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.hh"
28
29 #ifndef HB_NO_OT_SHAPE
30
31 #include "hb-ot-shape-complex.hh"
32
33
34 /* Thai / Lao shaper */
35
36
37 /* PUA shaping */
38
39
40 enum thai_consonant_type_t
41 {
42 NC,
43 AC,
44 RC,
45 DC,
46 NOT_CONSONANT,
47 NUM_CONSONANT_TYPES = NOT_CONSONANT
48 };
49
50 static thai_consonant_type_t
get_consonant_type(hb_codepoint_t u)51 get_consonant_type (hb_codepoint_t u)
52 {
53 if (u == 0x0E1Bu || u == 0x0E1Du || u == 0x0E1Fu/* || u == 0x0E2Cu*/)
54 return AC;
55 if (u == 0x0E0Du || u == 0x0E10u)
56 return RC;
57 if (u == 0x0E0Eu || u == 0x0E0Fu)
58 return DC;
59 if (hb_in_range<hb_codepoint_t> (u, 0x0E01u, 0x0E2Eu))
60 return NC;
61 return NOT_CONSONANT;
62 }
63
64
65 enum thai_mark_type_t
66 {
67 AV,
68 BV,
69 T,
70 NOT_MARK,
71 NUM_MARK_TYPES = NOT_MARK
72 };
73
74 static thai_mark_type_t
get_mark_type(hb_codepoint_t u)75 get_mark_type (hb_codepoint_t u)
76 {
77 if (u == 0x0E31u || hb_in_range<hb_codepoint_t> (u, 0x0E34u, 0x0E37u) ||
78 u == 0x0E47u || hb_in_range<hb_codepoint_t> (u, 0x0E4Du, 0x0E4Eu))
79 return AV;
80 if (hb_in_range<hb_codepoint_t> (u, 0x0E38u, 0x0E3Au))
81 return BV;
82 if (hb_in_range<hb_codepoint_t> (u, 0x0E48u, 0x0E4Cu))
83 return T;
84 return NOT_MARK;
85 }
86
87
88 enum thai_action_t
89 {
90 NOP,
91 SD, /* Shift combining-mark down */
92 SL, /* Shift combining-mark left */
93 SDL, /* Shift combining-mark down-left */
94 RD /* Remove descender from base */
95 };
96
97 static hb_codepoint_t
thai_pua_shape(hb_codepoint_t u,thai_action_t action,hb_font_t * font)98 thai_pua_shape (hb_codepoint_t u, thai_action_t action, hb_font_t *font)
99 {
100 struct thai_pua_mapping_t {
101 hb_codepoint_t u;
102 hb_codepoint_t win_pua;
103 hb_codepoint_t mac_pua;
104 } const *pua_mappings = nullptr;
105 static const thai_pua_mapping_t SD_mappings[] = {
106 {0x0E48u, 0xF70Au, 0xF88Bu}, /* MAI EK */
107 {0x0E49u, 0xF70Bu, 0xF88Eu}, /* MAI THO */
108 {0x0E4Au, 0xF70Cu, 0xF891u}, /* MAI TRI */
109 {0x0E4Bu, 0xF70Du, 0xF894u}, /* MAI CHATTAWA */
110 {0x0E4Cu, 0xF70Eu, 0xF897u}, /* THANTHAKHAT */
111 {0x0E38u, 0xF718u, 0xF89Bu}, /* SARA U */
112 {0x0E39u, 0xF719u, 0xF89Cu}, /* SARA UU */
113 {0x0E3Au, 0xF71Au, 0xF89Du}, /* PHINTHU */
114 {0x0000u, 0x0000u, 0x0000u}
115 };
116 static const thai_pua_mapping_t SDL_mappings[] = {
117 {0x0E48u, 0xF705u, 0xF88Cu}, /* MAI EK */
118 {0x0E49u, 0xF706u, 0xF88Fu}, /* MAI THO */
119 {0x0E4Au, 0xF707u, 0xF892u}, /* MAI TRI */
120 {0x0E4Bu, 0xF708u, 0xF895u}, /* MAI CHATTAWA */
121 {0x0E4Cu, 0xF709u, 0xF898u}, /* THANTHAKHAT */
122 {0x0000u, 0x0000u, 0x0000u}
123 };
124 static const thai_pua_mapping_t SL_mappings[] = {
125 {0x0E48u, 0xF713u, 0xF88Au}, /* MAI EK */
126 {0x0E49u, 0xF714u, 0xF88Du}, /* MAI THO */
127 {0x0E4Au, 0xF715u, 0xF890u}, /* MAI TRI */
