ReactOS  0.4.14-dev-614-gbfd8a84
ttkern.c
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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 1996-2018 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 
46  {
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 = FT_THROW( 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, format;
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 + 8 )
103  break;
104 
105  p_next += length;
106 
107  if ( p_next > p_limit ) /* handle broken table */
108  p_next = p_limit;
109 
110  format = coverage >> 8;
111 
112  /* we currently only support format 0 kerning tables */
113  if ( format != 0 )
114  goto NextTable;
115 
116  /* only use horizontal kerning tables */
117  if ( ( coverage & 3U ) != 0x0001 ||
118  p + 8 > p_next )
119  goto NextTable;
120 
121  num_pairs = FT_NEXT_USHORT( p );
122  p += 6;
123 
124  if ( ( p_next - p ) < 6 * (int)num_pairs ) /* handle broken count */
125  num_pairs = (FT_UInt)( ( p_next - p ) / 6 );
126 
127  avail |= mask;
128 
129  /*
130  * Now check whether the pairs in this table are ordered.
131  * We then can use binary search.
132  */
133  if ( num_pairs > 0 )
134  {
135  FT_ULong count;
136  FT_ULong old_pair;
137 
138 
139  old_pair = FT_NEXT_ULONG( p );
140  p += 2;
141 
142  for ( count = num_pairs - 1; count > 0; count-- )
143  {
144  FT_UInt32 cur_pair;
145 
146 
147  cur_pair = FT_NEXT_ULONG( p );
148  if ( cur_pair <= old_pair )
149  break;
150 
151  p += 2;
152  old_pair = cur_pair;
153  }
154 
155  if ( count == 0 )
156  ordered |= mask;
157  }
158 
159  NextTable:
160  p = p_next;
161  }
162 
163  face->num_kern_tables = nn;
164  face->kern_avail_bits = avail;
165  face->kern_order_bits = ordered;
166 
167  Exit:
168  return error;
169  }
170 
171 
172  FT_LOCAL_DEF( void )
174  {
175  FT_Stream stream = face->root.stream;
176 
177 
178  FT_FRAME_RELEASE( face->kern_table );
179  face->kern_table_size = 0;
180  face->num_kern_tables = 0;
181  face->kern_avail_bits = 0;
182  face->kern_order_bits = 0;
183  }
184 
185 
190  {
191  FT_Int result = 0;
192  FT_UInt count, mask;
193  FT_Byte* p = face->kern_table;
194  FT_Byte* p_limit = p + face->kern_table_size;
195 
196 
197  p += 4;
198  mask = 0x0001;
199 
200  for ( count = face->num_kern_tables;
201  count > 0 && p + 6 <= p_limit;
202  count--, mask <<= 1 )
203  {
204  FT_Byte* base = p;
205  FT_Byte* next;
208  FT_UInt coverage = FT_NEXT_USHORT( p );
209  FT_UInt num_pairs;
210  FT_Int value = 0;
211 
212  FT_UNUSED( version );
213 
214 
215  next = base + length;
216 
217  if ( next > p_limit ) /* handle broken table */
218  next = p_limit;
219 
220  if ( ( face->kern_avail_bits & mask ) == 0 )
221  goto NextTable;
222 
223  FT_ASSERT( p + 8 <= next ); /* tested in tt_face_load_kern */
224 
225  num_pairs = FT_NEXT_USHORT( p );
226  p += 6;
227 
228  if ( ( next - p ) < 6 * (int)num_pairs ) /* handle broken count */
229  num_pairs = (FT_UInt)( ( next - p ) / 6 );
230 
231  switch ( coverage >> 8 )
232  {
233  case 0:
234  {
236 
237 
238  if ( face->kern_order_bits & mask ) /* binary search */
239  {
240  FT_UInt min = 0;
241  FT_UInt max = num_pairs;
242 
243 
244  while ( min < max )
245  {
246  FT_UInt mid = ( min + max ) >> 1;
247  FT_Byte* q = p + 6 * mid;
248  FT_ULong key;
249 
250 
251  key = FT_NEXT_ULONG( q );
252 
253  if ( key == key0 )
254  {
255  value = FT_PEEK_SHORT( q );
256  goto Found;
257  }
258  if ( key < key0 )
259  min = mid + 1;
260  else
261  max = mid;
262  }
263  }
264  else /* linear search */
265  {
266  FT_UInt count2;
267 
268 
269  for ( count2 = num_pairs; count2 > 0; count2-- )
270  {
272 
273 
274  if ( key == key0 )
275  {
276  value = FT_PEEK_SHORT( p );
277  goto Found;
278  }
279  p += 2;
280  }
281  }
282  }
283  break;
284 
285  /*
286  * We don't support format 2 because we haven't seen a single font
287  * using it in real life...
