1 /*
2 * Copyright © 2010,2012 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 #include "hb.hh"
28
29 #ifndef HB_NO_OT_SHAPE
30
31 #include "hb-ot-shaper-arabic.hh"
32 #include "hb-ot-shape.hh"
33 #include "inttypes.h"
34
35 /* buffer var allocations */
36 #define arabic_shaping_action() ot_shaper_var_u8_auxiliary() /* arabic shaping action */
37
38 #define HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH HB_BUFFER_SCRATCH_FLAG_SHAPER0
39
40 /* See:
41 * https://github.com/harfbuzz/harfbuzz/commit/6e6f82b6f3dde0fc6c3c7d991d9ec6cfff57823d#commitcomment-14248516 */
42 #define HB_ARABIC_GENERAL_CATEGORY_IS_WORD(gen_cat) \
43 (FLAG_UNSAFE (gen_cat) & \
44 (FLAG (HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED) | \
45 FLAG (HB_UNICODE_GENERAL_CATEGORY_PRIVATE_USE) | \
46 /*FLAG (HB_UNICODE_GENERAL_CATEGORY_LOWERCASE_LETTER) |*/ \
47 FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_LETTER) | \
48 FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER) | \
49 /*FLAG (HB_UNICODE_GENERAL_CATEGORY_TITLECASE_LETTER) |*/ \
50 /*FLAG (HB_UNICODE_GENERAL_CATEGORY_UPPERCASE_LETTER) |*/ \
51 FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) | \
52 FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) | \
53 FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) | \
54 FLAG (HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER) | \
55 FLAG (HB_UNICODE_GENERAL_CATEGORY_LETTER_NUMBER) | \
56 FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_NUMBER) | \
57 FLAG (HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL) | \
58 FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL) | \
59 FLAG (HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL) | \
60 FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL)))
61
62
63 /*
64 * Joining types:
65 */
66
67 /*
68 * Bits used in the joining tables
69 */
70 enum hb_arabic_joining_type_t {
71 JOINING_TYPE_U = 0,
72 JOINING_TYPE_L = 1,
73 JOINING_TYPE_R = 2,
74 JOINING_TYPE_D = 3,
75 JOINING_TYPE_C = JOINING_TYPE_D,
76 JOINING_GROUP_ALAPH = 4,
77 JOINING_GROUP_DALATH_RISH = 5,
78 NUM_STATE_MACHINE_COLS = 6,
79
80 JOINING_TYPE_T = 7,
81 JOINING_TYPE_X = 8 /* means: use general-category to choose between U or T. */
82 };
83
84 #include "hb-ot-shaper-arabic-table.hh"
85
get_joining_type(hb_codepoint_t u,hb_unicode_general_category_t gen_cat)86 static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
87 {
88 unsigned int j_type = joining_type(u);
89 if (likely (j_type != JOINING_TYPE_X))
90 return j_type;
91
92 return (FLAG_UNSAFE(gen_cat) &
93 (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) |
94 FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
95 FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))
96 ) ? JOINING_TYPE_T : JOINING_TYPE_U;
97 }
98
99 #define FEATURE_IS_SYRIAC(tag) hb_in_range<unsigned char> ((unsigned char) (tag), '2', '3')
100
101 static const hb_tag_t arabic_features[] =
102 {
103 HB_TAG('i','s','o','l'),
104 HB_TAG('f','i','n','a'),
105 HB_TAG('f','i','n','2'),
106 HB_TAG('f','i','n','3'),
107 HB_TAG('m','e','d','i'),
108 HB_TAG('m','e','d','2'),
109 HB_TAG('i','n','i','t'),
110 HB_TAG_NONE
111 };
112
113
114 /* Same order as the feature array */
115 enum arabic_action_t {
116 ISOL,
117 FINA,
118 FIN2,
119 FIN3,
120 MEDI,
121 MED2,
122 INIT,
123
124 NONE,
125
126 ARABIC_NUM_FEATURES = NONE,
127
128 /* We abuse the same byte for other things... */
129 STCH_FIXED,
130 STCH_REPEATING,
131 };
132
133 static const struct arabic_state_table_entry {
134 uint8_t prev_action;
135 uint8_t curr_action;
136 uint16_t next_state;
137 } arabic_state_table[][NUM_STATE_MACHINE_COLS] =
138 {
139 /* jt_U, jt_L, jt_R, jt_D, jg_ALAPH, jg_DALATH_RISH */
140
141 /* State 0: prev was U, not willing to join. */
142 { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },
143
144 /* State 1: prev was R or ISOL/ALAPH, not willing to join. */
145 { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },
146
