */
244 hb_blob_destroy (head_blob);
245 return;
246 }
247 short_offset = 0 == head_table->indexToLocFormat;
248 hb_blob_destroy (head_blob);
249
250 loca_blob = Sanitizer<loca>().sanitize (face->reference_table (HB_OT_TAG_loca));
251 loca_table = loca_blob->as<loca> ();
252 glyf_blob = Sanitizer<glyf>().sanitize (face->reference_table (HB_OT_TAG_glyf));
253 glyf_table = glyf_blob->as<glyf> ();
254
255 num_glyphs = MAX (1u, hb_blob_get_length (loca_blob) / (short_offset ? 2 : 4)) - 1;
256 glyf_len = hb_blob_get_length (glyf_blob);
257 }
258
259 inline void fini (void)
260 {
261 hb_blob_destroy (loca_blob);
262 hb_blob_destroy (glyf_blob);
263 }
264
265 /*
266 * Returns true if the referenced glyph is a valid glyph and a composite glyph.
267 * If true is returned a pointer to the composite glyph will be written into
268 * composite.
269 */
270 inline bool get_composite (hb_codepoint_t glyph,
271 CompositeGlyphHeader::Iterator *composite /* OUT */) const
272 {
273 if (this->glyf_table == &Null(glyf) || !num_glyphs)
274 return false;
275
276 unsigned int start_offset, end_offset;
277 if (!get_offsets (glyph, &start_offset, &end_offset))
278 return false; /* glyph not found */
279
280 return CompositeGlyphHeader::get_iterator ((const char*) this->glyf_table + start_offset,
281 end_offset - start_offset,
282 composite);
283 }
284
285 enum simple_glyph_flag_t {
286 FLAG_X_SHORT = 0x02,
287 FLAG_Y_SHORT = 0x04,
288 FLAG_REPEAT = 0x08,
289 FLAG_X_SAME = 0x10,
290 FLAG_Y_SAME = 0x20
291 };
292
293 /* based on FontTools _g_l_y_f.py::trim */
294 inline bool remove_padding(unsigned int start_offset,
295 unsigned int *end_offset) const
296 {
297 if (*end_offset - start_offset < GlyphHeader::static_size)
298 return true;
299
300 const char *glyph = ((const char *) glyf_table) + start_offset;
301 const char * const glyph_end = glyph + (*end_offset - start_offset);
302 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph, 0);
303 int16_t num_contours = (int16_t) glyph_header.numberOfContours;
304
305 if (num_contours < 0)
306 /* Trimming for composites not implemented.
307 * If removing hints it falls out of that. */
308 return true;
309 else if (num_contours > 0)
310 {
311 /* simple glyph w/contours, possibly trimmable */
312 glyph += GlyphHeader::static_size + 2 * num_contours;
313
314 if (unlikely (glyph + 2 >= glyph_end)) return false;
315 uint16_t nCoordinates = (uint16_t) StructAtOffset<HBUINT16>(glyph - 2, 0) + 1;
316 uint16_t nInstructions = (uint16_t) StructAtOffset<HBUINT16>(glyph, 0);
317
318 glyph += 2 + nInstructions;
319 if (unlikely (glyph + 2 >= glyph_end)) return false;
320
321 unsigned int coordBytes = 0;
322 unsigned int coordsWithFlags = 0;
323 while (glyph < glyph_end)
324 {
325 uint8_t flag = (uint8_t) *glyph;
326 glyph++;
327
328 unsigned int repeat = 1;
329 if (flag & FLAG_REPEAT)
330 {
331 if (glyph >= glyph_end)
332 {
333 DEBUG_MSG(SUBSET, nullptr, "Bad flag");
334 return false;
335 }
336 repeat = ((uint8_t) *glyph) + 1;
337 glyph++;
338 }
339
340 unsigned int xBytes, yBytes;
341 xBytes = yBytes = 0;
342 if (flag & FLAG_X_SHORT)
343 xBytes = 1;
344 else if ((flag & FLAG_X_SAME) == 0)
345 xBytes = 2;
346
347 if (flag & FLAG_Y_SHORT)
348 yBytes = 1;
349 else if ((flag & FLAG_Y_SAME) == 0)
350 yBytes = 2;
351
352 coordBytes += (xBytes + yBytes) * repeat;
353 coordsWithFlags += repeat;
354 if (coordsWithFlags >= nCoordinates)
355 break;
356 }
357
358 if (coordsWithFlags != nCoordinates)
359 {
360 DEBUG_MSG(SUBSET, nullptr, "Expect %d coords to have flags, got flags for %d", nCoordinates, coordsWithFlags);
361 return false;
362 }
363 glyph += coordBytes;
364
365 if (glyph < glyph_end)
366 *end_offset -= glyph_end - glyph;
367 }
368 return true;
369 }
370
371 inline bool get_offsets (hb_codepoint_t glyph,
372 unsigned int *start_offset /* OUT */,
