summaryrefslogtreecommitdiff
path: root/pango/pango-coverage.c
blob: eccd4f9961a2221a124caac0afe90d588f5b5468 (plain)
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
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
/* Pango
 * pango-coverage.c: Coverage maps for fonts
 *
 * Copyright (C) 2000 Red Hat Software
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/**
 * SECTION:coverage-maps
 * @short_description:Unicode character range coverage storage
 * @title:Coverage Maps
 *
 * It is often necessary in Pango to determine if a particular font can
 * represent a particular character, and also how well it can represent
 * that character. The #PangoCoverage is a data structure that is used
 * to represent that information.
 */
#include "config.h"
#include <string.h>

#include "pango-coverage.h"

typedef struct _PangoBlockInfo PangoBlockInfo;

#define N_BLOCKS_INCREMENT 256

/* The structure of a PangoCoverage object is a two-level table, with blocks of size 256.
 * each block is stored as a packed array of 2 bit values for each index, in LSB order.
 */

struct _PangoBlockInfo
{
  guchar *data;
  PangoCoverageLevel level;	/* Used if data == NULL */
};

struct _PangoCoverage
{
  guint ref_count;
  int n_blocks;

  PangoBlockInfo *blocks;
};

/**
 * pango_coverage_new:
 *
 * Create a new #PangoCoverage
 *
 * Return value: the newly allocated #PangoCoverage,
 *               initialized to %PANGO_COVERAGE_NONE
 *               with a reference count of one, which
 *               should be freed with pango_coverage_unref().
 **/
PangoCoverage *
pango_coverage_new (void)
{
  PangoCoverage *coverage = g_slice_new (PangoCoverage);

  coverage->n_blocks = N_BLOCKS_INCREMENT;
  coverage->blocks = g_new0 (PangoBlockInfo, coverage->n_blocks);
  coverage->ref_count = 1;

  return coverage;
}

/**
 * pango_coverage_copy:
 * @coverage: a #PangoCoverage
 *
 * Copy an existing #PangoCoverage. (This function may now be unnecessary
 * since we refcount the structure. File a bug if you use it.)
 *
 * Return value: (transfer full): the newly allocated #PangoCoverage,
 *               with a reference count of one, which should be freed
 *               with pango_coverage_unref().
 **/
PangoCoverage *
pango_coverage_copy (PangoCoverage *coverage)
{
  int i;
  PangoCoverage *result;

  g_return_val_if_fail (coverage != NULL, NULL);

  result = g_slice_new (PangoCoverage);
  result->n_blocks = coverage->n_blocks;
  result->blocks = g_new (PangoBlockInfo, coverage->n_blocks);
  result->ref_count = 1;

  for (i=0; i<coverage->n_blocks; i++)
    {
      if (coverage->blocks[i].data)
	{
	  result->blocks[i].data = g_new (guchar, 64);
	  memcpy (result->blocks[i].data, coverage->blocks[i].data, 64);
	}
      else
	result->blocks[i].data = NULL;

      result->blocks[i].level = coverage->blocks[i].level;
    }

  return result;
}

/**
 * pango_coverage_ref:
 * @coverage: a #PangoCoverage
 *
 * Increase the reference count on the #PangoCoverage by one
 *
 * Return value: @coverage
 **/
PangoCoverage *
pango_coverage_ref (PangoCoverage *coverage)
{
  g_return_val_if_fail (coverage != NULL, NULL);

  g_atomic_int_inc ((int *) &coverage->ref_count);

  return coverage;
}

/**
 * pango_coverage_unref:
 * @coverage: a #PangoCoverage
 *
 * Decrease the reference count on the #PangoCoverage by one.
 * If the result is zero, free the coverage and all associated memory.
 **/
void
pango_coverage_unref (PangoCoverage *coverage)
{
  int i;

  g_return_if_fail (coverage != NULL);
  g_return_if_fail (coverage->ref_count > 0);

  if (g_atomic_int_dec_and_test ((int *) &coverage->ref_count))
    {
      for (i=0; i<coverage->n_blocks; i++)
	g_slice_free1 (64, coverage->blocks[i].data);

      g_free (coverage->blocks);
      g_slice_free (PangoCoverage, coverage);
    }
}

/**
 * pango_coverage_get:
 * @coverage: a #PangoCoverage
 * @index_: the index to check
 *
 * Determine whether a particular index is covered by @coverage
 *
 * Return value: the coverage level of @coverage for character @index_.
 **/
PangoCoverageLevel
pango_coverage_get (PangoCoverage *coverage,
		    int            index)
{
  int block_index;

  g_return_val_if_fail (coverage != NULL, PANGO_COVERAGE_NONE);

