File: shape.c

package info (click to toggle)
pango1.0 1.42.4-8~deb10u1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 9,564 kB
  • sloc: ansic: 42,694; sh: 4,360; makefile: 1,075; python: 305; perl: 56; cpp: 20
file content (235 lines) | stat: -rw-r--r-- 7,989 bytes parent folder | download | duplicates (3)
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
/* Pango
 * shape.c: Convert characters into glyphs.
 *
 * 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.
 */

/**
 * SECTION:glyphs
 * @short_description:Structures for storing information about glyphs
 * @title:Glyph Storage
 *
 * pango_shape() produces a string of glyphs which
 * can be measured or drawn to the screen. The following
 * structures are used to store information about
 * glyphs.
 */
#include "config.h"

#include "pango-impl-utils.h"
#include "pango-glyph.h"
#include "pango-engine-private.h"

#include <string.h>

/**
 * pango_shape:
 * @text:      the text to process
 * @length:    the length (in bytes) of @text
 * @analysis:  #PangoAnalysis structure from pango_itemize()
 * @glyphs:    glyph string in which to store results
 *
 * Given a segment of text and the corresponding
 * #PangoAnalysis structure returned from pango_itemize(),
 * convert the characters into glyphs. You may also pass
 * in only a substring of the item from pango_itemize().
 *
 * It is recommended that you use pango_shape_full() instead, since
 * that API allows for shaping interaction happening across text item
 * boundaries.
 */
void
pango_shape (const gchar      *text,
	     gint              length,
	     const PangoAnalysis *analysis,
	     PangoGlyphString *glyphs)
{
  pango_shape_full (text, length, text, length, analysis, glyphs);
}

/**
 * pango_shape_full:
 * @item_text:        valid UTF-8 text to shape.
 * @item_length:      the length (in bytes) of @item_text. -1 means nul-terminated text.
 * @paragraph_text: (allow-none): text of the paragraph (see details).  May be %NULL.
 * @paragraph_length: the length (in bytes) of @paragraph_text. -1 means nul-terminated text.
 * @analysis:  #PangoAnalysis structure from pango_itemize().
 * @glyphs:    glyph string in which to store results.
 *
 * Given a segment of text and the corresponding
 * #PangoAnalysis structure returned from pango_itemize(),
 * convert the characters into glyphs. You may also pass
 * in only a substring of the item from pango_itemize().
 *
 * This is similar to pango_shape(), except it also can optionally take
 * the full paragraph text as input, which will then be used to perform
 * certain cross-item shaping interactions.  If you have access to the broader
 * text of which @item_text is part of, provide the broader text as
 * @paragraph_text.  If @paragraph_text is %NULL, item text is used instead.
 *
 * Since: 1.32
 */
void
pango_shape_full (const gchar      *item_text,
		  gint              item_length,
		  const gchar      *paragraph_text,
		  gint              paragraph_length,
		  const PangoAnalysis *analysis,
		  PangoGlyphString *glyphs)
{
  int i;
  int last_cluster;

  glyphs->num_glyphs = 0;

  if (item_length == -1)
    item_length = strlen (item_text);

  if (!paragraph_text)
    {
      paragraph_text = item_text;
      paragraph_length = item_length;
    }
  if (paragraph_length == -1)
    paragraph_length = strlen (paragraph_text);

  g_return_if_fail (paragraph_text <= item_text);
  g_return_if_fail (paragraph_text + paragraph_length >= item_text + item_length);

  if (G_LIKELY (analysis->shape_engine && analysis->font))
    {
      _pango_engine_shape_shape (analysis->shape_engine, analysis->font,
				 item_text, item_length,
				 paragraph_text, paragraph_length,
				 analysis, glyphs);

