[CMAKE]
[reactos.git] / lib / 3rdparty / freetype / src / sfnt / ttkern.c
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 /* */
8 /* Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010 by */
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"
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 {
62 FT_ERROR(( "tt_face_load_kern:"
63 " kerning table is too small - ignored\n" ));
64 error = SFNT_Err_Table_Missing;
65 goto Exit;
66 }
67
68 if ( FT_FRAME_EXTRACT( table_size, face->kern_table ) )
69 {
70 FT_ERROR(( "tt_face_load_kern:"
71 " could not extract kerning table\n" ));
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;
90 FT_UInt32 mask = (FT_UInt32)1UL << nn;
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
102 if ( length <= 6 )
103 break;
104
105 p_next += length;
106
107 if ( p_next > p_limit ) /* handle broken table */
108 p_next = p_limit;
109
110 /* only use horizontal kerning tables */
111 if ( ( coverage & ~8 ) != 0x0001 ||
112 p + 8 > p_limit )
113 goto NextTable;
114
115 num_pairs = FT_NEXT_USHORT( p );
116 p += 6;
117
118 if ( ( p_next - p ) < 6 * (int)num_pairs ) /* handle broken count */
119 num_pairs = (FT_UInt)( ( p_next - p ) / 6 );
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 {
129 FT_ULong count;
130 FT_ULong old_pair;
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;
186 FT_UInt count, mask = 1;
187 FT_Byte* p = face->kern_table;
188 FT_Byte* p_limit = p + face->kern_table_size;
189
190
191 p += 4;
192 mask = 0x0001;
193
194 for ( count = face->num_kern_tables;
195 count > 0 && p + 6 <= p_limit;
196 count--, mask <<= 1 )
197 {
198 FT_Byte* base = p;
199 FT_Byte* next = base;
200 FT_UInt version = FT_NEXT_USHORT( p );
201 FT_UInt length = FT_NEXT_USHORT( p );
202 FT_UInt coverage = FT_NEXT_USHORT( p );
203 FT_UInt num_pairs;
204 FT_Int value = 0;
205
206 FT_UNUSED( version );
207
208
209 next = base + length;
210
211 if ( next > p_limit ) /* handle broken table */
212 next = p_limit;
213
214 if ( ( face->kern_avail_bits & mask ) == 0 )
215 goto NextTable;
216
217 if ( p + 8 > next )
218 goto NextTable;
219
220 num_pairs = FT_NEXT_USHORT( p );
221 p += 6;
222
223 if ( ( next - p ) < 6 * (int)num_pairs ) /* handle broken count */
224 num_pairs = (FT_UInt)( ( next - p ) / 6 );
225
226 switch ( coverage >> 8 )
227 {
228 case 0:
229 {
230 FT_ULong key0 = TT_KERN_INDEX( left_glyph, right_glyph );
231
232
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 */