pango-context.c

linux

	  PangoGravityHint gravity_hint = state->gravity_hint;

	  if (G_LIKELY (gravity == PANGO_GRAVITY_AUTO))
	    gravity = state->context->resolved_gravity;

	  state->resolved_gravity = pango_gravity_get_for_script (state->script,
								  gravity,
								  gravity_hint);
	}

      if (old_gravity != state->resolved_gravity)
	{
	  pango_font_description_set_gravity (state->font_desc, state->resolved_gravity);
	  state->changed |= FONT_CHANGED;
	}
    }

  if (state->changed & (SCRIPT_CHANGED | LANG_CHANGED))
    {
      PangoLanguage *old_derived_lang = state->derived_lang;
      state->derived_lang = compute_derived_language (state->lang, state->script);
      if (old_derived_lang != state->derived_lang)
	state->changed |= DERIVED_LANG_CHANGED;
    }

  if ((state->changed & DERIVED_LANG_CHANGED) || !state->lang_engine)
    {
      PangoMap *lang_map = get_lang_map (state->derived_lang);
      state->lang_engine = (PangoEngineLang *)pango_map_get_engine (lang_map, state->script);
    }

  if (state->changed & (SCRIPT_CHANGED | DERIVED_LANG_CHANGED))
    itemize_state_reset_shape_engines (state);

  if (state->changed & (FONT_CHANGED | DERIVED_LANG_CHANGED) &&
      state->current_fonts)
    {
      g_object_unref (state->current_fonts);
      state->current_fonts = NULL;
      state->cache = NULL;
    }

  if (!state->current_fonts)
    {
      state->current_fonts = pango_font_map_load_fontset (state->context->font_map,
							  state->context,
							  state->font_desc,
							  state->derived_lang);
      state->cache = get_shaper_font_cache (state->current_fonts);
    }

  if ((state->changed & FONT_CHANGED) && state->base_font)
    {
      g_object_unref (state->base_font);
      state->base_font = NULL;
    }
}

static void
itemize_state_process_run (ItemizeState *state)
{
  const char *p;
  gboolean last_was_forced_break = FALSE;

  /* Only one character has type G_UNICODE_LINE_SEPARATOR in Unicode 4.0;
   * update this if that changes. */
#define LINE_SEPARATOR 0x2028

  itemize_state_update_for_new_run (state);

  /* We should never get an empty run */
  g_assert (state->run_end != state->run_start);

  for (p = state->run_start;
       p < state->run_end;
       p = g_utf8_next_char (p))
    {
      gunichar wc = g_utf8_get_char (p);
      gboolean is_forced_break = (wc == '\t' || wc == LINE_SEPARATOR);
      PangoEngineShape *shape_engine;
      PangoFont *font;

      /* We don't want space characters to affect font selection; in general,
       * it's always wrong to select a font just to render a space.  But until
       * we have a better solution, choosing a font for spaces seems to work
       * better.  However, all fonts are assumed to cover ASCII space, so that
       * one is an exception.  See bug #355987.
       *
       * The exception of PrivateUse and Unassigned characters is necessary
       * to be able to render any of them. (for private or being encoded
       * scripts, etc.)
       */
      if (wc == 0x0020 ||
	  G_UNLIKELY (!g_unichar_isprint (wc) &&
		      g_unichar_type (wc) != G_UNICODE_PRIVATE_USE &&
		      g_unichar_type (wc) != G_UNICODE_UNASSIGNED))
	{
	  shape_engine = NULL;
	  font = NULL;
	}
      else
	{
	  get_shaper_and_font (state, wc, &shape_engine, &font);
	}

      itemize_state_add_character (state,
				   shape_engine, font,
				   is_forced_break || last_was_forced_break,
				   p);

      last_was_forced_break = is_forced_break;
    }

  /* Finish the final item from the current segment */
  state->item->length = (p - state->text) - state->item->offset;
  if (!state->item->analysis.shape_engine)
    {
      PangoEngineShape *shape_engine;
      PangoFont *font;

      if (!get_shaper_and_font (state, ' ', &shape_engine, &font))
	{
	  shape_engine = _pango_get_fallback_shaper ();
	  font = NULL;
	}

      itemize_state_fill_shaper (state, shape_engine, font);
    }
  state->item = NULL;
}

static void
itemize_state_finish (ItemizeState *state)
{
  g_free (state->embedding_levels);
  if (state->free_attr_iter)
    pango_attr_iterator_destroy (state->attr_iter);
  pango_script_iter_free (state->script_iter);
  pango_font_description_free (state->font_desc);

  itemize_state_reset_shape_engines (state);
  if (state->current_fonts)
    g_object_unref (state->current_fonts);
  if (state->base_font)
    g_object_unref (state->base_font);
}

