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 static constexpr hb_tag_t tableTag = HB_OT_TAG_loca;
49
50 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 static constexpr hb_tag_t tableTag = HB_OT_TAG_glyf;
75
76 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
84 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
105 _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
156 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
180 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
194 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
202 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 {
231 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
247 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 */
258 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 */
285 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
357 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
384 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
443 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 */