Line data Source code
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-ot-shape-complex-arabic-private.hh"
28 : #include "hb-ot-shape-private.hh"
29 :
30 :
31 : #ifndef HB_DEBUG_ARABIC
32 : #define HB_DEBUG_ARABIC (HB_DEBUG+0)
33 : #endif
34 :
35 :
36 : /* buffer var allocations */
37 : #define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */
38 :
39 : #define HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH HB_BUFFER_SCRATCH_FLAG_COMPLEX0
40 :
41 : /* See:
42 : * https://github.com/behdad/harfbuzz/commit/6e6f82b6f3dde0fc6c3c7d991d9ec6cfff57823d#commitcomment-14248516 */
43 : #define HB_ARABIC_GENERAL_CATEGORY_IS_WORD(gen_cat) \
44 : (FLAG_SAFE (gen_cat) & \
45 : (FLAG (HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED) | \
46 : FLAG (HB_UNICODE_GENERAL_CATEGORY_PRIVATE_USE) | \
47 : /*FLAG (HB_UNICODE_GENERAL_CATEGORY_LOWERCASE_LETTER) |*/ \
48 : FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_LETTER) | \
49 : FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER) | \
50 : /*FLAG (HB_UNICODE_GENERAL_CATEGORY_TITLECASE_LETTER) |*/ \
51 : /*FLAG (HB_UNICODE_GENERAL_CATEGORY_UPPERCASE_LETTER) |*/ \
52 : FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) | \
53 : FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) | \
54 : FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) | \
55 : FLAG (HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER) | \
56 : FLAG (HB_UNICODE_GENERAL_CATEGORY_LETTER_NUMBER) | \
57 : FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_NUMBER) | \
58 : FLAG (HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL) | \
59 : FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL) | \
60 : FLAG (HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL) | \
61 : FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL)))
62 :
63 :
64 : /*
65 : * Joining types:
66 : */
67 :
68 : /*
69 : * Bits used in the joining tables
70 : */
71 : enum hb_arabic_joining_type_t {
72 : JOINING_TYPE_U = 0,
73 : JOINING_TYPE_L = 1,
74 : JOINING_TYPE_R = 2,
75 : JOINING_TYPE_D = 3,
76 : JOINING_TYPE_C = JOINING_TYPE_D,
77 : JOINING_GROUP_ALAPH = 4,
78 : JOINING_GROUP_DALATH_RISH = 5,
79 : NUM_STATE_MACHINE_COLS = 6,
80 :
81 : JOINING_TYPE_T = 7,
82 : JOINING_TYPE_X = 8 /* means: use general-category to choose between U or T. */
83 : };
84 :
85 : #include "hb-ot-shape-complex-arabic-table.hh"
86 :
87 0 : static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
88 : {
89 0 : unsigned int j_type = joining_type(u);
90 0 : if (likely (j_type != JOINING_TYPE_X))
91 0 : return j_type;
92 :
93 : return (FLAG_SAFE(gen_cat) &
94 : (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) |
95 : FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
96 : FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))
97 0 : ) ? JOINING_TYPE_T : JOINING_TYPE_U;
98 : }
99 :
100 : #define FEATURE_IS_SYRIAC(tag) hb_in_range<unsigned char> ((unsigned char) (tag), '2', '3')
101 :
102 : static const hb_tag_t arabic_features[] =
103 : {
104 : HB_TAG('i','s','o','l'),
105 : HB_TAG('f','i','n','a'),
106 : HB_TAG('f','i','n','2'),
107 : HB_TAG('f','i','n','3'),
108 : HB_TAG('m','e','d','i'),
109 : HB_TAG('m','e','d','2'),
110 : HB_TAG('i','n','i','t'),
111 : HB_TAG_NONE
112 : };
113 :
114 :
115 : /* Same order as the feature array */
116 : enum arabic_action_t {
117 : ISOL,
118 : FINA,
119 : FIN2,
120 : FIN3,
121 : MEDI,
122 : MED2,
123 : INIT,
124 :
125 : NONE,
126 :
127 : ARABIC_NUM_FEATURES = NONE,
128 :
129 : /* We abuse the same byte for other things... */
130 : STCH_FIXED,
131 : STCH_REPEATING,
132 : };
133 :
134 : static const struct arabic_state_table_entry {
135 : uint8_t prev_action;
136 : uint8_t curr_action;
137 : uint16_t next_state;
