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1 /*
2  * Copyright © 2011,2012  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-fallback-private.hh"
28 #include "hb-ot-layout-gsubgpos-private.hh"
29 
30 static unsigned int
recategorize_combining_class(hb_codepoint_t u,unsigned int klass)31 recategorize_combining_class (hb_codepoint_t u,
32 			      unsigned int klass)
33 {
34   if (klass >= 200)
35     return klass;
36 
37   /* Thai / Lao need some per-character work. */
38   if ((u & ~0xFF) == 0x0E00u)
39   {
40     if (unlikely (klass == 0))
41     {
42       switch (u)
43       {
44         case 0x0E31u:
45         case 0x0E34u:
46         case 0x0E35u:
47         case 0x0E36u:
48         case 0x0E37u:
49         case 0x0E47u:
50         case 0x0E4Cu:
51         case 0x0E4Du:
52         case 0x0E4Eu:
53 	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
54 	  break;
55 
56         case 0x0EB1u:
57         case 0x0EB4u:
58         case 0x0EB5u:
59         case 0x0EB6u:
60         case 0x0EB7u:
61         case 0x0EBBu:
62         case 0x0ECCu:
63         case 0x0ECDu:
64 	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
65 	  break;
66 
67         case 0x0EBCu:
68 	  klass = HB_UNICODE_COMBINING_CLASS_BELOW;
69 	  break;
70       }
71     } else {
72       /* Thai virama is below-right */
73       if (u == 0x0E3Au)
74 	klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
75     }
76   }
77 
78   switch (klass)
79   {
80 
81     /* Hebrew */
82 
83     case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
84     case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
85     case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
86     case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
87     case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
88     case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
89     case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
90     case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
91     case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */
92     case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
93     case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
94       return HB_UNICODE_COMBINING_CLASS_BELOW;
95 
96     case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
97       return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
98 
99     case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
100       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
101 
102     case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
103     case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */
104       return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
105 
106     case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
107       return HB_UNICODE_COMBINING_CLASS_ABOVE;
108 
109     case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
110       break;
111 
112 
113     /* Arabic and Syriac */
114 
115     case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
116     case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
117     case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
118     case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
119     case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
120     case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
121     case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
122     case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
123       return HB_UNICODE_COMBINING_CLASS_ABOVE;
124 
125     case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
126     case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
127       return HB_UNICODE_COMBINING_CLASS_BELOW;
128 
129 
130     /* Thai */
131 
132     case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
133       return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
134 
135     case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
136       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
137 
138 
139     /* Lao */
140 
141     case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
142       return HB_UNICODE_COMBINING_CLASS_BELOW;
143 
144     case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
145       return HB_UNICODE_COMBINING_CLASS_ABOVE;
146 
147 
148     /* Tibetan */
149 
150     case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
151       return HB_UNICODE_COMBINING_CLASS_BELOW;
152 
153     case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
154       return HB_UNICODE_COMBINING_CLASS_ABOVE;
155 
156     case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
157       return HB_UNICODE_COMBINING_CLASS_BELOW;
158 
159   }
160 
161   return klass;
162 }
163 
164 void
_hb_ot_shape_fallback_position_recategorize_marks(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font HB_UNUSED,hb_buffer_t * buffer)165 _hb_ot_shape_fallback_position_recategorize_marks (const hb_ot_shape_plan_t *plan HB_UNUSED,
166 						   hb_font_t *font HB_UNUSED,
167 						   hb_buffer_t  *buffer)
168 {
169   unsigned int count = buffer->len;
170   hb_glyph_info_t *info = buffer->info;
171   for (unsigned int i = 0; i < count; i++)
172     if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
173       unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
174       combining_class = recategorize_combining_class (info[i].codepoint, combining_class);
175       _hb_glyph_info_set_modified_combining_class (&info[i], combining_class);
176     }
177 }
178 
179 
180 static void