128 {0x0E4Bu, 0xF716u, 0xF893u}, /* MAI CHATTAWA */
129 {0x0E4Cu, 0xF717u, 0xF896u}, /* THANTHAKHAT */
130 {0x0E31u, 0xF710u, 0xF884u}, /* MAI HAN-AKAT */
131 {0x0E34u, 0xF701u, 0xF885u}, /* SARA I */
132 {0x0E35u, 0xF702u, 0xF886u}, /* SARA II */
133 {0x0E36u, 0xF703u, 0xF887u}, /* SARA UE */
134 {0x0E37u, 0xF704u, 0xF888u}, /* SARA UEE */
135 {0x0E47u, 0xF712u, 0xF889u}, /* MAITAIKHU */
136 {0x0E4Du, 0xF711u, 0xF899u}, /* NIKHAHIT */
137 {0x0000u, 0x0000u, 0x0000u}
138 };
139 static const thai_pua_mapping_t RD_mappings[] = {
140 {0x0E0Du, 0xF70Fu, 0xF89Au}, /* YO YING */
141 {0x0E10u, 0xF700u, 0xF89Eu}, /* THO THAN */
142 {0x0000u, 0x0000u, 0x0000u}
143 };
144
145 switch (action) {
146 case NOP: return u;
147 case SD: pua_mappings = SD_mappings; break;
148 case SDL: pua_mappings = SDL_mappings; break;
149 case SL: pua_mappings = SL_mappings; break;
150 case RD: pua_mappings = RD_mappings; break;
151 }
152 for (; pua_mappings->u; pua_mappings++)
153 if (pua_mappings->u == u)
154 {
155 hb_codepoint_t glyph;
156 if (hb_font_get_glyph (font, pua_mappings->win_pua, 0, &glyph))
157 return pua_mappings->win_pua;
158 if (hb_font_get_glyph (font, pua_mappings->mac_pua, 0, &glyph))
159 return pua_mappings->mac_pua;
160 break;
161 }
162 return u;
163 }
164
165
166 static enum thai_above_state_t
167 { /* Cluster above looks like: */
168 T0, /* ⣤ */
169 T1, /* ⣼ */
170 T2, /* ⣾ */
171 T3, /* ⣿ */
172 NUM_ABOVE_STATES
173 } thai_above_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =
174 {
175 T0, /* NC */
176 T1, /* AC */
177 T0, /* RC */
178 T0, /* DC */
179 T3, /* NOT_CONSONANT */
180 };
181
182 static const struct thai_above_state_machine_edge_t {
183 thai_action_t action;
184 thai_above_state_t next_state;
185 } thai_above_state_machine[NUM_ABOVE_STATES][NUM_MARK_TYPES] =
186 { /*AV*/ /*BV*/ /*T*/
187 /*T0*/ {{NOP,T3}, {NOP,T0}, {SD, T3}},
188 /*T1*/ {{SL, T2}, {NOP,T1}, {SDL,T2}},
189 /*T2*/ {{NOP,T3}, {NOP,T2}, {SL, T3}},
190 /*T3*/ {{NOP,T3}, {NOP,T3}, {NOP,T3}},
191 };
192
193
194 static enum thai_below_state_t
195 {
196 B0, /* No descender */
197 B1, /* Removable descender */
198 B2, /* Strict descender */
199 NUM_BELOW_STATES
200 } thai_below_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =
201 {
202 B0, /* NC */
203 B0, /* AC */
204 B1, /* RC */
205 B2, /* DC */
206 B2, /* NOT_CONSONANT */
207 };
208
209 static const struct thai_below_state_machine_edge_t {
210 thai_action_t action;
211 thai_below_state_t next_state;
212 } thai_below_state_machine[NUM_BELOW_STATES][NUM_MARK_TYPES] =
213 { /*AV*/ /*BV*/ /*T*/
214 /*B0*/ {{NOP,B0}, {NOP,B2}, {NOP, B0}},
215 /*B1*/ {{NOP,B1}, {RD, B2}, {NOP, B1}},
216 /*B2*/ {{NOP,B2}, {SD, B2}, {NOP, B2}},
217 };
218
219
220 static void
