1 /* 2 * Copyright 2017 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_KERN_TABLE_HH 28 #define HB_OT_KERN_TABLE_HH 29 30 #include "hb-open-type-private.hh" 31 32 namespace OT { 33 34 35 /* 36 * kern -- Kerning 37 */ 38 39 #define HB_OT_TAG_kern HB_TAG('k','e','r','n') 40 41 struct hb_glyph_pair_t 42 { 43 hb_codepoint_t left; 44 hb_codepoint_t right; 45 }; 46 47 struct KernPair 48 { 49 inline int get_kerning (void) const 50 { return value; } 51 52 inline int cmp (const hb_glyph_pair_t &o) const 53 { 54 int ret = left.cmp (o.left); 55 if (ret) return ret; 56 return right.cmp (o.right); 57 } 58 59 inline bool sanitize (hb_sanitize_context_t *c) const 60 { 61 TRACE_SANITIZE (this); 62 return_trace (c->check_struct (this)); 63 } 64 65 protected: 66 GlyphID left; 67 GlyphID right; 68 FWORD value; 69 public: 70 DEFINE_SIZE_STATIC (6); 71 }; 72 73 struct KernSubTableFormat0 74 { 75 inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const 76 { 77 hb_glyph_pair_t pair = {left, right}; 78 int i = pairs.bsearch (pair); 79 if (i == -1) 80 return 0; 81 return pairs[i].get_kerning (); 82 } 83 84 inline bool sanitize (hb_sanitize_context_t *c) const 85 { 86 TRACE_SANITIZE (this); 87 return_trace (pairs.sanitize (c)); 88 } 89 90 protected: 91 BinSearchArrayOf<KernPair> pairs; /* Array of kerning pairs. */ 92 public: 93 DEFINE_SIZE_ARRAY (8, pairs); 94 }; 95 96 struct KernClassTable 97 { 98 inline unsigned int get_class (hb_codepoint_t g) const { return classes[g - firstGlyph]; } 99 100 inline bool sanitize (hb_sanitize_context_t *c) const 101 { 102 TRACE_SANITIZE (this); 103 return_trace (firstGlyph.sanitize (c) && classes.sanitize (c)); 104 } 105 106 protected: 107 UINT16 firstGlyph; /* First glyph in class range. */ 108 ArrayOf<UINT16> classes; /* Glyph classes. */ 109 public: 110 DEFINE_SIZE_ARRAY (4, classes); 111 }; 112 113 struct KernSubTableFormat2 114 { 115 inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, const char *end) const 116 { 117 unsigned int l = (this+leftClassTable).get_class (left); 118 unsigned int r = (this+leftClassTable).get_class (left); 119 unsigned int offset = l * rowWidth + r * sizeof (FWORD); 120 const FWORD *arr = &(this+array); 121 if (unlikely ((const void *) arr < (const void *) this || (const void *) arr >= (const void *) end)) 122 return 0; 123 const FWORD *v = &StructAtOffset<FWORD> (arr, offset); 124 if (unlikely ((const void *) v < (const void *) arr || (const void *) (v + 1) > (const void *) end)) 125 return 0; 126 return *v; 127 } 128 129 inline bool sanitize (hb_sanitize_context_t *c) const 130 { 131 TRACE_SANITIZE (this); 132 return_trace (rowWidth.sanitize (c) && 133 leftClassTable.sanitize (c, this) && 134 rightClassTable.sanitize (c, this) && 135 array.sanitize (c, this)); 136 } 137 138 protected: 139 UINT16 rowWidth; /* The width, in bytes, of a row in the table. */ 140 OffsetTo<KernClassTable> 141 leftClassTable; /* Offset from beginning of this subtable to 142 * left-hand class table. */ 143 OffsetTo<KernClassTable> 144 rightClassTable;/* Offset from beginning of this subtable to 145 * right-hand class table. */ 146 OffsetTo<FWORD> 147 array; /* Offset from beginning of this subtable to 148 * the start of the kerning array. */ 149 public: 150 DEFINE_SIZE_MIN (8); 151 }; 152 153 struct KernSubTable 154 { 155 inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, const char *end, unsigned