288  */
289 
290  default:
291  ;
292  }
293 
294  goto NextTable;
295 
296  Found:
297  if ( coverage & 8 ) /* override or add */
298  result = value;
299  else
300  result += value;
301 
302  NextTable:
303  p = next;
304  }
305 
306  return result;
307  }
308 
309 #undef TT_KERN_INDEX
310 
311 /* END */
int FT_Error
Definition: fttypes.h:300
#define max(a, b)
Definition: svc.c:63
unsigned long FT_ULong
Definition: fttypes.h:253
FT_UInt FT_UInt right_glyph
Definition: ttdriver.c:201
#define error(str)
Definition: mkdosfs.c:1605
tt_face_done_kern(TT_Face face)
Definition: ttkern.c:173
signed int FT_Int
Definition: fttypes.h:220
GLuint GLuint GLsizei count
Definition: gl.h:1545
tt_face_get_kerning(TT_Face face, FT_UInt left_glyph, FT_UInt right_glyph)
Definition: ttkern.c:187
#define U(x)
Definition: wordpad.c:44
static int avail
Definition: adh-main.c:39
GLint GLint GLsizei GLsizei GLsizei GLint GLenum format
Definition: gl.h:1546
GLenum GLint GLuint mask
Definition: glext.h:6028
#define FT_ERROR(varformat)
Definition: ftdebug.h:181
unsigned char FT_Byte
Definition: fttypes.h:154
#define FT_ASSERT(condition)
Definition: ftdebug.h:211
#define FT_THROW(e)
Definition: ftdebug.h:213
static const WCHAR version[]
Definition: asmname.c:66
return Found
Definition: dirsup.c:1270
#define FT_LOCAL_DEF(x)
Definition: ftconfig.h:388
#define TTAG_kern
Definition: tttags.h:72
GLenum GLuint GLenum GLsizei length
Definition: glext.h:5579
static void Exit(void)
Definition: sock.c:1331
GLdouble GLdouble GLdouble GLdouble q
Definition: gl.h:2063
Definition: parse.h:22
HKEY key
Definition: reg.c:42
FT_UInt left_glyph
Definition: ttdriver.c:201
GLsizei const GLfloat * value
Definition: glext.h:6069
#define FT_NEXT_USHORT(buffer)
Definition: ftstream.h:226
tt_face_load_kern(TT_Face face, FT_Stream stream)
Definition: ttkern.c:44
#define FT_FRAME_RELEASE(bytes)
Definition: ftstream.h:526
GLuint64EXT GLuint GLuint GLenum GLenum GLuint GLuint key0
Definition: glext.h:10608
static unsigned __int64 next
Definition: rand_nt.c:6
unsigned int FT_UInt
Definition: fttypes.h:231
#define FT_NEXT_ULONG(buffer)
Definition: ftstream.h:238
#define min(a, b)
Definition: monoChain.cc:55
#define FT_FRAME_EXTRACT(size, bytes)
Definition: ftstream.h:520
#define TT_KERN_INDEX(g1, g2)
Definition: ttkern.c:40
GLfloat GLfloat p
Definition: glext.h:8902
GLuint64EXT * result
Definition: glext.h:11304
#define FT_UNUSED(arg)
Definition: ftconfig.h:101
#define UL
Definition: tui.h:83
GLenum GLuint GLint GLenum face
Definition: glext.h:7025
Definition: path.c:41
LOCAL int table_size
Definition: write.c:65
#define FT_PEEK_SHORT(p)
Definition: ftstream.h:168