do_thai_pua_shaping(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_buffer_t * buffer,hb_font_t * font)221 do_thai_pua_shaping (const hb_ot_shape_plan_t *plan HB_UNUSED,
222 hb_buffer_t *buffer,
223 hb_font_t *font)
224 {
225 #ifdef HB_NO_OT_SHAPE_COMPLEX_THAI_FALLBACK
226 return;
227 #endif
228
229 thai_above_state_t above_state = thai_above_start_state[NOT_CONSONANT];
230 thai_below_state_t below_state = thai_below_start_state[NOT_CONSONANT];
231 unsigned int base = 0;
232
233 hb_glyph_info_t *info = buffer->info;
234 unsigned int count = buffer->len;
235 for (unsigned int i = 0; i < count; i++)
236 {
237 thai_mark_type_t mt = get_mark_type (info[i].codepoint);
238
239 if (mt == NOT_MARK) {
240 thai_consonant_type_t ct = get_consonant_type (info[i].codepoint);
241 above_state = thai_above_start_state[ct];
242 below_state = thai_below_start_state[ct];
243 base = i;
244 continue;
245 }
246
247 const thai_above_state_machine_edge_t &above_edge = thai_above_state_machine[above_state][mt];
248 const thai_below_state_machine_edge_t &below_edge = thai_below_state_machine[below_state][mt];
249 above_state = above_edge.next_state;
250 below_state = below_edge.next_state;
251
252 /* At least one of the above/below actions is NOP. */
253 thai_action_t action = above_edge.action != NOP ? above_edge.action : below_edge.action;
254
255 buffer->unsafe_to_break (base, i);
256 if (action == RD)
257 info[base].codepoint = thai_pua_shape (info[base].codepoint, action, font);
258 else
259 info[i].codepoint = thai_pua_shape (info[i].codepoint, action, font);
260 }
261 }
262
263
264 static void
preprocess_text_thai(const hb_ot_shape_plan_t * plan,hb_buffer_t * buffer,hb_font_t * font)265 preprocess_text_thai (const hb_ot_shape_plan_t *plan,
266 hb_buffer_t *buffer,
267 hb_font_t *font)
268 {
269 /* This function implements the shaping logic documented here:
270 *
271 * https://linux.thai.net/~thep/th-otf/shaping.html
272 *
273 * The first shaping rule listed there is needed even if the font has Thai
274 * OpenType tables. The rest do fallback positioning based on PUA codepoints.
275 * We implement that only if there exist no Thai GSUB in the font.
276 */
277
278 /* The following is NOT specified in the MS OT Thai spec, however, it seems
279 * to be what Uniscribe and other engines implement. According to Eric Muller:
280 *
281 * When you have a SARA AM, decompose it in NIKHAHIT + SARA AA, *and* move the
282 * NIKHAHIT backwards over any tone mark (0E48-0E4B).
283 *
284 * <0E14, 0E4B, 0E33> -> <0E14, 0E4D, 0E4B, 0E32>
285 *
286 * This reordering is legit only when the NIKHAHIT comes from a SARA AM, not
287 * when it's there to start with. The string <0E14, 0E4B, 0E4D> is probably
288 * not what a user wanted, but the rendering is nevertheless nikhahit above
289 * chattawa.
290 *
291 * Same for Lao.
