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-complex-khmer.hh"
28#include "hb-ot-layout.hh"
29
30
31/*
32 * Khmer shaper.
33 */
34
35struct feature_list_t {
36 hb_tag_t tag;
37 hb_ot_map_feature_flags_t flags;
38};
39
40static const feature_list_t
41khmer_features[] =
42{
43 /*
44 * Basic features.
45 * These features are applied in order, one at a time, after reordering.
46 */
47 {HB_TAG('p','r','e','f'), F_NONE},
48 {HB_TAG('b','l','w','f'), F_NONE},
49 {HB_TAG('a','b','v','f'), F_NONE},
50 {HB_TAG('p','s','t','f'), F_NONE},
51 {HB_TAG('c','f','a','r'), F_NONE},
52 /*
53 * Other features.
54 * These features are applied all at once.
55 */
56 {HB_TAG('p','r','e','s'), F_GLOBAL},
57 {HB_TAG('a','b','v','s'), F_GLOBAL},
58 {HB_TAG('b','l','w','s'), F_GLOBAL},
59 {HB_TAG('p','s','t','s'), F_GLOBAL},
60 /* Positioning features, though we don't care about the types. */
61 {HB_TAG('d','i','s','t'), F_GLOBAL},
62 {HB_TAG('a','b','v','m'), F_GLOBAL},
63 {HB_TAG('b','l','w','m'), F_GLOBAL},
64};
65
66/*
67 * Must be in the same order as the khmer_features array.
68 */
69enum {
70 PREF,
71 BLWF,
72 ABVF,
73 PSTF,
74 CFAR,
75
76 _PRES,
77 _ABVS,
78 _BLWS,
79 _PSTS,
80 _DIST,
81 _ABVM,
82 _BLWM,
83
84 KHMER_NUM_FEATURES,
85 KHMER_BASIC_FEATURES = _PRES /* Don't forget to update this! */
86};
87
88static void
89setup_syllables (const hb_ot_shape_plan_t *plan,
90 hb_font_t *font,
91 hb_buffer_t *buffer);
92static void
93reorder (const hb_ot_shape_plan_t *plan,
94 hb_font_t *font,
95 hb_buffer_t *buffer);
96static void
97clear_syllables (const hb_ot_shape_plan_t *plan,
98 hb_font_t *font,
99 hb_buffer_t *buffer);
100
101static void
102collect_features_khmer (hb_ot_shape_planner_t *plan)
103{
104 hb_ot_map_builder_t *map = &plan->map;
105
106 /* Do this before any lookups have been applied. */
107 map->add_gsub_pause (setup_syllables);
108 map->add_gsub_pause (reorder);
109
110 /* Testing suggests that Uniscribe does NOT pause between basic
111 * features. Test with KhmerUI.ttf and the following three
112 * sequences:
113 *
114 * U+1789,U+17BC
115 * U+1789,U+17D2,U+1789
116 * U+1789,U+17D2,U+1789,U+17BC
117 *
118 * https://github.com/harfbuzz/harfbuzz/issues/974
119 */
120 map->add_global_bool_feature (HB_TAG('l','o','c','l'));
121 map->add_global_bool_feature (HB_TAG('c','c','m','p'));
122
123 unsigned int i = 0;
124 for (; i < KHMER_BASIC_FEATURES; i++) {
125 map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
126 }
127
128 map->add_gsub_pause (clear_syllables);
129
130 for (; i < KHMER_NUM_FEATURES; i++) {
131 map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
132 }
133
134 map->add_global_bool_feature (HB_TAG('c','a','l','t'));
135 map->add_global_bool_feature (HB_TAG('c','l','i','g'));
136
137}
138
139static void
140override_features_khmer (hb_ot_shape_planner_t *plan)
141{
142 /* Uniscribe does not apply 'kern' in Khmer. */
143 if (hb_options ().uniscribe_bug_compatible)
144 {
145 plan->map.add_feature (HB_TAG('k','e','r','n'), 0, F_GLOBAL);
146 }
147
148 plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);
149}
150
151
152struct would_substitute_feature_t
153{
154 inline void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
155 {
156 zero_context = zero_context_;
157 map->get_stage_lookups (0/*GSUB*/,
158 map->get_feature_stage (0/*GSUB*/, feature_tag),
159 &lookups, &count);
160 }
161
162 inline bool would_substitute (const hb_codepoint_t *glyphs,
163 unsigned int glyphs_count,
164 hb_face_t *face) const
165 {
166 for (unsigned int i = 0; i < count; i++)
167 if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
168 return true;
169 return false;
170 }
171
172 private:
173 const hb_ot_map_t::lookup_map_t *lookups;
174 unsigned int count;
175 bool zero_context;
176};
177
178struct khmer_shape_plan_t
179{
180 ASSERT_POD ();
181
182 inline bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
183 {
184 hb_codepoint_t glyph = virama_glyph;
185 if (unlikely (virama_glyph == (hb_codepoint_t) -1))
186 {
187 if (!font->get_nominal_glyph (0x17D2u, &glyph))
188 glyph = 0;
189 /* Technically speaking, the spec says we should apply 'locl' to virama too.
