1 /*
2 * Copyright © 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 #ifndef HB_OT_SHAPER_ARABIC_FALLBACK_HH
28 #define HB_OT_SHAPER_ARABIC_FALLBACK_HH
29
30 #include "hb.hh"
31
32 #include "hb-ot-shape.hh"
33 #include "hb-ot-layout-gsub-table.hh"
34
35
36 /* Features ordered the same as the entries in shaping_table rows,
37 * followed by rlig. Don't change.
38 *
39 * We currently support one subtable per lookup, and one lookup
40 * per feature. But we allow duplicate features, so we use that!
41 */
42 static const hb_tag_t arabic_fallback_features[] =
43 {
44 HB_TAG('i','n','i','t'),
45 HB_TAG('m','e','d','i'),
46 HB_TAG('f','i','n','a'),
47 HB_TAG('i','s','o','l'),
48 HB_TAG('r','l','i','g'),
49 HB_TAG('r','l','i','g'),
50 HB_TAG('r','l','i','g'),
51 };
52
53 static OT::SubstLookup *
arabic_fallback_synthesize_lookup_single(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font,unsigned int feature_index)54 arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
55 hb_font_t *font,
56 unsigned int feature_index)
57 {
58 OT::HBGlyphID16 glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
59 OT::HBGlyphID16 substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
60 unsigned int num_glyphs = 0;
61
62 /* Populate arrays */
63 for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
64 {
65 hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
66 hb_codepoint_t u_glyph, s_glyph;
67
68 if (!s ||
69 !hb_font_get_glyph (font, u, 0, &u_glyph) ||
70 !hb_font_get_glyph (font, s, 0, &s_glyph) ||
71 u_glyph == s_glyph ||
72 u_glyph > 0xFFFFu || s_glyph > 0xFFFFu)
73 continue;
74
75 glyphs[num_glyphs] = u_glyph;
76 substitutes[num_glyphs] = s_glyph;
77
78 num_glyphs++;
79 }
80
81 if (!num_glyphs)
82 return nullptr;
83
84 /* Bubble-sort or something equally good!
85 * May not be good-enough for presidential candidate interviews, but good-enough for us... */
86 hb_stable_sort (&glyphs[0], num_glyphs,
87 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp,
88 &substitutes[0]);
89
90
91 /* Each glyph takes four bytes max, and there's some overhead. */
92 char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
93 hb_serialize_context_t c (buf, sizeof (buf));
94 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
95 bool ret = lookup->serialize_single (&c,
96 OT::LookupFlag::IgnoreMarks,
97 hb_sorted_array (glyphs, num_glyphs),
98 hb_array (substitutes, num_glyphs));
99 c.end_serialize ();
100
101 return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr;
102 }
103
104 template <typename T>
105 static OT::SubstLookup *
arabic_fallback_synthesize_lookup_ligature(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font,const T & ligature_table,unsigned lookup_flags)106 arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
107 hb_font_t *font,
108 const T &ligature_table,
109 unsigned lookup_flags)
110 {
111 OT::HBGlyphID16 first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
112 unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
113 unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
114 unsigned int num_first_glyphs = 0;
115
116 /* We know that all our ligatures have the same number of components. */
117 OT::HBGlyphID16 ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
118 unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
119 OT::HBGlyphID16 component_list[ARRAY_LENGTH_CONST (ligature_list) *
120 ARRAY_LENGTH_CONST (ligature_table[0].ligatures[0].components)];
121 unsigned int num_ligatures = 0;
122 unsigned int num_components = 0;
123
124 /* Populate arrays */
125
126 /* Sort out the first-glyphs */
127 for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
128 {
129 hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
130 hb_codepoint_t first_glyph;
131 if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
132 continue;
133 first_glyphs[num_first_glyphs] = first_glyph;
134 ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
135 first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
136 num_first_glyphs++;
137 }
138 hb_stable_sort (&first_glyphs[0], num_first_glyphs,
139 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp,
140 &first_glyphs_indirection[0]);
141
142 /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
143 for (unsigned int i = 0; i < num_first_glyphs; i++)
144 {
145 unsigned int first_glyph_idx = first_glyphs_indirection[i];
146
147 for (unsigned int ligature_idx = 0; ligature_idx < ARRAY_LENGTH (ligature_table[0].ligatures); ligature_idx++)
148 {
149 hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].ligature;
150 hb_codepoint_t ligature_glyph;
151 if (!hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
152 continue;
153
154 const auto &components = ligature_table[first_glyph_idx].ligatures[ligature_idx].components;
155 unsigned component_count = ARRAY_LENGTH_CONST (components);
156
157 for (unsigned i = 0; i < component_count; i++)
158 {
159 hb_codepoint_t component_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[i];
160 hb_codepoint_t component_glyph;
161 if (!component_u ||
162 !hb_font_get_glyph (font, component_u, 0, &component_glyph))
163 continue;
164
165 component_list[num_components++] = component_glyph;
166 }
167
168 component_count_list[num_ligatures] = 1 + component_count;
169 ligature_list[num_ligatures] = ligature_glyph;
170
171 ligature_per_first_glyph_count_list[i]++;
172
173 num_ligatures++;
174 }
175 }
176
177 if (!num_ligatures)
178 return nullptr;
179
180
181 /* 16 bytes per ligature ought to be enough... */
182 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
183 hb_serialize_context_t c (buf, sizeof (buf));
184 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
185 bool ret = lookup->serialize_ligature (&c,
186 lookup_flags,
187 hb_sorted_array (first_glyphs, num_first_glyphs),
188 hb_array (ligature_per_first_glyph_count_list, num_first_glyphs),
189 hb_array (ligature_list, num_ligatures),
190 hb_array (component_count_list, num_ligatures),
191 hb_array (component_list, num_components));
192 c.end_serialize ();
193
194 return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr;