147 /* State 2: prev was D/L in ISOL form, willing to join. */
148 { {NONE,NONE,0}, {NONE,ISOL,2}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },
149
150 /* State 3: prev was D in FINA form, willing to join. */
151 { {NONE,NONE,0}, {NONE,ISOL,2}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },
152
153 /* State 4: prev was FINA ALAPH, not willing to join. */
154 { {NONE,NONE,0}, {NONE,ISOL,2}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },
155
156 /* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
157 { {NONE,NONE,0}, {NONE,ISOL,2}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },
158
159 /* State 6: prev was DALATH/RISH, not willing to join. */
160 { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
161 };
162
163
164 static bool
165 arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
166 hb_font_t *font,
167 hb_buffer_t *buffer);
168
169 static bool
170 record_stch (const hb_ot_shape_plan_t *plan,
171 hb_font_t *font,
172 hb_buffer_t *buffer);
173
174 static bool
deallocate_buffer_var(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)175 deallocate_buffer_var (const hb_ot_shape_plan_t *plan,
176 hb_font_t *font,
177 hb_buffer_t *buffer)
178 {
179 HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
180 return false;
181 }
182
183 static void
collect_features_arabic(hb_ot_shape_planner_t * plan)184 collect_features_arabic (hb_ot_shape_planner_t *plan)
185 {
186 hb_ot_map_builder_t *map = &plan->map;
187
188 /* We apply features according to the Arabic spec, with pauses
189 * in between most.
190 *
191 * The pause between init/medi/... and rlig is required. See eg:
192 * https://bugzilla.mozilla.org/show_bug.cgi?id=644184
193 *
194 * The pauses between init/medi/... themselves are not necessarily
195 * needed as only one of those features is applied to any character.
196 * The only difference it makes is when fonts have contextual
197 * substitutions. We now follow the order of the spec, which makes
198 * for better experience if that's what Uniscribe is doing.
199 *
200 * At least for Arabic, looks like Uniscribe has a pause between
201 * rlig and calt. Otherwise the IranNastaliq's ALLAH ligature won't
202 * work. However, testing shows that rlig and calt are applied
203 * together for Mongolian in Uniscribe. As such, we only add a
204 * pause for Arabic, not other scripts.
205 */
206
207
208 map->enable_feature (HB_TAG('s','t','c','h'));
209 map->add_gsub_pause (record_stch);
210
211 map->enable_feature (HB_TAG('c','c','m','p'), F_MANUAL_ZWJ);
212 map->enable_feature (HB_TAG('l','o','c','l'), F_MANUAL_ZWJ);
213
214 map->add_gsub_pause (nullptr);
215
216 for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
217 {
218 bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);
219 map->add_feature (arabic_features[i], F_MANUAL_ZWJ | (has_fallback ? F_HAS_FALLBACK : F_NONE));
220 map->add_gsub_pause (nullptr);
221 }
222 map->add_gsub_pause (deallocate_buffer_var);
223
224 /* Normally, Unicode says a ZWNJ means "don't ligate". In Arabic script
225 * however, it says a ZWJ should also mean "don't ligate". So we run
226 * the main ligating features as MANUAL_ZWJ. */
227
228 map->enable_feature (HB_TAG('r','l','i','g'), F_MANUAL_ZWJ | F_HAS_FALLBACK);
229
230 if (plan->props.script == HB_SCRIPT_ARABIC)
231 map->add_gsub_pause (arabic_fallback_shape);
232
233 map->enable_feature (HB_TAG('c','a','l','t'), F_MANUAL_ZWJ);
234 /* https://github.com/harfbuzz/harfbuzz/issues/1573 */
235 if (!map->has_feature (HB_TAG('r','c','l','t')))
236 {
237 map->add_gsub_pause (nullptr);
238 map->enable_feature (HB_TAG('r','c','l','t'), F_MANUAL_ZWJ);
239 }
240
241 map->enable_feature (HB_TAG('l','i','g','a'), F_MANUAL_ZWJ);
242 map->enable_feature (HB_TAG('c','l','i','g'), F_MANUAL_ZWJ);
243
244 /* The spec includes 'cswh'. Earlier versions of Windows
245 * used to enable this by default, but testing suggests
246 * that Windows 8 and later do not enable it by default,
247 * and spec now says 'Off by default'.