138 : } arabic_state_table[][NUM_STATE_MACHINE_COLS] =
139 : {
140 : /* jt_U, jt_L, jt_R, jt_D, jg_ALAPH, jg_DALATH_RISH */
141 :
142 : /* State 0: prev was U, not willing to join. */
143 : { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },
144 :
145 : /* State 1: prev was R or ISOL/ALAPH, not willing to join. */
146 : { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },
147 :
148 : /* State 2: prev was D/L in ISOL form, willing to join. */
149 : { {NONE,NONE,0}, {NONE,ISOL,2}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },
150 :
151 : /* State 3: prev was D in FINA form, willing to join. */
152 : { {NONE,NONE,0}, {NONE,ISOL,2}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },
153 :
154 : /* State 4: prev was FINA ALAPH, not willing to join. */
155 : { {NONE,NONE,0}, {NONE,ISOL,2}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },
156 :
157 : /* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
158 : { {NONE,NONE,0}, {NONE,ISOL,2}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },
159 :
160 : /* State 6: prev was DALATH/RISH, not willing to join. */
161 : { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
162 : };
163 :
164 :
165 : static void
166 : nuke_joiners (const hb_ot_shape_plan_t *plan,
167 : hb_font_t *font,
168 : hb_buffer_t *buffer);
169 :
170 : static void
171 : arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
172 : hb_font_t *font,
173 : hb_buffer_t *buffer);
174 :
175 : static void
176 : record_stch (const hb_ot_shape_plan_t *plan,
177 : hb_font_t *font,
178 : hb_buffer_t *buffer);
179 :
180 : static void
181 0 : collect_features_arabic (hb_ot_shape_planner_t *plan)
182 : {
183 0 : hb_ot_map_builder_t *map = &plan->map;
184 :
185 : /* We apply features according to the Arabic spec, with pauses
186 : * in between most.
187 : *
188 : * The pause between init/medi/... and rlig is required. See eg:
189 : * https://bugzilla.mozilla.org/show_bug.cgi?id=644184
190 : *
191 : * The pauses between init/medi/... themselves are not necessarily
192 : * needed as only one of those features is applied to any character.
193 : * The only difference it makes is when fonts have contextual
194 : * substitutions. We now follow the order of the spec, which makes
195 : * for better experience if that's what Uniscribe is doing.
196 : *
197 : * At least for Arabic, looks like Uniscribe has a pause between
198 : * rlig and calt. Otherwise the IranNastaliq's ALLAH ligature won't
199 : * work. However, testing shows that rlig and calt are applied
200 : * together for Mongolian in Uniscribe. As such, we only add a
201 : * pause for Arabic, not other scripts.
202 : */
203 :
204 0 : map->add_gsub_pause (nuke_joiners);
205 :
206 0 : map->add_global_bool_feature (HB_TAG('s','t','c','h'));
207 0 : map->add_gsub_pause (record_stch);
208 :
209 0 : map->add_global_bool_feature (HB_TAG('c','c','m','p'));
210 0 : map->add_global_bool_feature (HB_TAG('l','o','c','l'));
211 :
212 0 : map->add_gsub_pause (NULL);
213 :
214 0 : for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
215 : {
216 0 : bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);
217 0 : map->add_feature (arabic_features[i], 1, has_fallback ? F_HAS_FALLBACK : F_NONE);
218 0 : map->add_gsub_pause (NULL);
219 : }
220 :
221 0 : map->add_feature (HB_TAG('r','l','i','g'), 1, F_GLOBAL|F_HAS_FALLBACK);
222 0 : if (plan->props.script == HB_SCRIPT_ARABIC)
223 0 : map->add_gsub_pause (arabic_fallback_shape);
224 :
225 0 : map->add_global_bool_feature (HB_TAG('c','a','l','t'));
226 :
227 : /* The spec includes 'cswh'. Earlier versions of Windows
228 : * used to enable this by default, but testing suggests
229 : * that Windows 8 and later do not enable it by default,
230 : * and spec now says 'Off by default'.
