(render_glyphs): If a font is not found, use

[m17n/m17n-lib.git] / src / draw.c

/* draw.c -- drawing module.
   Copyright (C) 2003, 2004
     National Institute of Advanced Industrial Science and Technology (AIST)
     Registration Number H15PRO112

   This file is part of the m17n library.

   The m17n library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public License
   as published by the Free Software Foundation; either version 2.1 of
   the License, or (at your option) any later version.

   The m17n 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the m17n library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.  */

/***en
    @addtogroup m17nDraw
    @brief Drawing M-texts on a window.

    The m17n GUI API provides functions to draw M-texts.

    The fonts used for drawing are selected automatically based on the
    fontset and the properties of a face.  A face also specifies the
    appearance of M-texts, i.e. font size, color, underline, etc.

    The drawing format of M-texts can be controlled in a variety of
    ways, which provides powerful 2-dimensional layouting
    facility.  */

/***ja
    @addtogroup m17nDraw
    @brief M-text ¤ò¥¦¥£¥ó¥É¥¦¤ËÉÁ²è¤¹¤ë.

    m17n-gui API ¤Ë¤Ï¡¢M-text ¤òɽ¼¨¤¹¤ë¤¿¤á¤Î´Ø¿ô¤¬ÍÑ°Õ¤µ¤ì¤Æ¤¤¤ë¡£

    ɽ¼¨¤ËÍѤ¤¤é¤ì¤ë¥Õ¥©¥ó¥È¤Ï¡¢¥Õ¥©¥ó¥È¥»¥Ã¥È¤È face ¥×¥í¥Ñ¥Æ¥£¤Ë´ð¤Å
    ¤¤¤Æ¼«Æ°Åª¤Ë·èÄꤵ¤ì¤ë¡£¤Þ¤¿¡¢¥Õ¥©¥ó¥È¤Î¥µ¥¤¥º¤ä¿§¤ä²¼Àþ¤Ê¤É¤Î¸«±É
    ¤¨¤â face ¤Ë¤è¤Ã¤Æ·è¤Þ¤ë¡£

    M-text ¤ÎÉÁ²è¥Õ¥©¡¼¥Þ¥Ã¥È¤Ï¿ÍͤÊÊýË¡¤ÇÀ©¸æ¤Ç¤­¤ë¤Î¤Ç¡¢¶¯ÎϤÊÆó¼¡
    ¸µ¥ì¥¤¥¢¥¦¥Èµ¡Ç½¤¬¼Â¸½¤Ç¤­¤ë¡£
    */

/*=*/

#if !defined (FOR_DOXYGEN) || defined (DOXYGEN_INTERNAL_MODULE)
/*** @addtogroup m17nInternal
     @{ */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>

#include "config.h"
#include "m17n-gui.h"
#include "m17n-misc.h"
#include "internal.h"
#include "symbol.h"
#include "textprop.h"
#include "internal-gui.h"
#include "face.h"
#include "font.h"

#ifdef HAVE_FRIBIDI
#include <fribidi/fribidi.h>
#endif /* HAVE_FRIBIDI */

#define MAX(x, y) ((x) > (y) ? (x) : (y))
#define MIN(x, y) ((x) < (y) ? (x) : (y))

static MSymbol M_glyph_string;

/* Special scripts */
static MSymbol Mlatin, Minherited;
/* Special categories */
static MSymbol McatCc, McatCf;

static MSymbol Mdepth;

\f
/* Glyph-string composer.  */

static MSymbol MbidiR;
static MSymbol MbidiAL;
static MSymbol MbidiRLE;
static MSymbol MbidiRLO;
static MSymbol MbidiBN;
static MSymbol MbidiS;

static void
visual_order (MGlyphString *gstring)
{
  int len = gstring->used - 2;
  MGlyph *glyphs;
  int *idx = alloca (sizeof (int) * len);
  int gidx;
  int bidi_sensitive = gstring->control.orientation_reversed;
  int size = 0;
  MGlyph *g = MGLYPH (1);
  int i;
#ifdef HAVE_FRIBIDI
  FriBidiCharType base = (gstring->control.orientation_reversed
                          ? FRIBIDI_TYPE_RTL : FRIBIDI_TYPE_LTR);
  FriBidiChar *logical = alloca (sizeof (FriBidiChar) * len);
  FriBidiChar *visual;
  FriBidiStrIndex *indices;
  FriBidiLevel *levels = alloca (sizeof (FriBidiLevel) * len);
#else  /* not HAVE_FRIBIDI */
  int *logical = alloca (sizeof (int) * len);
  int *indices;
  char *levels = alloca (len);
#endif /* not HAVE_FRIBIDI */