248 * We disabled this in ae23c24c32.
249 * Note that IranNastaliq uses this feature extensively
250 * to fixup broken glyph sequences. Oh well...
251 * Test case: U+0643,U+0640,U+0631. */
252 //map->enable_feature (HB_TAG('c','s','w','h'), F_MANUAL_ZWJ);
253 map->enable_feature (HB_TAG('m','s','e','t'), F_MANUAL_ZWJ);
254 }
255
256 #include "hb-ot-shaper-arabic-fallback.hh"
257
258 struct arabic_shape_plan_t
259 {
260 /* The "+ 1" in the next array is to accommodate for the "NONE" command,
261 * which is not an OpenType feature, but this simplifies the code by not
262 * having to do a "if (... < NONE) ..." and just rely on the fact that
263 * mask_array[NONE] == 0. */
264 hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
265
266 hb_atomic_ptr_t<arabic_fallback_plan_t> fallback_plan;
267
268 unsigned int do_fallback : 1;
269 unsigned int has_stch : 1;
270 };
271
272 void *
data_create_arabic(const hb_ot_shape_plan_t * plan)273 data_create_arabic (const hb_ot_shape_plan_t *plan)
274 {
275 arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) hb_calloc (1, sizeof (arabic_shape_plan_t));
276 if (unlikely (!arabic_plan))
277 return nullptr;
278
279 arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;
280 arabic_plan->has_stch = !!plan->map.get_1_mask (HB_TAG ('s','t','c','h'));
281 for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
282 arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
283 arabic_plan->do_fallback = arabic_plan->do_fallback &&
284 (FEATURE_IS_SYRIAC (arabic_features[i]) ||
285 plan->map.needs_fallback (arabic_features[i]));
286 }
287
288 return arabic_plan;
289 }
290
291 void
data_destroy_arabic(void * data)292 data_destroy_arabic (void *data)
293 {
294 arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;
295
296 arabic_fallback_plan_destroy (arabic_plan->fallback_plan);
297
298 hb_free (data);
299 }
300
301 static void
arabic_joining(hb_buffer_t * buffer)302 arabic_joining (hb_buffer_t *buffer)
303 {
304 unsigned int count = buffer->len;
305 hb_glyph_info_t *info = buffer->info;
306 unsigned int prev = UINT_MAX, state = 0;
307
308 /* Check pre-context */
309 for (unsigned int i = 0; i < buffer->context_len[0]; i++)
310 {
311 unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
312
313 if (unlikely (this_type == JOINING_TYPE_T))
314 continue;
315
316 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
317 state = entry->next_state;
318 break;
319 }
320
321 for (unsigned int i = 0; i < count; i++)
322 {
323 unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
324
325 if (unlikely (this_type == JOINING_TYPE_T)) {
326 info[i].arabic_shaping_action() = NONE;
327 continue;
328 }
329
330 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
331
332 if (entry->prev_action != NONE && prev != UINT_MAX)
333 {
334 info[prev].arabic_shaping_action() = entry->prev_action;
335 buffer->safe_to_insert_tatweel (prev, i + 1);
336 }
337 else
338 {
339 if (prev == UINT_MAX)
340 {
341 if (this_type >= JOINING_TYPE_R)
342 buffer->unsafe_to_concat_from_outbuffer (0, i + 1);
343 }
344 else
345 {
346 if (this_type >= JOINING_TYPE_R ||
347 (2 <= state && state <= 5) /* States that have a possible prev_action. */)
348 buffer->unsafe_to_concat (prev, i + 1);
349 }
350 }
351
352 info[i].arabic_shaping_action() = entry->curr_action;
