Initial revision

1 files changed, 234 insertions, 0 deletions

diff --git a/pango/itemize.c b/pango/itemize.c
new file mode 100644
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--- /dev/null
+++ b/pango/itemize.c
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+/* Pango
+ * itemize.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 <fribidi/fribidi.h>
+#include <unicode.h>
+#include "pango.h"
+#include "iconv.h"
+#include "utils.h"
+#include "modules.h"
+
+static void add_engines (PangoContext     *context,
+			 gchar              *text, 
+			 gint                length,
+			 PangoLangRange   *lang_info,
+			 gint                n_langs,
+			 gboolean            force_exact,
+			 PangoEngineInfo **shape_engines,
+			 PangoEngineInfo **lang_engines);
+
+/**
+ * pango_itemize:
+ * @context:   a structure holding information that affects
+               the itemization process.
+ * @text:      the text to itemize.
+ * @length:    the number of bytes (not characters) in text.
+ *             This must be >= 0.
+ * @lang_info: an array of language tagging information.
+ * @n_langs:   the number of elements in @lang_info.
+ *
+ * Breaks a piece of text into segments with consistent
+ * directional level and shaping engine.
+ *
+ * Returns a GList of PangoItem structures.
+ */
+GList *
+pango_itemize (PangoContext   *context, 
+		  gchar            *text, 
+		  gint              length,
+		  PangoLangRange *lang_info,
+		  gint              n_langs)
+{
+  guint16 *text_ucs2;
+  gint n_chars;
+  guint8 *embedding_levels;
+  FriBidiCharType base_dir;
+  gint i;
+  PangoItem *item;
+  char *p, *next;
+  GList *result = NULL;
+  
+  PangoEngineInfo **shape_engines;
+  PangoEngineInfo  **lang_engines;
+
+  g_return_val_if_fail (context != NULL, NULL);
+  g_return_val_if_fail (text != NULL, NULL);
+  g_return_val_if_fail (length >= 0, NULL);
+
+
+  if (context->direction == PANGO_DIRECTION_RTL)
+    base_dir = FRIBIDI_TYPE_RTL;
+  else
+    base_dir = FRIBIDI_TYPE_LTR;
+  
+  if (length == 0)
+    return NULL;
+  
+  /* First, apply the bidirectional algorithm to break
+   * the text into directional runs.
+   */
+  text_ucs2 = _pango_utf8_to_ucs2 (text, length);
+  if (!text_ucs2)
+    return NULL;
+
+  n_chars = unicode_strlen (text, length);
+  embedding_levels = g_new (guint8, n_chars);
+
+  /* Storing these as ranges would be a lot more efficient,
+   * but also more complicated... we take the simple
+   * approach for now.
+   */
+  shape_engines = g_new0 (PangoEngineInfo *, n_chars);
+  lang_engines = g_new0 (PangoEngineInfo *, n_chars);
+
+  fribidi_log2vis_get_embedding_levels (text_ucs2, n_chars, &base_dir,
+					embedding_levels);
+
+  /* Now, make shaping-engine affilitations for characters in
+   * each run that have high-affinity. This means that there
+   * is a shaping engine specific to the current
+   * language/character pair.
+   */
+
+  add_engines (context, text, length, lang_info, n_langs,
+  	       TRUE, shape_engines, lang_engines);
+
+  /* Fill in low-affinity shaping-engine affiliations for
+   * remainder of characters.
+   */
+
+  add_engines (context, text, length, lang_info, n_langs,
+  	       FALSE, shape_engines, lang_engines);
+
+  /* Make a GList of PangoItems out of the above results
+   */
+
+  item = NULL;
+  p = text;
+  for (i=0; i<n_chars; i++)
+    {
+      next = unicode_next_utf8 (p);
+      
+      if (i == 0 ||
+	  embedding_levels[i] != embedding_levels[i-1] ||
+	  shape_engines[i] != shape_engines[i-1] ||
+	  lang_engines[i] != lang_engines[i-1])
+	{
+	  if (item)
+	    result = g_list_prepend (result, item);
+	  item = g_new (PangoItem, 1);
+	  item->offset = p - text;
+	  item->num_chars = 0;
+	  item->analysis.level = embedding_levels[i];
+	  
+	  if (shape_engines[i])
+	    item->analysis.shape_engine = (PangoEngineShape *)_pango_load_engine (shape_engines[i]->id);
+	  else
+	    item->analysis.shape_engine = NULL;
+	  
+	  if (lang_engines[i])
+	    item->analysis.lang_engine = (PangoEngineLang *)_pango_load_engine (lang_engines[i]->id);
+	  else
+	    item->analysis.lang_engine = NULL;
+	}
+
+      item->length = (next - text) - item->offset;
+      item->num_chars++;
+      p = next;
+    }  
+
+  if (item)
+    result = g_list_prepend (result, item);
+
+  g_free (text_ucs2);
+  
+  return g_list_reverse (result);
+}
+
+static void
+add_engines (PangoContext     *context,
+	     gchar              *text, 
+	     gint                length,
+	     PangoLangRange   *lang_info,
+	     gint                n_langs,
+	     gboolean            force_exact,
+	     PangoEngineInfo **shape_engines,
+	     PangoEngineInfo **lang_engines)
+{
+  char *pos;
+  char *last_lang = NULL;
+  gint n_chars;
+  PangoMap *shape_map = NULL;
+  PangoMap *lang_map = NULL;
+  GUChar4 wc;
+  int i, j;
+
+  n_chars = unicode_strlen (text, length);
+
+  pos = text;
+  last_lang = NULL;
+  for (i=0, j=0; i<n_chars; i++)
+    {
+      char *lang;
+      PangoSubmap *submap;
+      PangoMapEntry *entry;
+
+      while (j < n_langs && lang_info[j].start < pos - text)
+	j++;
+      
+      if (j < n_langs && (pos - text) < lang_info[j].start + lang_info[j].length)
+	lang = lang_info[j].lang;
+      else
+	lang = context->lang;
+
+      if (last_lang != lang ||
+	  last_lang == 0 || lang == 0 ||
+	  strcmp (lang, last_lang) != 0)
+	{
+	  lang_map = _pango_find_map (lang, PANGO_ENGINE_TYPE_LANG,
+					 PANGO_RENDER_TYPE_NONE);
+	  shape_map = _pango_find_map (lang, PANGO_ENGINE_TYPE_SHAPE,
+					  context->render_type);
+	  last_lang = lang;
+	}
+
+      pos  = unicode_get_utf8 (pos, &wc);
+
+      if (!lang_engines[i])
+	{
+	  submap = &lang_map->submaps[wc / 256];
+	  entry = submap->is_leaf ? &submap->d.entry : &submap->d.leaves[wc % 256];
+	  
+	  if (entry->info && (!force_exact || entry->is_exact))
+	    lang_engines[i] = entry->info;
+	}
+
+      if (!shape_engines[i])
+	{
+	  submap = &shape_map->submaps[wc / 256];
+	  entry = submap->is_leaf ? &submap->d.entry : &submap->d.leaves[wc % 256];
+
+	  if (entry->info && (!force_exact || entry->is_exact))
+	    shape_engines[i] = entry->info;
+	}
+    }
+}
+