  while (g->type != GLYPH_ANCHOR)
    {
      MSymbol bidi = (MSymbol) mchar_get_prop (g->c, Mbidi_category);

      if (bidi == MbidiR || bidi == MbidiAL
          || bidi == MbidiRLE || bidi == MbidiRLO)
        {
          bidi_sensitive = 1;
          levels[size] = 1;
        }
      else
        levels[size] = 0;
      idx[size] = GLYPH_INDEX (g);
      logical[size++] = g++->c;
      while (g->type != GLYPH_ANCHOR && g->combining_code)
        g++;
    }

  if (! bidi_sensitive)
    return;

  glyphs = alloca (sizeof (MGlyph) * gstring->used);
  memcpy (glyphs, gstring->glyphs, (sizeof (MGlyph) * gstring->used));
#ifdef HAVE_FRIBIDI
  visual = alloca (sizeof (FriBidiChar) * size);
  indices = alloca (sizeof (FriBidiStrIndex) * size);

  fribidi_log2vis (logical, size, &base, visual, NULL, indices, levels);
#else  /* not HAVE_FRIBIDI */
  indices = alloca (sizeof (int) * size);
  for (i = 0; i < size; i++)
    {
      if (levels[i])
        {
          int j, k;

          for (j = i + 1; j < size && levels[j]; j++);
          for (k = j--; i < k; i++, j--)
            indices[i] = j;
          i--;
        }
      else
        indices[i] = i;
    }
#endif /* not HAVE_FRIBIDI */

  /* IDX are indices to gstring->glyphs[].  The glyphs for LOGICAL[N]
     starts from gstring->glyphs[IDX[N]].

     INDICES are indices to LOGICAL[].  The glyph for VISUAL[N] is
     originally at LOGICAL[INDICES[N]].  */

  for (i = 0, gidx = 1; i < size; i++)
    {
      int j = indices[i];
      int k = idx[j];

      glyphs[k].bidi_level = levels[j];
#ifdef HAVE_FRIBIDI
      if (visual[i] != logical[j])
        {
          /* Mirrored.  */
          glyphs[k].c = visual[i];
          if (glyphs[k].rface->rfont)
            glyphs[k].code = mfont__encode_char (glyphs[k].rface->rfont,
                                                 glyphs[k].c);
        }
#endif /* not HAVE_FRIBIDI */
      *(MGLYPH (gidx)) = glyphs[k];
      for (gidx++, k++;
           k < gstring->used - 1 && glyphs[k].combining_code;
           gidx++, k++)
        {
          glyphs[k].bidi_level = levels[j];
          *(MGLYPH (gidx)) = glyphs[k];
        }
    }
}

static void
reorder_combining_chars (MGlyphString *gstring, int from, int to)
{
  MGlyph *g, *gbeg = MGLYPH (from + 1), *gend = MGLYPH (to), temp;
  int reordered = 1;
  
  while (reordered)
    {
      reordered = 0;
      for (g = gbeg; g != gend; g++)
        if (COMBINING_CODE_CLASS (g->combining_code) > 0
            && (COMBINING_CODE_CLASS (g[-1].combining_code)
                > COMBINING_CODE_CLASS (g->combining_code)))
          {
            reordered = 1;
            temp = *g;
            *g = g[-1];
            g[-1] = temp;
          }
    }
}


/** Scan M-text MT from FROM to TO, and compose glyphs in GSTRING for
    displaying them on FRAME.

    This function fills members <type>, <rface>, <c>, <pos>, <to>,
    <code> of glyphs.  The other members are filled by
    layout_glyph_string.  */

static void
compose_glyph_string (MFrame *frame, MText *mt, int from, int to,
                      MGlyphString *gstring)
{
  MRealizedFace *default_rface = frame->rface;
  int stop, face_change, language_change, charset_change;
  MGlyph g_tmp, *g;
  int pos;
  MSymbol language = Mnil, script = Mnil, charset = Mnil;
  MRealizedFace *rface = default_rface;
  int non_ascii_found;
  int size = gstring->control.fixed_width;
  int i, limit;
  int last;

  MLIST_RESET (gstring);
  gstring->from = from;

  /* At first generate glyphs while using the member <enabled> as a
     flag for rface re-checking.  */
  INIT_GLYPH (g_tmp);