353
354 prev = i;
355 state = entry->next_state;
356 }
357
358 for (unsigned int i = 0; i < buffer->context_len[1]; i++)
359 {
360 unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
361
362 if (unlikely (this_type == JOINING_TYPE_T))
363 continue;
364
365 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
366 if (entry->prev_action != NONE && prev != UINT_MAX)
367 {
368 info[prev].arabic_shaping_action() = entry->prev_action;
369 buffer->safe_to_insert_tatweel (prev, buffer->len);
370 }
371 else if (2 <= state && state <= 5) /* States that have a possible prev_action. */
372 {
373 buffer->unsafe_to_concat (prev, buffer->len);
374 }
375 break;
376 }
377 }
378
379 static void
mongolian_variation_selectors(hb_buffer_t * buffer)380 mongolian_variation_selectors (hb_buffer_t *buffer)
381 {
382 /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
383 unsigned int count = buffer->len;
384 hb_glyph_info_t *info = buffer->info;
385 for (unsigned int i = 1; i < count; i++)
386 if (unlikely (hb_in_ranges<hb_codepoint_t> (info[i].codepoint, 0x180Bu, 0x180Du, 0x180Fu, 0x180Fu)))
387 info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
388 }
389
390 void
setup_masks_arabic_plan(const arabic_shape_plan_t * arabic_plan,hb_buffer_t * buffer,hb_script_t script)391 setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,
392 hb_buffer_t *buffer,
393 hb_script_t script)
394 {
395 HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
396
397 arabic_joining (buffer);
398 if (script == HB_SCRIPT_MONGOLIAN)
399 mongolian_variation_selectors (buffer);
400
401 unsigned int count = buffer->len;
402 hb_glyph_info_t *info = buffer->info;
403 for (unsigned int i = 0; i < count; i++)
404 info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
405 }
406
407 static void
setup_masks_arabic(const hb_ot_shape_plan_t * plan,hb_buffer_t * buffer,hb_font_t * font HB_UNUSED)408 setup_masks_arabic (const hb_ot_shape_plan_t *plan,
409 hb_buffer_t *buffer,
410 hb_font_t *font HB_UNUSED)
411 {
412 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
413 setup_masks_arabic_plan (arabic_plan, buffer, plan->props.script);
414 }
415
416 static bool
arabic_fallback_shape(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)417 arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
418 hb_font_t *font,
419 hb_buffer_t *buffer)
420 {
421 #ifdef HB_NO_OT_SHAPER_ARABIC_FALLBACK
422 return false;
423 #endif
424
425 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
426
427 if (!arabic_plan->do_fallback)
428 return false;
429
430 retry:
431 arabic_fallback_plan_t *fallback_plan = arabic_plan->fallback_plan;
432 if (unlikely (!fallback_plan))
433 {
434 /* This sucks. We need a font to build the fallback plan... */
435 fallback_plan = arabic_fallback_plan_create (plan, font);
436 if (unlikely (!arabic_plan->fallback_plan.cmpexch (nullptr, fallback_plan)))
437 {
438 arabic_fallback_plan_destroy (fallback_plan);
439 goto retry;
440 }
441 }
442
443 arabic_fallback_plan_shape (fallback_plan, font, buffer);
444 return true;
445 }
446
447 /*
448 * Stretch feature: "stch".
449 * See example here:
450 * https://docs.microsoft.com/en-us/typography/script-development/syriac
451 * We implement this in a generic way, such that the Arabic subtending
452 * marks can use it as well.
