summaryrefslogtreecommitdiff
path: root/pango/pango-ot-buffer.c
blob: 8804ebd840e144a2d7b4677d3a693ec7bcb85e34 (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
/* Pango
 * pango-ot-buffer.c: Buffer of glyphs for shaping/positioning
 *
 * Copyright (C) 2004 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 "pango-ot-private.h"
#include "pangofc-private.h"

/**
 * pango_ot_buffer_new
 * @font: a #PangoFcFont
 *
 * Creates a new #PangoOTBuffer for the given OpenType font.
 *
 * Return value: the newly allocated #PangoOTBuffer, which should
 *               be freed with pango_ot_buffer_destroy().
 *
 * Since: 1.4
 **/
PangoOTBuffer *
pango_ot_buffer_new (PangoFcFont *font)
{
  /* We lock the font here immediately for the silly reason
   * of getting the FT_Memory; otherwise we'd have to
   * add a new operation to PangoFcFontmap; callers will
   * probably already have the font locked, however,
   * so there is little performance penalty.
   */
  PangoOTBuffer *buffer = g_slice_new (PangoOTBuffer);
  FT_Face face = pango_fc_font_lock_face (font);

  if (hb_buffer_new (face->memory, &buffer->buffer) != FT_Err_Ok)
    g_warning ("Allocation of HB_Buffer failed"); /* this doesn't happen */

  buffer->font = g_object_ref (font);
  buffer->applied_gpos = FALSE;
  buffer->rtl = FALSE;
  buffer->zero_width_marks = FALSE;

  pango_fc_font_unlock_face (font);

  return buffer;
}

/**
 * pango_ot_buffer_destroy
 * @buffer: a #PangoOTBuffer
 *
 * Destroys a #PangoOTBuffer and free all associated memory.
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_destroy (PangoOTBuffer *buffer)
{
  hb_buffer_free (buffer->buffer);
  g_object_unref (buffer->font);
  g_slice_free (PangoOTBuffer, buffer);
}

/**
 * pango_ot_buffer_clear
 * @buffer: a #PangoOTBuffer
 *
 * Empties a #PangoOTBuffer, make it ready to add glyphs to.
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_clear (PangoOTBuffer *buffer)
{
  hb_buffer_clear (buffer->buffer);
  buffer->applied_gpos = FALSE;
}

/**
 * pango_ot_buffer_add_glyph
 * @buffer: a #PangoOTBuffer
 * @glyph: the glyph index to add, like a #PangoGlyph
 * @properties: the glyph properties
 * @cluster: the cluster that this glyph belongs to
 *
 * Appends a glyph to a #PangoOTBuffer, with @properties identifying which
 * features should be applied on this glyph.  See pango_ruleset_add_feature().
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_add_glyph (PangoOTBuffer *buffer,
			   guint          glyph,
			   guint          properties,
			   guint          cluster)
{
  hb_buffer_add_glyph (buffer->buffer,
			glyph, properties, cluster);
}

/**
 * pango_ot_buffer_set_rtl
 * @buffer: a #PangoOTBuffer
 * @rtl: %TRUE for right-to-left text
 *
 * Sets whether glyphs will be rendered right-to-left.  This setting
 * is needed for proper horizontal positioning of right-to-left scripts.
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_set_rtl (PangoOTBuffer *buffer,
			 gboolean       rtl)
{
  buffer->rtl = rtl != FALSE;
}

/**
 * pango_ot_buffer_set_zero_width_marks
 * @buffer: a #PangoOTBuffer
 * @zero_width_marks: %TRUE if characters with a mark class should
 *  be forced to zero width.
 *
 * Sets whether characters with a mark class should be forced to zero width.
 * This setting is needed for proper positioning of Arabic accents,
 * but will produce incorrect results with standard OpenType Indic
 * fonts.
 *
 * Since: 1.6
 **/
void
pango_ot_buffer_set_zero_width_marks (PangoOTBuffer     *buffer,
				      gboolean           zero_width_marks)
{
  buffer->zero_width_marks = zero_width_marks != FALSE;
}

/**
 * pango_ot_buffer_get_glyphs
 * @buffer: a #PangoOTBuffer
 * @glyphs: location to store the array of glyphs, or %NULL
 * @n_glyphs: location to store the number of glyphs, or %NULL
 *
 * Gets the glyph array contained in a #PangoOTBuffer.  The glyphs are
 * owned by the buffer and should not be freed, and are only valid as long
 * as buffer is not modified.
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_get_glyphs (const PangoOTBuffer  *buffer,
			    PangoOTGlyph        **glyphs,
			    int                  *n_glyphs)
{
  if (glyphs)
    *glyphs = (PangoOTGlyph *)buffer->buffer->in_string;

  if (n_glyphs)
    *n_glyphs = buffer->buffer->in_length;
}

static void
swap_range (PangoGlyphString *glyphs, int start, int end)
{
  int i, j;

  for (i = start, j = end - 1; i < j; i++, j--)
    {
      PangoGlyphInfo glyph_info;
      gint log_cluster;

      glyph_info = glyphs->glyphs[i];
      glyphs->glyphs[i] = glyphs->glyphs[j];
      glyphs->glyphs[j] = glyph_info;

      log_cluster = glyphs->log_clusters[i];
      glyphs->log_clusters[i] = glyphs->log_clusters[j];
      glyphs->log_clusters[j] = log_cluster;
    }
}

static void
apply_gpos_ltr (PangoGlyphString *glyphs,
		HB_Position      positions,
		gboolean         is_hinted)
{
  int i;

