pango/shape.c

   1 /* Pango
   2  * shape.c: Convert characters into glyphs.
   3  *
   4  * Copyright (C) 1999 Red Hat Software
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Library General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Library General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Library General Public
  17  * License along with this library; if not, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 02111-1307, USA.
  20  */
  21
  22 #include "config.h"
  23
  24 #include "pango-impl-utils.h"
  25 #include "pango-glyph.h"
  26 #include "pango-engine-private.h"
  27
  28 #include <string.h>
  29
  30 /**
  31  * pango_shape:
  32  * @text:      the text to process
  33  * @length:    the length (in bytes) of @text
  34  * @analysis:  #PangoAnalysis structure from pango_itemize()
  35  * @glyphs:    glyph string in which to store results
  36  *
  37  * Given a segment of text and the corresponding
  38  * #PangoAnalysis structure returned from pango_itemize(),
  39  * convert the characters into glyphs. You may also pass
  40  * in only a substring of the item from pango_itemize().
  41  */
  42 void
  43 pango_shape (const gchar      *text,
  44              gint              length,
  45              const PangoAnalysis *analysis,
  46              PangoGlyphString *glyphs)
  47 {
  48   int i;
  49   int last_cluster;
  50
  51   glyphs->num_glyphs = 0;
  52
  53   if (G_LIKELY (analysis->shape_engine && analysis->font))
  54     {
  55       _pango_engine_shape_shape (analysis->shape_engine, analysis->font,
  56                                  text, length, analysis, glyphs);
  57
  58       if (G_UNLIKELY (glyphs->num_glyphs == 0))
  59         {
  60           /* If a font has been correctly chosen, but no glyphs are output,
  61            * there's probably something wrong with the shaper, or the font.
  62            *
  63            * Trying to be informative, we print out the font description,
  64            * shaper name, and the text, but to not flood the terminal with
  65            * zillions of the message, we set a flag to only err once per
  66            * font/engine pair.
  67            *
  68            * To do the flag fast, we use the engine qname to qflag the font,
  69            * but also the font description to flag the engine.  This is
  70            * supposed to be fast to check, but also avoid writing out
  71            * duplicate warnings when a new PangoFont is created.
  72            */
  73           GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
  74           GQuark warned_quark = g_type_qname (engine_type);
  75
  76           if (!g_object_get_qdata (G_OBJECT (analysis->font), warned_quark))
  77             {
  78               PangoFontDescription *desc;
  79               char *font_name;
  80               const char *engine_name;
  81
  82               desc = pango_font_describe (analysis->font);
  83               font_name = pango_font_description_to_string (desc);
  84               pango_font_description_free (desc);
  85
  86               if (!g_object_get_data (G_OBJECT (analysis->shape_engine), font_name))
  87                 {
  88                   engine_name = g_type_name (engine_type);
  89                   if (!engine_name)
  90                     engine_name = "(unknown)";
  91
  92                   g_warning ("shaping failure, expect ugly output. shape-engine='%s', font='%s', text='%.*s'",
  93                              engine_name,
  94                              font_name,
  95                              length == -1 ? (gint) strlen (text) : length, text);
  96
  97                   g_object_set_data_full (G_OBJECT (analysis->shape_engine), font_name,
  98                                           GINT_TO_POINTER (1), NULL);
  99                 }
 100
 101               g_free (font_name);
 102
 103               g_object_set_qdata_full (G_OBJECT (analysis->font), warned_quark,
 104                                        GINT_TO_POINTER (1), NULL);
 105             }
 106         }
 107     }
 108   else
 109     glyphs->num_glyphs = 0;
 110
 111   if (G_UNLIKELY (!glyphs->num_glyphs))
 112     {
 113       PangoEngineShape *fallback_engine = _pango_get_fallback_shaper ();
 114
 115       _pango_engine_shape_shape (fallback_engine, analysis->font,
 116                                  text, length, analysis, glyphs);
 117       if (G_UNLIKELY (!glyphs->num_glyphs))
 118         return;
 119     }
 120
 121   /* make sure last_cluster is invalid */
 122   last_cluster = glyphs->log_clusters[0] - 1;
 123   for (i = 0; i < glyphs->num_glyphs; i++)
 124     {
 125       /* Set glyphs[i].attr.is_cluster_start based on log_clusters[] */
 126       if (glyphs->log_clusters[i] != last_cluster)
 127         {
 128           glyphs->glyphs[i].attr.is_cluster_start = TRUE;
 129           last_cluster = glyphs->log_clusters[i];
 130         }
 131       else
 132         glyphs->glyphs[i].attr.is_cluster_start = FALSE;
 133
 134
 135       /* Shift glyph if width is negative, and negate width.
 136        * This is useful for rotated font matrices and shouldn't
 137        * harm in normal cases.
 138        */
 139       if (glyphs->glyphs[i].geometry.width < 0)
 140         {
 141           glyphs->glyphs[i].geometry.width = -glyphs->glyphs[i].geometry.width;
 142           glyphs->glyphs[i].geometry.x_offset += glyphs->glyphs[i].geometry.width;
 143         }
 144     }
 145
 146   /* Make sure glyphstring direction conforms to analysis->level */
 147   if (G_UNLIKELY ((analysis->level & 1) &&
 148                   glyphs->log_clusters[0] < glyphs->log_clusters[glyphs->num_glyphs - 1]))
 149     {
 150       /* Warn once per shaper */
 151       static GQuark warned_quark = 0;
 152
 153       if (!warned_quark)
 154         warned_quark = g_quark_from_static_string ("pango-shape-warned");
 155
 156       if (analysis->shape_engine && !g_object_get_qdata (G_OBJECT (analysis->shape_engine), warned_quark))
 157         {
 158           GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
 159           const char *engine_name = g_type_name (engine_type);
 160           if (!engine_name)
 161             engine_name = "(unknown)";
 162
 163           g_warning ("Expected RTL run but shape-engine='%s' returned LTR. Fixing.", engine_name);
 164
 165           g_object_set_qdata_full (G_OBJECT (analysis->shape_engine), warned_quark,
 166                                    GINT_TO_POINTER (1), NULL);
 167         }
 168
 169       /* *Fix* it so we don't crash later */
 170       pango_glyph_string_reverse_range (glyphs, 0, glyphs->num_glyphs);
 171     }
 172 }