  /* index should really have been defined unsigned.  Work around
   * it by just returning NONE.
   */
  if (G_UNLIKELY (index < 0))
    return PANGO_COVERAGE_NONE;

  block_index = index / 256;

  if (block_index >= coverage->n_blocks)
    return PANGO_COVERAGE_NONE;
  else
    {
      guchar *data = coverage->blocks[block_index].data;
      if (data)
	{
	  int i = index % 256;
	  int shift = (i % 4) * 2;

	  return (data[i/4] >> shift) & 0x3;
	}
      else
	return coverage->blocks[block_index].level;
    }
}

/**
 * pango_coverage_set:
 * @coverage: a #PangoCoverage
 * @index_: the index to modify
 * @level: the new level for @index_
 *
 * Modify a particular index within @coverage
 **/
void
pango_coverage_set (PangoCoverage     *coverage,
		    int                index,
		    PangoCoverageLevel level)
{
  int block_index, i;
  guchar *data;

  g_return_if_fail (coverage != NULL);
  g_return_if_fail (index >= 0);
  g_return_if_fail ((guint) level <= 3);

  block_index = index / 256;

  if (block_index >= coverage->n_blocks)
    {
      int old_n_blocks = coverage->n_blocks;

      coverage->n_blocks =
	N_BLOCKS_INCREMENT * ((block_index + N_BLOCKS_INCREMENT) / N_BLOCKS_INCREMENT);

      coverage->blocks = g_renew (PangoBlockInfo, coverage->blocks, coverage->n_blocks);
      memset (coverage->blocks + old_n_blocks, 0,
	      sizeof (PangoBlockInfo) * (coverage->n_blocks - old_n_blocks));
    }

  data = coverage->blocks[block_index].data;
  if (!data)
    {
      guchar byte;

      if (level == coverage->blocks[block_index].level)
	return;

      data = g_slice_alloc (64);
      coverage->blocks[block_index].data = data;

      byte = coverage->blocks[block_index].level |
	(coverage->blocks[block_index].level << 2) |
	(coverage->blocks[block_index].level << 4) |
	(coverage->blocks[block_index].level << 6);

      memset (data, byte, 64);
    }

  i = index % 256;
  data[i/4] |= level << ((i % 4) * 2);
}

/**
 * pango_coverage_max:
 * @coverage: a #PangoCoverage
 * @other: another #PangoCoverage
 *
 * Set the coverage for each index in @coverage to be the max (better)
 * value of the current coverage for the index and the coverage for
 * the corresponding index in @other.
 **/
void
pango_coverage_max (PangoCoverage *coverage,
		    PangoCoverage *other)
{
  int block_index, i;
  int old_blocks;

  g_return_if_fail (coverage != NULL);

  old_blocks = MIN (coverage->n_blocks, other->n_blocks);

  if (other->n_blocks > coverage->n_blocks)
    {
      coverage->n_blocks = other->n_blocks;
      coverage->blocks = g_renew (PangoBlockInfo, coverage->blocks, coverage->n_blocks);

      for (block_index = old_blocks; block_index < coverage->n_blocks; block_index++)
	{
	  if (other->blocks[block_index].data)
	    {
	      coverage->blocks[block_index].data = g_new (guchar, 64);
	      memcpy (coverage->blocks[block_index].data, other->blocks[block_index].data, 64);
	    }
	  else
	    coverage->blocks[block_index].data = NULL;

	  coverage->blocks[block_index].level = other->blocks[block_index].level;
	}
    }

  for (block_index = 0; block_index < old_blocks; block_index++)
    {
      if (!coverage->blocks[block_index].data && !other->blocks[block_index].data)
	{
	  coverage->blocks[block_index].level = MAX (coverage->blocks[block_index].level, other->blocks[block_index].level);
	}
      else if (coverage->blocks[block_index].data && other->blocks[block_index].data)
	{
	  guchar *data = coverage->blocks[block_index].data;

	  for (i=0; i<64; i++)
	    {
	      int byte1 = data[i];
	      int byte2 = other->blocks[block_index].data[i];

	      /* There are almost certainly some clever logical ops to do this */
	      data[i] =
		MAX (byte1 & 0x3, byte2 & 0x3) |
		MAX (byte1 & 0xc, byte2 & 0xc) |
		MAX (byte1 & 0x30, byte2 & 0x30) |
		MAX (byte1 & 0xc0, byte2 & 0xc0);
	    }
	}
      else
	{
	  guchar *src, *dest;
	  int level, byte2;

	  if (coverage->blocks[block_index].data)
	    {
	      src = dest = coverage->blocks[block_index].data;
	      level = other->blocks[block_index].level;
	    }
	  else
	    {
	      src = other->blocks[block_index].data;
	      dest = g_new (guchar, 64);
	      coverage->blocks[block_index].data = dest;
	      level = coverage->blocks[block_index].level;
	    }

	  byte2 = level | (level << 2) | (level << 4) | (level << 6);

	  for (i=0; i<64; i++)
	    {
	      int byte1 = src[i];