  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      FT_Pos x_pos = positions[i].x_pos;
      FT_Pos y_pos = positions[i].y_pos;
      int back = i;
      int j;
      int adjustment;


      adjustment = PANGO_UNITS_26_6(positions[i].x_advance);

      if (is_hinted)
	adjustment = PANGO_UNITS_ROUND (adjustment);

      if (positions[i].new_advance)
	glyphs->glyphs[i].geometry.width  = adjustment;
      else
	glyphs->glyphs[i].geometry.width += adjustment;


      while (positions[back].back != 0)
	{
	  back  -= positions[back].back;
	  x_pos += positions[back].x_pos;
	  y_pos += positions[back].y_pos;
	}

      for (j = back; j < i; j++)
	glyphs->glyphs[i].geometry.x_offset -= glyphs->glyphs[j].geometry.width;

      glyphs->glyphs[i].geometry.x_offset += PANGO_UNITS_26_6(x_pos);
      glyphs->glyphs[i].geometry.y_offset -= PANGO_UNITS_26_6(y_pos);
    }
}

static void
apply_gpos_rtl (PangoGlyphString *glyphs,
		HB_Position      positions,
		gboolean         is_hinted)
{
  int i;

  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      int i_rev = glyphs->num_glyphs - i - 1;
      int back_rev = i_rev;
      int back;
      FT_Pos x_pos = positions[i_rev].x_pos;
      FT_Pos y_pos = positions[i_rev].y_pos;
      int j;
      int adjustment;


      adjustment = PANGO_UNITS_26_6(positions[i_rev].x_advance);

      if (is_hinted)
	adjustment = PANGO_UNITS_ROUND (adjustment);

      if (positions[i_rev].new_advance)
	glyphs->glyphs[i].geometry.width  = adjustment;
      else
	glyphs->glyphs[i].geometry.width += adjustment;


      while (positions[back_rev].back != 0)
	{
	  back_rev -= positions[back_rev].back;
	  x_pos += positions[back_rev].x_pos;
	  y_pos += positions[back_rev].y_pos;
	}

      back = glyphs->num_glyphs - back_rev - 1;

      for (j = i; j < back; j++)
	glyphs->glyphs[i].geometry.x_offset += glyphs->glyphs[j].geometry.width;

      glyphs->glyphs[i].geometry.x_offset += PANGO_UNITS_26_6(x_pos);
      glyphs->glyphs[i].geometry.y_offset -= PANGO_UNITS_26_6(y_pos);
    }
}

/**
 * pango_ot_buffer_output
 * @buffer: a #PangoOTBuffer
 * @glyphs: a #PangoGlyphString
 *
 * Exports the glyphs in a #PangoOTBuffer into a #PangoGlyphString.  This is
 * typically used after the OpenType layout processing is over, to convert the
 * resulting glyphs into a generic Pango glyph string.
 *
 * Since: 1.4
 **/
void
pango_ot_buffer_output (const PangoOTBuffer *buffer,
			PangoGlyphString    *glyphs)
{
  FT_Face face;
  PangoOTInfo *info;
  HB_GDEF gdef = NULL;
  unsigned int i;
  int last_cluster;

  face = pango_fc_font_lock_face (buffer->font);
  g_assert (face);

  /* Copy glyphs into output glyph string */
  pango_glyph_string_set_size (glyphs, buffer->buffer->in_length);

  last_cluster = -1;
  for (i = 0; i < buffer->buffer->in_length; i++)
    {
      HB_GlyphItem item = &buffer->buffer->in_string[i];

      glyphs->glyphs[i].glyph = item->gindex;

      glyphs->log_clusters[i] = item->cluster;
      if (glyphs->log_clusters[i] != last_cluster)
	glyphs->glyphs[i].attr.is_cluster_start = 1;
      else
	glyphs->glyphs[i].attr.is_cluster_start = 0;

      last_cluster = glyphs->log_clusters[i];
    }

  info = pango_ot_info_get (face);
  gdef = pango_ot_info_get_gdef (info);

  /* Apply default positioning */
  for (i = 0; i < (unsigned int)glyphs->num_glyphs; i++)
    {
      if (glyphs->glyphs[i].glyph)
	{
	  PangoRectangle logical_rect;

	  FT_UShort property;

	  if (buffer->zero_width_marks &&
	      gdef &&
	      HB_GDEF_Get_Glyph_Property (gdef, glyphs->glyphs[i].glyph, &property) == FT_Err_Ok &&
	      (property == HB_GDEF_MARK || (property & HB_LOOKUP_FLAG_IGNORE_SPECIAL_MARKS) != 0))
	    {
	      glyphs->glyphs[i].geometry.width = 0;
	    }
	  else
	    {
	      pango_font_get_glyph_extents ((PangoFont *)buffer->font, glyphs->glyphs[i].glyph, NULL, &logical_rect);
	      glyphs->glyphs[i].geometry.width = logical_rect.width;
	    }
	}
      else
	glyphs->glyphs[i].geometry.width = 0;

      glyphs->glyphs[i].geometry.x_offset = 0;
      glyphs->glyphs[i].geometry.y_offset = 0;
    }

  if (buffer->rtl)
    {
      /* Swap all glyphs */
      swap_range (glyphs, 0, glyphs->num_glyphs);
    }

  if (buffer->applied_gpos)
    {
      if (buffer->rtl)
	apply_gpos_rtl (glyphs, buffer->buffer->positions, buffer->font->is_hinted);
      else
	apply_gpos_ltr (glyphs, buffer->buffer->positions, buffer->font->is_hinted);
    }
  else
    pango_fc_font_kern_glyphs (buffer->font, glyphs);

  pango_fc_font_unlock_face (buffer->font);
}