/* Pango

 * reorder-items.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 "config.h"

#include "pango-glyph.h"

/*

 * NB: The contents of the file implement the exact same algorithm

 *     pango-layout.c:pango_layout_line_reorder().

 */

static GList *reorder_items_recurse (GList *items, int n_items);

/**

 * pango_reorder_items:

 * @logical_items: (element-type Pango.Item): a #GList of #PangoItem in logical order.

 *

 * From a list of items in logical order and the associated

 * directional levels, produce a list in visual order.

 * The original list is unmodified.

 *

 * Returns: (transfer full) (element-type Pango.Item): a #GList

 *          of #PangoItem structures in visual order.

 *

 * (Please open a bug if you use this function.

 *  It is not a particularly convenient interface, and the code

 *  is duplicated elsewhere in Pango for that reason.)

 */

GList *

pango_reorder_items (GList *logical_items)

{

  return reorder_items_recurse (logical_items, g_list_length (logical_items));

}

static GList *

reorder_items_recurse (GList *items, int n_items)

{

  GList *tmp_list, *level_start_node;

  int i, level_start_i;

  int min_level = G_MAXINT;

  GList *result = NULL;

  if (n_items == 0)

    return NULL;

  tmp_list = items;

  for (i=0; i

    {

      PangoItem *item = tmp_list->data;

      min_level = MIN (min_level, item->analysis.level);

      tmp_list = tmp_list->next;

    }

  level_start_i = 0;

  level_start_node = items;

  tmp_list = items;

  for (i=0; i

    {

      PangoItem *item = tmp_list->data;

      if (item->analysis.level == min_level)

	{

	  if (min_level % 2)

	    {

	      if (i > level_start_i)

		result = g_list_concat (reorder_items_recurse (level_start_node, i - level_start_i), result);

	      result = g_list_prepend (result, item);

	    }

	  else

	    {

	      if (i > level_start_i)

		result = g_list_concat (result, reorder_items_recurse (level_start_node, i - level_start_i));

	      result = g_list_append (result, item);

	    }

	  level_start_i = i + 1;

	  level_start_node = tmp_list->next;

	}

      tmp_list = tmp_list->next;

    }

  if (min_level % 2)

    {

      if (i > level_start_i)

	result = g_list_concat (reorder_items_recurse (level_start_node, i - level_start_i), result);

    }

  else

    {

      if (i > level_start_i)

	result = g_list_concat (result, reorder_items_recurse (level_start_node, i - level_start_i));

    }

  return result;

}