  /** Put anchor glyphs at the head and tail.  */
  g_tmp.type = GLYPH_ANCHOR;
  g_tmp.pos = g_tmp.to = from;
  g_tmp.c = 0;
  APPEND_GLYPH (gstring, g_tmp);

  stop = face_change = charset_change = language_change = pos = from;
  last = 0;
  non_ascii_found = 0;
  while (1)
    {
      int c;
      MSymbol this_script;

      if (pos < mtext_nchars (mt))
        c = mtext_ref_char (mt, pos);
      else
        c = '\n';
      g_tmp.category = Mnil;
      if (c < 0x100)
        {
          if (c == ' ' || c == '\n' || c == '\t')
            g_tmp.type = GLYPH_SPACE, this_script = Mnil;
          else
            g_tmp.type = GLYPH_CHAR, this_script = Mlatin;
        }
      else
        {
          g_tmp.category = mchar_get_prop (c, Mcategory);
          g_tmp.type = GLYPH_CHAR;
          this_script = (MSymbol) mchar_get_prop (c, Mscript);
          if (this_script == Minherited)
            this_script = script;
        }

      if (pos == stop || script != this_script
          || MGLYPH (last)->type != g_tmp.type)
        {
          g = MGLYPH (last);
          if (non_ascii_found && g->type == GLYPH_CHAR)
            while (g < gstring->glyphs + gstring->used)
              g = mface__for_chars (script, language, charset,
                                    g, gstring->glyphs + gstring->used, size);
          last = gstring->used;
          non_ascii_found = 0;
          script = this_script;
          if (pos == to)
            break;
          if (pos < mtext_nchars (mt) && pos == language_change)
            {
              language = (MSymbol) mtext_get_prop (mt, pos, Mlanguage);
              mtext_prop_range (mt, Mlanguage, pos, NULL, &language_change, 0);
            }
          if (pos < mtext_nchars (mt) && pos == charset_change)
            {
              charset = (MSymbol) mtext_get_prop (mt, pos, Mcharset);
              mtext_prop_range (mt, Mcharset, pos, NULL, &charset_change, 0);
            }
          if (pos < mtext_nchars (mt) && pos == face_change)
            {
              MFace *faces[64];
              int num = mtext_get_prop_values (mt, pos, Mface,
                                               (void **) faces, 64);

              mtext_prop_range (mt, Mface, pos, NULL, &face_change, 1);
              rface = (num > 0
                       ? mface__realize (frame, faces, num,
                                         language, charset, size)
                       : default_rface);
            }
          stop = to;
          if (stop > language_change)
            stop = language_change;
          if (stop > charset_change)
            stop = charset_change;
          if (face_change < stop)
            stop = face_change;         
        }

      g_tmp.c = g_tmp.code = c;
      g_tmp.pos = pos++;
      g_tmp.to = pos;
      g_tmp.rface = rface;
      
      if (c >= 0x100)
        non_ascii_found = 1;
      else if (g_tmp.type == GLYPH_CHAR && (c <= 32 || c == 127))
        {
          g_tmp.code = '^';
          APPEND_GLYPH (gstring, g_tmp);
          if (c < ' ')
            g_tmp.code = g_tmp.c + 0x40;
          else
            g_tmp.code = '?';
        }
      APPEND_GLYPH (gstring, g_tmp);
      if (c == '\n'
          && gstring->control.two_dimensional)
        break;
    }

  limit = pos - from;

  /* Append an anchor glyph.  */
  g_tmp.type = GLYPH_ANCHOR;
  g_tmp.c = 0;
  g_tmp.code = MCHAR_INVALID_CODE;
  g_tmp.pos = g_tmp.to = pos;
  g_tmp.rface = NULL;
  APPEND_GLYPH (gstring, g_tmp);

  gstring->to = pos;

  /* Next, run FLT if necessary.  */
  for (i = 1, g = MGLYPH (i); g->type != GLYPH_ANCHOR;)
    {
      MGlyph *this = g;

      if (this->type == GLYPH_CHAR && this->rface->rfont)
        {
          int start = i++;

          if (this->rface->rfont->layouter != Mnil)
            {
              MGlyph *prev;
              unsigned code;

              for (prev = MGLYPH (start - 1);
                   (prev->type == GLYPH_CHAR
                    && prev->category == McatCf
                    && (code = mfont__encode_char (this->rface->rfont, prev->c)
                        != MCHAR_INVALID_CODE));
                   start--, prev--)
                prev->code = code;

              for (g++;
                   (g->type == GLYPH_CHAR
                    && (g->rface->rfont == this->rface->rfont
                        || (g->category == McatCf
                            && ((code = mfont__encode_char (this->rface->rfont,
                                                            g->c))
                                != MCHAR_INVALID_CODE))));
                   i++, g++)
                if (g->rface->rfont != this->rface->rfont)
                  {
                    g->rface->rfont = this->rface->rfont;
                    g->code = code;
                  }
              i = mfont__flt_run (gstring, start, i, this->rface);
            }
          else
            {
              while (this->type == GLYPH_CHAR
                     && this->c >= 0x100
                     && this->category
                     && MSYMBOL_NAME (this->category)[0] == 'M'
                     && this->rface->rfont
                     && this->rface->rfont->layouter == Mnil)
                {
                  int class = (int) mchar_get_prop (this->c,
                                                    Mcombining_class);
                  this->combining_code
                    = MAKE_COMBINING_CODE_BY_CLASS (class);
                  i++, this++;
                }
              if (start + 1 < i)
                reorder_combining_chars (gstring, start, i);
            }
          g = MGLYPH (i);
        }
      else
        i++, g++;
    }