231 : * We disabled this in ae23c24c32.
232 : * Note that IranNastaliq uses this feature extensively
233 : * to fixup broken glyph sequences. Oh well...
234 : * Test case: U+0643,U+0640,U+0631. */
235 : //map->add_gsub_pause (NULL);
236 : //map->add_global_bool_feature (HB_TAG('c','s','w','h'));
237 0 : map->add_global_bool_feature (HB_TAG('m','s','e','t'));
238 0 : }
239 :
240 : #include "hb-ot-shape-complex-arabic-fallback.hh"
241 :
242 : struct arabic_shape_plan_t
243 : {
244 : ASSERT_POD ();
245 :
246 : /* The "+ 1" in the next array is to accommodate for the "NONE" command,
247 : * which is not an OpenType feature, but this simplifies the code by not
248 : * having to do a "if (... < NONE) ..." and just rely on the fact that
249 : * mask_array[NONE] == 0. */
250 : hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
251 :
252 : arabic_fallback_plan_t *fallback_plan;
253 :
254 : unsigned int do_fallback : 1;
255 : unsigned int has_stch : 1;
256 : };
257 :
258 : void *
259 0 : data_create_arabic (const hb_ot_shape_plan_t *plan)
260 : {
261 0 : arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) calloc (1, sizeof (arabic_shape_plan_t));
262 0 : if (unlikely (!arabic_plan))
263 0 : return NULL;
264 :
265 0 : arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;
266 0 : arabic_plan->has_stch = !!plan->map.get_1_mask (HB_TAG ('s','t','c','h'));
267 0 : for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
268 0 : arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
269 0 : arabic_plan->do_fallback = arabic_plan->do_fallback &&
270 0 : (FEATURE_IS_SYRIAC (arabic_features[i]) ||
271 0 : plan->map.needs_fallback (arabic_features[i]));
272 : }
273 :
274 0 : return arabic_plan;
275 : }
276 :
277 : void
278 0 : data_destroy_arabic (void *data)
279 : {
280 0 : arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;
281 :
282 0 : arabic_fallback_plan_destroy (arabic_plan->fallback_plan);
283 :
284 0 : free (data);
285 0 : }
286 :
287 : static void
288 0 : arabic_joining (hb_buffer_t *buffer)
289 : {
290 0 : unsigned int count = buffer->len;
291 0 : hb_glyph_info_t *info = buffer->info;
292 0 : unsigned int prev = (unsigned int) -1, state = 0;
293 :
294 : /* Check pre-context */
295 0 : for (unsigned int i = 0; i < buffer->context_len[0]; i++)
296 : {
297 0 : unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
298 :
299 0 : if (unlikely (this_type == JOINING_TYPE_T))
300 0 : continue;
301 :
302 0 : const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
303 0 : state = entry->next_state;
304 0 : break;
305 : }
306 :
307 0 : for (unsigned int i = 0; i < count; i++)
308 : {
309 0 : unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
310 :
311 0 : if (unlikely (this_type == JOINING_TYPE_T)) {
312 0 : info[i].arabic_shaping_action() = NONE;
313 0 : continue;
314 : }
315 :
316 0 : const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
317 :
318 0 : if (entry->prev_action != NONE && prev != (unsigned int) -1)
319 0 : info[prev].arabic_shaping_action() = entry->prev_action;
320 :
321 0 : info[i].arabic_shaping_action() = entry->curr_action;
322 :
323 0 : prev = i;
324 0 : state = entry->next_state;
325 : }
326 :
327 0 : for (unsigned int i = 0; i < buffer->context_len[1]; i++)