453 */
454
455 static bool
record_stch(const hb_ot_shape_plan_t * plan,hb_font_t * font HB_UNUSED,hb_buffer_t * buffer)456 record_stch (const hb_ot_shape_plan_t *plan,
457 hb_font_t *font HB_UNUSED,
458 hb_buffer_t *buffer)
459 {
460 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
461 if (!arabic_plan->has_stch)
462 return false;
463
464 /* 'stch' feature was just applied. Look for anything that multiplied,
465 * and record it for stch treatment later. Note that rtlm, frac, etc
466 * are applied before stch, but we assume that they didn't result in
467 * anything multiplying into 5 pieces, so it's safe-ish... */
468
469 unsigned int count = buffer->len;
470 hb_glyph_info_t *info = buffer->info;
471 for (unsigned int i = 0; i < count; i++)
472 if (unlikely (_hb_glyph_info_multiplied (&info[i])))
473 {
474 unsigned int comp = _hb_glyph_info_get_lig_comp (&info[i]);
475 info[i].arabic_shaping_action() = comp % 2 ? STCH_REPEATING : STCH_FIXED;
476 buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH;
477 }
478 return false;
479 }
480
481 static void
apply_stch(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_buffer_t * buffer,hb_font_t * font)482 apply_stch (const hb_ot_shape_plan_t *plan HB_UNUSED,
483 hb_buffer_t *buffer,
484 hb_font_t *font)
485 {
486 if (likely (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH)))
487 return;
488
489 bool rtl = buffer->props.direction == HB_DIRECTION_RTL;
490
491 if (!rtl)
492 buffer->reverse ();
493
494 /* We do a two pass implementation:
495 * First pass calculates the exact number of extra glyphs we need,
496 * We then enlarge buffer to have that much room,
497 * Second pass applies the stretch, copying things to the end of buffer.
498 */
499
500 int sign = font->x_scale < 0 ? -1 : +1;
501 unsigned int extra_glyphs_needed = 0; // Set during MEASURE, used during CUT
502 enum { MEASURE, CUT } /* step_t */;
503
504 for (unsigned int step = MEASURE; step <= CUT; step = step + 1)
505 {
506 unsigned int count = buffer->len;
507 hb_glyph_info_t *info = buffer->info;
508 hb_glyph_position_t *pos = buffer->pos;
509 unsigned int new_len = count + extra_glyphs_needed; // write head during CUT
510 unsigned int j = new_len;
511 for (unsigned int i = count; i; i--)
512 {
513 if (!hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
514 {
515 if (step == CUT)
516 {
517 --j;
518 info[j] = info[i - 1];
519 pos[j] = pos[i - 1];
520 }
521 continue;
522 }
523
524 /* Yay, justification! */
525
526 hb_position_t w_total = 0; // Total to be filled
527 hb_position_t w_fixed = 0; // Sum of fixed tiles
528 hb_position_t w_repeating = 0; // Sum of repeating tiles
529 int n_fixed = 0;
530 int n_repeating = 0;
531
532 unsigned int end = i;
533 while (i &&
534 hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
535 {
536 i--;
537 hb_position_t width = font->get_glyph_h_advance (info[i].codepoint);
538 if (info[i].arabic_shaping_action() == STCH_FIXED)
539 {
540 w_fixed += width;
541 n_fixed++;
542 }
543 else
544 {
545 w_repeating += width;
546 n_repeating++;
547 }
548 }
549 unsigned int start = i;
550 unsigned int context = i;
551 while (context &&
552 !hb_in_range<uint8_t> (info[context - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING) &&
553 (_hb_glyph_info_is_default_ignorable (&info[context - 1]) ||
554 HB_ARABIC_GENERAL_CATEGORY_IS_WORD (_hb_glyph_info_get_general_category (&info[context - 1]))))
555 {
556 context--;
557 w_total += pos[context].x_advance;
558 }
559 i++; // Don't touch i again.
