The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 1 | /***************************************************************************/ |
| 2 | /* */ |
| 3 | /* ttkern.c */ |
| 4 | /* */ |
| 5 | /* Load the basic TrueType kerning table. This doesn't handle */ |
| 6 | /* kerning data within the GPOS table at the moment. */ |
| 7 | /* */ |
Xin Li | 460e8ff | 2017-02-07 15:19:10 -0800 | [diff] [blame] | 8 | /* Copyright 1996-2016 by */ |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 9 | /* David Turner, Robert Wilhelm, and Werner Lemberg. */ |
| 10 | /* */ |
| 11 | /* This file is part of the FreeType project, and may only be used, */ |
| 12 | /* modified, and distributed under the terms of the FreeType project */ |
| 13 | /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
| 14 | /* this file you indicate that you have read the license and */ |
| 15 | /* understand and accept it fully. */ |
| 16 | /* */ |
| 17 | /***************************************************************************/ |
| 18 | |
| 19 | |
| 20 | #include <ft2build.h> |
| 21 | #include FT_INTERNAL_DEBUG_H |
| 22 | #include FT_INTERNAL_STREAM_H |
| 23 | #include FT_TRUETYPE_TAGS_H |
| 24 | #include "ttkern.h" |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 25 | |
| 26 | #include "sferrors.h" |
| 27 | |
| 28 | |
| 29 | /*************************************************************************/ |
| 30 | /* */ |
| 31 | /* The macro FT_COMPONENT is used in trace mode. It is an implicit */ |
| 32 | /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */ |
| 33 | /* messages during execution. */ |
| 34 | /* */ |
| 35 | #undef FT_COMPONENT |
| 36 | #define FT_COMPONENT trace_ttkern |
| 37 | |
| 38 | |
| 39 | #undef TT_KERN_INDEX |
| 40 | #define TT_KERN_INDEX( g1, g2 ) ( ( (FT_ULong)(g1) << 16 ) | (g2) ) |
| 41 | |
| 42 | |
| 43 | FT_LOCAL_DEF( FT_Error ) |
| 44 | tt_face_load_kern( TT_Face face, |
| 45 | FT_Stream stream ) |
| 46 | { |
| 47 | FT_Error error; |
| 48 | FT_ULong table_size; |
| 49 | FT_Byte* p; |
| 50 | FT_Byte* p_limit; |
| 51 | FT_UInt nn, num_tables; |
| 52 | FT_UInt32 avail = 0, ordered = 0; |
| 53 | |
| 54 | |
| 55 | /* the kern table is optional; exit silently if it is missing */ |
| 56 | error = face->goto_table( face, TTAG_kern, stream, &table_size ); |
| 57 | if ( error ) |
| 58 | goto Exit; |
| 59 | |
| 60 | if ( table_size < 4 ) /* the case of a malformed table */ |
| 61 | { |
David 'Digit' Turner | 295ffce | 2010-03-03 14:24:57 -0800 | [diff] [blame] | 62 | FT_ERROR(( "tt_face_load_kern:" |
| 63 | " kerning table is too small - ignored\n" )); |
Victoria Lease | 727dee1 | 2013-06-10 13:55:54 -0700 | [diff] [blame] | 64 | error = FT_THROW( Table_Missing ); |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 65 | goto Exit; |
| 66 | } |
| 67 | |
| 68 | if ( FT_FRAME_EXTRACT( table_size, face->kern_table ) ) |
| 69 | { |
David 'Digit' Turner | 295ffce | 2010-03-03 14:24:57 -0800 | [diff] [blame] | 70 | FT_ERROR(( "tt_face_load_kern:" |
| 71 | " could not extract kerning table\n" )); |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 72 | goto Exit; |
| 73 | } |
| 74 | |
| 75 | face->kern_table_size = table_size; |
| 76 | |
| 77 | p = face->kern_table; |
| 78 | p_limit = p + table_size; |
| 79 | |
| 80 | p += 2; /* skip version */ |
| 81 | num_tables = FT_NEXT_USHORT( p ); |
| 82 | |
| 83 | if ( num_tables > 32 ) /* we only support up to 32 sub-tables */ |
| 84 | num_tables = 32; |
| 85 | |
| 86 | for ( nn = 0; nn < num_tables; nn++ ) |
| 87 | { |
| 88 | FT_UInt num_pairs, length, coverage; |
| 89 | FT_Byte* p_next; |
