/* Pango

 * pango-bidi-type.c: Bidirectional Character Types

 *

 * Copyright (C) 2008 Jürg Billeter <j@bitron.ch>

 *

 * 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.

 */

/**

 * SECTION:bidi

 * @short_description:Types and functions to help with handling bidirectional text

 * @title:Bidirectional Text

 * @see_also:

 * pango_context_get_base_dir(),

 * pango_context_set_base_dir(),

 * pango_itemize_with_base_dir()

 *

 * Pango supports bidirectional text (like Arabic and Hebrew) automatically.

 * Some applications however, need some help to correctly handle bidirectional text.

 *

 * The #PangoDirection type can be used with pango_context_set_base_dir() to

 * instruct Pango about direction of text, though in most cases Pango detects

 * that correctly and automatically.  The rest of the facilities in this section

 * are used internally by Pango already, and are provided to help applications

 * that need more direct control over bidirectional setting of text.

 */

#include "config.h"

#include <string.h>

#include <fribidi.h>

#include "pango-bidi-type.h"

#include "pango-utils.h"

#if FRIBIDI_MAJOR_VERSION >= 1

#define USE_FRIBIDI_EX_API

#endif

/**

 * pango_bidi_type_for_unichar:

 * @ch: a Unicode character

 *

 * Determines the normative bidirectional character type of a

 * character, as specified in the Unicode Character Database.

 *

 * A simplified version of this function is available as

 * pango_unichar_direction().

 *

 * Return value: the bidirectional character type, as used in the

 * Unicode bidirectional algorithm.

 *

 * Since: 1.22

 */

PangoBidiType

pango_bidi_type_for_unichar (gunichar ch)

{

  FriBidiCharType fribidi_ch_type;

  G_STATIC_ASSERT (sizeof (FriBidiChar) == sizeof (gunichar));

  fribidi_ch_type = fribidi_get_bidi_type (ch);

  switch (fribidi_ch_type)

    {

    case FRIBIDI_TYPE_LTR:  return PANGO_BIDI_TYPE_L;

    case FRIBIDI_TYPE_LRE:  return PANGO_BIDI_TYPE_LRE;

    case FRIBIDI_TYPE_LRO:  return PANGO_BIDI_TYPE_LRO;

    case FRIBIDI_TYPE_RTL:  return PANGO_BIDI_TYPE_R;

    case FRIBIDI_TYPE_AL:   return PANGO_BIDI_TYPE_AL;

    case FRIBIDI_TYPE_RLE:  return PANGO_BIDI_TYPE_RLE;

    case FRIBIDI_TYPE_RLO:  return PANGO_BIDI_TYPE_RLO;

    case FRIBIDI_TYPE_PDF:  return PANGO_BIDI_TYPE_PDF;

    case FRIBIDI_TYPE_EN:   return PANGO_BIDI_TYPE_EN;

    case FRIBIDI_TYPE_ES:   return PANGO_BIDI_TYPE_ES;

    case FRIBIDI_TYPE_ET:   return PANGO_BIDI_TYPE_ET;

    case FRIBIDI_TYPE_AN:   return PANGO_BIDI_TYPE_AN;

    case FRIBIDI_TYPE_CS:   return PANGO_BIDI_TYPE_CS;

    case FRIBIDI_TYPE_NSM:  return PANGO_BIDI_TYPE_NSM;

    case FRIBIDI_TYPE_BN:   return PANGO_BIDI_TYPE_BN;

    case FRIBIDI_TYPE_BS:   return PANGO_BIDI_TYPE_B;

    case FRIBIDI_TYPE_SS:   return PANGO_BIDI_TYPE_S;

    case FRIBIDI_TYPE_WS:   return PANGO_BIDI_TYPE_WS;

    case FRIBIDI_TYPE_ON:   return PANGO_BIDI_TYPE_ON;

    default:

      /* TODO

       * This function has not been updated for latest FriBidi.

       * Should add new types and / or deprecate this function. */

      return PANGO_BIDI_TYPE_ON;

    }

}

/* Some bidi-related functions */

/**

 * pango_log2vis_get_embedding_levels:

 * @text:      the text to itemize.