  /* At last, reorder glyphs visually if necessary.  */
  if (gstring->control.enable_bidi)
    visual_order (gstring);
}


static int
combining_code_from_class (int class)
{
  int code;

  if (class < 200)
    code = MAKE_COMBINING_CODE (3, 1, 3, 1, 128, 128);
  else if (class == 200)        /* below left attached */
    code = MAKE_COMBINING_CODE (2, 0, 0, 1, 128, 128);
  else if (class == 202)        /* below attached*/
    code = MAKE_COMBINING_CODE (2, 1, 0, 1, 128, 128);
  else if (class == 204)        /* below right attached */
    code = MAKE_COMBINING_CODE (2, 2, 0, 1, 128, 128);
  else if (class == 208)        /* left attached */
    code = MAKE_COMBINING_CODE (3, 0, 3, 2, 128, 128);
  else if (class == 210)        /* right attached */
    code = MAKE_COMBINING_CODE (3, 2, 3, 0, 128, 128);
  else if (class == 212)        /* above left attached */
    code = MAKE_COMBINING_CODE (0, 0, 2, 1, 128, 128);
  else if (class == 214)        /* above attached */
    code = MAKE_COMBINING_CODE (0, 1, 2, 1, 128, 128);
  else if (class == 216)        /* above right attached */
    code = MAKE_COMBINING_CODE (0, 2, 2, 1, 128, 128);
  else if (class == 218)        /* below left */
    code = MAKE_COMBINING_CODE (2, 0, 0, 1, 122, 128);
  else if (class == 220)        /* below */
    code = MAKE_COMBINING_CODE (2, 1, 0, 1, 122, 128);
  else if (class == 222)        /* below right */
    code = MAKE_COMBINING_CODE (2, 2, 0, 1, 122, 128);
  else if (class == 224)        /* left */
    code = MAKE_COMBINING_CODE (3, 0, 3, 2, 128, 122);
  else if (class == 226)        /* right */
    code = MAKE_COMBINING_CODE (3, 2, 3, 0, 128, 133);
  else if (class == 228)        /* above left */
    code = MAKE_COMBINING_CODE (0, 0, 2, 1, 133, 128);
  else if (class == 230)        /* above */
    code = MAKE_COMBINING_CODE (0, 1, 2, 1, 133, 128);
  else if (class == 232)        /* above right */
    code = MAKE_COMBINING_CODE (0, 2, 2, 1, 133, 128);
  else if (class == 233)        /* double below */
    code = MAKE_COMBINING_CODE (2, 2, 0, 2, 122, 128);
  else if (class == 234)        /* double above */
    code = MAKE_COMBINING_CODE (0, 2, 2, 2, 133, 128);
  else if (class == 240)        /* iota subscript */
    code = MAKE_COMBINING_CODE (2, 1, 0, 1, 122, 128);
  else                          /* unknown */
    code = MAKE_COMBINING_CODE (3, 1, 3, 1, 128, 128);
  return code;
}


static void
layout_glyphs (MFrame *frame, MGlyphString *gstring, int from, int to)
{
  int g_physical_ascent, g_physical_descent;
  int g_width, g_lbearing, g_rbearing;
  MGlyph *g = MGLYPH (from);
  MGlyph *last_g = MGLYPH (to);

  g_physical_ascent = gstring->physical_ascent;
  g_physical_descent = gstring->physical_descent;
  g_width = g_lbearing = g_rbearing = 0;

  mfont__get_metric (gstring, from, to);

  while (g < last_g)
    {
      MGlyph *base = g++;
      MRealizedFont *rfont = base->rface->rfont;
      int size = rfont->font.property[MFONT_SIZE];
      int width, lbearing, rbearing;

