summaryrefslogtreecommitdiff
path: root/pango/glyphstring.c
blob: 307c9faf5e818ad24b44bea7010903b5d2c3f5d4 (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
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
/* Pango
 * glyphstring.c:
 *
 * Copyright (C) 1999 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.
 */

#include <config.h>
#include <glib.h>
#include "pango-glyph.h"
#include "pango-font.h"
#include "pango-impl-utils.h"

/**
 * pango_glyph_string_new:
 *
 * Create a new #PangoGlyphString.
 *
 * Return value: the newly allocated #PangoGlyphString, which
 *               should be freed with pango_glyph_string_free().
 */
PangoGlyphString *
pango_glyph_string_new (void)
{
  PangoGlyphString *string = g_slice_new (PangoGlyphString);

  string->num_glyphs = 0;
  string->space = 0;
  string->glyphs = NULL;
  string->log_clusters = NULL;

  return string;
}

/**
 * pango_glyph_string_set_size:
 * @string:    a #PangoGlyphString.
 * @new_len:   the new length of the string.
 *
 * Resize a glyph string to the given length.
 */
void
pango_glyph_string_set_size (PangoGlyphString *string, gint new_len)
{
  g_return_if_fail (new_len >= 0);

  while (new_len > string->space)
    {
      if (string->space == 0)
	string->space = 1;
      else
	string->space *= 2;

      if (string->space < 0)
	{
	  g_warning ("glyph string length overflows maximum integer size, truncated");
	  new_len = string->space = G_MAXINT - 8;
	}
    }

  string->glyphs = g_realloc (string->glyphs, string->space * sizeof (PangoGlyphInfo));
  string->log_clusters = g_realloc (string->log_clusters, string->space * sizeof (gint));
  string->num_glyphs = new_len;
}

GType
pango_glyph_string_get_type (void)
{
  static GType our_type = 0;

  if (G_UNLIKELY (our_type == 0))
    our_type = g_boxed_type_register_static (I_("PangoGlyphString"),
					     (GBoxedCopyFunc)pango_glyph_string_copy,
					     (GBoxedFreeFunc)pango_glyph_string_free);

  return our_type;
}

/**
 * pango_glyph_string_copy:
 * @string: a #PangoGlyphString, may be %NULL
 *
 * Copy a glyph string and associated storage.
 *
 * Return value: the newly allocated #PangoGlyphString, which
 *               should be freed with pango_glyph_string_free(),
 *               or %NULL if @string was %NULL.
 */
PangoGlyphString *
pango_glyph_string_copy (PangoGlyphString *string)
{
  PangoGlyphString *new_string;

  if (string == NULL)
    return NULL;
  
  new_string = g_slice_new (PangoGlyphString);

  *new_string = *string;

  new_string->glyphs = g_memdup (string->glyphs,
				 string->space * sizeof (PangoGlyphInfo));
  new_string->log_clusters = g_memdup (string->log_clusters,
				       string->space * sizeof (gint));

  return new_string;
}

/**
 * pango_glyph_string_free:
 * @string: a #PangoGlyphString, may be %NULL
 *
 * Free a glyph string and associated storage.
 */
void
pango_glyph_string_free (PangoGlyphString *string)
{
  if (string == NULL)
    return;

  g_free (string->glyphs);
  g_free (string->log_clusters);
  g_slice_free (PangoGlyphString, string);
}

/**
 * pango_glyph_string_extents_range:
 * @glyphs:   a #PangoGlyphString
 * @start:    start index
 * @end:      end index (the range is the set of bytes with
	      indices such that start <= index < end)
 * @font:     a #PangoFont
 * @ink_rect: rectangle used to store the extents of the glyph string range as drawn
 *            or %NULL to indicate that the result is not needed.
 * @logical_rect: rectangle used to store the logical extents of the glyph string range
 *            or %NULL to indicate that the result is not needed.
 *
 * Computes the extents of a sub-portion of a glyph string. The extents are
 * relative to the start of the glyph string range (the origin of their
 * coordinate system is at the start of the range, not at the start of the entire
 * glyph string).
 **/
void
pango_glyph_string_extents_range (PangoGlyphString *glyphs,
				  int               start,
				  int               end,
				  PangoFont        *font,
				  PangoRectangle   *ink_rect,
				  PangoRectangle   *logical_rect)
{
  int x_pos = 0;
  int i;