292 *
293 * Note:
294 *
295 * Uniscribe also does some below-marks reordering. Namely, it positions U+0E3A
296 * after U+0E38 and U+0E39. We do that by modifying the ccc for U+0E3A.
297 * See unicode->modified_combining_class (). Lao does NOT have a U+0E3A
298 * equivalent.
299 */
300
301
302 /*
303 * Here are the characters of significance:
304 *
305 * Thai Lao
306 * SARA AM: U+0E33 U+0EB3
307 * SARA AA: U+0E32 U+0EB2
308 * Nikhahit: U+0E4D U+0ECD
309 *
310 * Testing shows that Uniscribe reorder the following marks:
311 * Thai: <0E31,0E34..0E37,0E47..0E4E>
312 * Lao: <0EB1,0EB4..0EB7,0EC7..0ECE>
313 *
314 * Note how the Lao versions are the same as Thai + 0x80.
315 */
316
317 /* We only get one script at a time, so a script-agnostic implementation
318 * is adequate here. */
319 #define IS_SARA_AM(x) (((x) & ~0x0080u) == 0x0E33u)
320 #define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0x0E33u + 0x0E4Du)
321 #define SARA_AA_FROM_SARA_AM(x) ((x) - 1)
322 #define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080u, 0x0E34u, 0x0E37u, 0x0E47u, 0x0E4Eu, 0x0E31u, 0x0E31u))
323
324 buffer->clear_output ();
325 unsigned int count = buffer->len;
326 for (buffer->idx = 0; buffer->idx < count && buffer->successful;)
327 {
328 hb_codepoint_t u = buffer->cur().codepoint;
329 if (likely (!IS_SARA_AM (u))) {
330 buffer->next_glyph ();
331 continue;
332 }
333
334 /* Is SARA AM. Decompose and reorder. */
335 hb_glyph_info_t &nikhahit = buffer->output_glyph (NIKHAHIT_FROM_SARA_AM (u));
336 _hb_glyph_info_set_continuation (&nikhahit);
337 buffer->replace_glyph (SARA_AA_FROM_SARA_AM (u));
338 if (unlikely (!buffer->successful))
339 return;
340
341 /* Make Nikhahit be recognized as a ccc=0 mark when zeroing widths. */
342 unsigned int end = buffer->out_len;
343 _hb_glyph_info_set_general_category (&buffer->out_info[end - 2], HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK);
344
345 /* Ok, let's see... */
346 unsigned int start = end - 2;
347 while (start > 0 && IS_TONE_MARK (buffer->out_info[start - 1].codepoint))
348 start--;
349
350 if (start + 2 < end)
351 {
352 /* Move Nikhahit (end-2) to the beginning */
353 buffer->merge_out_clusters (start, end);
354 hb_glyph_info_t t = buffer->out_info[end - 2];
355 memmove (buffer->out_info + start + 1,
356 buffer->out_info + start,
357 sizeof (buffer->out_info[0]) * (end - start - 2));
358 buffer->out_info[start] = t;
359 }
360 else
361 {
362 /* Since we decomposed, and NIKHAHIT is combining, merge clusters with the
363 * previous cluster. */
364 if (start && buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)
365 buffer->merge_out_clusters (start - 1, end);
366 }
367 }
368 buffer->swap_buffers ();
369
370 /* If font has Thai GSUB, we are done. */
371 if (plan->props.script == HB_SCRIPT_THAI && !plan->map.found_script[0])
372 do_thai_pua_shaping (plan, buffer, font);
373 }
374
375 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_thai =
376 {
377 nullptr, /* collect_features */
378 nullptr, /* override_features */
379 nullptr, /* data_create */
380 nullptr, /* data_destroy */
381 preprocess_text_thai,
382 nullptr, /* postprocess_glyphs */
383 HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
384 nullptr, /* decompose */
385 nullptr, /* compose */
386 nullptr, /* setup_masks */
387 HB_TAG_NONE, /* gpos_tag */
388 nullptr, /* reorder_marks */
389 HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
390 false,/* fallback_position */
391 };
392
393
394 #endif
395