      if (g == last_g || ! g->combining_code)
        {
          /* No combining.  */
          if (base->left_padding && base->lbearing < 0)
            {
              base->xoff = - base->lbearing;
              base->width += base->xoff;
              base->rbearing += base->xoff;
              base->lbearing = 0;
            }
          if (base->right_padding && base->rbearing > base->width)
            {
              base->width = base->rbearing;
            }
          lbearing = (base->lbearing < 0 ? base->lbearing : 0);
          rbearing = base->rbearing;
        }
      else
        {
          /* With combining glyphs.  */
          int left = -base->width;
          int right = 0;
          int top = - base->ascent;
          int bottom = base->descent;
          int height = bottom - top;
          int begin = base->pos;
          int end = base->to;
          int i;

          width = base->width;
          lbearing = (base->lbearing < 0 ? base->lbearing : 0);
          rbearing = base->rbearing;

          while (g != last_g && g->combining_code)
            {
              int combining_code, base_x, base_y, add_x, add_y, off_x, off_y;

              combining_code = g->combining_code;
              if (COMBINING_BY_CLASS_P (combining_code))
                g->combining_code = combining_code
                  = combining_code_from_class (COMBINING_CODE_CLASS
                                               (combining_code));

              rfont = g->rface->rfont;
              size = rfont->font.property[MFONT_SIZE];
              off_x = (size * (COMBINING_CODE_OFF_X (combining_code) - 128)
                       / 1000);
              off_y = (size * (COMBINING_CODE_OFF_Y (combining_code) - 128)
                       / 1000);
              base_x = COMBINING_CODE_BASE_X (combining_code);
              base_y = COMBINING_CODE_BASE_Y (combining_code);
              add_x = COMBINING_CODE_ADD_X (combining_code);
              add_y = COMBINING_CODE_ADD_Y (combining_code);

              if (begin > g->pos)
                begin = g->pos;
              else if (end < g->to)
                end = g->to;
                
              g->xoff = left + (width * base_x - g->width * add_x) / 2 + off_x;
              if (g->xoff < left)
                left = g->xoff;
              if (g->xoff + g->width > right)
                right = g->xoff + g->width;
              width = right - left;
              if (g->xoff + g->lbearing < left + lbearing)
                lbearing = g->xoff + g->lbearing - left;
              if (g->xoff + g->rbearing > left + rbearing)
                rbearing = g->xoff + g->rbearing - left;

              if (base_y < 3)
                g->yoff = top + height * base_y / 2;
              else
                g->yoff = 0;
              if (add_y < 3)
                g->yoff -= (g->ascent + g->descent) * add_y / 2 - g->ascent;
              g->yoff -= off_y;
              if (g->yoff - g->ascent < top)
                top = g->yoff - g->ascent;
              if (g->yoff + g->descent > bottom)
                bottom = g->yoff + g->descent;
              height = bottom - top;

              g->width = 0;
              g++;
            }

          base->ascent = - top;
          base->descent = bottom;
          base->lbearing = lbearing;
          base->rbearing = rbearing;
          if (left < - base->width)
            {
              base->xoff = - base->width - left;
              base->width += base->xoff;
              base->rbearing += base->xoff;
              base->lbearing += base->xoff;
            }
          if (right > 0)
            {
              base->width += right;
              base->rbearing += right;
              base->right_padding = 1;
              for (i = 1; base + i != g; i++)
                base[i].xoff -= right;
            }

          for (i = 0; base + i != g; i++)
            {
              base[i].pos = begin;
              base[i].to = end;
            }
        }

      g_physical_ascent = MAX (g_physical_ascent, base->ascent);
      g_physical_descent = MAX (g_physical_descent, base->descent);
      g_lbearing = MIN (g_lbearing, g_width + lbearing);
      g_rbearing = MAX (g_rbearing, g_width + rbearing);
      g_width += base->width;
    }

  gstring->physical_ascent = g_physical_ascent;
  gstring->physical_descent = g_physical_descent;
  gstring->sub_width = g_width;
  gstring->sub_lbearing = g_lbearing;
  gstring->sub_rbearing = g_rbearing;
}


/** Decide the layout of glyphs in GSTRING.  Space glyphs are handled
    by this function directly.  Character glyphs are handled by
    layouter functions registered in font drivers.

