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::HBGlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
53 OT::HBGlyphID 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] = u_glyph;
70 substitutes[num_glyphs] = 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,
81 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID::cmp,
82 &substitutes[0]);
83
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 hb_sorted_array (glyphs, num_glyphs),
92 hb_array (substitutes, num_glyphs));
93 c.end_serialize ();
94
95 return ret ? c.copy<OT::SubstLookup> () : nullptr;
96}
97
98static OT::SubstLookup *
99arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
100 hb_font_t *font)
101{
102 OT::HBGlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
103 unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
104 unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
105 unsigned int num_first_glyphs = 0;
106
107 /* We know that all our ligatures are 2-component */
108 OT::HBGlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
109 unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
110 OT::HBGlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
111 unsigned int num_ligatures = 0;
112
113 /* Populate arrays */
114
115 /* Sort out the first-glyphs */
116 for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
117 {
118 hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
119 hb_codepoint_t first_glyph;
120 if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
121 continue;
122 first_glyphs[num_first_glyphs] = first_glyph;
123 ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
124 first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
125 num_first_glyphs++;
126 }
127 hb_stable_sort (&first_glyphs[0], num_first_glyphs,
128 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID::cmp,
129 &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] = ligature_glyph;
149 component_count_list[num_ligatures] = 2;
150 component_list[num_ligatures] = second_glyph;
151 num_ligatures++;
152 }
153 }
154
155 if (!num_ligatures)
156 return nullptr;
157
158
159 /* 16 bytes per ligature ought to be enough... */
160 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
161 hb_serialize_context_t c (buf, sizeof (buf));
162 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
163 bool ret = lookup->serialize_ligature (&c,
164 OT::LookupFlag::IgnoreMarks,
165 hb_sorted_array (first_glyphs, num_first_glyphs),
166 hb_array (ligature_per_first_glyph_count_list, num_first_glyphs),
167 hb_array (ligature_list, num_ligatures),
168 hb_array (component_count_list, num_ligatures),
169 hb_array (component_list, num_ligatures));
170 c.end_serialize ();
171 /* TODO sanitize the results? */
172
173 return ret ? c.copy<OT::SubstLookup> () : nullptr;
174}
175
176static OT::SubstLookup *
177arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
178 hb_font_t *font,
179 unsigned int feature_index)
180{
181 if (feature_index < 4)
182 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
183 else
184 return arabic_fallback_synthesize_lookup_ligature (plan, font);
185}
186
187#define ARABIC_FALLBACK_MAX_LOOKUPS 5
188
189struct arabic_fallback_plan_t
190{
191 unsigned int num_lookups;
192 bool free_lookups;
193
194 hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
195 OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
196 OT::hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
197};
198
199#if defined(_WIN32) && !defined(HB_NO_WIN1256)
200#define HB_WITH_WIN1256
201#endif
202
203#ifdef HB_WITH_WIN1256
204#include "hb-ot-shape-complex-arabic-win1256.hh"
205#endif
206
207struct ManifestLookup
208{
209 public:
210 OT::Tag tag;
211 OT::OffsetTo<OT::SubstLookup> lookupOffset;
212 public:
213 DEFINE_SIZE_STATIC (6);
214};
215typedef OT::ArrayOf<ManifestLookup> Manifest;
216
217static bool
218arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED,
219 const hb_ot_shape_plan_t *plan HB_UNUSED,
220 hb_font_t *font HB_UNUSED)
221{
222#ifdef HB_WITH_WIN1256
223 /* Does this font look like it's Windows-1256-encoded? */
224 hb_codepoint_t g;
225 if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
226 hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
227 hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
228 hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
229 hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
230 return false;
231
232 const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
233 static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) ==
234 ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), "");
235 /* TODO sanitize the table? */
236
237 unsigned j = 0;
238 unsigned int count = manifest.len;
239 for (unsigned int i = 0; i < count; i++)
240 {
241 fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
242 if (fallback_plan->mask_array[j])
243 {
244 fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
245 if (fallback_plan->lookup_array[j])
246 {
247 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
248 j++;
249 }
250 }
251 }
252
253 fallback_plan->num_lookups = j;
254 fallback_plan->free_lookups = false;
255
256 return j > 0;
257#else
258 return false;
259#endif
260}
261
262static bool
263arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
264 const hb_ot_shape_plan_t *plan,
265 hb_font_t *font)
266{
267 static_assert ((ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");
268 unsigned int j = 0;
269 for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
270 {
271 fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
272 if (fallback_plan->mask_array[j])
273 {
274 fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
275 if (fallback_plan->lookup_array[j])
276 {
277 fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
278 j++;
279 }
280 }
281 }
282
283 fallback_plan->num_lookups = j;
284 fallback_plan->free_lookups = true;
285
286 return j > 0;
287}
288
289static arabic_fallback_plan_t *
290arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
291 hb_font_t *font)
292{
293 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
294 if (unlikely (!fallback_plan))
295 return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
296
297 fallback_plan->num_lookups = 0;
298 fallback_plan->free_lookups = false;
299
300 /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
301 * in case the font has cmap entries for the presentation-forms characters. */
302 if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
303 return fallback_plan;
304
305 /* See if this looks like a Windows-1256-encoded font. If it does, use a
306 * hand-coded GSUB table. */
307 if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
308 return fallback_plan;
309
310 assert (fallback_plan->num_lookups == 0);
311 free (fallback_plan);
312 return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
313}
314
315static void
316arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
317{
318 if (!fallback_plan || fallback_plan->num_lookups == 0)
319 return;
320
321 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
322 if (fallback_plan->lookup_array[i])
323 {
324 fallback_plan->accel_array[i].fini ();
325 if (fallback_plan->free_lookups)
326 free (fallback_plan->lookup_array[i]);
327 }
328
329 free (fallback_plan);
330}
331
332static void
333arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
334 hb_font_t *font,
335 hb_buffer_t *buffer)
336{
337 OT::hb_ot_apply_context_t c (0, font, buffer);
338 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
339 if (fallback_plan->lookup_array[i]) {
340 c.set_lookup_mask (fallback_plan->mask_array[i]);
341 hb_ot_layout_substitute_lookup (&c,
342 *fallback_plan->lookup_array[i],
343 fallback_plan->accel_array[i]);
344 }
345}
346
347
348#endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */
349