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-private.hh"
28#include "hb-ot-shape-private.hh"
29
30
31/* buffer var allocations */
32#define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */
33
34
35/*
36 * Bits used in the joining tables
37 */
38enum {
39  JOINING_TYPE_U		= 0,
40  JOINING_TYPE_L		= 1,
41  JOINING_TYPE_R		= 2,
42  JOINING_TYPE_D		= 3,
43  JOINING_TYPE_C		= JOINING_TYPE_D,
44  JOINING_GROUP_ALAPH		= 4,
45  JOINING_GROUP_DALATH_RISH	= 5,
46  NUM_STATE_MACHINE_COLS	= 6,
47
48  JOINING_TYPE_T = 7,
49  JOINING_TYPE_X = 8  /* means: use general-category to choose between U or T. */
50};
51
52/*
53 * Joining types:
54 */
55
56#include "hb-ot-shape-complex-arabic-table.hh"
57
58static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
59{
60  unsigned int j_type = joining_type(u);
61  if (likely (j_type != JOINING_TYPE_X))
62    return j_type;
63
64  return (FLAG(gen_cat) &
65	  (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) |
66	   FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
67	   FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))
68	 ) ?  JOINING_TYPE_T : JOINING_TYPE_U;
69}
70
71#define FEATURE_IS_SYRIAC(tag) hb_in_range<unsigned char> ((unsigned char) (tag), '2', '3')
72
73static const hb_tag_t arabic_features[] =
74{
75  HB_TAG('i','s','o','l'),
76  HB_TAG('f','i','n','a'),
77  HB_TAG('f','i','n','2'),
78  HB_TAG('f','i','n','3'),
79  HB_TAG('m','e','d','i'),
80  HB_TAG('m','e','d','2'),
81  HB_TAG('i','n','i','t'),
82  HB_TAG_NONE
83};
84
85
86/* Same order as the feature array */
87enum {
88  ISOL,
89  FINA,
90  FIN2,
91  FIN3,
92  MEDI,
93  MED2,
94  INIT,
95
96  NONE,
97
98  ARABIC_NUM_FEATURES = NONE
99};
100
101static const struct arabic_state_table_entry {
102	uint8_t prev_action;
103	uint8_t curr_action;
104	uint16_t next_state;
105} arabic_state_table[][NUM_STATE_MACHINE_COLS] =
106{
107  /*   jt_U,          jt_L,          jt_R,          jt_D,          jg_ALAPH,      jg_DALATH_RISH */
108
109  /* State 0: prev was U, not willing to join. */
110  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },
111
112  /* State 1: prev was R or ISOL/ALAPH, not willing to join. */
113  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },
114
115  /* State 2: prev was D/L in ISOL form, willing to join. */
116  { {NONE,NONE,0}, {NONE,ISOL,2}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },
117
118  /* State 3: prev was D in FINA form, willing to join. */
119  { {NONE,NONE,0}, {NONE,ISOL,2}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },
120
121  /* State 4: prev was FINA ALAPH, not willing to join. */
122  { {NONE,NONE,0}, {NONE,ISOL,2}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },
123
124  /* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
125  { {NONE,NONE,0}, {NONE,ISOL,2}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },
126
127  /* State 6: prev was DALATH/RISH, not willing to join. */
128  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
129};
130
131
132static void
133nuke_joiners (const hb_ot_shape_plan_t *plan,
134	      hb_font_t *font,
135	      hb_buffer_t *buffer);
136
137static void
138arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
139		       hb_font_t *font,
140		       hb_buffer_t *buffer);
141
142static void
143collect_features_arabic (hb_ot_shape_planner_t *plan)
144{
145  hb_ot_map_builder_t *map = &plan->map;
146
147  /* We apply features according to the Arabic spec, with pauses
148   * in between most.
149   *
150   * The pause between init/medi/... and rlig is required.  See eg:
151   * https://bugzilla.mozilla.org/show_bug.cgi?id=644184
152   *
153   * The pauses between init/medi/... themselves are not necessarily
154   * needed as only one of those features is applied to any character.
155   * The only difference it makes is when fonts have contextual
156   * substitutions.  We now follow the order of the spec, which makes
157   * for better experience if that's what Uniscribe is doing.
158   *
159   * At least for Arabic, looks like Uniscribe has a pause between
160   * rlig and calt.  Otherwise the IranNastaliq's ALLAH ligature won't
161   * work.  However, testing shows that rlig and calt are applied
162   * together for Mongolian in Uniscribe.  As such, we only add a
163   * pause for Arabic, not other scripts.
164   */
165
166  map->add_gsub_pause (nuke_joiners);
167
168  map->add_global_bool_feature (HB_TAG('c','c','m','p'));
169  map->add_global_bool_feature (HB_TAG('l','o','c','l'));
170
171  map->add_gsub_pause (NULL);
172
173  for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
174  {
175    bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);
176    map->add_feature (arabic_features[i], 1, has_fallback ? F_HAS_FALLBACK : F_NONE);
177    map->add_gsub_pause (NULL);
178  }
179
180  map->add_feature (HB_TAG('r','l','i','g'), 1, F_GLOBAL|F_HAS_FALLBACK);
181  if (plan->props.script == HB_SCRIPT_ARABIC)
182    map->add_gsub_pause (arabic_fallback_shape);
183
184  map->add_global_bool_feature (HB_TAG('c','a','l','t'));
185  map->add_gsub_pause (NULL);
186
187  /* The spec includes 'cswh'.  Earlier versions of Windows
188   * used to enable this by default, but testing suggests
189   * that Windows 8 and later do not enable it by default,
190   * and spec now says 'Off by default'.
191   * We disabled this in ae23c24c32.
