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