373 unsigned int *end_offset /* OUT */) const
374 {
375 if (unlikely (glyph >= num_glyphs))
376 return false;
377
378 if (short_offset)
379 {
380 const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ;
381 *start_offset = 2 * offsets[glyph];
382 *end_offset = 2 * offsets[glyph + 1];
383 }
384 else
385 {
386 const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ;
387
388 *start_offset = offsets[glyph];
389 *end_offset = offsets[glyph + 1];
390 }
391
392 if (*start_offset > *end_offset || *end_offset > glyf_len)
393 return false;
394
395 return true;
396 }
397
398 inline bool get_instruction_offsets(unsigned int start_offset,
399 unsigned int end_offset,
400 unsigned int *instruction_start /* OUT */,
401 unsigned int *instruction_end /* OUT */) const
402 {
403 if (end_offset - start_offset < GlyphHeader::static_size)
404 {
405 *instruction_start = 0;
406 *instruction_end = 0;
407 return true; /* Empty glyph; no instructions. */
408 }
409 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
410 int16_t num_contours = (int16_t) glyph_header.numberOfContours;
411 if (num_contours < 0)
412 {
413 CompositeGlyphHeader::Iterator composite_it;
414 if (unlikely (!CompositeGlyphHeader::get_iterator (
415 (const char*) this->glyf_table + start_offset,
416 end_offset - start_offset, &composite_it))) return false;
417 const CompositeGlyphHeader *last;
418 do {
419 last = composite_it.current;
420 } while (composite_it.move_to_next());
421
422 if ( (uint16_t) last->flags & CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS)
423 *instruction_start = ((char *) last - (char *) glyf_table->dataZ) + last->get_size();
424 else
425 *instruction_start = end_offset;
426 *instruction_end = end_offset;
427 if (unlikely (*instruction_start > *instruction_end))
428 {
429 DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside [%d, %d]", *instruction_start, start_offset, end_offset);
430 return false;
431 }
432 }
433 else
434 {
435 unsigned int instruction_length_offset = start_offset + GlyphHeader::static_size + 2 * num_contours;
436 if (unlikely (instruction_length_offset + 2 > end_offset))
437 {
438 DEBUG_MSG(SUBSET, nullptr, "Glyph size is too short, missing field instructionLength.");
439 return false;
440 }
441
442 const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (glyf_table, instruction_length_offset);
443 unsigned int start = instruction_length_offset + 2;
444 unsigned int end = start + (uint16_t) instruction_length;
445 if (unlikely (end > end_offset)) // Out of bounds of the current glyph
446 {
447 DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries.");
448 return false;
449 }
450
451 *instruction_start = start;
452 *instruction_end = end;
453 }
454 return true;
455 }
456
457 inline bool get_extents (hb_codepoint_t glyph,
458 hb_glyph_extents_t *extents) const
459 {
460 unsigned int start_offset, end_offset;
461 if (!get_offsets (glyph, &start_offset, &end_offset))
462 return false;
463
464 if (end_offset - start_offset < GlyphHeader::static_size)
465 return true; /* Empty glyph; zero extents. */
466
467 const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
468
469 extents->x_bearing = MIN (glyph_header.xMin, glyph_header.xMax);
470 extents->y_bearing = MAX (glyph_header.yMin, glyph_header.yMax);
471 extents->width = MAX (glyph_header.xMin, glyph_header.xMax) - extents->x_bearing;
472 extents->height = MIN (glyph_header.yMin, glyph_header.yMax) - extents->y_bearing;
473
474 return true;
475 }
476
477 private:
478 bool short_offset;
479 unsigned int num_glyphs;
480 const loca *loca_table;
481 const glyf *glyf_table;
482 hb_blob_t *loca_blob;
483 hb_blob_t *glyf_blob;
484 unsigned int glyf_len;
485 };
486
487 protected:
488 HBUINT8 dataZ[VAR]; /* Glyphs data. */
489
490 DEFINE_SIZE_ARRAY (0, dataZ);
491 };
492
493 } /* namespace OT */
494
495
496 #endif /* HB_OT_GLYF_TABLE_HH */