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-private.hh"
31
32 #include "hb-ot-shape-private.hh"
33 #include "hb-ot-layout-gsub-table.hh"
34
35
36 static const hb_tag_t arabic_fallback_features[] =
37 {
38 HB_TAG('i','n','i','t'),
39 HB_TAG('m','e','d','i'),
40 HB_TAG('f','i','n','a'),
41 HB_TAG('i','s','o','l'),
42 HB_TAG('r','l','i','g'),
43 };
44
45 /* Same order as the fallback feature array */
46 enum {
47 FALLBACK_INIT,
48 FALLBACK_MEDI,
49 FALLBACK_FINA,
50 FALLBACK_ISOL,
51 FALLBACK_RLIG,
52 ARABIC_NUM_FALLBACK_FEATURES
53 };
54
55 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)56 arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
57 hb_font_t *font,
58 unsigned int feature_index)
59 {
60 OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
61 OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
62 unsigned int num_glyphs = 0;
63
64 /* Populate arrays */
65 for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
66 {
67 hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
68 hb_codepoint_t u_glyph, s_glyph;
69
70 if (!s ||
71 !hb_font_get_glyph (font, u, 0, &u_glyph) ||
72 !hb_font_get_glyph (font, s, 0, &s_glyph) ||
73 u_glyph == s_glyph ||
74 u_glyph > 0xFFFF || s_glyph > 0xFFFF)
75 continue;
76
77 glyphs[num_glyphs].set (u_glyph);
78 substitutes[num_glyphs].set (s_glyph);
79
80 num_glyphs++;
81 }
82
83 /* Bubble-sort!
84 * May not be good-enough for presidential candidate interviews, but good-enough for us... */
85 hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);
86
87 OT::Supplier<OT::GlyphID> glyphs_supplier (glyphs, num_glyphs);
88 OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);
89
90 /* Each glyph takes four bytes max, and there's some overhead. */
91 char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
92 OT::hb_serialize_context_t c (buf, sizeof (buf));
93 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
94 bool ret = lookup->serialize_single (&c,
95 OT::LookupFlag::IgnoreMarks,
96 glyphs_supplier,
97 substitutes_supplier,
98 num_glyphs);
99 c.end_serialize ();
100 /* TODO sanitize the results? */
101
102 return ret ? c.copy<OT::SubstLookup> () : NULL;
103 }
104
105 static OT::SubstLookup *
arabic_fallback_synthesize_lookup_ligature(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font)106 arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
107 hb_font_t *font)
108 {
109 OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
110 unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
111 unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
112 unsigned int num_first_glyphs = 0;
113
114 /* We know that all our ligatures are 2-component */
115 OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
116 unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
117 OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
118 unsigned int num_ligatures = 0;
119
120 /* Populate arrays */
121
122 /* Sort out the first-glyphs */
123 for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
124 {
125 hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
126 hb_codepoint_t first_glyph;
127 if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
128 continue;
129 first_glyphs[num_first_glyphs].set (first_glyph);
130 ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
131 first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
132 num_first_glyphs++;
133 }
134 hb_bubble_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);
135
136 /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
137 for (unsigned int i = 0; i < num_first_glyphs; i++)
138 {
139 unsigned int first_glyph_idx = first_glyphs_indirection[i];
140
141 for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
142 {
143 hb_codepoint_t second_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
144 hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
145 hb_codepoint_t second_glyph, ligature_glyph;
146 if (!second_u ||
147 !hb_font_get_glyph (font, second_u, 0, &second_glyph) ||
148 !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
149 continue;
150
151 ligature_per_first_glyph_count_list[i]++;
152
153 ligature_list[num_ligatures].set (ligature_glyph);
154 component_count_list[num_ligatures] = 2;
155 component_list[num_ligatures].set (second_glyph);
156 num_ligatures++;
157 }
158 }
159
160 OT::Supplier<OT::GlyphID> first_glyphs_supplier (first_glyphs, num_first_glyphs);
161 OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier (ligature_per_first_glyph_count_list, num_first_glyphs);
162 OT::Supplier<OT::GlyphID> ligatures_supplier (ligature_list, num_ligatures);
163 OT::Supplier<unsigned int > component_count_supplier (component_count_list, num_ligatures);
164 OT::Supplier<OT::GlyphID> component_supplier (component_list, num_ligatures);
165
166 /* 16 bytes per ligature ought to be enough... */
167 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
168 OT::hb_serialize_context_t c (buf, sizeof (buf));
169 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
170 bool ret = lookup->serialize_ligature (&c,
171 OT::LookupFlag::IgnoreMarks,
172 first_glyphs_supplier,
173 ligature_per_first_glyph_count_supplier,
174 num_first_glyphs,
175 ligatures_supplier,
176 component_count_supplier,
177 component_supplier);
178
179 c.end_serialize ();
180 /* TODO sanitize the results? */
181
182 return ret ? c.copy<OT::SubstLookup> () : NULL;
183 }
184
185 static OT::SubstLookup *
arabic_fallback_synthesize_lookup(const hb_ot_shape_plan_t * plan,hb_font_t * font,unsigned int feature_index)186 arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
187 hb_font_t *font,
188 unsigned int feature_index)
189 {
190 if (feature_index < 4)
191 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
192 else
193 return arabic_fallback_synthesize_lookup_ligature (plan, font);
194 }
195
196 struct arabic_fallback_plan_t
197 {
198 ASSERT_POD ();
199
200 hb_mask_t mask_array[ARABIC_NUM_FALLBACK_FEATURES];
201 OT::SubstLookup *lookup_array[ARABIC_NUM_FALLBACK_FEATURES];
202 hb_set_digest_t digest_array[ARABIC_NUM_FALLBACK_FEATURES];
203 };
204
205 static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
206
207 static arabic_fallback_plan_t *
arabic_fallback_plan_create(const hb_ot_shape_plan_t * plan,hb_font_t * font)208 arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
209 hb_font_t *font)
210 {
211 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
212 if (unlikely (!fallback_plan))
213 return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
214
215 for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++) {
216 fallback_plan->mask_array[i] = plan->map.get_1_mask (arabic_fallback_features[i]);
217 if (fallback_plan->mask_array[i]) {
218 fallback_plan->lookup_array[i] = arabic_fallback_synthesize_lookup (plan, font, i);
219 if (fallback_plan->lookup_array[i])
220 fallback_plan->lookup_array[i]->add_coverage (&fallback_plan->digest_array[i]);
221 }
222 }
223
224 return fallback_plan;
225 }
226
227 static void
arabic_fallback_plan_destroy(arabic_fallback_plan_t * fallback_plan)228 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
229 {
230 if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
231 return;
232
233 for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
234 if (fallback_plan->lookup_array[i])
235 free (fallback_plan->lookup_array[i]);
236
237 free (fallback_plan);
238 }
239
240 static void
arabic_fallback_plan_shape(arabic_fallback_plan_t * fallback_plan,hb_font_t * font,hb_buffer_t * buffer)241 arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
242 hb_font_t *font,
243 hb_buffer_t *buffer)
244 {
245 for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
246 if (fallback_plan->lookup_array[i]) {
247 OT::hb_apply_context_t c (0, font, buffer, fallback_plan->mask_array[i], true/*auto_zwj*/);
248 fallback_plan->lookup_array[i]->apply_string (&c, &fallback_plan->digest_array[i]);
249 }
250 }
251
252
253 #endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */
254