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-shape-complex-arabic.hh"
32#include "hb-ot-shape.hh"
33
34
35/* buffer var allocations */
36#define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */
37
38#define HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH HB_BUFFER_SCRATCH_FLAG_COMPLEX0
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 */
70enum 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-shape-complex-arabic-table.hh"
85
86static 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
101static 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 */
115enum 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
133static 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
164static void
165arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
166 hb_font_t *font,
167 hb_buffer_t *buffer);
168
169static void
170record_stch (const hb_ot_shape_plan_t *plan,
171 hb_font_t *font,
172 hb_buffer_t *buffer);
173
174static void
175collect_features_arabic (hb_ot_shape_planner_t *plan)
176{
177 hb_ot_map_builder_t *map = &plan->map;
178
179 /* We apply features according to the Arabic spec, with pauses
180 * in between most.
181 *
182 * The pause between init/medi/... and rlig is required. See eg:
183 * https://bugzilla.mozilla.org/show_bug.cgi?id=644184
184 *
185 * The pauses between init/medi/... themselves are not necessarily
186 * needed as only one of those features is applied to any character.
187 * The only difference it makes is when fonts have contextual
188 * substitutions. We now follow the order of the spec, which makes
189 * for better experience if that's what Uniscribe is doing.
190 *
191 * At least for Arabic, looks like Uniscribe has a pause between
192 * rlig and calt. Otherwise the IranNastaliq's ALLAH ligature won't
193 * work. However, testing shows that rlig and calt are applied
194 * together for Mongolian in Uniscribe. As such, we only add a
195 * pause for Arabic, not other scripts.
196 *
197 * A pause after calt is required to make KFGQPC Uthmanic Script HAFS
198 * work correctly. See https://github.com/harfbuzz/harfbuzz/issues/505
199 */
200
201
202 map->enable_feature (HB_TAG('s','t','c','h'));
203 map->add_gsub_pause (record_stch);
204
205 map->enable_feature (HB_TAG('c','c','m','p'));
206 map->enable_feature (HB_TAG('l','o','c','l'));
207
208 map->add_gsub_pause (nullptr);
209
210 for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
211 {
212 bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);
213 map->add_feature (arabic_features[i], has_fallback ? F_HAS_FALLBACK : F_NONE);
214 map->add_gsub_pause (nullptr);
215 }
216
217 /* Normally, Unicode says a ZWNJ means "don't ligate". In Arabic script
218 * however, it says a ZWJ should also mean "don't ligate". So we run
219 * the main ligating features as MANUAL_ZWJ. */
220
221 map->enable_feature (HB_TAG('r','l','i','g'), F_MANUAL_ZWJ | F_HAS_FALLBACK);
222
223 if (plan->props.script == HB_SCRIPT_ARABIC)
224 map->add_gsub_pause (arabic_fallback_shape);
225
226 /* No pause after rclt. See 98460779bae19e4d64d29461ff154b3527bf8420. */
227 map->enable_feature (HB_TAG('r','c','l','t'), F_MANUAL_ZWJ);
228 map->enable_feature (HB_TAG('c','a','l','t'), F_MANUAL_ZWJ);
229 map->add_gsub_pause (nullptr);
230
231 /* The spec includes 'cswh'. Earlier versions of Windows
232 * used to enable this by default, but testing suggests
233 * that Windows 8 and later do not enable it by default,
234 * and spec now says 'Off by default'.
235 * We disabled this in ae23c24c32.
236 * Note that IranNastaliq uses this feature extensively
237 * to fixup broken glyph sequences. Oh well...