int format) const 156 { 157 switch (format) { 158 case 0: return u.format0.get_kerning (left, right); 159 case 2: return u.format2.get_kerning (left, right, end); 160 default:return 0; 161 } 162 } 163 164 inline bool sanitize (hb_sanitize_context_t *c, unsigned int format) const 165 { 166 TRACE_SANITIZE (this); 167 switch (format) { 168 case 0: return_trace (u.format0.sanitize (c)); 169 case 2: return_trace (u.format2.sanitize (c)); 170 default:return_trace (true); 171 } 172 } 173 174 protected: 175 union { 176 KernSubTableFormat0 format0; 177 KernSubTableFormat2 format2; 178 } u; 179 public: 180 DEFINE_SIZE_MIN (0); 181 }; 182 183 184 template <typename T> 185 struct KernSubTableWrapper 186 { 187 /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */ 188 inline const T* thiz (void) const { return static_cast<const T *> (this); } 189 190 inline bool is_horizontal (void) const 191 { return (thiz()->coverage & T::COVERAGE_CHECK_FLAGS) == T::COVERAGE_CHECK_HORIZONTAL; } 192 193 inline bool is_override (void) const 194 { return bool (thiz()->coverage & T::COVERAGE_OVERRIDE_FLAG); } 195 196 inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, const char *end) const 197 { return thiz()->subtable.get_kerning (left, right, end, thiz()->format); } 198 199 inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right, const char *end) const 200 { return is_horizontal () ? get_kerning (left, right, end) : 0; } 201 202 inline unsigned int get_size (void) const { return thiz()->length; } 203 204 inline bool sanitize (hb_sanitize_context_t *c) const 205 { 206 TRACE_SANITIZE (this); 207 return_trace (c->check_struct (thiz()) && 208 thiz()->length >= thiz()->min_size && 209 c->check_array (thiz(), 1, thiz()->length) && 210 thiz()->subtable.sanitize (c, thiz()->format)); 211 } 212 }; 213 214 template <typename T> 215 struct KernTable 216 { 217 /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */ 218 inline const T* thiz (void) const { return static_cast<const T *> (this); } 219 220 inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right, unsigned int table_length) const 221 { 222 int v = 0; 223 const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (thiz()->data); 224 unsigned int count = thiz()->nTables; 225 for (unsigned int i = 0; i < count; i++) 226 { 227 if (st->is_override ()) 228 v = 0; 229 v += st->get_h_kerning (left, right, table_length + (const char *) this); 230 st = &StructAfter<typename T::SubTableWrapper> (*st); 231 } 232 return v; 233 } 234 235 inline bool sanitize (hb_sanitize_context_t *c) const 236 { 237 TRACE_SANITIZE (this); 238 if (unlikely (!c->check_struct (thiz()) || 239 thiz()->version != T::VERSION)) 240 return_trace (false); 241 242 const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (thiz()->data); 243 unsigned int count = thiz()->nTables; 244 for (unsigned int i = 0; i < count; i++) 245 { 246 if (unlikely (!st->sanitize (c))) 247 return_trace (false); 248 st = &StructAfter<typename T::SubTableWrapper> (*st); 249 } 250 251 return_trace (true); 252 } 253 }; 254 255 struct KernOT : KernTable<KernOT> 256 { 257 friend struct KernTable<KernOT>; 258 259 static const uint16_t VERSION = 0x0000u; 260 261 struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper> 262 { 263 friend struct KernSubTableWrapper<SubTableWrapper>; 264 265 enum coverage_flags_t { 266 COVERAGE_DIRECTION_FLAG = 0x01u, 267 