	      /* There are almost certainly some clever logical ops to do this */
	      dest[i] =
		MAX (byte1 & 0x3, byte2 & 0x3) |
		MAX (byte1 & 0xc, byte2 & 0xc) |
		MAX (byte1 & 0x30, byte2 & 0x30) |
		MAX (byte1 & 0xc0, byte2 & 0xc0);
	    }
	}
    }
}

#define PANGO_COVERAGE_MAGIC 0xc89dbd5e

/**
 * pango_coverage_to_bytes:
 * @coverage: a #PangoCoverage
 * @bytes: (out) (array length=n_bytes) (element-type guint8):
 *   location to store result (must be freed with g_free())
 * @n_bytes: (out): location to store size of result
 *
 * Convert a #PangoCoverage structure into a flat binary format
 **/
void
pango_coverage_to_bytes   (PangoCoverage  *coverage,
			   guchar        **bytes,
			   int            *n_bytes)
{
  int i, j;
  int size = 8 + 4 * coverage->n_blocks;
  guchar *data;
  int offset;

  for (i=0; i<coverage->n_blocks; i++)
    {
      if (coverage->blocks[i].data)
	size += 64;
    }

  data = g_malloc (size);

  *(guint32 *)&data[0] = g_htonl (PANGO_COVERAGE_MAGIC); /* Magic */
  *(guint32 *)&data[4] = g_htonl (coverage->n_blocks);
  offset = 8;

  for (i=0; i<coverage->n_blocks; i++)
    {
      guint32 header_val;

      /* Check for solid blocks. This is a sort of random place
       * to do the optimization, but we care most about getting
       * it right when storing it somewhere persistant.
       */
      if (coverage->blocks[i].data != NULL)
	{
	  guchar *data = coverage->blocks[i].data;
	  guchar first_val = data[0];

	  if (first_val == 0 || first_val == 0xff)
	    {
	      for (j = 1 ; j < 64; j++)
		if (data[j] != first_val)
		  break;

	      if (j == 64)
		{
		  g_slice_free1 (64, data);
		  coverage->blocks[i].data = NULL;
		  coverage->blocks[i].level = first_val & 0x3;
		}
	    }
	}

      if (coverage->blocks[i].data != NULL)
	header_val = (guint32)-1;
      else
	header_val = coverage->blocks[i].level;

      *(guint32 *)&data[offset] = g_htonl (header_val);
      offset += 4;

      if (coverage->blocks[i].data)
	{
	  memcpy (data + offset, coverage->blocks[i].data, 64);
	  offset += 64;
	}
    }

  *bytes = data;
  *n_bytes = size;
}

static guint32
pango_coverage_get_uint32 (guchar **ptr)
{
  guint32 val;

  memcpy (&val, *ptr, 4);
  *ptr += 4;

  return g_ntohl (val);
}

/**
 * pango_coverage_from_bytes:
 * @bytes: (array length=n_bytes) (element-type guint8): binary data
 *   representing a #PangoCoverage
 * @n_bytes: the size of @bytes in bytes
 *
 * Convert data generated from pango_coverage_to_bytes() back
 * to a #PangoCoverage
 *
 * Return value: (transfer full): a newly allocated #PangoCoverage, or
 *               %NULL if the data was invalid.
 **/
PangoCoverage *
pango_coverage_from_bytes (guchar *bytes,
			   int     n_bytes)
{
  PangoCoverage *coverage = g_slice_new0 (PangoCoverage);
  guchar *ptr = bytes;
  int i;

  coverage->ref_count = 1;

  if (n_bytes < 8)
    goto error;

  if (pango_coverage_get_uint32 (&ptr) != PANGO_COVERAGE_MAGIC)
    goto error;

  coverage->n_blocks = pango_coverage_get_uint32 (&ptr);
  coverage->blocks = g_new0 (PangoBlockInfo, coverage->n_blocks);

  for (i = 0; i < coverage->n_blocks; i++)
    {
      guint val;

      if (ptr + 4 > bytes + n_bytes)
	goto error;

      val = pango_coverage_get_uint32 (&ptr);
      if (val == (guint32)-1)
	{
	  if (ptr + 64 > bytes + n_bytes)
	    goto error;

	  coverage->blocks[i].data = g_new (guchar, 64);
	  memcpy (coverage->blocks[i].data, ptr, 64);
	  ptr += 64;
	}
      else
	coverage->blocks[i].level = val;
    }

  return coverage;

 error:

  pango_coverage_unref (coverage);
  return NULL;
}