238 * Test case: U+0643,U+0640,U+0631. */
239 //map->enable_feature (HB_TAG('c','s','w','h'));
240 map->enable_feature (HB_TAG('m','s','e','t'));
241}
242
243#include "hb-ot-shape-complex-arabic-fallback.hh"
244
245struct arabic_shape_plan_t
246{
247 /* The "+ 1" in the next array is to accommodate for the "NONE" command,
248 * which is not an OpenType feature, but this simplifies the code by not
249 * having to do a "if (... < NONE) ..." and just rely on the fact that
250 * mask_array[NONE] == 0. */
251 hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
252
253 hb_atomic_ptr_t<arabic_fallback_plan_t> fallback_plan;
254
255 unsigned int do_fallback : 1;
256 unsigned int has_stch : 1;
257};
258
259void *
260data_create_arabic (const hb_ot_shape_plan_t *plan)
261{
262 arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) calloc (1, sizeof (arabic_shape_plan_t));
263 if (unlikely (!arabic_plan))
264 return nullptr;
265
266 arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;
267 arabic_plan->has_stch = !!plan->map.get_1_mask (HB_TAG ('s','t','c','h'));
268 for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
269 arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
270 arabic_plan->do_fallback = arabic_plan->do_fallback &&
271 (FEATURE_IS_SYRIAC (arabic_features[i]) ||
272 plan->map.needs_fallback (arabic_features[i]));
273 }
274
275 return arabic_plan;
276}
277
278void
279data_destroy_arabic (void *data)
280{
281 arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;
282
283 arabic_fallback_plan_destroy (arabic_plan->fallback_plan);
284
285 free (data);
286}
287
288static void
289arabic_joining (hb_buffer_t *buffer)
290{
291 unsigned int count = buffer->len;
292 hb_glyph_info_t *info = buffer->info;
293 unsigned int prev = UINT_MAX, state = 0;
294
295 /* Check pre-context */
296 for (unsigned int i = 0; i < buffer->context_len[0]; i++)
297 {
298 unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
299
300 if (unlikely (this_type == JOINING_TYPE_T))
301 continue;
302
303 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
304 state = entry->next_state;
305 break;
306 }
307
308 for (unsigned int i = 0; i < count; i++)
309 {
310 unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
311
312 if (unlikely (this_type == JOINING_TYPE_T)) {
313 info[i].arabic_shaping_action() = NONE;
314 continue;
315 }
316
317 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
318
319 if (entry->prev_action != NONE && prev != UINT_MAX)
320 {
321 info[prev].arabic_shaping_action() = entry->prev_action;
322 buffer->unsafe_to_break (prev, i + 1);
323 }
324
325 info[i].arabic_shaping_action() = entry->curr_action;
326
327 prev = i;
328 state = entry->next_state;
329 }
330
331 for (unsigned int i = 0; i < buffer->context_len[1]; i++)
332 {
333 unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
334
335 if (unlikely (this_type == JOINING_TYPE_T))
336 continue;
337
338 const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
339 if (entry->prev_action != NONE && prev != UINT_MAX)
340 info[prev].arabic_shaping_action() = entry->prev_action;
341 break;
342 }
343}
344
345static void
346mongolian_variation_selectors (hb_buffer_t *buffer)
347{
348 /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
349 unsigned int count = buffer->len;
350 hb_glyph_info_t *info = buffer->info;
351 for (unsigned int i = 1; i < count; i++)
352 if (unlikely (hb_in_range<hb_codepoint_t> (info[i].codepoint, 0x180Bu, 0x180Du)))
353 info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
354}
355
356void
357setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,
358 hb_buffer_t *buffer,
359 hb_script_t script)
360{
361 HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
362
363 arabic_joining (buffer);
364 if (script == HB_SCRIPT_MONGOLIAN)
365 mongolian_variation_selectors (buffer);
366
367 unsigned int count = buffer->len;
368 hb_glyph_info_t *info = buffer->info;
369 for (unsigned int i = 0; i < count; i++)
370 info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
371}
372
373static void
374setup_masks_arabic (const hb_ot_shape_plan_t *plan,
375 hb_buffer_t *buffer,
376 hb_font_t *font HB_UNUSED)
377{
378 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
379 setup_masks_arabic_plan (arabic_plan, buffer, plan->props.script);
380}
381
382static void
383arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
384 hb_font_t *font,
385 hb_buffer_t *buffer)
386{
387#ifdef HB_NO_OT_SHAPE_COMPLEX_ARABIC_FALLBACK
388 return;
389#endif
390
391 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
392
393 if (!arabic_plan->do_fallback)
394 return;
395
396retry:
397 arabic_fallback_plan_t *fallback_plan = arabic_plan->fallback_plan;
398 if (unlikely (!fallback_plan))
399 {
400 /* This sucks. We need a font to build the fallback plan... */
401 fallback_plan = arabic_fallback_plan_create (plan, font);
402 if (unlikely (!arabic_plan->fallback_plan.cmpexch (nullptr, fallback_plan)))
403 {
404 arabic_fallback_plan_destroy (fallback_plan);
405 goto retry;
406 }
407 }
408
409 arabic_fallback_plan_shape (fallback_plan, font, buffer);
410}
411
412/*
413 * Stretch feature: "stch".