/**
 * pango_itemize_with_base_dir:
 * @context:   a structure holding information that affects
	       the itemization process.
 * @text:      the text to itemize.
 * @start_index: first byte in @text to process
 * @length:    the number of bytes (not characters) to process
 *             after @start_index.
 *             This must be >= 0.
 * @base_dir:  base direction to use for bidirectional processing
 * @attrs:     the set of attributes that apply to @text.
 * @cached_iter:      Cached attribute iterator, or %NULL
 *
 * Like pango_itemize(), but the base direction to use when
 * computing bidirectional levels (see pango_context_set_base_dir ()),
 * is specified explicitly rather than gotten from the #PangoContext.
 *
 * Return value: a #GList of #PangoItem structures.  The items should be
 * freed using pango_item_free() probably in combination with g_list_foreach(),
 * and the list itself using g_list_free().
 *
 * Since: 1.4
 */
GList *
pango_itemize_with_base_dir (PangoContext      *context,
			     PangoDirection     base_dir,
			     const char        *text,
			     int                start_index,
			     int                length,
			     PangoAttrList     *attrs,
			     PangoAttrIterator *cached_iter)
{
  ItemizeState state;

  g_return_val_if_fail (context != NULL, NULL);
  g_return_val_if_fail (start_index >= 0, NULL);
  g_return_val_if_fail (length >= 0, NULL);
  g_return_val_if_fail (length == 0 || text != NULL, NULL);

  if (length == 0)
    return NULL;

  itemize_state_init (&state, context, text, base_dir, start_index, length,
		      attrs, cached_iter, NULL);

  do
    itemize_state_process_run (&state);
  while (itemize_state_next (&state));

  itemize_state_finish (&state);

  return g_list_reverse (state.result);
}

static GList *
itemize_with_font (PangoContext               *context,
		   const char                 *text,
		   int                         start_index,
		   int                         length,
		   const PangoFontDescription *desc)
{
  ItemizeState state;

  if (length == 0)
    return NULL;

  itemize_state_init (&state, context, text, context->base_dir, start_index, length,
		      NULL, NULL, desc);

  do
    itemize_state_process_run (&state);
  while (itemize_state_next (&state));

  itemize_state_finish (&state);

  return g_list_reverse (state.result);
}

/**
 * pango_itemize:
 * @context:   a structure holding information that affects
	       the itemization process.
 * @text:      the text to itemize.
 * @start_index: first byte in @text to process
 * @length:    the number of bytes (not characters) to process
 *             after @start_index.
 *             This must be >= 0.
 * @attrs:     the set of attributes that apply to @text.
 * @cached_iter:      Cached attribute iterator, or %NULL
 *
 * Breaks a piece of text into segments with consistent
 * directional level and shaping engine. Each byte of @text will
 * be contained in exactly one of the items in the returned list;
 * the generated list of items will be in logical order (the start
 * offsets of the items are ascending).
 *
 * @cached_iter should be an iterator over @attrs currently positioned at a
 * range before or containing @start_index; @cached_iter will be advanced to
 * the range covering the position just after @start_index + @length.
 * (i.e. if itemizing in a loop, just keep passing in the same @cached_iter).
 *
 * Return value: a #GList of #PangoItem structures.
 */
GList *
pango_itemize (PangoContext      *context,
	       const char        *text,
	       int                start_index,
	       int                length,
	       PangoAttrList     *attrs,
	       PangoAttrIterator *cached_iter)
{
  g_return_val_if_fail (context != NULL, NULL);
  g_return_val_if_fail (start_index >= 0, NULL);
  g_return_val_if_fail (length >= 0, NULL);
  g_return_val_if_fail (length == 0 || text != NULL, NULL);

  return pango_itemize_with_base_dir (context, context->base_dir,
				      text, start_index, length, attrs, cached_iter);
}

static gboolean
get_first_metrics_foreach (PangoFontset  *fontset,
			   PangoFont     *font,
			   gpointer       data)
{
  PangoFontMetrics *fontset_metrics = data;
  PangoLanguage *language = PANGO_FONTSET_GET_CLASS (fontset)->get_language (fontset);
  PangoFontMetrics *font_metrics = pango_font_get_metrics (font, language);
  guint save_ref_count;

