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. */
38static 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
47static OT::SubstLookup *
48arabic_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 Supplier<OT::GlyphID> glyphs_supplier (glyphs, num_glyphs);
83 Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);
84
85 /* Each glyph takes four bytes max, and there's some overhead. */
86 char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
87 hb_serialize_context_t c (buf, sizeof (buf));
88 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
89 bool ret = lookup->serialize_single (&c,
90 OT::LookupFlag::IgnoreMarks,
91 glyphs_supplier,
92 substitutes_supplier,
93 num_glyphs);
94 c.end_serialize ();
95 /* TODO sanitize the results? */
96
97 return ret ? c.copy<OT::SubstLookup> () : nullptr;
98}
99
100static OT::SubstLookup *
101arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
102 hb_font_t *font)
103{
104 OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
105 unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
106 unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
107 unsigned int num_first_glyphs = 0;
108
109 /* We know that all our ligatures are 2-component */
110 OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
111 unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
112 OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
113 unsigned int num_ligatures = 0;
114
115 /* Populate arrays */
116
117 /* Sort out the first-glyphs */
118 for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
119 {
120 hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
121 hb_codepoint_t first_glyph;
122 if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
123 continue;
124 first_glyphs[num_first_glyphs].set (first_glyph);
125 ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
126 first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
127 num_first_glyphs++;
128 }
129 hb_stable_sort (&first_glyphs[0], num_first_glyphs, (int(*)(const OT::GlyphID*, const OT::GlyphID *)) OT::GlyphID::cmp, &first_glyphs_indirection[0]);
130
131 /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
132 for (unsigned int i = 0; i < num_first_glyphs; i++)
133 {
134 unsigned int first_glyph_idx = first_glyphs_indirection[i];
135
136 for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
137 {
138 hb_codepoint_t second_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
139 hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
140 hb_codepoint_t second_glyph, ligature_glyph;
141 if (!second_u ||
142 !hb_font_get_glyph (font, second_u, 0, &second_glyph) ||
143 !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
144 continue;
145
146 ligature_per_first_glyph_count_list[i]++;
147
148 ligature_list[num_ligatures].set (ligature_glyph);
149 component_count_list[num_ligatures] = 2;
150 component_list[num_ligatures].set (second_glyph);
151 num_ligatures++;
152 }
153 }
154
155 if (!num_ligatures)
156 return nullptr;
157
158 Supplier<OT::GlyphID> first_glyphs_supplier (first_glyphs, num_first_glyphs);
159 Supplier<unsigned int > ligature_per_first_glyph_count_supplier (ligature_per_first_glyph_count_list, num_first_glyphs);
160 Supplier<OT::GlyphID> ligatures_supplier (ligature_list, num_ligatures);
161 Supplier<unsigned int > component_count_supplier (component_count_list, num_ligatures);
162 Supplier<OT::GlyphID> component_supplier (component_list, num_ligatures);
163
164 /* 16 bytes per ligature ought to be enough... */
165 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
166 hb_serialize_context_t c (buf, sizeof (buf));
167 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
168 bool ret = lookup->serialize_ligature (&c,
169 OT::LookupFlag::IgnoreMarks,
170 first_glyphs_supplier,
171 ligature_per_first_glyph_count_supplier,
172 num_first_glyphs,
173 ligatures_supplier,
174 component_count_supplier,
175 component_supplier);
176 c.end_serialize ();
177 /* TODO sanitize the results? */
178
179 return ret ? c.copy<OT::SubstLookup> () : nullptr;
180}
181
182static OT::SubstLookup *
183arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
184 hb_font_t *font,
185 unsigned int feature_index)
186{
187 if (feature_index < 4)
188 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
189 else
190 return arabic_fallback_synthesize_lookup_ligature (plan, font);
191}
192
193#define ARABIC_FALLBACK_MAX_LOOKUPS 5
194
195struct arabic_fallback_plan_t
196{
197 ASSERT_POD ();
198
199 unsigned int num_lookups;
200 bool free_lookups;
201
202 hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
203 OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
204 hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
205};
206
207#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(HB_NO_WIN1256)
208#define HB_WITH_WIN1256
209#endif
210
211#ifdef HB_WITH_WIN1256
212#include "hb-ot-shape-complex-arabic-win1256.hh"
213#endif
214
215struct ManifestLookup
216{
217 OT::Tag tag;
218 OT::OffsetTo<OT::SubstLookup> lookupOffset;
219};
220typedef OT::ArrayOf<ManifestLookup> Manifest;
221
222static bool
223arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan,
224 const hb_ot_shape_plan_t *plan,
225 hb_font_t *font)
226{
227#ifdef HB_WITH_WIN1256
228 /* Does this font look like it's Windows-1256-encoded? */
229 hb_codepoint_t g;
230 if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
231 hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
232 hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
233 hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
234 hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
235 return false;
236
237 const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
238 static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) / sizeof (ManifestLookup)
239 <= ARABIC_FALLBACK_MAX_LOOKUPS, "");
240 /* TODO sanitize the table? */
241
242 unsigned j = 0;
243 unsigned int count = manifest.len;
244 for (unsigned int i = 0; i < count; i++)
245 {
246 fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
247 if (fallback_plan->mask_array[j])
248 {
249 fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
250 if (fallback_plan->lookup_array[j])
251 {
252 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
253 j++;
254 }
255 }
256 }
257
258 fallback_plan->num_lookups = j;
259 fallback_plan->free_lookups = false;
260
261 return j > 0;
262#else
263 return false;
264#endif
265}
266
267static bool
268arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
269 const hb_ot_shape_plan_t *plan,
270 hb_font_t *font)
271{
272 static_assert ((ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");
273 unsigned int j = 0;
274 for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
275 {
276 fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
277 if (fallback_plan->mask_array[j])
278 {
279 fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
280 if (fallback_plan->lookup_array[j])
281 {
282 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
283 j++;
284 }
285 }
286 }
287
288 fallback_plan->num_lookups = j;
289 fallback_plan->free_lookups = true;
290
291 return j > 0;
292}
293
294static arabic_fallback_plan_t *
295arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
296 hb_font_t *font)
297{
298 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
299 if (unlikely (!fallback_plan))
300 return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
301
302 fallback_plan->num_lookups = 0;
303 fallback_plan->free_lookups = false;
304
305 /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
306 * in case the font has cmap entries for the presentation-forms characters. */
307 if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
308 return fallback_plan;
309
310 /* See if this looks like a Windows-1256-encoded font. If it does, use a
311 * hand-coded GSUB table. */
312 if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
313 return fallback_plan;
314
315 assert (fallback_plan->num_lookups == 0);
316 free (fallback_plan);
317 return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
318}
319
320static void
321arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
322{
323 if (!fallback_plan || fallback_plan->num_lookups == 0)
324 return;
325
326 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
327 if (fallback_plan->lookup_array[i])
328 {
329 fallback_plan->accel_array[i].fini ();
330 if (fallback_plan->free_lookups)
331 free (fallback_plan->lookup_array[i]);
332 }
333
334 free (fallback_plan);
335}
336
337static void
338arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
339 hb_font_t *font,
340 hb_buffer_t *buffer)
341{
342 OT::hb_ot_apply_context_t c (0, font, buffer);
343 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
344 if (fallback_plan->lookup_array[i]) {
345 c.set_lookup_mask (fallback_plan->mask_array[i]);
346 hb_ot_layout_substitute_lookup (&c,
347 *fallback_plan->lookup_array[i],
348 fallback_plan->accel_array[i]);
349 }
350}
351
352
353#endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */
354