David 'Digit' Turner | 295ffce | 2010-03-03 14:24:57 -0800 | [diff] [blame] | 90 | FT_UInt32 mask = (FT_UInt32)1UL << nn; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 91 | |
| 92 | |
| 93 | if ( p + 6 > p_limit ) |
| 94 | break; |
| 95 | |
| 96 | p_next = p; |
| 97 | |
| 98 | p += 2; /* skip version */ |
| 99 | length = FT_NEXT_USHORT( p ); |
| 100 | coverage = FT_NEXT_USHORT( p ); |
| 101 | |
Makoto Onuki | ec62c52 | 2015-06-09 16:35:08 -0700 | [diff] [blame] | 102 | if ( length <= 6 + 8 ) |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 103 | break; |
| 104 | |
| 105 | p_next += length; |
| 106 | |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 107 | if ( p_next > p_limit ) /* handle broken table */ |
| 108 | p_next = p_limit; |
| 109 | |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 110 | /* only use horizontal kerning tables */ |
Makoto Onuki | ec62c52 | 2015-06-09 16:35:08 -0700 | [diff] [blame] | 111 | if ( ( coverage & ~8U ) != 0x0001 || |
| 112 | p + 8 > p_limit ) |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 113 | goto NextTable; |
| 114 | |
| 115 | num_pairs = FT_NEXT_USHORT( p ); |
| 116 | p += 6; |
| 117 | |
Nick Kralevich | aacb8e1 | 2010-09-14 17:02:58 -0700 | [diff] [blame] | 118 | if ( ( p_next - p ) < 6 * (int)num_pairs ) /* handle broken count */ |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 119 | num_pairs = (FT_UInt)( ( p_next - p ) / 6 ); |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 120 | |
| 121 | avail |= mask; |
| 122 | |
| 123 | /* |
| 124 | * Now check whether the pairs in this table are ordered. |
| 125 | * We then can use binary search. |
| 126 | */ |
| 127 | if ( num_pairs > 0 ) |
| 128 | { |
David 'Digit' Turner | 295ffce | 2010-03-03 14:24:57 -0800 | [diff] [blame] | 129 | FT_ULong count; |
| 130 | FT_ULong old_pair; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 131 | |
| 132 | |
| 133 | old_pair = FT_NEXT_ULONG( p ); |
| 134 | p += 2; |
| 135 | |
| 136 | for ( count = num_pairs - 1; count > 0; count-- ) |
| 137 | { |
| 138 | FT_UInt32 cur_pair; |
| 139 | |
| 140 | |
| 141 | cur_pair = FT_NEXT_ULONG( p ); |
| 142 | if ( cur_pair <= old_pair ) |
| 143 | break; |
| 144 | |
| 145 | p += 2; |
| 146 | old_pair = cur_pair; |
| 147 | } |
| 148 | |
| 149 | if ( count == 0 ) |
| 150 | ordered |= mask; |
| 151 | } |
| 152 | |
| 153 | NextTable: |
| 154 | p = p_next; |
| 155 | } |
| 156 | |
| 157 | face->num_kern_tables = nn; |
| 158 | face->kern_avail_bits = avail; |
| 159 | face->kern_order_bits = ordered; |
| 160 | |
| 161 | Exit: |
| 162 | return error; |
| 163 | } |
| 164 | |
| 165 | |
| 166 | FT_LOCAL_DEF( void ) |
| 167 | tt_face_done_kern( TT_Face face ) |
| 168 | { |
| 169 | FT_Stream stream = face->root.stream; |
| 170 | |
| 171 | |
| 172 | FT_FRAME_RELEASE( face->kern_table ); |
| 173 | face->kern_table_size = 0; |
| 174 | face->num_kern_tables = 0; |
| 175 | face->kern_avail_bits = 0; |
| 176 | face->kern_order_bits = 0; |
| 177 | } |
| 178 | |
| 179 | |
| 180 | FT_LOCAL_DEF( FT_Int ) |
| 181 | tt_face_get_kerning( TT_Face face, |
| 182 | FT_UInt left_glyph, |
| 183 | FT_UInt right_glyph ) |
| 184 | { |
| 185 | FT_Int result = 0; |
Victoria Lease | ec0bab5 | 2013-12-12 09:12:18 -0800 | [diff] [blame] | 186 | FT_UInt count, mask; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 187 | FT_Byte* p = face->kern_table; |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 188 | FT_Byte* p_limit = p + face->kern_table_size; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 189 | |
| 190 | |
| 191 | p += 4; |