190 * Maybe one day... */
191
192 /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
193 * during shape planning... Instead, overwrite it here. It's safe. Don't worry! */
194 virama_glyph = glyph;
195 }
196
197 *pglyph = glyph;
198 return glyph != 0;
199 }
200
201 mutable hb_codepoint_t virama_glyph;
202
203 would_substitute_feature_t pref;
204
205 hb_mask_t mask_array[KHMER_NUM_FEATURES];
206};
207
208static void *
209data_create_khmer (const hb_ot_shape_plan_t *plan)
210{
211 khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) calloc (1, sizeof (khmer_shape_plan_t));
212 if (unlikely (!khmer_plan))
213 return nullptr;
214
215 khmer_plan->virama_glyph = (hb_codepoint_t) -1;
216
217 khmer_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), true);
218
219 for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++)
220 khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ?
221 0 : plan->map.get_1_mask (khmer_features[i].tag);
222
223 return khmer_plan;
224}
225
226static void
227data_destroy_khmer (void *data)
228{
229 free (data);
230}
231
232
233enum syllable_type_t {
234 consonant_syllable,
235 broken_cluster,
236 non_khmer_cluster,
237};
238
239#include "hb-ot-shape-complex-khmer-machine.hh"
240
241static void
242setup_masks_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,
243 hb_buffer_t *buffer,
244 hb_font_t *font HB_UNUSED)
245{
246 HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category);
247 HB_BUFFER_ALLOCATE_VAR (buffer, khmer_position);
248
249 /* We cannot setup masks here. We save information about characters
250 * and setup masks later on in a pause-callback. */
251
252 unsigned int count = buffer->len;
253 hb_glyph_info_t *info = buffer->info;
254 for (unsigned int i = 0; i < count; i++)
255 set_khmer_properties (info[i]);
256}
257
258static void
259setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
260 hb_font_t *font HB_UNUSED,
261 hb_buffer_t *buffer)
262{
263 find_syllables (buffer);
264 foreach_syllable (buffer, start, end)
265 buffer->unsafe_to_break (start, end);
266}
267
268
269/* Rules from:
270 * https://docs.microsoft.com/en-us/typography/script-development/devanagari */
271
272static void
273reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,
274 hb_face_t *face,
275 hb_buffer_t *buffer,
276 unsigned int start, unsigned int end)
277{
278 const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;
279 hb_glyph_info_t *info = buffer->info;
280
281 /* Setup masks. */
282 {
283 /* Post-base */
284 hb_mask_t mask = khmer_plan->mask_array[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[PSTF];
285 for (unsigned int i = start + 1; i < end; i++)
286 info[i].mask |= mask;
287 }
288
289 unsigned int num_coengs = 0;
290 for (unsigned int i = start + 1; i < end; i++)
291 {
292 /* """
293 * When a COENG + (Cons | IndV) combination are found (and subscript count
294 * is less than two) the character combination is handled according to the
295 * subscript type of the character following the COENG.
296 *
297 * ...
298 *
299 * Subscript Type 2 - The COENG + RO characters are reordered to immediately
300 * before the base glyph. Then the COENG + RO characters are assigned to have
301 * the 'pref' OpenType feature applied to them.
302 * """
303 */
304 if (info[i].khmer_category() == OT_Coeng && num_coengs <= 2 && i + 1 < end)
305 {
306 num_coengs++;
307
308 if (info[i + 1].khmer_category() == OT_Ra)
309 {
310 for (unsigned int j = 0; j < 2; j++)
311 info[i + j].mask |= khmer_plan->mask_array[PREF];
312
313 /* Move the Coeng,Ro sequence to the start. */
314 buffer->merge_clusters (start, i + 2);
315 hb_glyph_info_t t0 = info[i];
316 hb_glyph_info_t t1 = info[i + 1];
317 memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0]));
318 info[start] = t0;
319 info[start + 1] = t1;
320
321 /* Mark the subsequent stuff with 'cfar'. Used in Khmer.
322 * Read the feature spec.