560
561 DEBUG_MSG (ARABIC, nullptr, "%s stretch at (%u,%u,%u)",
562 step == MEASURE ? "measuring" : "cutting", context, start, end);
563 DEBUG_MSG (ARABIC, nullptr, "rest of word: count=%u width %" PRId32 "", start - context, w_total);
564 DEBUG_MSG (ARABIC, nullptr, "fixed tiles: count=%d width=%" PRId32 "", n_fixed, w_fixed);
565 DEBUG_MSG (ARABIC, nullptr, "repeating tiles: count=%d width=%" PRId32 "", n_repeating, w_repeating);
566
567 /* Number of additional times to repeat each repeating tile. */
568 int n_copies = 0;
569
570 hb_position_t w_remaining = w_total - w_fixed;
571 if (sign * w_remaining > sign * w_repeating && sign * w_repeating > 0)
572 n_copies = (sign * w_remaining) / (sign * w_repeating) - 1;
573
574 /* See if we can improve the fit by adding an extra repeat and squeezing them together a bit. */
575 hb_position_t extra_repeat_overlap = 0;
576 hb_position_t shortfall = sign * w_remaining - sign * w_repeating * (n_copies + 1);
577 if (shortfall > 0 && n_repeating > 0)
578 {
579 ++n_copies;
580 hb_position_t excess = (n_copies + 1) * sign * w_repeating - sign * w_remaining;
581 if (excess > 0)
582 {
583 extra_repeat_overlap = excess / (n_copies * n_repeating);
584 w_remaining = 0;
585 }
586 }
587
588 if (step == MEASURE)
589 {
590 extra_glyphs_needed += n_copies * n_repeating;
591 DEBUG_MSG (ARABIC, nullptr, "will add extra %d copies of repeating tiles", n_copies);
592 }
593 else
594 {
595 buffer->unsafe_to_break (context, end);
596 hb_position_t x_offset = w_remaining / 2;
597 for (unsigned int k = end; k > start; k--)
598 {
599 hb_position_t width = font->get_glyph_h_advance (info[k - 1].codepoint);
600
601 unsigned int repeat = 1;
602 if (info[k - 1].arabic_shaping_action() == STCH_REPEATING)
603 repeat += n_copies;
604
605 DEBUG_MSG (ARABIC, nullptr, "appending %u copies of glyph %" PRIu32 "; j=%u",
606 repeat, info[k - 1].codepoint, j);
607 pos[k - 1].x_advance = 0;
608 for (unsigned int n = 0; n < repeat; n++)
609 {
610 if (rtl)
611 {
612 x_offset -= width;
613 if (n > 0)
614 x_offset += extra_repeat_overlap;
615 }
616 pos[k - 1].x_offset = x_offset;
617 /* Append copy. */
618 --j;
619 info[j] = info[k - 1];
620 pos[j] = pos[k - 1];
621
622 if (!rtl)
623 {
624 x_offset += width;
625 if (n > 0)
626 x_offset -= extra_repeat_overlap;
627 }
628 }
629 }
630 }
631 }
632
633 if (step == MEASURE)
634 {
635 if (unlikely (!buffer->ensure (count + extra_glyphs_needed)))
636 break;
637 }
638 else
639 {
640 assert (j == 0);
641 buffer->len = new_len;
642 }
643 }
644
645 if (!rtl)
646 buffer->reverse ();
647 }
648
649
650 static void
postprocess_glyphs_arabic(const hb_ot_shape_plan_t * plan,hb_buffer_t * buffer,hb_font_t * font)651 postprocess_glyphs_arabic (const hb_ot_shape_plan_t *plan,
652 hb_buffer_t *buffer,
653 hb_font_t *font)
654 {
655 apply_stch (plan, buffer, font);
656 }
657
658 /* https://www.unicode.org/reports/tr53/ */
659
660 static hb_codepoint_t
661 modifier_combining_marks[] =
662 {
663 0x0654u, /* ARABIC HAMZA ABOVE */
664 0x0655u, /* ARABIC HAMZA BELOW */
665 0x0658u, /* ARABIC MARK NOON GHUNNA */
666 0x06DCu, /* ARABIC SMALL HIGH SEEN */
667 0x06E3u, /* ARABIC SMALL LOW SEEN */
668 0x06E7u, /* ARABIC SMALL HIGH YEH */
669 0x06E8u, /* ARABIC SMALL HIGH NOON */
670 0x08CAu, /* ARABIC SMALL HIGH FARSI YEH */
671 0x08CBu, /* ARABIC SMALL HIGH YEH BARREE WITH TWO DOTS BELOW */
672 0x08CDu, /* ARABIC SMALL HIGH ZAH */
673 0x08CEu, /* ARABIC LARGE ROUND DOT ABOVE */
674 0x08CFu, /* ARABIC LARGE ROUND DOT BELOW */