414 * See example here:
415 * https://docs.microsoft.com/en-us/typography/script-development/syriac
416 * We implement this in a generic way, such that the Arabic subtending
417 * marks can use it as well.
418 */
419
420static void
421record_stch (const hb_ot_shape_plan_t *plan,
422 hb_font_t *font HB_UNUSED,
423 hb_buffer_t *buffer)
424{
425 const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
426 if (!arabic_plan->has_stch)
427 return;
428
429 /* 'stch' feature was just applied. Look for anything that multiplied,
430 * and record it for stch treatment later. Note that rtlm, frac, etc
431 * are applied before stch, but we assume that they didn't result in
432 * anything multiplying into 5 pieces, so it's safe-ish... */
433
434 unsigned int count = buffer->len;
435 hb_glyph_info_t *info = buffer->info;
436 for (unsigned int i = 0; i < count; i++)
437 if (unlikely (_hb_glyph_info_multiplied (&info[i])))
438 {
439 unsigned int comp = _hb_glyph_info_get_lig_comp (&info[i]);
440 info[i].arabic_shaping_action() = comp % 2 ? STCH_REPEATING : STCH_FIXED;
441 buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH;
442 }
443}
444
445static void
446apply_stch (const hb_ot_shape_plan_t *plan HB_UNUSED,
447 hb_buffer_t *buffer,
448 hb_font_t *font)
449{
450 if (likely (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH)))
451 return;
452
453 /* The Arabic shaper currently always processes in RTL mode, so we should
454 * stretch / position the stretched pieces to the left / preceding glyphs. */
455
456 /* We do a two pass implementation:
457 * First pass calculates the exact number of extra glyphs we need,
458 * We then enlarge buffer to have that much room,
459 * Second pass applies the stretch, copying things to the end of buffer.
460 */
461
462 int sign = font->x_scale < 0 ? -1 : +1;
463 unsigned int extra_glyphs_needed = 0; // Set during MEASURE, used during CUT
464 enum { MEASURE, CUT } /* step_t */;
465
466 for (unsigned int step = MEASURE; step <= CUT; step = step + 1)
467 {
468 unsigned int count = buffer->len;
469 hb_glyph_info_t *info = buffer->info;
470 hb_glyph_position_t *pos = buffer->pos;
471 unsigned int new_len = count + extra_glyphs_needed; // write head during CUT
472 unsigned int j = new_len;
473 for (unsigned int i = count; i; i--)
474 {
475 if (!hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
476 {
477 if (step == CUT)
478 {
479 --j;
480 info[j] = info[i - 1];
481 pos[j] = pos[i - 1];
482 }
483 continue;
484 }
485
486 /* Yay, justification! */
487
488 hb_position_t w_total = 0; // Total to be filled
489 hb_position_t w_fixed = 0; // Sum of fixed tiles
490 hb_position_t w_repeating = 0; // Sum of repeating tiles
491 int n_fixed = 0;
492 int n_repeating = 0;
493
494 unsigned int end = i;
495 while (i &&
496 hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
497 {
498 i--;
499 hb_position_t width = font->get_glyph_h_advance (info[i].codepoint);
500 if (info[i].arabic_shaping_action() == STCH_FIXED)
501 {
502 w_fixed += width;
503 n_fixed++;
504 }
505 else
506 {
507 w_repeating += width;
508 n_repeating++;
509 }
510 }
511 unsigned int start = i;
512 unsigned int context = i;
513 while (context &&
514 !hb_in_range<uint8_t> (info[context - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING) &&
515 (_hb_glyph_info_is_default_ignorable (&info[context - 1]) ||
516 HB_ARABIC_GENERAL_CATEGORY_IS_WORD (_hb_glyph_info_get_general_category (&info[context - 1]))))
517 {
518 context--;
519 w_total += pos[context].x_advance;
520 }
521 i++; // Don't touch i again.