328 : {
329 0 : unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
330 :
331 0 : if (unlikely (this_type == JOINING_TYPE_T))
332 0 : continue;
333 :
334 0 : const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
335 0 : if (entry->prev_action != NONE && prev != (unsigned int) -1)
336 0 : info[prev].arabic_shaping_action() = entry->prev_action;
337 0 : break;
338 : }
339 0 : }
340 :
341 : static void
342 0 : mongolian_variation_selectors (hb_buffer_t *buffer)
343 : {
344 : /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
345 0 : unsigned int count = buffer->len;
346 0 : hb_glyph_info_t *info = buffer->info;
347 0 : for (unsigned int i = 1; i < count; i++)
348 0 : if (unlikely (hb_in_range (info[i].codepoint, 0x180Bu, 0x180Du)))
349 0 : info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
350 0 : }
351 :
352 : void
353 0 : setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,
354 : hb_buffer_t *buffer,
355 : hb_script_t script)
356 : {
357 0 : HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
358 :
359 0 : arabic_joining (buffer);
360 0 : if (script == HB_SCRIPT_MONGOLIAN)
361 0 : mongolian_variation_selectors (buffer);
362 :
363 0 : unsigned int count = buffer->len;
364 0 : hb_glyph_info_t *info = buffer->info;
365 0 : for (unsigned int i = 0; i < count; i++)
366 0 : info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
367 0 : }
368 :
369 : static void
370 0 : setup_masks_arabic (const hb_ot_shape_plan_t *plan,
371 : hb_buffer_t *buffer,
372 : hb_font_t *font HB_UNUSED)
373 : {
374 0 : const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
375 0 : setup_masks_arabic_plan (arabic_plan, buffer, plan->props.script);
376 0 : }
377 :
378 :
379 : static void
380 0 : nuke_joiners (const hb_ot_shape_plan_t *plan HB_UNUSED,
381 : hb_font_t *font HB_UNUSED,
382 : hb_buffer_t *buffer)
383 : {
384 0 : unsigned int count = buffer->len;
385 0 : hb_glyph_info_t *info = buffer->info;
386 0 : for (unsigned int i = 0; i < count; i++)
387 0 : if (_hb_glyph_info_is_zwj (&info[i]))
388 0 : _hb_glyph_info_flip_joiners (&info[i]);
389 0 : }
390 :
391 : static void
392 0 : arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
393 : hb_font_t *font,
394 : hb_buffer_t *buffer)
395 : {
396 0 : const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
397 :
398 0 : if (!arabic_plan->do_fallback)
399 0 : return;
400 :
401 : retry:
402 0 : arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_atomic_ptr_get (&arabic_plan->fallback_plan);
403 0 : if (unlikely (!fallback_plan))
404 : {
405 : /* This sucks. We need a font to build the fallback plan... */
406 0 : fallback_plan = arabic_fallback_plan_create (plan, font);
407 0 : if (unlikely (!hb_atomic_ptr_cmpexch (&(const_cast<arabic_shape_plan_t *> (arabic_plan))->fallback_plan, NULL, fallback_plan))) {
408 0 : arabic_fallback_plan_destroy (fallback_plan);
409 0 : goto retry;
410 : }
411 : }
412 :
413 0 : arabic_fallback_plan_shape (fallback_plan, font, buffer);
414 : }
415 :
416 : /*
417 : * Stretch feature: "stch".
418 : * See example here:
419 : * https://www.microsoft.com/typography/OpenTypeDev/syriac/intro.htm
420 : * We implement this in a generic way, such that the Arabic subtending
421 : * marks can use it as well.