zero_mark_advances(hb_buffer_t * buffer,unsigned int start,unsigned int end)181 zero_mark_advances (hb_buffer_t *buffer,
182 		    unsigned int start,
183 		    unsigned int end)
184 {
185   hb_glyph_info_t *info = buffer->info;
186   for (unsigned int i = start; i < end; i++)
187     if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
188     {
189       buffer->pos[i].x_advance = 0;
190       buffer->pos[i].y_advance = 0;
191     }
192 }
193 
194 static inline void
position_mark(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer,hb_glyph_extents_t & base_extents,unsigned int i,unsigned int combining_class)195 position_mark (const hb_ot_shape_plan_t *plan,
196 	       hb_font_t *font,
197 	       hb_buffer_t  *buffer,
198 	       hb_glyph_extents_t &base_extents,
199 	       unsigned int i,
200 	       unsigned int combining_class)
201 {
202   hb_glyph_extents_t mark_extents;
203   if (!font->get_glyph_extents (buffer->info[i].codepoint,
204 				&mark_extents))
205     return;
206 
207   hb_position_t y_gap = font->y_scale / 16;
208 
209   hb_glyph_position_t &pos = buffer->pos[i];
210   pos.x_offset = pos.y_offset = 0;
211 
212 
213   /* We dont position LEFT and RIGHT marks. */
214 
215   /* X positioning */
216   switch (combining_class)
217   {
218     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
219     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
220       if (buffer->props.direction == HB_DIRECTION_LTR) {
221 	pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
222         break;
223       } else if (buffer->props.direction == HB_DIRECTION_RTL) {
224 	pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
225         break;
226       }
227       /* Fall through */
228 
229     default:
230     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
231     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
232     case HB_UNICODE_COMBINING_CLASS_BELOW:
233     case HB_UNICODE_COMBINING_CLASS_ABOVE:
234       /* Center align. */
235       pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
236       break;
237 
238     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
239     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
240     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
241       /* Left align. */
242       pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
243       break;
244 
245     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
246     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
247     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
248       /* Right align. */
249       pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
250       break;
251   }
252 
253   /* Y positioning */
254   switch (combining_class)
255   {
256     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
257     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
258     case HB_UNICODE_COMBINING_CLASS_BELOW:
259     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
260       /* Add gap, fall-through. */
261       base_extents.height -= y_gap;
262 
263     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
264     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
265       pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
266       /* Never shift up "below" marks. */
267       if ((y_gap > 0) == (pos.y_offset > 0))
268       {
269 	base_extents.height -= pos.y_offset;
270 	pos.y_offset = 0;
271       }
272       base_extents.height += mark_extents.height;
273       break;
274 
275     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
276     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
277     case HB_UNICODE_COMBINING_CLASS_ABOVE:
278     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
279       /* Add gap, fall-through. */
280       base_extents.y_bearing += y_gap;
281       base_extents.height -= y_gap;
282 
283     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
284     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
285       pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
286       /* Don't shift down "above" marks too much. */
287       if ((y_gap > 0) != (pos.y_offset > 0))
288       {
289 	unsigned int correction = -pos.y_offset / 2;
290 	base_extents.y_bearing += correction;
291 	base_extents.height -= correction;
292 	pos.y_offset += correction;
293       }
294       base_extents.y_bearing -= mark_extents.height;
295       base_extents.height += mark_extents.height;
296       break;
297   }
298 }
299 
300 static inline void
position_around_base(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer,unsigned int base,unsigned int end)301 position_around_base (const hb_ot_shape_plan_t *plan,
302 		      hb_font_t *font,
303 		      hb_buffer_t  *buffer,
304 		      unsigned int base,
305 		      unsigned int end)
306 {
307   hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
308   hb_glyph_extents_t base_extents;
309   if (!font->get_glyph_extents (buffer->info[base].codepoint,
310 				&base_extents))
311   {
312     /* If extents don't work, zero marks and go home. */
313     zero_mark_advances (buffer, base + 1, end);
314     return;
315   }
316   base_extents.x_bearing += buffer->pos[base].x_offset;
317   base_extents.y_bearing += buffer->pos[base].y_offset;
318 
319   unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);
320   unsigned int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);
321 
322   hb_position_t x_offset = 0, y_offset = 0;
323   if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
324     x_offset -= buffer->pos[base].x_advance;