675 0x08D3u, /* ARABIC SMALL LOW WAW */
676 0x08F3u, /* ARABIC SMALL HIGH WAW */
677 };
678
679 static inline bool
info_is_mcm(const hb_glyph_info_t & info)680 info_is_mcm (const hb_glyph_info_t &info)
681 {
682 hb_codepoint_t u = info.codepoint;
683 for (unsigned int i = 0; i < ARRAY_LENGTH (modifier_combining_marks); i++)
684 if (u == modifier_combining_marks[i])
685 return true;
686 return false;
687 }
688
689 static void
reorder_marks_arabic(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_buffer_t * buffer,unsigned int start,unsigned int end)690 reorder_marks_arabic (const hb_ot_shape_plan_t *plan HB_UNUSED,
691 hb_buffer_t *buffer,
692 unsigned int start,
693 unsigned int end)
694 {
695 hb_glyph_info_t *info = buffer->info;
696
697 DEBUG_MSG (ARABIC, buffer, "Reordering marks from %u to %u", start, end);
698
699 unsigned int i = start;
700 for (unsigned int cc = 220; cc <= 230; cc += 10)
701 {
702 DEBUG_MSG (ARABIC, buffer, "Looking for %u's starting at %u", cc, i);
703 while (i < end && info_cc(info[i]) < cc)
704 i++;
705 DEBUG_MSG (ARABIC, buffer, "Looking for %u's stopped at %u", cc, i);
706
707 if (i == end)
708 break;
709
710 if (info_cc(info[i]) > cc)
711 continue;
712
713 unsigned int j = i;
714 while (j < end && info_cc(info[j]) == cc && info_is_mcm (info[j]))
715 j++;
716
717 if (i == j)
718 continue;
719
720 DEBUG_MSG (ARABIC, buffer, "Found %u's from %u to %u", cc, i, j);
721
722 /* Shift it! */
723 DEBUG_MSG (ARABIC, buffer, "Shifting %u's: %u %u", cc, i, j);
724 hb_glyph_info_t temp[HB_OT_SHAPE_MAX_COMBINING_MARKS];
725 assert (j - i <= ARRAY_LENGTH (temp));
726 buffer->merge_clusters (start, j);
727 memmove (temp, &info[i], (j - i) * sizeof (hb_glyph_info_t));
728 memmove (&info[start + j - i], &info[start], (i - start) * sizeof (hb_glyph_info_t));
729 memmove (&info[start], temp, (j - i) * sizeof (hb_glyph_info_t));
730
731 /* Renumber CC such that the reordered sequence is still sorted.
732 * 22 and 26 are chosen because they are smaller than all Arabic categories,
733 * and are folded back to 220/230 respectively during fallback mark positioning.
734 *
735 * We do this because the CGJ-handling logic in the normalizer relies on
736 * mark sequences having an increasing order even after this reordering.
737 * https://github.com/harfbuzz/harfbuzz/issues/554
738 * This, however, does break some obscure sequences, where the normalizer
739 * might compose a sequence that it should not. For example, in the seequence
740 * ALEF, HAMZAH, MADDAH, we should NOT try to compose ALEF+MADDAH, but with this
741 * renumbering, we will.
742 */
743 unsigned int new_start = start + j - i;
744 unsigned int new_cc = cc == 220 ? HB_MODIFIED_COMBINING_CLASS_CCC22 : HB_MODIFIED_COMBINING_CLASS_CCC26;
745 while (start < new_start)
746 {
747 _hb_glyph_info_set_modified_combining_class (&info[start], new_cc);
748 start++;
749 }
750
751 i = j;
752 }
753 }
754
755 const hb_ot_shaper_t _hb_ot_shaper_arabic =
756 {
757 collect_features_arabic,
758 nullptr, /* override_features */
759 data_create_arabic,
760 data_destroy_arabic,
761 nullptr, /* preprocess_text */
762 postprocess_glyphs_arabic,
763 nullptr, /* decompose */
764 nullptr, /* compose */
765 setup_masks_arabic,
766 reorder_marks_arabic,
767 HB_TAG_NONE, /* gpos_tag */
768 HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
769 HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
770 true, /* fallback_position */
771 };
772
773
774 #endif
775