422 : */
423 :
424 : static void
425 0 : record_stch (const hb_ot_shape_plan_t *plan,
426 : hb_font_t *font,
427 : hb_buffer_t *buffer)
428 : {
429 0 : const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
430 0 : if (!arabic_plan->has_stch)
431 0 : return;
432 :
433 : /* 'stch' feature was just applied. Look for anything that multiplied,
434 : * and record it for stch treatment later. Note that rtlm, frac, etc
435 : * are applied before stch, but we assume that they didn't result in
436 : * anything multiplying into 5 pieces, so it's safe-ish... */
437 :
438 0 : unsigned int count = buffer->len;
439 0 : hb_glyph_info_t *info = buffer->info;
440 0 : for (unsigned int i = 0; i < count; i++)
441 0 : if (unlikely (_hb_glyph_info_multiplied (&info[i])))
442 : {
443 0 : unsigned int comp = _hb_glyph_info_get_lig_comp (&info[i]);
444 0 : info[i].arabic_shaping_action() = comp % 2 ? STCH_REPEATING : STCH_FIXED;
445 0 : buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH;
446 : }
447 : }
448 :
449 : static void
450 0 : apply_stch (const hb_ot_shape_plan_t *plan,
451 : hb_buffer_t *buffer,
452 : hb_font_t *font)
453 : {
454 0 : if (likely (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH)))
455 0 : return;
456 :
457 : /* The Arabic shaper currently always processes in RTL mode, so we should
458 : * stretch / position the stretched pieces to the left / preceding glyphs. */
459 :
460 : /* We do a two pass implementation:
461 : * First pass calculates the exact number of extra glyphs we need,
462 : * We then enlarge buffer to have that much room,
463 : * Second pass applies the stretch, copying things to the end of buffer.
464 : */
465 :
466 0 : int sign = font->x_scale < 0 ? -1 : +1;
467 0 : unsigned int extra_glyphs_needed = 0; // Set during MEASURE, used during CUT
468 : typedef enum { MEASURE, CUT } step_t;
469 :
470 0 : for (step_t step = MEASURE; step <= CUT; step = (step_t) (step + 1))
471 : {
472 0 : unsigned int count = buffer->len;
473 0 : hb_glyph_info_t *info = buffer->info;
474 0 : hb_glyph_position_t *pos = buffer->pos;
475 0 : unsigned int new_len = count + extra_glyphs_needed; // write head during CUT
476 0 : unsigned int j = new_len;
477 0 : for (unsigned int i = count; i; i--)
478 : {
479 0 : if (!hb_in_range<unsigned> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
480 : {
481 0 : if (step == CUT)
482 : {
483 0 : --j;
484 0 : info[j] = info[i - 1];
485 0 : pos[j] = pos[i - 1];
486 : }
487 0 : continue;
488 : }
489 :
490 : /* Yay, justification! */
491 :
492 0 : hb_position_t w_total = 0; // Total to be filled
493 0 : hb_position_t w_fixed = 0; // Sum of fixed tiles
494 0 : hb_position_t w_repeating = 0; // Sum of repeating tiles
495 0 : int n_fixed = 0;
496 0 : int n_repeating = 0;
497 :
498 0 : unsigned int end = i;
499 0 : while (i &&
500 0 : hb_in_range<unsigned> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
501 : {
502 0 : i--;
503 0 : hb_position_t width = font->get_glyph_h_advance (info[i].codepoint);
504 0 : if (info[i].arabic_shaping_action() == STCH_FIXED)
505 : {
506 0 : w_fixed += width;
507 0 : n_fixed++;
508 : }
509 : else
510 : {
511 0 : w_repeating += width;
512 0 : n_repeating++;
513 : }
514 : }
515 0 : unsigned int start = i;
516 0 : unsigned int context = i;
517 0 : while (context &&
518 0 : !hb_in_range<unsigned> (info[context - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING) &&
519 0 : (_hb_glyph_info_is_default_ignorable (&info[context - 1]) ||
520 0 : HB_ARABIC_GENERAL_CATEGORY_IS_WORD (_hb_glyph_info_get_general_category (&info[context - 1]))))
521 : {
522 0 : context--;
523 0 : w_total += pos[context].x_advance;
524 : }
525 0 : i++; // Don't touch i again.