325     y_offset -= buffer->pos[base].y_advance;
326   }
327 
328   hb_glyph_extents_t component_extents = base_extents;
329   unsigned int last_lig_component = (unsigned int) -1;
330   unsigned int last_combining_class = 255;
331   hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */
332   hb_glyph_info_t *info = buffer->info;
333   for (unsigned int i = base + 1; i < end; i++)
334     if (_hb_glyph_info_get_modified_combining_class (&info[i]))
335     {
336       if (num_lig_components > 1) {
337 	unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&info[i]);
338 	unsigned int this_lig_component = _hb_glyph_info_get_lig_comp (&info[i]) - 1;
339 	/* Conditions for attaching to the last component. */
340 	if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
341 	  this_lig_component = num_lig_components - 1;
342 	if (last_lig_component != this_lig_component)
343 	{
344 	  last_lig_component = this_lig_component;
345 	  last_combining_class = 255;
346 	  component_extents = base_extents;
347 	  if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
348 	    if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
349 	      horiz_dir = plan->props.direction;
350 	    else
351 	      horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
352 	  }
353 	  if (horiz_dir == HB_DIRECTION_LTR)
354 	    component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
355 	  else
356 	    component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
357 	  component_extents.width /= num_lig_components;
358 	}
359       }
360 
361       unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
362       if (last_combining_class != this_combining_class)
363       {
364 	last_combining_class = this_combining_class;
365         cluster_extents = component_extents;
366       }
367 
368       position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
369 
370       buffer->pos[i].x_advance = 0;
371       buffer->pos[i].y_advance = 0;
372       buffer->pos[i].x_offset += x_offset;
373       buffer->pos[i].y_offset += y_offset;
374 
375     } else {
376       if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
377 	x_offset -= buffer->pos[i].x_advance;
378 	y_offset -= buffer->pos[i].y_advance;
379       } else {
380 	x_offset += buffer->pos[i].x_advance;
381 	y_offset += buffer->pos[i].y_advance;
382       }
383     }
384 }
385 
386 static inline void
position_cluster(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer,unsigned int start,unsigned int end)387 position_cluster (const hb_ot_shape_plan_t *plan,
388 		  hb_font_t *font,
389 		  hb_buffer_t  *buffer,
390 		  unsigned int start,
391 		  unsigned int end)
392 {
393   if (end - start < 2)
394     return;
395 
396   /* Find the base glyph */
397   hb_glyph_info_t *info = buffer->info;
398   for (unsigned int i = start; i < end; i++)
399     if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))
400     {
401       /* Find mark glyphs */
402       unsigned int j;
403       for (j = i + 1; j < end; j++)
404 	if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[j])))
405 	  break;
406 
407       position_around_base (plan, font, buffer, i, j);
408 
409       i = j - 1;
410     }
411 }
412 
413 void
_hb_ot_shape_fallback_position(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)414 _hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
415 				hb_font_t *font,
416 				hb_buffer_t  *buffer)
417 {
418   _hb_buffer_assert_gsubgpos_vars (buffer);
419 
420   unsigned int start = 0;
421   unsigned int last_cluster = buffer->info[0].cluster;
422   unsigned int count = buffer->len;
423   for (unsigned int i = 1; i < count; i++)
424     if (buffer->info[i].cluster != last_cluster) {
425       position_cluster (plan, font, buffer, start, i);
426       start = i;
427       last_cluster = buffer->info[i].cluster;
428     }
429   position_cluster (plan, font, buffer, start, count);
430 }
431 
432 
433 /* Performs old-style TrueType kerning. */
434 void
_hb_ot_shape_fallback_kern(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)435 _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
436 			    hb_font_t *font,
437 			    hb_buffer_t  *buffer)
438 {
439   if (!plan->has_kern) return;
440 
441   OT::hb_apply_context_t c (1, font, buffer);
442   c.set_lookup_mask (plan->kern_mask);
443   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
444 
445   unsigned int count = buffer->len;
446   hb_glyph_info_t *info = buffer->info;
447   hb_glyph_position_t *pos = buffer->pos;
448   for (unsigned int idx = 0; idx < count;)
449   {
450     OT::hb_apply_context_t::skipping_forward_iterator_t skippy_iter (&c, idx, 1);
451     if (!skippy_iter.next ())
452     {
453       idx++;
454       continue;
455     }
456 
457     hb_position_t x_kern, y_kern;
458     font->get_glyph_kerning_for_direction (info[idx].codepoint,
459 					   info[skippy_iter.idx].codepoint,
460 					   buffer->props.direction,
461 					   &x_kern, &y_kern);
462 
463     if (x_kern)
464     {
465       hb_position_t kern1 = x_kern >> 1;
466       hb_position_t kern2 = x_kern - kern1;
467       pos[idx].x_advance += kern1;
468       pos[skippy_iter.idx].x_advance += kern2;
469       pos[skippy_iter.idx].x_offset += kern2;
470     }
471 
472     if (y_kern)
473     {
474       hb_position_t kern1 = y_kern >> 1;
475       hb_position_t kern2 = y_kern - kern1;
476       pos[idx].y_advance += kern1;
477       pos[skippy_iter.idx].y_advance += kern2;
478       pos[skippy_iter.idx].y_offset += kern2;
479     }
480 
481     idx = skippy_iter.idx;
482   }
483 }
484