  /* Initialize the fontset metrics to metrics of the first font in the
   * fontset; saving the refcount and restoring it is a bit of hack but avoids
   * having to update this code for each metrics addition.
   */
  save_ref_count = fontset_metrics->ref_count;
  *fontset_metrics = *font_metrics;
  fontset_metrics->ref_count = save_ref_count;

  pango_font_metrics_unref (font_metrics);

  return TRUE;			/* Stops iteration */
}

static PangoFontMetrics *
get_base_metrics (PangoFontset *fontset)
{
  PangoFontMetrics *metrics = pango_font_metrics_new ();

  /* Initialize the metrics from the first font in the fontset */
  pango_fontset_foreach (fontset, get_first_metrics_foreach, metrics);

  return metrics;
}

static void
update_metrics_from_items (PangoFontMetrics *metrics,
			   PangoLanguage    *language,
			   GList            *items)

{
  GHashTable *fonts_seen = g_hash_table_new (NULL, NULL);
  int count = 0;
  GList *l;

  for (l = items; l; l = l->next)
    {
      PangoItem *item = l->data;
      PangoFont *font = item->analysis.font;

      if (font != NULL && g_hash_table_lookup (fonts_seen, font) == NULL)
	{
	  PangoFontMetrics *raw_metrics = pango_font_get_metrics (font, language);
	  g_hash_table_insert (fonts_seen, font, font);

	  /* metrics will already be initialized from the first font in the fontset */
	  metrics->ascent = MAX (metrics->ascent, raw_metrics->ascent);
	  metrics->descent = MAX (metrics->descent, raw_metrics->descent);

	  if (count == 0)
	    {
	      metrics->approximate_char_width = raw_metrics->approximate_char_width;
	      metrics->approximate_digit_width = raw_metrics->approximate_digit_width;
	    }
	  else
	    {
	      metrics->approximate_char_width += raw_metrics->approximate_char_width;
	      metrics->approximate_digit_width += raw_metrics->approximate_digit_width;
	    }
	  count++;
	  pango_font_metrics_unref (raw_metrics);
	}
    }

  g_hash_table_destroy (fonts_seen);

  if (count)
    {
      metrics->approximate_char_width /= count;
      metrics->approximate_digit_width /= count;
    }
}

/**
 * pango_context_get_metrics:
 * @context: a #PangoContext
 * @desc: a #PangoFontDescription structure
 * @language: language tag used to determine which script to get the metrics
 *            for. %NULL means that the language tag from the context will
 *            be used. If no language tag is set on the context, metrics
 *            large enough to cover a range of languages will be returned.
 *            The process of determining such metrics is slow, so it is best
 *            to always make sure some real language tag will be used.
 *
 * Get overall metric information for a particular font
 * description.  Since the metrics may be substantially different for
 * different scripts, a language tag can be provided to indicate that
 * the metrics should be retrieved that correspond to the script(s)
 * used by that language.
 *
 * The #PangoFontDescription is interpreted in the same way as
 * by pango_itemize(), and the family name may be a comma separated
 * list of figures. If characters from multiple of these families
 * would be used to render the string, then the returned fonts would
 * be a composite of the metrics for the fonts loaded for the
 * individual families.
 *
 * Return value: a #PangoFontMetrics object. The caller must call pango_font_metrics_unref()
 *   when finished using the object.
 **/
PangoFontMetrics *
pango_context_get_metrics (PangoContext                 *context,
			   const PangoFontDescription   *desc,
			   PangoLanguage                *language)
{
  PangoFontset *current_fonts = NULL;
  PangoFontMetrics *metrics;
  const char *sample_str;
  GList *items;

  g_return_val_if_fail (PANGO_IS_CONTEXT (context), NULL);
  g_return_val_if_fail (desc != NULL, NULL);

  if (!language)
    language = context->language;

  current_fonts = pango_font_map_load_fontset (context->font_map, context, desc, language);
  metrics = get_base_metrics (current_fonts);

  sample_str = pango_language_get_sample_string (language);
  items = itemize_with_font (context, sample_str, 0, strlen (sample_str), desc);

  update_metrics_from_items (metrics, language, items);

  g_list_foreach (items, (GFunc)pango_item_free, NULL);
  g_list_free (items);

  g_object_unref (current_fonts);

  return metrics;
}