526 :
527 0 : DEBUG_MSG (ARABIC, NULL, "%s stretch at (%d,%d,%d)",
528 0 : step == MEASURE ? "measuring" : "cutting", context, start, end);
529 0 : DEBUG_MSG (ARABIC, NULL, "rest of word: count=%d width %d", start - context, w_total);
530 0 : DEBUG_MSG (ARABIC, NULL, "fixed tiles: count=%d width=%d", n_fixed, w_fixed);
531 0 : DEBUG_MSG (ARABIC, NULL, "repeating tiles: count=%d width=%d", n_repeating, w_repeating);
532 :
533 : /* Number of additional times to repeat each repeating tile. */
534 0 : int n_copies = 0;
535 :
536 0 : hb_position_t w_remaining = w_total - w_fixed;
537 0 : if (sign * w_remaining > sign * w_repeating && sign * w_repeating > 0)
538 0 : n_copies = (sign * w_remaining) / (sign * w_repeating) - 1;
539 :
540 : /* See if we can improve the fit by adding an extra repeat and squeezing them together a bit. */
541 0 : hb_position_t extra_repeat_overlap = 0;
542 0 : hb_position_t shortfall = sign * w_remaining - sign * w_repeating * (n_copies + 1);
543 0 : if (shortfall > 0 && n_repeating > 0)
544 : {
545 0 : ++n_copies;
546 0 : hb_position_t excess = (n_copies + 1) * sign * w_repeating - sign * w_remaining;
547 0 : if (excess > 0)
548 0 : extra_repeat_overlap = excess / (n_copies * n_repeating);
549 : }
550 :
551 0 : if (step == MEASURE)
552 : {
553 0 : extra_glyphs_needed += n_copies * n_repeating;
554 0 : DEBUG_MSG (ARABIC, NULL, "will add extra %d copies of repeating tiles", n_copies);
555 : }
556 : else
557 : {
558 0 : hb_position_t x_offset = 0;
559 0 : for (unsigned int k = end; k > start; k--)
560 : {
561 0 : hb_position_t width = font->get_glyph_h_advance (info[k - 1].codepoint);
562 :
563 0 : unsigned int repeat = 1;
564 0 : if (info[k - 1].arabic_shaping_action() == STCH_REPEATING)
565 0 : repeat += n_copies;
566 :
567 0 : DEBUG_MSG (ARABIC, NULL, "appending %d copies of glyph %d; j=%d",
568 0 : repeat, info[k - 1].codepoint, j);
569 0 : for (unsigned int n = 0; n < repeat; n++)
570 : {
571 0 : x_offset -= width;
572 0 : if (n > 0)
573 0 : x_offset += extra_repeat_overlap;
574 0 : pos[k - 1].x_offset = x_offset;
575 : /* Append copy. */
576 0 : --j;
577 0 : info[j] = info[k - 1];
578 0 : pos[j] = pos[k - 1];
579 : }
580 : }
581 : }
582 : }
583 :
584 0 : if (step == MEASURE)
585 : {
586 0 : if (unlikely (!buffer->ensure (count + extra_glyphs_needed)))
587 0 : break;
588 : }
589 : else
590 : {
591 0 : assert (j == 0);
592 0 : buffer->len = new_len;
593 : }
594 : }
595 : }
596 :
597 :
598 : static void
599 0 : postprocess_glyphs_arabic (const hb_ot_shape_plan_t *plan,
600 : hb_buffer_t *buffer,
601 : hb_font_t *font)
602 : {
603 0 : apply_stch (plan, buffer, font);
604 :
605 0 : HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
606 0 : }
607 :
608 : const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
609 : {
610 : "arabic",
611 : collect_features_arabic,
612 : NULL, /* override_features */
613 : data_create_arabic,
614 : data_destroy_arabic,
615 : NULL, /* preprocess_text */
616 : postprocess_glyphs_arabic,
617 : HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
618 : NULL, /* decompose */
619 : NULL, /* compose */
620 : setup_masks_arabic,
621 : NULL, /* disable_otl */
622 : HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
623 : true, /* fallback_position */
624 : };
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