 * @length:    the number of bytes (not characters) to process, or -1

 *             if @text is nul-terminated and the length should be calculated.

 * @pbase_dir: input base direction, and output resolved direction.

 *

 * This will return the bidirectional embedding levels of the input paragraph

 * as defined by the Unicode Bidirectional Algorithm available at:

 *

 *   http://www.unicode.org/reports/tr9/

 *

 * If the input base direction is a weak direction, the direction of the

 * characters in the text will determine the final resolved direction.

 *

 * Return value: a newly allocated array of embedding levels, one item per

 *               character (not byte), that should be freed using g_free.

 *

 * Since: 1.4

 */

guint8 *

pango_log2vis_get_embedding_levels (const gchar    *text,

				    int             length,

				    PangoDirection *pbase_dir)

{

  glong n_chars, i;

  guint8 *embedding_levels_list;

  const gchar *p;

  FriBidiParType fribidi_base_dir;

  FriBidiCharType *bidi_types;

#ifdef USE_FRIBIDI_EX_API

  FriBidiBracketType *bracket_types;

#endif

  FriBidiLevel max_level;

  FriBidiCharType ored_types = 0;

  FriBidiCharType anded_strongs = FRIBIDI_TYPE_RLE;

  G_STATIC_ASSERT (sizeof (FriBidiLevel) == sizeof (guint8));

  G_STATIC_ASSERT (sizeof (FriBidiChar) == sizeof (gunichar));

  switch (*pbase_dir)

    {

    case PANGO_DIRECTION_LTR:

    case PANGO_DIRECTION_TTB_RTL:

      fribidi_base_dir = FRIBIDI_PAR_LTR;

      break;

    case PANGO_DIRECTION_RTL:

    case PANGO_DIRECTION_TTB_LTR:

      fribidi_base_dir = FRIBIDI_PAR_RTL;

      break;

    case PANGO_DIRECTION_WEAK_RTL:

      fribidi_base_dir = FRIBIDI_PAR_WRTL;

      break;

    case PANGO_DIRECTION_WEAK_LTR:

    case PANGO_DIRECTION_NEUTRAL:

    default:

      fribidi_base_dir = FRIBIDI_PAR_WLTR;

      break;

    }

  if (length < 0)

    length = strlen (text);

  n_chars = g_utf8_strlen (text, length);

  bidi_types = g_new (FriBidiCharType, n_chars);

#ifdef USE_FRIBIDI_EX_API

  bracket_types = g_new (FriBidiBracketType, n_chars);

#endif

  embedding_levels_list = g_new (guint8, n_chars);

  for (i = 0, p = text; p < text + length; p = g_utf8_next_char(p), i++)

    {

      gunichar ch = g_utf8_get_char (p);

      FriBidiCharType char_type = fribidi_get_bidi_type (ch);

      if (i == n_chars)

        break;

      bidi_types[i] = char_type;

      ored_types |= char_type;

      if (FRIBIDI_IS_STRONG (char_type))

        anded_strongs &= char_type;

#ifdef USE_FRIBIDI_EX_API

      if (G_UNLIKELY(bidi_types[i] == FRIBIDI_TYPE_ON))

        bracket_types[i] = fribidi_get_bracket (ch);

      else

        bracket_types[i] = FRIBIDI_NO_BRACKET;

#endif

    }

    /* Short-circuit (malloc-expensive) FriBidi call for unidirectional

     * text.

     *

     * For details see:

     * https://bugzilla.gnome.org/show_bug.cgi?id=590183

     */

#ifndef FRIBIDI_IS_ISOLATE

#define FRIBIDI_IS_ISOLATE(x) 0

#endif

    /* The case that all resolved levels will be ltr.

     * No isolates, all strongs be LTR, there should be no Arabic numbers

     * (or letters for that matter), and one of the following:

     *

     * o base_dir doesn't have an RTL taste.

     * o there are letters, and base_dir is weak.