323 * This allows distinguishing the following cases with MS Khmer fonts:
324 * U+1784,U+17D2,U+179A,U+17D2,U+1782
325 * U+1784,U+17D2,U+1782,U+17D2,U+179A
326 */
327 if (khmer_plan->mask_array[CFAR])
328 for (unsigned int j = i + 2; j < end; j++)
329 info[j].mask |= khmer_plan->mask_array[CFAR];
330
331 num_coengs = 2; /* Done. */
332 }
333 }
334
335 /* Reorder left matra piece. */
336 else if (info[i].khmer_position() == POS_PRE_M)
337 {
338 /* Move to the start. */
339 buffer->merge_clusters (start, i + 1);
340 hb_glyph_info_t t = info[i];
341 memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0]));
342 info[start] = t;
343 }
344 }
345}
346
347static void
348initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
349 hb_face_t *face,
350 hb_buffer_t *buffer,
351 unsigned int start, unsigned int end)
352{
353 syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
354 switch (syllable_type)
355 {
356 case broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */
357 case consonant_syllable:
358 reorder_consonant_syllable (plan, face, buffer, start, end);
359 break;
360
361 case non_khmer_cluster:
362 break;
363 }
364}
365
366static inline void
367insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
368 hb_font_t *font,
369 hb_buffer_t *buffer)
370{
371 /* Note: This loop is extra overhead, but should not be measurable. */
372 bool has_broken_syllables = false;
373 unsigned int count = buffer->len;
374 hb_glyph_info_t *info = buffer->info;
375 for (unsigned int i = 0; i < count; i++)
376 if ((info[i].syllable() & 0x0F) == broken_cluster)
377 {
378 has_broken_syllables = true;
379 break;
380 }
381 if (likely (!has_broken_syllables))
382 return;
383
384
385 hb_codepoint_t dottedcircle_glyph;
386 if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
387 return;
388
389 hb_glyph_info_t dottedcircle = {0};
390 dottedcircle.codepoint = 0x25CCu;
391 set_khmer_properties (dottedcircle);
392 dottedcircle.codepoint = dottedcircle_glyph;
393
394 buffer->clear_output ();
395
396 buffer->idx = 0;
397 unsigned int last_syllable = 0;
398 while (buffer->idx < buffer->len && buffer->successful)
399 {
400 unsigned int syllable = buffer->cur().syllable();
401 syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
402 if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
403 {
404 last_syllable = syllable;
405
406 hb_glyph_info_t ginfo = dottedcircle;
407 ginfo.cluster = buffer->cur().cluster;
408 ginfo.mask = buffer->cur().mask;
409 ginfo.syllable() = buffer->cur().syllable();
410 /* TODO Set glyph_props? */
411
412 /* Insert dottedcircle after possible Repha. */
413 while (buffer->idx < buffer->len && buffer->successful &&
414 last_syllable == buffer->cur().syllable() &&
415 buffer->cur().khmer_category() == OT_Repha)
416 buffer->next_glyph ();
417
418 buffer->output_info (ginfo);
419 }
420 else
421 buffer->next_glyph ();
422 }
423
424 buffer->swap_buffers ();
425}
426
427static void
428reorder (const hb_ot_shape_plan_t *plan,
429 hb_font_t *font,
430 hb_buffer_t *buffer)
431{
432 insert_dotted_circles (plan, font, buffer);
433
434 foreach_syllable (buffer, start, end)
435 initial_reordering_syllable (plan, font->face, buffer, start, end);
436
437 HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);
438 HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_position);
439}
440
441static void
442clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
443 hb_font_t *font HB_UNUSED,
444 hb_buffer_t *buffer)
445{
446 /* TODO: In USE, we clear syllables right after reorder. Figure out
447 * what Uniscribe does. */
448 hb_glyph_info_t *info = buffer->info;
449 unsigned int count = buffer->len;
450 for (unsigned int i = 0; i < count; i++)
451 info[i].syllable() = 0;
452}
453
454
455static bool
456decompose_khmer (const hb_ot_shape_normalize_context_t *c,
457 hb_codepoint_t ab,
458 hb_codepoint_t *a,
459 hb_codepoint_t *b)
460{
461 switch (ab)
462 {
463 /*
464 * Decompose split matras that don't have Unicode decompositions.
465 */
466
467 /* Khmer */
468 case 0x17BEu : *a = 0x17C1u; *b= 0x17BEu; return true;
469 case 0x17BFu : *a = 0x17C1u; *b= 0x17BFu; return true;
470 case 0x17C0u : *a = 0x17C1u; *b= 0x17C0u; return true;
471 case 0x17C4u : *a = 0x17C1u; *b= 0x17C4u; return true;
472 case 0x17C5u : *a = 0x17C1u; *b= 0x17C5u; return true;
473 }
474
475 return (bool) c->unicode->decompose (ab, a, b);
476}
477
478static bool
479compose_khmer (const hb_ot_shape_normalize_context_t *c,
480 hb_codepoint_t a,
481 hb_codepoint_t b,
482 hb_codepoint_t *ab)
483{
484 /* Avoid recomposing split matras. */
485 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
486 return false;
487
488 return (bool) c->unicode->compose (a, b, ab);
489}
490
491
492const hb_ot_complex_shaper_t _hb_ot_complex_shaper_khmer =
493{
494 collect_features_khmer,
495 override_features_khmer,
496 data_create_khmer,
497 data_destroy_khmer,
498 nullptr, /* preprocess_text */
499 nullptr, /* postprocess_glyphs */
500 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
501 decompose_khmer,
502 compose_khmer,
503 setup_masks_khmer,
504 nullptr, /* disable_otl */
505 nullptr, /* reorder_marks */
506 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
507 false, /* fallback_position */
508};
509