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