    This function fill-in all the remaining members of glyphs.  */

static void
layout_glyph_string (MFrame *frame, MGlyphString *gstring)
{
  /* Default width of TAB.  */
  int tab_width = frame->space_width * (gstring->control.tab_width
                                        ? gstring->control.tab_width : 8);
  int tab_found = 0;
  MGlyph *g;
  MGlyph pad;
  MDrawControl *control = &(gstring->control);
  int width;
  MFaceBoxProp *box;
  int box_line_height = 0;
  int ignore_formatting_char = control->ignore_formatting_char;

  gstring->ascent = gstring->descent = 0;
  gstring->physical_ascent = gstring->physical_descent = 0;
  gstring->width = gstring->lbearing = gstring->rbearing = 0;

  g = MGLYPH (1);
  box = NULL;
  while (g->type != GLYPH_ANCHOR)
    {
      if (box != g->rface->box)
        {
          int gidx = GLYPH_INDEX (g);

          if (box)
            {
              /* Insert the right side of the box.  That glyph belongs
                 to the previous grapheme cluster.  */
              MGlyph box_glyph = g[-1];

              box_glyph.type = GLYPH_BOX;
              box_glyph.width
                = (control->fixed_width
                   ? frame->space_width
                   : box->inner_hmargin + box->width + box->outer_hmargin);
              box_glyph.lbearing = 0;
              box_glyph.rbearing = box_glyph.width;
              box_glyph.xoff = 0;
              box_glyph.right_padding = 1;
              gstring->width += box_glyph.width;
              gstring->rbearing += box_glyph.width;
              INSERT_GLYPH (gstring, gidx, box_glyph);
              gidx++;
              g = MGLYPH (gidx);
            }
          box = g->rface->box;
          if (box)
            {
              /* Insert the left side of the box.  That glyph belongs
                 to the following grapheme cluster.  */
              MGlyph box_glyph = *g;
              int box_height = (box->width
                                + box->inner_vmargin + box->outer_vmargin);

              if (box_line_height < box_height)
                box_line_height = box_height;
              box_glyph.type = GLYPH_BOX;
              box_glyph.width
                = (control->fixed_width
                   ? frame->space_width
                   : box->inner_hmargin + box->width + box->outer_hmargin);
              box_glyph.lbearing = 0;
              box_glyph.rbearing = box_glyph.width;
              box_glyph.xoff = 0;
              box_glyph.left_padding = 1;
              gstring->width += box_glyph.width;
              gstring->rbearing += box_glyph.width;
              INSERT_GLYPH (gstring, gidx, box_glyph);
              gidx++;
              g = MGLYPH (gidx);
            }
        }

      if (g->category == McatCf && ignore_formatting_char)
        g->type = GLYPH_SPACE;

      if (g->type == GLYPH_CHAR)
        {
          MRealizedFace *rface = g->rface;
          MRealizedFont *rfont = rface->rfont;
          MGlyph *fromg = g;
          int from = GLYPH_INDEX (g);

          for (g++; g->type == GLYPH_CHAR; g++)
            if (! rfont != ! g->rface->rfont
                || box != g->rface->box
                || ((fromg->code == MCHAR_INVALID_CODE)
                    != (g->code == MCHAR_INVALID_CODE))
                || (g->category == McatCf && ignore_formatting_char))
              break;
          if (rfont && fromg->code != MCHAR_INVALID_CODE)
            {
              int extra_width;
              int to = GLYPH_INDEX (g);

              layout_glyphs (frame, gstring, from, to);
              extra_width = - gstring->sub_lbearing;
              if (extra_width > 0
                  && (GLYPH_INDEX (g) > 1
                      || control->align_head))
                {
                  g = MGLYPH (from);
                  pad = *g;
                  pad.type = GLYPH_PAD;
                  pad.xoff = 0;
                  pad.lbearing = 0;
                  pad.width = pad.rbearing = extra_width;
                  INSERT_GLYPH (gstring, from, pad);
                  to++;
                  gstring->sub_lbearing = 0;
                  gstring->sub_width += extra_width;
                  gstring->sub_rbearing += extra_width;

                  g = MGLYPH (from - 1);
                  if (g->type == GLYPH_SPACE)
                    {
                      /* The pad just inserted is absorbed (maybe
                         partially) by the previous space while
                         keeping at least some space width.  For the
                         moment, we use the arbitrary width 2-pixel.
                         Perhaps, it should be decided by the current
                         face, or a default value of the current
                         frame, which is, however, not yet
                         implemented.  */
                      if (extra_width + 2 < g->width)
                        {
                          g->width -= extra_width;
                        }
                      else
                        {
                          extra_width -= g->width - 2;
                          g->width = 2;
                        }
                      gstring->width -= extra_width;
                      gstring->rbearing -= extra_width;
                    }
                }

              extra_width = gstring->sub_rbearing - gstring->sub_width;
              if (extra_width > 0)
                {
                  g = MGLYPH (to);
                  if (g->type == GLYPH_SPACE && box == g->rface->box)
                    {
                      g--;
                      pad = *g;
                      pad.type = GLYPH_PAD;
                      pad.xoff = 0;
                      pad.lbearing = 0;
                      pad.width = pad.rbearing = extra_width;
                      INSERT_GLYPH (gstring, to, pad);
                      to++;
                    }
                  else
                    g[-1].width += extra_width;
                  gstring->sub_width += extra_width;
                }

