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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 "pango.h"
#include "iconv.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 (length == 0 || text != NULL, NULL);
if (length == 0)
return 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 = g_utf8_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);
pango_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 = g_utf8_next_char (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 = pango_item_new ();
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 = g_utf8_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;
}
wc = g_utf8_get_char (pos);
pos = g_utf8_next_char (pos);
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;
}
}
}
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