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 */
42static 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
53static OT::SubstLookup *
54arabic_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
104template <typename T>
105static OT::SubstLookup *
106arabic_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 bool matched = true;
158 for (unsigned j = 0; j < component_count; j++)
159 {
160 hb_codepoint_t component_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[j];
161 hb_codepoint_t component_glyph;
162 if (!component_u ||
163 !hb_font_get_nominal_glyph (font, component_u, &component_glyph))
164 {
165 matched = false;
166 break;
167 }
168
169 component_list[num_components++] = component_glyph;
170 }
171 if (!matched)
172 continue;
173
174 component_count_list[num_ligatures] = 1 + component_count;
175 ligature_list[num_ligatures] = ligature_glyph;
176
177 ligature_per_first_glyph_count_list[i]++;
178
179 num_ligatures++;
180 }
181 }
182
183 if (!num_ligatures)
184 return nullptr;
185
186
187 /* 16 bytes per ligature ought to be enough... */
188 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
189 hb_serialize_context_t c (buf, sizeof (buf));
190 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
191 bool ret = lookup->serialize_ligature (&c,
192 lookup_flags,
193 hb_sorted_array (first_glyphs, num_first_glyphs),
194 hb_array (ligature_per_first_glyph_count_list, num_first_glyphs),
195 hb_array (ligature_list, num_ligatures),
196 hb_array (component_count_list, num_ligatures),
197 hb_array (component_list, num_components));
198 c.end_serialize ();
199
200 return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr;
201}
202
203static OT::SubstLookup *
204arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
205 hb_font_t *font,
206 unsigned int feature_index)
207{
208 if (feature_index < 4)
209 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
210 else
211 {
212 switch (feature_index) {
213 case 4: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_3_table, OT::LookupFlag::IgnoreMarks);
214 case 5: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_table, OT::LookupFlag::IgnoreMarks);
215 case 6: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_mark_table, 0);
216 }
217 }
218 assert (false);
219 return nullptr;
220}
221
222#define ARABIC_FALLBACK_MAX_LOOKUPS ARRAY_LENGTH_CONST (arabic_fallback_features)
223
224struct arabic_fallback_plan_t
225{
226 unsigned int num_lookups;
227 bool free_lookups;
228
229 hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
230 OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
231 OT::hb_ot_layout_lookup_accelerator_t *accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
232};
233
234#if defined(_WIN32) && !defined(HB_NO_WIN1256)
235#define HB_WITH_WIN1256
236#endif
237
238#ifdef HB_WITH_WIN1256
239#include "hb-ot-shaper-arabic-win1256.hh"
240#endif
241
242struct ManifestLookup
243{
244 public:
245 OT::Tag tag;
246 OT::Offset16To<OT::SubstLookup> lookupOffset;
247 public:
248 DEFINE_SIZE_STATIC (6);
249};
250typedef OT::Array16Of<ManifestLookup> Manifest;
251
252static bool
253arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED,
254 const hb_ot_shape_plan_t *plan HB_UNUSED,
255 hb_font_t *font HB_UNUSED)
256{
257#ifdef HB_WITH_WIN1256
258 /* Does this font look like it's Windows-1256-encoded? */
259 hb_codepoint_t g;
260 if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
261 hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
262 hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
263 hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
264 hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
265 return false;
266
267 const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
268 static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) <=
269 ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), "");
270
271 unsigned j = 0;
272 unsigned int count = manifest.len;
273 for (unsigned int i = 0; i < count; i++)
274 {
275 fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
276 if (fallback_plan->mask_array[j])
277 {
278 fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
279 if (fallback_plan->lookup_array[j])
280 {
281 fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]);
282 j++;
283 }
284 }
285 }
286
287 fallback_plan->num_lookups = j;
288 fallback_plan->free_lookups = false;
289
290 return j > 0;
291#else
292 return false;
293#endif
294}
295
296static bool
297arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
298 const hb_ot_shape_plan_t *plan,
299 hb_font_t *font)
300{
301 static_assert ((ARRAY_LENGTH_CONST (arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");
302 unsigned int j = 0;
303 for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
304 {
305 fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
306 if (fallback_plan->mask_array[j])
307 {
308 fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
309 if (fallback_plan->lookup_array[j])
310 {
311 fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]);
312 j++;
313 }
314 }
315 }
316
317 fallback_plan->num_lookups = j;
318 fallback_plan->free_lookups = true;
319
320 return j > 0;
321}
322
323static arabic_fallback_plan_t *
324arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
325 hb_font_t *font)
326{
327 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_calloc (1, sizeof (arabic_fallback_plan_t));
328 if (unlikely (!fallback_plan))
329 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
330
331 fallback_plan->num_lookups = 0;
332 fallback_plan->free_lookups = false;
333
334 /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
335 * in case the font has cmap entries for the presentation-forms characters. */
336 if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
337 return fallback_plan;
338
339 /* See if this looks like a Windows-1256-encoded font. If it does, use a
340 * hand-coded GSUB table. */
341 if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
342 return fallback_plan;
343
344 assert (fallback_plan->num_lookups == 0);
345 hb_free (fallback_plan);
346 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t));
347}
348
349static void
350arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
351{
352 if (!fallback_plan || fallback_plan->num_lookups == 0)
353 return;
354
355 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
356 if (fallback_plan->lookup_array[i])
357 {
358 hb_free (fallback_plan->accel_array[i]);
359 if (fallback_plan->free_lookups)
360 hb_free (fallback_plan->lookup_array[i]);
361 }
362
363 hb_free (fallback_plan);
364}
365
366static void
367arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
368 hb_font_t *font,
369 hb_buffer_t *buffer)
370{
371 OT::hb_ot_apply_context_t c (0, font, buffer, hb_blob_get_empty ());
372 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
373 if (fallback_plan->lookup_array[i]) {
374 c.set_lookup_mask (fallback_plan->mask_array[i]);
375 if (fallback_plan->accel_array[i])
376 hb_ot_layout_substitute_lookup (&c,
377 *fallback_plan->lookup_array[i],
378 *fallback_plan->accel_array[i]);
379 }
380}
381
382
383#endif /* HB_OT_SHAPER_ARABIC_FALLBACK_HH */
384