522
523 DEBUG_MSG (ARABIC, nullptr, "%s stretch at (%d,%d,%d)",
524 step == MEASURE ? "measuring" : "cutting", context, start, end);
525 DEBUG_MSG (ARABIC, nullptr, "rest of word: count=%d width %d", start - context, w_total);
526 DEBUG_MSG (ARABIC, nullptr, "fixed tiles: count=%d width=%d", n_fixed, w_fixed);
527 DEBUG_MSG (ARABIC, nullptr, "repeating tiles: count=%d width=%d", n_repeating, w_repeating);
528
529 /* Number of additional times to repeat each repeating tile. */
530 int n_copies = 0;
531
532 hb_position_t w_remaining = w_total - w_fixed;
533 if (sign * w_remaining > sign * w_repeating && sign * w_repeating > 0)
534 n_copies = (sign * w_remaining) / (sign * w_repeating) - 1;
535
536 /* See if we can improve the fit by adding an extra repeat and squeezing them together a bit. */
537 hb_position_t extra_repeat_overlap = 0;
538 hb_position_t shortfall = sign * w_remaining - sign * w_repeating * (n_copies + 1);
539 if (shortfall > 0 && n_repeating > 0)
540 {
541 ++n_copies;
542 hb_position_t excess = (n_copies + 1) * sign * w_repeating - sign * w_remaining;
543 if (excess > 0)
544 extra_repeat_overlap = excess / (n_copies * n_repeating);
545 }
546
547 if (step == MEASURE)
548 {
549 extra_glyphs_needed += n_copies * n_repeating;
550 DEBUG_MSG (ARABIC, nullptr, "will add extra %d copies of repeating tiles", n_copies);
551 }
552 else
553 {
554 buffer->unsafe_to_break (context, end);
555 hb_position_t x_offset = 0;
556 for (unsigned int k = end; k > start; k--)
557 {
558 hb_position_t width = font->get_glyph_h_advance (info[k - 1].codepoint);
559
560 unsigned int repeat = 1;
561 if (info[k - 1].arabic_shaping_action() == STCH_REPEATING)
562 repeat += n_copies;
563
564 DEBUG_MSG (ARABIC, nullptr, "appending %d copies of glyph %d; j=%d",
565 repeat, info[k - 1].codepoint, j);
566 for (unsigned int n = 0; n < repeat; n++)
567 {
568 x_offset -= width;
569 if (n > 0)
570 x_offset += extra_repeat_overlap;
571 pos[k - 1].x_offset = x_offset;
572 /* Append copy. */
573 --j;
574 info[j] = info[k - 1];
575 pos[j] = pos[k - 1];
576 }
577 }
578 }
579 }
580
581 if (step == MEASURE)
582 {
583 if (unlikely (!buffer->ensure (count + extra_glyphs_needed)))
584 break;
585 }
586 else
587 {
588 assert (j == 0);
589 buffer->len = new_len;
590 }
591 }
592}
593
594
595static void
596postprocess_glyphs_arabic (const hb_ot_shape_plan_t *plan,
597 hb_buffer_t *buffer,
598 hb_font_t *font)
599{
600 apply_stch (plan, buffer, font);
601
602 HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
603}
604
605/* https://www.unicode.org/reports/tr53/ */
606
607static hb_codepoint_t
608modifier_combining_marks[] =
609{
610 0x0654u, /* ARABIC HAMZA ABOVE */
611 0x0655u, /* ARABIC HAMZA BELOW */
612 0x0658u, /* ARABIC MARK NOON GHUNNA */
613 0x06DCu, /* ARABIC SMALL HIGH SEEN */
614 0x06E3u, /* ARABIC SMALL LOW SEEN */
615 0x06E7u, /* ARABIC SMALL HIGH YEH */
616 0x06E8u, /* ARABIC SMALL HIGH NOON */
617 0x08D3u, /* ARABIC SMALL LOW WAW */
618 0x08F3u, /* ARABIC SMALL HIGH WAW */
619};
620
621static inline bool
622info_is_mcm (const hb_glyph_info_t &info)
623{
624 hb_codepoint_t u = info.codepoint;