              if (gstring->lbearing > gstring->width + gstring->sub_lbearing)
                gstring->lbearing = gstring->width + gstring->sub_lbearing;
              if (gstring->rbearing < gstring->width + gstring->sub_rbearing)
                gstring->rbearing = gstring->width + gstring->sub_rbearing;
              gstring->width += gstring->sub_width;
              if (gstring->ascent < rface->ascent)
                gstring->ascent = rface->ascent;
              if (gstring->descent < rface->descent)
                gstring->descent = rface->descent;
              g = MGLYPH (to);
            }
          else
            {
              for (; fromg < g; fromg++)
                {
                  if ((fromg->c >= 0x200B && fromg->c <= 0x200F)
                      || (fromg->c >= 0x202A && fromg->c <= 0x202E))
                    fromg->width = fromg->rbearing = 1;
                  else
                    fromg->width = fromg->rbearing = rface->space_width;
                  fromg->xoff = fromg->lbearing = 0;
                  fromg->ascent = fromg->descent = 0;
                  gstring->width += fromg->width;
                  gstring->rbearing += fromg->width;
                }
              if (gstring->ascent < frame->rface->ascent)
                gstring->ascent = frame->rface->ascent;
              if (gstring->descent < frame->descent)
                gstring->descent = frame->rface->descent;
            }
        }
      else if (g->type == GLYPH_SPACE)
        {
          if (g->c == ' ')
            g->width = g->rface->space_width;
          else if (g->c == '\n')
            {
              g->width = control->cursor_width;
              if (g->width)
                {
                  if (control->cursor_bidi)
                    g->width = 3;
                  else if (g->width < 0)
                    g->width = g->rface->space_width;
                }
            }
          else if (g->c == '\t')
            {
              g->width = tab_width - ((gstring->indent + gstring->width)
                                      % tab_width);
              tab_found = 1;
            }
          else
            g->width = 1;
          if (g[-1].type == GLYPH_PAD)
            {
              /* This space glyph absorbs (maybe partially) the
                 previous padding glyph.  */
              g->width -= g[-1].width;
              if (g->width < 1)
                /* But, keep at least some space width.  For the
                   moment, we use the arbitrary width 2-pixel.  */
                g->width = 2;
            }
          g->rbearing = g->width;
          gstring->width += g->width;
          gstring->rbearing += g->width;
          if (g->rface->rfont)
            {
              if (gstring->ascent < g->rface->ascent)
                gstring->ascent = g->rface->ascent;
              if (gstring->descent < g->rface->descent)
                gstring->descent = g->rface->descent;
            }
          g++;
        }
      else
        {
          gstring->width += g->width;
          gstring->rbearing += g->width;
          g++;
        }
    }

  if (box)
    {
      /* Insert the right side of the box.  */
      int gidx = GLYPH_INDEX (g);
      MGlyph box_glyph = g[-1];

      box_glyph.type = GLYPH_BOX;
      box_glyph.width
        = (control->fixed_width
           ? frame->space_width
           : box->inner_hmargin + box->width + box->outer_hmargin);
      box_glyph.lbearing = 0;
      box_glyph.rbearing = box_glyph.width;
      box_glyph.xoff = 0;
      box_glyph.right_padding = 1;
      gstring->width += box_glyph.width;
      gstring->rbearing += box_glyph.width;
      INSERT_GLYPH (gstring, gidx, box_glyph);
    }

  gstring->text_ascent = gstring->ascent;
  gstring->text_descent = gstring->descent;
  if (gstring->text_ascent < gstring->physical_ascent)
    gstring->text_ascent = gstring->physical_ascent;
  if (gstring->text_descent < gstring->physical_descent)
    gstring->text_descent = gstring->physical_descent;
  gstring->line_ascent = gstring->text_ascent;
  gstring->line_descent = gstring->text_descent;
  if (box_line_height > 0)
    {
      gstring->line_ascent += box_line_height;
      gstring->physical_ascent = gstring->line_ascent;
      gstring->line_descent += box_line_height;
      gstring->physical_descent = gstring->line_descent;
    }

  if (gstring->line_ascent < control->min_line_ascent)
    gstring->line_ascent = control->min_line_ascent;
  else if (control->max_line_ascent
           && control->max_line_ascent > control->min_line_ascent
           && gstring->line_ascent > control->max_line_ascent)
    gstring->line_ascent = control->max_line_ascent;