| 192 | mask = 0x0001; |
| 193 | |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 194 | for ( count = face->num_kern_tables; |
| 195 | count > 0 && p + 6 <= p_limit; |
| 196 | count--, mask <<= 1 ) |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 197 | { |
| 198 | FT_Byte* base = p; |
Victoria Lease | ec0bab5 | 2013-12-12 09:12:18 -0800 | [diff] [blame] | 199 | FT_Byte* next; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 200 | FT_UInt version = FT_NEXT_USHORT( p ); |
| 201 | FT_UInt length = FT_NEXT_USHORT( p ); |
| 202 | FT_UInt coverage = FT_NEXT_USHORT( p ); |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 203 | FT_UInt num_pairs; |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 204 | FT_Int value = 0; |
| 205 | |
| 206 | FT_UNUSED( version ); |
| 207 | |
| 208 | |
| 209 | next = base + length; |
| 210 | |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 211 | if ( next > p_limit ) /* handle broken table */ |
| 212 | next = p_limit; |
| 213 | |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 214 | if ( ( face->kern_avail_bits & mask ) == 0 ) |
| 215 | goto NextTable; |
| 216 | |
| 217 | if ( p + 8 > next ) |
| 218 | goto NextTable; |
| 219 | |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 220 | num_pairs = FT_NEXT_USHORT( p ); |
| 221 | p += 6; |
| 222 | |
Nick Kralevich | aacb8e1 | 2010-09-14 17:02:58 -0700 | [diff] [blame] | 223 | if ( ( next - p ) < 6 * (int)num_pairs ) /* handle broken count */ |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 224 | num_pairs = (FT_UInt)( ( next - p ) / 6 ); |
| 225 | |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 226 | switch ( coverage >> 8 ) |
| 227 | { |
| 228 | case 0: |
| 229 | { |
David 'Digit' Turner | 77f63d2 | 2009-06-08 15:18:21 +0200 | [diff] [blame] | 230 | FT_ULong key0 = TT_KERN_INDEX( left_glyph, right_glyph ); |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 231 | |
| 232 | |
The Android Open Source Project | 049d6fe | 2009-03-03 19:29:31 -0800 | [diff] [blame] | 233 | if ( face->kern_order_bits & mask ) /* binary search */ |
| 234 | { |
| 235 | FT_UInt min = 0; |
| 236 | FT_UInt max = num_pairs; |
| 237 | |
| 238 | |
| 239 | while ( min < max ) |
| 240 | { |
| 241 | FT_UInt mid = ( min + max ) >> 1; |
| 242 | FT_Byte* q = p + 6 * mid; |
| 243 | FT_ULong key; |
| 244 | |
| 245 | |
| 246 | key = FT_NEXT_ULONG( q ); |
| 247 | |
| 248 | if ( key == key0 ) |
| 249 | { |
| 250 | value = FT_PEEK_SHORT( q ); |
| 251 | goto Found; |
| 252 | } |
| 253 | if ( key < key0 ) |
| 254 | min = mid + 1; |
| 255 | else |
| 256 | max = mid; |
| 257 | } |
| 258 | } |
| 259 | else /* linear search */ |
| 260 | { |
| 261 | FT_UInt count2; |
| 262 | |
| 263 | |
| 264 | for ( count2 = num_pairs; count2 > 0; count2-- ) |
| 265 | { |
| 266 | FT_ULong key = FT_NEXT_ULONG( p ); |
| 267 | |
| 268 | |
| 269 | if ( key == key0 ) |
| 270 | { |
| 271 | value = FT_PEEK_SHORT( p ); |
| 272 | goto Found; |
| 273 | } |
| 274 | p += 2; |
| 275 | } |
| 276 | } |
| 277 | } |
| 278 | break; |
| 279 | |
| 280 | /* |
| 281 | * We don't support format 2 because we haven't seen a single font |
| 282 | * using it in real life... |
| 283 | */ |
| 284 | |
| 285 | default: |
| 286 | ; |
| 287 | } |
| 288 | |
| 289 | goto NextTable; |
| 290 | |
| 291 | Found: |
| 292 | if ( coverage & 8 ) /* override or add */ |
| 293 | result = value; |
| 294 | else |
| 295 | result += value; |
| 296 | |
| 297 | NextTable: |
| 298 | p = next; |
| 299 | } |
| 300 | |
| 301 | return result; |
| 302 | } |
| 303 | |
| 304 | #undef TT_KERN_INDEX |
| 305 | |
| 306 | /* END */ |