625 for (unsigned int i = 0; i < ARRAY_LENGTH (modifier_combining_marks); i++)
626 if (u == modifier_combining_marks[i])
627 return true;
628 return false;
629}
630
631static void
632reorder_marks_arabic (const hb_ot_shape_plan_t *plan HB_UNUSED,
633 hb_buffer_t *buffer,
634 unsigned int start,
635 unsigned int end)
636{
637 hb_glyph_info_t *info = buffer->info;
638
639 DEBUG_MSG (ARABIC, buffer, "Reordering marks from %d to %d", start, end);
640
641 unsigned int i = start;
642 for (unsigned int cc = 220; cc <= 230; cc += 10)
643 {
644 DEBUG_MSG (ARABIC, buffer, "Looking for %d's starting at %d", cc, i);
645 while (i < end && info_cc(info[i]) < cc)
646 i++;
647 DEBUG_MSG (ARABIC, buffer, "Looking for %d's stopped at %d", cc, i);
648
649 if (i == end)
650 break;
651
652 if (info_cc(info[i]) > cc)
653 continue;
654
655 unsigned int j = i;
656 while (j < end && info_cc(info[j]) == cc && info_is_mcm (info[j]))
657 j++;
658
659 if (i == j)
660 continue;
661
662 DEBUG_MSG (ARABIC, buffer, "Found %d's from %d to %d", cc, i, j);
663
664 /* Shift it! */
665 DEBUG_MSG (ARABIC, buffer, "Shifting %d's: %d %d", cc, i, j);
666 hb_glyph_info_t temp[HB_OT_SHAPE_COMPLEX_MAX_COMBINING_MARKS];
667 assert (j - i <= ARRAY_LENGTH (temp));
668 buffer->merge_clusters (start, j);
669 memmove (temp, &info[i], (j - i) * sizeof (hb_glyph_info_t));
670 memmove (&info[start + j - i], &info[start], (i - start) * sizeof (hb_glyph_info_t));
671 memmove (&info[start], temp, (j - i) * sizeof (hb_glyph_info_t));
672
673 /* Renumber CC such that the reordered sequence is still sorted.
674 * 22 and 26 are chosen because they are smaller than all Arabic categories,
675 * and are folded back to 220/230 respectively during fallback mark positioning.
676 *
677 * We do this because the CGJ-handling logic in the normalizer relies on
678 * mark sequences having an increasing order even after this reordering.
679 * https://github.com/harfbuzz/harfbuzz/issues/554
680 * This, however, does break some obscure sequences, where the normalizer
681 * might compose a sequence that it should not. For example, in the seequence
682 * ALEF, HAMZAH, MADDAH, we should NOT try to compose ALEF+MADDAH, but with this
683 * renumbering, we will.
684 */
685 unsigned int new_start = start + j - i;
686 unsigned int new_cc = cc == 220 ? HB_MODIFIED_COMBINING_CLASS_CCC22 : HB_MODIFIED_COMBINING_CLASS_CCC26;
687 while (start < new_start)
688 {
689 _hb_glyph_info_set_modified_combining_class (&info[start], new_cc);
690 start++;
691 }
692
693 i = j;
694 }
695}
696
697const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
698{
699 collect_features_arabic,
700 nullptr, /* override_features */
701 data_create_arabic,
702 data_destroy_arabic,
703 nullptr, /* preprocess_text */
704 postprocess_glyphs_arabic,
705 HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
706 nullptr, /* decompose */
707 nullptr, /* compose */
708 setup_masks_arabic,
709 HB_TAG_NONE, /* gpos_tag */
710 reorder_marks_arabic,
711 HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
712 true, /* fallback_position */
713};
714
715
716#endif
717