  /* Note that the handling of empty rectangles for ink
   * and logical rectangles is different. A zero-height ink
   * rectangle makes no contribution to the overall ink rect,
   * while a zero-height logical rect still reserves horizontal
   * width. Also, we may return zero-width, positive height
   * logical rectangles, while we'll never do that for the
   * ink rect.
   */
  g_return_if_fail (start <= end);

  if (G_UNLIKELY (!ink_rect && !logical_rect))
    return;

  if (ink_rect)
    {
      ink_rect->x = 0;
      ink_rect->y = 0;
      ink_rect->width = 0;
      ink_rect->height = 0;
    }

  if (logical_rect)
    {
      logical_rect->x = 0;
      logical_rect->y = 0;
      logical_rect->width = 0;
      logical_rect->height = 0;
    }

  for (i = start; i < end; i++)
    {
      PangoRectangle glyph_ink;
      PangoRectangle glyph_logical;

      PangoGlyphGeometry *geometry = &glyphs->glyphs[i].geometry;

      pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph,
				    ink_rect ? &glyph_ink : NULL,
				    logical_rect ? &glyph_logical : NULL);

      if (ink_rect && glyph_ink.width != 0 && glyph_ink.height != 0)
	{
	  if (ink_rect->width == 0 || ink_rect->height == 0)
	    {
	      ink_rect->x = x_pos + glyph_ink.x + geometry->x_offset;
	      ink_rect->width = glyph_ink.width;
	      ink_rect->y = glyph_ink.y + geometry->y_offset;
	      ink_rect->height = glyph_ink.height;
	    }
	  else
	    {
	      int new_x, new_y;

	      new_x = MIN (ink_rect->x, x_pos + glyph_ink.x + geometry->x_offset);
	      ink_rect->width = MAX (ink_rect->x + ink_rect->width,
				     x_pos + glyph_ink.x + glyph_ink.width + geometry->x_offset) - new_x;
	      ink_rect->x = new_x;

	      new_y = MIN (ink_rect->y, glyph_ink.y + geometry->y_offset);
	      ink_rect->height = MAX (ink_rect->y + ink_rect->height,
				      glyph_ink.y + glyph_ink.height + geometry->y_offset) - new_y;
	      ink_rect->y = new_y;
	    }
	}

      if (logical_rect)
	{
	  logical_rect->width += geometry->width;

	  if (i == start)
	    {
	      logical_rect->y = glyph_logical.y;
	      logical_rect->height = glyph_logical.height;
	    }
	  else
	    {
	      int new_y = MIN (logical_rect->y, glyph_logical.y);
	      logical_rect->height = MAX (logical_rect->y + logical_rect->height,
					  glyph_logical.y + glyph_logical.height) - new_y;
	      logical_rect->y = new_y;
	    }
	}

      x_pos += geometry->width;
    }
}

/**
 * pango_glyph_string_extents:
 * @glyphs:   a #PangoGlyphString
 * @font:     a #PangoFont
 * @ink_rect: rectangle used to store the extents of the glyph string as drawn
 *            or %NULL to indicate that the result is not needed.
 * @logical_rect: rectangle used to store the logical extents of the glyph string
 *            or %NULL to indicate that the result is not needed.
 *
 * Compute the logical and ink extents of a glyph string. See the documentation
 * for pango_font_get_glyph_extents() for details about the interpretation
 * of the rectangles.
 */
void
pango_glyph_string_extents (PangoGlyphString *glyphs,
			    PangoFont        *font,
			    PangoRectangle   *ink_rect,
			    PangoRectangle   *logical_rect)
{
  pango_glyph_string_extents_range (glyphs, 0, glyphs->num_glyphs,
				    font, ink_rect, logical_rect);
}

/**
 * pango_glyph_string_get_width:
 * @glyphs:   a #PangoGlyphString
 *
 * Computes the logical width of the glyph string as can also be computed
 * using pango_glyph_string_extents().  However, since this only computes the
 * width, it's much faster.  This is in fact only a convenience function that
 * computes the sum of geometry.width for each glyph in the @glyphs.
 *
 * Return value: the logical width of the glyph string.
 *
 * Since: 1.14
 */
int
pango_glyph_string_get_width (PangoGlyphString *glyphs)
{
  int i;
  int width = 0;

  for (i = 0; i < glyphs->num_glyphs; i++)
    width += glyphs->glyphs[i].geometry.width;

  return width;
}

/**
 * pango_glyph_string_get_logical_widths:
 * @glyphs: a #PangoGlyphString
 * @text: the text corresponding to the glyphs
 * @length: the length of @text, in bytes
 * @embedding_level: the embedding level of the string
 * @logical_widths: an array whose length is g_utf8_strlen (text, length)
 *                  to be filled in with the resulting character widths.
 *
 * Given a #PangoGlyphString resulting from pango_shape() and the corresponding
 * text, determine the screen width corresponding to each character. When
 * multiple characters compose a single cluster, the width of the entire
 * cluster is divided equally among the characters.
 **/
void
pango_glyph_string_get_logical_widths (PangoGlyphString *glyphs,
				       const char       *text,
				       int               length,
				       int               embedding_level,
				       int              *logical_widths)
{
  int i, j;
  int last_cluster = 0;
  int width = 0;
  int last_cluster_width = 0;
  const char *p = text;		/* Points to start of current cluster */

  for (i=0; i<=glyphs->num_glyphs; i++)
    {
      int glyph_index = (embedding_level % 2 == 0) ? i : glyphs->num_glyphs - i - 1;

