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      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  */
     38 enum {
     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 
     58 static 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 
     73 static 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 */
     87 enum {
     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 
    101 static 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 
    132 static void
    133 nuke_joiners (const hb_ot_shape_plan_t *plan,
    134 	      hb_font_t *font,
    135 	      hb_buffer_t *buffer);
    136 
    137 static void
    138 arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
    139 		       hb_font_t *font,
    140 		       hb_buffer_t *buffer);
    141 
    142 static void
    143 collect_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 
    201 struct 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 
    215 static void *
    216 data_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 
    233 static void
    234 data_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 
    243 static void
    244 arabic_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   if (!(buffer->flags & HB_BUFFER_FLAG_BOT))
    252     for (unsigned int i = 0; i < buffer->context_len[0]; i++)
    253     {
    254       unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
    255 
    256       if (unlikely (this_type == JOINING_TYPE_T))
    257 	continue;
    258 
    259       const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
    260       state = entry->next_state;
    261       break;
    262     }
    263 
    264   for (unsigned int i = 0; i < count; i++)
    265   {
    266     unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
    267 
    268     if (unlikely (this_type == JOINING_TYPE_T)) {
    269       info[i].arabic_shaping_action() = NONE;
    270       continue;
    271     }
    272 
    273     const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
    274 
    275     if (entry->prev_action != NONE && prev != (unsigned int) -1)
    276       info[prev].arabic_shaping_action() = entry->prev_action;
    277 
    278     info[i].arabic_shaping_action() = entry->curr_action;
    279 
    280     prev = i;
    281     state = entry->next_state;
    282   }
    283 
    284   if (!(buffer->flags & HB_BUFFER_FLAG_EOT))
    285     for (unsigned int i = 0; i < buffer->context_len[1]; i++)
    286     {
    287       unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
    288 
    289       if (unlikely (this_type == JOINING_TYPE_T))
    290 	continue;
    291 
    292       const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
    293       if (entry->prev_action != NONE && prev != (unsigned int) -1)
    294 	info[prev].arabic_shaping_action() = entry->prev_action;
    295       break;
    296     }
    297 }
    298 
    299 static void
    300 mongolian_variation_selectors (hb_buffer_t *buffer)
    301 {
    302   /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
    303   unsigned int count = buffer->len;
    304   hb_glyph_info_t *info = buffer->info;
    305   for (unsigned int i = 1; i < count; i++)
    306     if (unlikely (hb_in_range (info[i].codepoint, 0x180Bu, 0x180Du)))
    307       info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
    308 }
    309 
    310 static void
    311 setup_masks_arabic (const hb_ot_shape_plan_t *plan,
    312 		    hb_buffer_t              *buffer,
    313 		    hb_font_t                *font HB_UNUSED)
    314 {
    315   HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
    316 
    317   const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
    318 
    319   arabic_joining (buffer);
    320   if (plan->props.script == HB_SCRIPT_MONGOLIAN)
    321     mongolian_variation_selectors (buffer);
    322 
    323   unsigned int count = buffer->len;
    324   hb_glyph_info_t *info = buffer->info;
    325   for (unsigned int i = 0; i < count; i++)
    326     info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
    327 
    328   HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
    329 }
    330 
    331 
    332 static void
    333 nuke_joiners (const hb_ot_shape_plan_t *plan HB_UNUSED,
    334 	      hb_font_t *font HB_UNUSED,
    335 	      hb_buffer_t *buffer)
    336 {
    337   unsigned int count = buffer->len;
    338   hb_glyph_info_t *info = buffer->info;
    339   for (unsigned int i = 0; i < count; i++)
    340     if (_hb_glyph_info_is_zwj (&info[i]))
    341       _hb_glyph_info_flip_joiners (&info[i]);
    342 }
    343 
    344 static void
    345 arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
    346 		       hb_font_t *font,
    347 		       hb_buffer_t *buffer)
    348 {
    349   const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
    350 
    351   if (!arabic_plan->do_fallback)
    352     return;
    353 
    354 retry:
    355   arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_atomic_ptr_get (&arabic_plan->fallback_plan);
    356   if (unlikely (!fallback_plan))
    357   {
    358     /* This sucks.  We need a font to build the fallback plan... */
    359     fallback_plan = arabic_fallback_plan_create (plan, font);
    360     if (unlikely (!hb_atomic_ptr_cmpexch (&(const_cast<arabic_shape_plan_t *> (arabic_plan))->fallback_plan, NULL, fallback_plan))) {
    361       arabic_fallback_plan_destroy (fallback_plan);
    362       goto retry;
    363     }
    364   }
    365 
    366   arabic_fallback_plan_shape (fallback_plan, font, buffer);
    367 }
    368 
    369 
    370 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
    371 {
    372   "arabic",
    373   collect_features_arabic,
    374   NULL, /* override_features */
    375   data_create_arabic,
    376   data_destroy_arabic,
    377   NULL, /* preprocess_text_arabic */
    378   HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
    379   NULL, /* decompose */
    380   NULL, /* compose */
    381   setup_masks_arabic,
    382   HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
    383   true, /* fallback_position */
    384 };
    385