195 }
196
197 static OT::SubstLookup *
arabic_fallback_synthesize_lookup(const hb_ot_shape_plan_t * plan,hb_font_t * font,unsigned int feature_index)198 arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
199 hb_font_t *font,
200 unsigned int feature_index)
201 {
202 if (feature_index < 4)
203 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
204 else
205 {
206 switch (feature_index) {
207 case 4: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_3_table, OT::LookupFlag::IgnoreMarks);
208 case 5: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_table, OT::LookupFlag::IgnoreMarks);
209 case 6: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_mark_table, 0);
210 }
211 }
212 assert (false);
213 return nullptr;
214 }
215
216 #define ARABIC_FALLBACK_MAX_LOOKUPS ARRAY_LENGTH_CONST (arabic_fallback_features)
217
218 struct arabic_fallback_plan_t
219 {
220 unsigned int num_lookups;
221 bool free_lookups;
222
223 hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
224 OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
225 OT::hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
226 };
227
228 #if defined(_WIN32) && !defined(HB_NO_WIN1256)
229 #define HB_WITH_WIN1256
230 #endif
231
232 #ifdef HB_WITH_WIN1256
233 #include "hb-ot-shaper-arabic-win1256.hh"
234 #endif
235
236 struct ManifestLookup
237 {
238 public:
239 OT::Tag tag;
240 OT::Offset16To<OT::SubstLookup> lookupOffset;
241 public:
242 DEFINE_SIZE_STATIC (6);
243 };
244 typedef OT::Array16Of<ManifestLookup> Manifest;
245
246 static bool
arabic_fallback_plan_init_win1256(arabic_fallback_plan_t * fallback_plan HB_UNUSED,const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font HB_UNUSED)247 arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED,
248 const hb_ot_shape_plan_t *plan HB_UNUSED,
249 hb_font_t *font HB_UNUSED)
250 {
251 #ifdef HB_WITH_WIN1256
252 /* Does this font look like it's Windows-1256-encoded? */
253 hb_codepoint_t g;
254 if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
255 hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
256 hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
257 hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
258 hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
259 return false;
260
261 const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
262 static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) <=
263 ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), "");
264
265 unsigned j = 0;
266 unsigned int count = manifest.len;
267 for (unsigned int i = 0; i < count; i++)
268 {
269 fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
270 if (fallback_plan->mask_array[j])
271 {
272 fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
273 if (fallback_plan->lookup_array[j])
274 {
275 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
276 j++;
277 }
278 }
279 }
280
281 fallback_plan->num_lookups = j;
282 fallback_plan->free_lookups = false;
283
284 return j > 0;
285 #else
286 return false;
287 #endif
288 }
289
290 static bool
arabic_fallback_plan_init_unicode(arabic_fallback_plan_t * fallback_plan,const hb_ot_shape_plan_t * plan,hb_font_t * font)291 arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
292 const hb_ot_shape_plan_t *plan,
293 hb_font_t *font)
294 {
295 static_assert ((ARRAY_LENGTH_CONST (arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");
296 unsigned int j = 0;
297 for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
298 {
299 fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
300 if (fallback_plan->mask_array[j])
301 {
302 fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
303 if (fallback_plan->lookup_array[j])
304 {
305 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
306 j++;
307 }
308 }
309 }
310
311 fallback_plan->num_lookups = j;
312 fallback_plan->free_lookups = true;
313
314 return j > 0;
315 }
316
317 static arabic_fallback_plan_t *
arabic_fallback_plan_create(const hb_ot_shape_plan_t * plan,hb_font_t * font)318 arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
319 hb_font_t *font)
320 {
321 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_calloc (1, sizeof (arabic_fallback_plan_t));
322 if (unlikely (!fallback_plan))
323 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
324
325 fallback_plan->num_lookups = 0;
326 fallback_plan->free_lookups = false;
327
328 /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
329 * in case the font has cmap entries for the presentation-forms characters. */
330 if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
331 return fallback_plan;
332
333 /* See if this looks like a Windows-1256-encoded font. If it does, use a
334 * hand-coded GSUB table. */
335 if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
336 return fallback_plan;
337
338 assert (fallback_plan->num_lookups == 0);
339 hb_free (fallback_plan);
340 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
341 }
342
343 static void
arabic_fallback_plan_destroy(arabic_fallback_plan_t * fallback_plan)344 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
345 {
346 if (!fallback_plan || fallback_plan->num_lookups == 0)
347 return;
348
349 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
350 if (fallback_plan->lookup_array[i])
351 {
352 fallback_plan->accel_array[i].fini ();
353 if (fallback_plan->free_lookups)
354 hb_free (fallback_plan->lookup_array[i]);
355 }
356
357 hb_free (fallback_plan);
358 }
359
360 static void
arabic_fallback_plan_shape(arabic_fallback_plan_t * fallback_plan,hb_font_t * font,hb_buffer_t * buffer)361 arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
362 hb_font_t *font,
363 hb_buffer_t *buffer)
364 {
365 OT::hb_ot_apply_context_t c (0, font, buffer);
366 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
367 if (fallback_plan->lookup_array[i]) {
368 c.set_lookup_mask (fallback_plan->mask_array[i]);
369 hb_ot_layout_substitute_lookup (&c,
370 *fallback_plan->lookup_array[i],
371 fallback_plan->accel_array[i]);
372 }
373 }
374
375
376 #endif /* HB_OT_SHAPER_ARABIC_FALLBACK_HH */
377