COVERAGE_MINIMUM_FLAG = 0x02u, 268 COVERAGE_CROSSSTREAM_FLAG = 0x04u, 269 COVERAGE_OVERRIDE_FLAG = 0x08u, 270 271 COVERAGE_VARIATION_FLAG = 0x00u, /* Not supported. */ 272 273 COVERAGE_CHECK_FLAGS = 0x07u, 274 COVERAGE_CHECK_HORIZONTAL = 0x01u 275 }; 276 277 protected: 278 UINT16 versionZ; /* Unused. */ 279 UINT16 length; /* Length of the subtable (including this header). */ 280 UINT8 format; /* Subtable format. */ 281 UINT8 coverage; /* Coverage bits. */ 282 KernSubTable subtable; /* Subtable data. */ 283 public: 284 DEFINE_SIZE_MIN (6); 285 }; 286 287 protected: 288 UINT16 version; /* Version--0x0000u */ 289 UINT16 nTables; /* Number of subtables in the kerning table. */ 290 UINT8 data[VAR]; 291 public: 292 DEFINE_SIZE_ARRAY (4, data); 293 }; 294 295 struct KernAAT : KernTable<KernAAT> 296 { 297 friend struct KernTable<KernAAT>; 298 299 static const uint32_t VERSION = 0x00010000u; 300 301 struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper> 302 { 303 friend struct KernSubTableWrapper<SubTableWrapper>; 304 305 enum coverage_flags_t { 306 COVERAGE_DIRECTION_FLAG = 0x80u, 307 COVERAGE_CROSSSTREAM_FLAG = 0x40u, 308 COVERAGE_VARIATION_FLAG = 0x20u, 309 310 COVERAGE_OVERRIDE_FLAG = 0x00u, /* Not supported. */ 311 312 COVERAGE_CHECK_FLAGS = 0xE0u, 313 COVERAGE_CHECK_HORIZONTAL = 0x00u 314 }; 315 316 protected: 317 UINT32 length; /* Length of the subtable (including this header). */ 318 UINT8 coverage; /* Coverage bits. */ 319 UINT8 format; /* Subtable format. */ 320 UINT16 tupleIndex; /* The tuple index (used for variations fonts). 321 * This value specifies which tuple this subtable covers. */ 322 KernSubTable subtable; /* Subtable data. */ 323 public: 324 DEFINE_SIZE_MIN (8); 325 }; 326 327 protected: 328 UINT32 version; /* Version--0x00010000u */ 329 UINT32 nTables; /* Number of subtables in the kerning table. */ 330 UINT8 data[VAR]; 331 public: 332 DEFINE_SIZE_ARRAY (8, data); 333 }; 334 335 struct kern 336 { 337 static const hb_tag_t tableTag = HB_OT_TAG_kern; 338 339 inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right, unsigned int table_length) const 340 { 341 switch (u.major) { 342 case 0: return u.ot.get_h_kerning (left, right, table_length); 343 case 1: return u.aat.get_h_kerning (left, right, table_length); 344 default:return 0; 345 } 346 } 347 348 inline bool sanitize (hb_sanitize_context_t *c) const 349 { 350 TRACE_SANITIZE (this); 351 if (!u.major.sanitize (c)) return_trace (false); 352 switch (u.major) { 353 case 0: return_trace (u.ot.sanitize (c)); 354 case 1: return_trace (u.aat.sanitize (c)); 355 default:return_trace (true); 356 } 357 } 358 359 struct accelerator_t 360 { 361 inline void init (hb_face_t *face) 362 { 363 blob = Sanitizer<kern>::sanitize (face->reference_table (HB_OT_TAG_kern)); 364 table = Sanitizer<kern>::lock_instance (blob); 365 table_length = hb_blob_get_length (blob); 366 } 367 inline void fini (void) 368 { 369 hb_blob_destroy (blob); 370 } 371 372 inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const 373 { return table->get_h_kerning (left, right, table_length); } 374 375 private: 376 hb_blob_t *blob; 377 const kern *table; 378 unsigned int table_length; 379 }; 380 381 protected: 382 union { 383 UINT16 major; 384 KernOT ot; 385 KernAAT aat; 386 } u; 387 public: 388 DEFINE_SIZE_UNION (2, major); 389 }; 390 391 } /* namespace OT */ 392 393 394 #endif /* HB_OT_KERN_TABLE_HH */ 395