      /* If this glyph belongs to a new cluster, or we're at the end, find
       * the start of the next cluster, and assign the widths for this cluster.
       */
      if (i == glyphs->num_glyphs || p != text + glyphs->log_clusters[glyph_index])
	{
	  int next_cluster = last_cluster;

	  if (i < glyphs->num_glyphs)
	    {
	      while (p < text + glyphs->log_clusters[glyph_index])
		{
		  next_cluster++;
		  p = g_utf8_next_char (p);
		}
	    }
	  else
	    {
	      while (p < text + length)
		{
		  next_cluster++;
		  p = g_utf8_next_char (p);
		}
	    }

	  for (j = last_cluster; j < next_cluster; j++)
	    logical_widths[j] = (width - last_cluster_width) / (next_cluster - last_cluster);

	  last_cluster = next_cluster;
	  last_cluster_width = width;
	}

      if (i < glyphs->num_glyphs)
	width += glyphs->glyphs[glyph_index].geometry.width;
    }
}

/* The initial implementation here is script independent,
 * but it might actually need to be virtualized into the
 * rendering modules. Otherwise, we probably will end up
 * enforcing unnatural cursor behavior for some languages.
 *
 * The only distinction that Uniscript makes is whether
 * cursor positioning is allowed within clusters or not.
 */

/**
 * pango_glyph_string_index_to_x:
 * @glyphs:    the glyphs return from pango_shape()
 * @text:      the text for the run
 * @length:    the number of bytes (not characters) in @text.
 * @analysis:  the analysis information return from pango_itemize()
 * @index_:    the byte index within @text
 * @trailing:  whether we should compute the result for the beginning (%FALSE)
 *             or end (%TRUE) of the character.
 * @x_pos:     location to store result
 *
 * Converts from character position to x position. (X position
 * is measured from the left edge of the run). Character positions
 * are computed by dividing up each cluster into equal portions.
 */

void
pango_glyph_string_index_to_x (PangoGlyphString *glyphs,
			       char             *text,
			       int               length,
			       PangoAnalysis    *analysis,
			       int               index,
			       gboolean          trailing,
			       int              *x_pos)
{
  int i;
  int start_xpos = 0;
  int end_xpos = 0;
  int width = 0;

  int start_index = -1;
  int end_index = -1;

  int cluster_chars = 0;
  int cluster_offset = 0;

  char *p;

  g_return_if_fail (glyphs != NULL);
  g_return_if_fail (length >= 0);
  g_return_if_fail (length == 0 || text != NULL);

  if (!x_pos) /* Allow the user to do the useless */
    return;

  if (glyphs->num_glyphs == 0)
    {
      *x_pos = 0;
      return;
    }

  /* Calculate the starting and ending character positions
   * and x positions for the cluster
   */
  if (analysis->level % 2) /* Right to left */
    {
      for (i = glyphs->num_glyphs - 1; i >= 0; i--)
	width += glyphs->glyphs[i].geometry.width;

      for (i = glyphs->num_glyphs - 1; i >= 0; i--)
	{
	  if (glyphs->log_clusters[i] > index)
	    {
	      end_index = glyphs->log_clusters[i];
	      end_xpos = width;
	      break;
	    }

	  if (glyphs->log_clusters[i] != start_index)
	    {
	      start_index = glyphs->log_clusters[i];
	      start_xpos = width;
	    }

	  width -= glyphs->glyphs[i].geometry.width;
	}
    }
  else /* Left to right */
    {
      for (i = 0; i < glyphs->num_glyphs; i++)
	{
	  if (glyphs->log_clusters[i] > index)
	    {
	      end_index = glyphs->log_clusters[i];
	      end_xpos = width;
	      break;
	    }

	  if (glyphs->log_clusters[i] != start_index)
	    {
	      start_index = glyphs->log_clusters[i];
	      start_xpos = width;
	    }

	  width += glyphs->glyphs[i].geometry.width;
	}
    }

  if (end_index == -1)
    {
      end_index = length;
      end_xpos = (analysis->level % 2) ? 0 : width;
    }