192   * Note that IranNastaliq uses this feature extensively
193   * to fixup broken glyph sequences.  Oh well...
194   * Test case: U+0643,U+0640,U+0631. */
195  //map->add_global_bool_feature (HB_TAG('c','s','w','h'));
196  map->add_global_bool_feature (HB_TAG('m','s','e','t'));
197}
198
199#include "hb-ot-shape-complex-arabic-fallback.hh"
200
201struct arabic_shape_plan_t
202{
203  ASSERT_POD ();
204
205  /* The "+ 1" in the next array is to accommodate for the "NONE" command,
206   * which is not an OpenType feature, but this simplifies the code by not
207   * having to do a "if (... < NONE) ..." and just rely on the fact that
208   * mask_array[NONE] == 0. */
209  hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
210
211  bool do_fallback;
212  arabic_fallback_plan_t *fallback_plan;
213};
214
215static void *
216data_create_arabic (const hb_ot_shape_plan_t *plan)
217{
218  arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) calloc (1, sizeof (arabic_shape_plan_t));
219  if (unlikely (!arabic_plan))
220    return NULL;
221
222  arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;
223  for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
224    arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
225    arabic_plan->do_fallback = arabic_plan->do_fallback &&
226			       (FEATURE_IS_SYRIAC (arabic_features[i]) ||
227			        plan->map.needs_fallback (arabic_features[i]));
228  }
229
230  return arabic_plan;
231}
232
233static void
234data_destroy_arabic (void *data)
235{
236  arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;
237
238  arabic_fallback_plan_destroy (arabic_plan->fallback_plan);
239
240  free (data);
241}
242
243static void
244arabic_joining (hb_buffer_t *buffer)
245{
246  unsigned int count = buffer->len;
247  hb_glyph_info_t *info = buffer->info;
248  unsigned int prev = (unsigned int) -1, state = 0;
249
250  /* Check pre-context */
251  for (unsigned int i = 0; i < buffer->context_len[0]; i++)
252  {
253    unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
254
255    if (unlikely (this_type == JOINING_TYPE_T))
256      continue;
257
258    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
259    state = entry->next_state;
260    break;
261  }
262
263  for (unsigned int i = 0; i < count; i++)
264  {
265    unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
266
267    if (unlikely (this_type == JOINING_TYPE_T)) {
268      info[i].arabic_shaping_action() = NONE;
269      continue;
270    }
271
272    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
273
274    if (entry->prev_action != NONE && prev != (unsigned int) -1)
275      info[prev].arabic_shaping_action() = entry->prev_action;
276
277    info[i].arabic_shaping_action() = entry->curr_action;
278
279    prev = i;
280    state = entry->next_state;
281  }
282
283  for (unsigned int i = 0; i < buffer->context_len[1]; i++)
284  {
285    unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
286
287    if (unlikely (this_type == JOINING_TYPE_T))
288      continue;
289
290    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
291    if (entry->prev_action != NONE && prev != (unsigned int) -1)
292      info[prev].arabic_shaping_action() = entry->prev_action;
293    break;
294  }
295}
296
297static void
298mongolian_variation_selectors (hb_buffer_t *buffer)
299{
300  /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
301  unsigned int count = buffer->len;
302  hb_glyph_info_t *info = buffer->info;
303  for (unsigned int i = 1; i < count; i++)
304    if (unlikely (hb_in_range (info[i].codepoint, 0x180Bu, 0x180Du)))
305      info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
306}
307
308static void
309setup_masks_arabic (const hb_ot_shape_plan_t *plan,
310		    hb_buffer_t              *buffer,
311		    hb_font_t                *font HB_UNUSED)
312{
313  HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
314
315  const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
316
317  arabic_joining (buffer);
318  if (plan->props.script == HB_SCRIPT_MONGOLIAN)
319    mongolian_variation_selectors (buffer);
320
321  unsigned int count = buffer->len;
322  hb_glyph_info_t *info = buffer->info;
323  for (unsigned int i = 0; i < count; i++)
324    info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
325
326  HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
327}
328
329
330static void
331nuke_joiners (const hb_ot_shape_plan_t *plan HB_UNUSED,
332	      hb_font_t *font HB_UNUSED,
333	      hb_buffer_t *buffer)
334{
335  unsigned int count = buffer->len;
336  hb_glyph_info_t *info = buffer->info;
337  for (unsigned int i = 0; i < count; i++)
338    if (_hb_glyph_info_is_zwj (&info[i]))
339      _hb_glyph_info_flip_joiners (&info[i]);
340}
341
342static void
343arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
344		       hb_font_t *font,
345		       hb_buffer_t *buffer)
346{
347  const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
348
349  if (!arabic_plan->do_fallback)
350    return;
351
352retry:
353  arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_atomic_ptr_get (&arabic_plan->fallback_plan);
354  if (unlikely (!fallback_plan))
355  {
356    /* This sucks.  We need a font to build the fallback plan... */
357    fallback_plan = arabic_fallback_plan_create (plan, font);
358    if (unlikely (!hb_atomic_ptr_cmpexch (&(const_cast<arabic_shape_plan_t *> (arabic_plan))->fallback_plan, NULL, fallback_plan))) {
359      arabic_fallback_plan_destroy (fallback_plan);
360      goto retry;
361    }
362  }
363
364  arabic_fallback_plan_shape (fallback_plan, font, buffer);
365}
366
367
368const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
369{
370  "arabic",
371  collect_features_arabic,
372  NULL, /* override_features */
373  data_create_arabic,
374  data_destroy_arabic,
375  NULL, /* preprocess_text_arabic */
376  HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
377  NULL, /* decompose */
378  NULL, /* compose */
379  setup_masks_arabic,
380  HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
381  true, /* fallback_position */
382};
383