     */

    if (!FRIBIDI_IS_ISOLATE (ored_types) &&

	!FRIBIDI_IS_RTL (ored_types) &&

	!FRIBIDI_IS_ARABIC (ored_types) &&

	(!FRIBIDI_IS_RTL (fribidi_base_dir) ||

	  (FRIBIDI_IS_WEAK (fribidi_base_dir) &&

	   FRIBIDI_IS_LETTER (ored_types))

	))

      {

        /* all LTR */

	fribidi_base_dir = FRIBIDI_PAR_LTR;

	memset (embedding_levels_list, 0, n_chars);

	goto resolved;

      }

    /* The case that all resolved levels will be RTL is much more complex.

     * No isolates, no numbers, all strongs are RTL, and one of

     * the following:

     *

     * o base_dir has an RTL taste (may be weak).

     * o there are letters, and base_dir is weak.

     */

    else if (!FRIBIDI_IS_ISOLATE (ored_types) &&

	     !FRIBIDI_IS_NUMBER (ored_types) &&

	     FRIBIDI_IS_RTL (anded_strongs) &&

	     (FRIBIDI_IS_RTL (fribidi_base_dir) ||

	       (FRIBIDI_IS_WEAK (fribidi_base_dir) &&

		FRIBIDI_IS_LETTER (ored_types))

	     ))

      {

        /* all RTL */

	fribidi_base_dir = FRIBIDI_PAR_RTL;

	memset (embedding_levels_list, 1, n_chars);

	goto resolved;

      }

#ifdef USE_FRIBIDI_EX_API

  max_level = fribidi_get_par_embedding_levels_ex (bidi_types, bracket_types, n_chars,

						   &fribidi_base_dir,

						   (FriBidiLevel*)embedding_levels_list);

#else

  max_level = fribidi_get_par_embedding_levels (bidi_types, n_chars,

						&fribidi_base_dir,

						(FriBidiLevel*)embedding_levels_list);

#endif

  if (G_UNLIKELY(max_level == 0))

    {

      /* fribidi_get_par_embedding_levels() failed. */

      memset (embedding_levels_list, 0, length);

    }

resolved:

  g_free (bidi_types);

#ifdef USE_FRIBIDI_EX_API

  g_free (bracket_types);

#endif

  *pbase_dir = (fribidi_base_dir == FRIBIDI_PAR_LTR) ?  PANGO_DIRECTION_LTR : PANGO_DIRECTION_RTL;

  return embedding_levels_list;

}

/**

 * pango_unichar_direction:

 * @ch: a Unicode character

 *

 * Determines the inherent direction of a character; either

 * %PANGO_DIRECTION_LTR, %PANGO_DIRECTION_RTL, or

 * %PANGO_DIRECTION_NEUTRAL.

 *

 * This function is useful to categorize characters into left-to-right

 * letters, right-to-left letters, and everything else.  If full

 * Unicode bidirectional type of a character is needed,

 * pango_bidi_type_for_unichar() can be used instead.

 *

 * Return value: the direction of the character.

 */

PangoDirection

pango_unichar_direction (gunichar ch)

{

  FriBidiCharType fribidi_ch_type;

  G_STATIC_ASSERT (sizeof (FriBidiChar) == sizeof (gunichar));

  fribidi_ch_type = fribidi_get_bidi_type (ch);

  if (!FRIBIDI_IS_STRONG (fribidi_ch_type))

    return PANGO_DIRECTION_NEUTRAL;

  else if (FRIBIDI_IS_RTL (fribidi_ch_type))

    return PANGO_DIRECTION_RTL;

  else

    return PANGO_DIRECTION_LTR;

}

/**

 * pango_get_mirror_char:

 * @ch: a Unicode character

 * @mirrored_ch: location to store the mirrored character

 *

 * If @ch has the Unicode mirrored property and there is another Unicode

 * character that typically has a glyph that is the mirror image of @ch's

 * glyph, puts that character in the address pointed to by @mirrored_ch.

 *

 * Use g_unichar_get_mirror_char() instead; the docs for that function

 * provide full details.

 *

 * Return value: %TRUE if @ch has a mirrored character and @mirrored_ch is

 * filled in, %FALSE otherwise

 **/

gboolean

pango_get_mirror_char (gunichar        ch,

		       gunichar       *mirrored_ch)

{

  return g_unichar_get_mirror_char (ch, mirrored_ch);

}