  /* Calculate offset of character within cluster */

  p = text + start_index;
  while (p < text + end_index)
    {
      if (p < text + index)
	cluster_offset++;
      cluster_chars++;
      p = g_utf8_next_char (p);
    }

  if (trailing)
    cluster_offset += 1;

  *x_pos = ((cluster_chars - cluster_offset) * start_xpos +
	    cluster_offset * end_xpos) / cluster_chars;
}

/**
 * pango_glyph_string_x_to_index:
 * @glyphs:    the glyphs returned from pango_shape()
 * @text:      the text for the run
 * @length:    the number of bytes (not characters) in text.
 * @analysis:  the analysis information return from pango_itemize()
 * @x_pos:     the x offset (in #PangoGlyphUnit)
 * @index_:    location to store calculated byte index within @text
 * @trailing:  location to store a boolean indicating
 *             whether the user clicked on the leading or trailing
 *             edge of the character.
 *
 * Convert from x offset to character position. Character positions
 * are computed by dividing up each cluster into equal portions.
 * In scripts where positioning within a cluster is not allowed
 * (such as Thai), the returned value may not be a valid cursor
 * position; the caller must combine the result with the logical
 * attributes for the text to compute the valid cursor position.
 */
void
pango_glyph_string_x_to_index (PangoGlyphString *glyphs,
			       char             *text,
			       int               length,
			       PangoAnalysis    *analysis,
			       int               x_pos,
			       int              *index,
			       gboolean         *trailing)
{
  int i;
  int start_xpos = 0;
  int end_xpos = 0;
  int width = 0;

  int start_index = -1;
  int end_index = -1;

  int cluster_chars = 0;
  char *p;

  gboolean found = FALSE;

  /* Find the cluster containing the position */

  width = 0;

  if (analysis->level % 2) /* Right to left */
    {
      for (i = glyphs->num_glyphs - 1; i >= 0; i--)
	width += glyphs->glyphs[i].geometry.width;

      for (i = glyphs->num_glyphs - 1; i >= 0; i--)
	{
	  if (glyphs->log_clusters[i] != start_index)
	    {
	      if (found)
		{
		  end_index = glyphs->log_clusters[i];
		  end_xpos = width;
		  break;
		}
	      else
		{
		  start_index = glyphs->log_clusters[i];
		  start_xpos = width;
		}
	    }

	  width -= glyphs->glyphs[i].geometry.width;

	  if (width <= x_pos && x_pos < width + glyphs->glyphs[i].geometry.width)
	    found = TRUE;
	}
    }
  else /* Left to right */
    {
      for (i = 0; i < glyphs->num_glyphs; i++)
	{
	  if (glyphs->log_clusters[i] != start_index)
	    {
	      if (found)
		{
		  end_index = glyphs->log_clusters[i];
		  end_xpos = width;
		  break;
		}
	      else
		{
		  start_index = glyphs->log_clusters[i];
		  start_xpos = width;
		}
	    }

	  if (width <= x_pos && x_pos < width + glyphs->glyphs[i].geometry.width)
	    found = TRUE;

	  width += glyphs->glyphs[i].geometry.width;
	}
    }

  if (end_index == -1)
    {
      end_index = length;
      end_xpos = (analysis->level % 2) ? 0 : width;
    }

  /* Calculate number of chars within cluster */
  p = text + start_index;
  while (p < text + end_index)
    {
      p = g_utf8_next_char (p);
      cluster_chars++;
    }

  if (start_xpos == end_xpos)
    {
      if (index)
	*index = start_index;
      if (trailing)
	*trailing = FALSE;
    }
  else
    {
      double cp = ((double)(x_pos - start_xpos) * cluster_chars) / (end_xpos - start_xpos);

      /* LTR and right-to-left have to be handled separately
       * here because of the edge condition when we are exactly
       * at a pixel boundary; end_xpos goes with the next
       * character for LTR, with the previous character for RTL.
       */
      if (start_xpos < end_xpos) /* Left-to-right */
	{
	  if (index)
	    {
	      char *p = text + start_index;
	      int i = 0;

	      while (i + 1 <= cp)
		{
		  p = g_utf8_next_char (p);
		  i++;
		}

	      *index = (p - text);
	    }

	  if (trailing)
	    *trailing = (cp - (int)cp >= 0.5) ? TRUE : FALSE;
	}
      else /* Right-to-left */
	{
	  if (index)
	    {
	      char *p = text + start_index;
	      int i = 0;

	      while (i + 1 < cp)
		{
		  p = g_utf8_next_char (p);
		  i++;
		}

	      *index = (p - text);
	    }

	  if (trailing)
	    {
	      double cp_flip = cluster_chars - cp;
	      *trailing = (cp_flip - (int)cp_flip >= 0.5) ? FALSE : TRUE;
	    }
	}
    }
}