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