1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
|
/***************************************************************************/
/* */
/* ttkern.c */
/* */
/* Load the basic TrueType kerning table. This doesn't handle */
/* kerning data within the GPOS table at the moment. */
/* */
/* Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2007 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_TRUETYPE_TAGS_H
#include "ttkern.h"
#include "ttload.h"
#include "sferrors.h"
/*************************************************************************/
/* */
/* The macro FT_COMPONENT is used in trace mode. It is an implicit */
/* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */
/* messages during execution. */
/* */
#undef FT_COMPONENT
#define FT_COMPONENT trace_ttkern
#undef TT_KERN_INDEX
#define TT_KERN_INDEX( g1, g2 ) ( ( (FT_ULong)(g1) << 16 ) | (g2) )
FT_LOCAL_DEF( FT_Error )
tt_face_load_kern( TT_Face face,
FT_Stream stream )
{
FT_Error error;
FT_ULong table_size;
FT_Byte* p;
FT_Byte* p_limit;
FT_UInt nn, num_tables;
FT_UInt32 avail = 0, ordered = 0;
/* the kern table is optional; exit silently if it is missing */
error = face->goto_table( face, TTAG_kern, stream, &table_size );
if ( error )
goto Exit;
if ( table_size < 4 ) /* the case of a malformed table */
{
FT_ERROR(( "kerning table is too small - ignored\n" ));
error = SFNT_Err_Table_Missing;
goto Exit;
}
if ( FT_FRAME_EXTRACT( table_size, face->kern_table ) )
{
FT_ERROR(( "could not extract kerning table\n" ));
goto Exit;
}
face->kern_table_size = table_size;
p = face->kern_table;
p_limit = p + table_size;
p += 2; /* skip version */
num_tables = FT_NEXT_USHORT( p );
if ( num_tables > 32 ) /* we only support up to 32 sub-tables */
num_tables = 32;
for ( nn = 0; nn < num_tables; nn++ )
{
FT_UInt num_pairs, length, coverage;
FT_Byte* p_next;
FT_UInt32 mask = 1UL << nn;
if ( p + 6 > p_limit )
break;
p_next = p;
p += 2; /* skip version */
length = FT_NEXT_USHORT( p );
coverage = FT_NEXT_USHORT( p );
if ( length <= 6 )
break;
p_next += length;
/* only use horizontal kerning tables */
if ( ( coverage & ~8 ) != 0x0001 ||
p + 8 > p_limit )
goto NextTable;
num_pairs = FT_NEXT_USHORT( p );
p += 6;
if ( p + 6 * num_pairs > p_limit )
goto NextTable;
avail |= mask;
/*
* Now check whether the pairs in this table are ordered.
* We then can use binary search.
*/
if ( num_pairs > 0 )
{
FT_UInt count;
FT_UInt old_pair;
old_pair = FT_NEXT_ULONG( p );
p += 2;
for ( count = num_pairs - 1; count > 0; count-- )
{
FT_UInt32 cur_pair;
cur_pair = FT_NEXT_ULONG( p );
if ( cur_pair <= old_pair )
break;
p += 2;
old_pair = cur_pair;
}
if ( count == 0 )
ordered |= mask;
}
NextTable:
p = p_next;
}
face->num_kern_tables = nn;
face->kern_avail_bits = avail;
face->kern_order_bits = ordered;
Exit:
return error;
}
FT_LOCAL_DEF( void )
tt_face_done_kern( TT_Face face )
{
FT_Stream stream = face->root.stream;
FT_FRAME_RELEASE( face->kern_table );
face->kern_table_size = 0;
face->num_kern_tables = 0;
face->kern_avail_bits = 0;
face->kern_order_bits = 0;
}
FT_LOCAL_DEF( FT_Int )
tt_face_get_kerning( TT_Face face,
FT_UInt left_glyph,
FT_UInt right_glyph )
{
FT_Int result = 0;
FT_UInt count, mask = 1;
FT_Byte* p = face->kern_table;
p += 4;
mask = 0x0001;
for ( count = face->num_kern_tables; count > 0; count--, mask <<= 1 )
{
FT_Byte* base = p;
FT_Byte* next = base;
FT_UInt version = FT_NEXT_USHORT( p );
FT_UInt length = FT_NEXT_USHORT( p );
FT_UInt coverage = FT_NEXT_USHORT( p );
FT_Int value = 0;
FT_UNUSED( version );
next = base + length;
if ( ( face->kern_avail_bits & mask ) == 0 )
goto NextTable;
if ( p + 8 > next )
goto NextTable;
switch ( coverage >> 8 )
{
case 0:
{
FT_UInt num_pairs = FT_NEXT_USHORT( p );
FT_ULong key0 = TT_KERN_INDEX( left_glyph, right_glyph );
p += 6;
if ( face->kern_order_bits & mask ) /* binary search */
{
FT_UInt min = 0;
FT_UInt max = num_pairs;
while ( min < max )
{
FT_UInt mid = ( min + max ) >> 1;
FT_Byte* q = p + 6 * mid;
FT_ULong key;
key = FT_NEXT_ULONG( q );
if ( key == key0 )
{
value = FT_PEEK_SHORT( q );
goto Found;
}
if ( key < key0 )
min = mid + 1;
else
max = mid;
}
}
else /* linear search */
{
FT_UInt count2;
for ( count2 = num_pairs; count2 > 0; count2-- )
{
FT_ULong key = FT_NEXT_ULONG( p );
if ( key == key0 )
{
value = FT_PEEK_SHORT( p );
goto Found;
}
p += 2;
}
}
}
break;
/*
* We don't support format 2 because we haven't seen a single font
* using it in real life...
*/
default:
;
}
goto NextTable;
Found:
if ( coverage & 8 ) /* override or add */
result = value;
else
result += value;
NextTable:
p = next;
}
return result;
}
#undef TT_KERN_INDEX
/* END */
|