      if (G_UNLIKELY (glyphs->num_glyphs == 0))
	{
	  /* If a font has been correctly chosen, but no glyphs are output,
	   * there's probably something wrong with the shaper, or the font.
	   *
	   * Trying to be informative, we print out the font description,
	   * shaper name, and the text, but to not flood the terminal with
	   * zillions of the message, we set a flag to only err once per
	   * font/engine pair.
	   *
	   * To do the flag fast, we use the engine qname to qflag the font,
	   * but also the font description to flag the engine.  This is
	   * supposed to be fast to check, but also avoid writing out
	   * duplicate warnings when a new PangoFont is created.
	   */
	  GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
	  GQuark warned_quark = g_type_qname (engine_type);

	  if (!g_object_get_qdata (G_OBJECT (analysis->font), warned_quark))
	    {
	      PangoFontDescription *desc;
	      char *font_name;
	      const char *engine_name;

	      desc = pango_font_describe (analysis->font);
	      font_name = pango_font_description_to_string (desc);
	      pango_font_description_free (desc);

	      if (!g_object_get_data (G_OBJECT (analysis->shape_engine), font_name))
	        {
		  engine_name = g_type_name (engine_type);
		  if (!engine_name)
		    engine_name = "(unknown)";

		  g_warning ("shaping failure, expect ugly output. shape-engine='%s', font='%s', text='%.*s'",
			     engine_name, font_name, item_length, item_text);

		  g_object_set_data_full (G_OBJECT (analysis->shape_engine), font_name,
					  GINT_TO_POINTER (1), NULL);
	        }

	      g_free (font_name);

	      g_object_set_qdata_full (G_OBJECT (analysis->font), warned_quark,
				       GINT_TO_POINTER (1), NULL);
	    }
	}
    }
  else
    glyphs->num_glyphs = 0;

  if (G_UNLIKELY (!glyphs->num_glyphs))
    {
      PangoEngineShape *fallback_engine = _pango_get_fallback_shaper ();

      _pango_engine_shape_shape (fallback_engine, analysis->font,
				 item_text, item_length,
				 paragraph_text, paragraph_length,
				 analysis, glyphs);
      if (G_UNLIKELY (!glyphs->num_glyphs))
        return;
    }

  /* make sure last_cluster is invalid */
  last_cluster = glyphs->log_clusters[0] - 1;
  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      /* Set glyphs[i].attr.is_cluster_start based on log_clusters[] */
      if (glyphs->log_clusters[i] != last_cluster)
	{
	  glyphs->glyphs[i].attr.is_cluster_start = TRUE;
	  last_cluster = glyphs->log_clusters[i];
	}
      else
	glyphs->glyphs[i].attr.is_cluster_start = FALSE;


      /* Shift glyph if width is negative, and negate width.
       * This is useful for rotated font matrices and shouldn't
       * harm in normal cases.
       */
      if (glyphs->glyphs[i].geometry.width < 0)
	{
	  glyphs->glyphs[i].geometry.width = -glyphs->glyphs[i].geometry.width;
	  glyphs->glyphs[i].geometry.x_offset += glyphs->glyphs[i].geometry.width;
	}
    }

  /* Make sure glyphstring direction conforms to analysis->level */
  if (G_UNLIKELY ((analysis->level & 1) &&
		  glyphs->log_clusters[0] < glyphs->log_clusters[glyphs->num_glyphs - 1]))
    {
      /* Warn once per shaper */
      static GQuark warned_quark = 0; /* MT-safe */

      if (!warned_quark)
	warned_quark = g_quark_from_static_string ("pango-shape-warned");

      if (analysis->shape_engine && !g_object_get_qdata (G_OBJECT (analysis->shape_engine), warned_quark))
	{
	  GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
	  const char *engine_name = g_type_name (engine_type);
	  if (!engine_name)
	    engine_name = "(unknown)";

	  g_warning ("Expected RTL run but shape-engine='%s' returned LTR. Fixing.", engine_name);

	  g_object_set_qdata_full (G_OBJECT (analysis->shape_engine), warned_quark,
				   GINT_TO_POINTER (1), NULL);
	}

      /* *Fix* it so we don't crash later */
      pango_glyph_string_reverse_range (glyphs, 0, glyphs->num_glyphs);
    }
}