  if (gstring->line_descent < control->min_line_descent)
    gstring->line_descent = control->min_line_descent;
  else if (control->max_line_descent
           && control->max_line_descent > control->min_line_descent
           && gstring->line_descent > control->max_line_descent)
    gstring->line_descent = control->max_line_descent;
  gstring->height = gstring->line_ascent + gstring->line_descent;

  if (control->orientation_reversed
      && tab_found)
    {
      /* We must adjust TAB width for RTL orientation.  */
      width = gstring->indent;

      for (g = MGLYPH (gstring->used - 2); g->type != GLYPH_ANCHOR; g--)
        {
          if (g->type == GLYPH_CHAR && g->c == '\t')
            {
              int this_width = tab_width - (width % tab_width);

              if (g[1].type == GLYPH_PAD)
                this_width -= g[1].width;
              if (g[-1].type == GLYPH_PAD)
                this_width -= g[-1].width;              
              if (this_width < 2)
                this_width = 2;
              gstring->width += this_width - g->width;
              gstring->rbearing += this_width - g->width;
              g->width = this_width;
              width += this_width;
            }
          else
            width += g->width;
        }
    }
}


static MDrawRegion
draw_background (MFrame *frame, MDrawWindow win, int x, int y,
                 MGlyphString *gstring, int from, int to,
                 int *from_idx, int *to_idx, int *to_x)
{
  MGlyph *g = MGLYPH (1);
  MDrawRegion region = (MDrawRegion) NULL;
  MDrawControl *control = &gstring->control;
  int cursor_pos = -1;
  int prev_pos = -1;
  int cursor_bidi = control->cursor_bidi;

  if (control->with_cursor && control->cursor_width)
    {
      if (gstring->from <= control->cursor_pos
          && gstring->to > control->cursor_pos)
        cursor_pos = control->cursor_pos;
      if (cursor_bidi
          && gstring->from <= control->cursor_pos - 1
          && gstring->to > control->cursor_pos - 1)
        prev_pos = control->cursor_pos - 1;
    }

  *from_idx = *to_idx = 0;
  while (g->type != GLYPH_ANCHOR)
    {
      if (g->pos >= from && g->pos < to)
        {
          MGlyph *fromg = g, *cursor = NULL;
          MRealizedFace *rface = g->rface;
          int width = 0;
          int cursor_width = 0;
          int cursor_x;

          if (! *from_idx)
            *from_idx = GLYPH_INDEX (g);
          while (g->pos >= from && g->pos < to
                 && g->rface == rface)
            {
              g->enabled = 1;
              if (g->type != GLYPH_BOX
                  && g->pos <= cursor_pos && g->to > cursor_pos)
                {
                  if (! cursor)
                    cursor = g, cursor_x = x + width;
                  cursor_width += g->width;
                }
              width += g++->width;
            }
          if (width > 0
              && (control->as_image
                  || rface->face.property[MFACE_BACKGROUND] != Mnil
                  || rface->face.property[MFACE_VIDEOMODE] == Mreverse))
            {
              int this_x = x, this_width = width;

              if (fromg->type == GLYPH_BOX)
                this_x += fromg->width, this_width -= fromg->width;
              if (g[-1].type == GLYPH_BOX)
                this_width -= g[-1].width;
              mwin__fill_space (frame, win, rface, 0,
                                this_x, y - gstring->text_ascent, this_width,
                                gstring->text_ascent + gstring->text_descent,
                                control->clip_region);
            }
          if (cursor)
            {
              MDrawMetric rect;
            
              rect.x = cursor_x;
              rect.y = y - gstring->text_ascent;
              rect.height = gstring->text_ascent + gstring->text_descent;
              if (! cursor_bidi)
                {
                  rect.width = ((control->cursor_width > 0
                                 && control->cursor_width < cursor_width)
                                ? control->cursor_width : cursor_width);
                }
              else
                {
                  if (cursor->bidi_level % 2)
                    rect.x += cursor_width - 1;
                  rect.width = 1;
                }
              mwin__fill_space (frame, win, rface, 1,
                                rect.x, rect.y, rect.width, rect.height,
                                control->clip_region);
              if (! region)
                region = mwin__region_from_rect (&rect);
              else
                mwin__region_add_rect (region, &rect);
              mwin__verify_region (frame, region);
              if (cursor_bidi)
                {
                  if (cursor->bidi_level % 2)
                    rect.x -= 3;
                  rect.height = 2;
                  rect.width = cursor_width < 4 ? cursor_width : 4;
                  mwin__fill_space (frame, win, rface, 1,
                                    rect.x, rect.y, rect.width, rect.height,
                                    control->clip_region);
                  mwin__region_add_rect (region, &rect);
                  mwin__verify_region (frame, region);
                }
            }

          if (prev_pos >= 0)
            {
              int temp_width = 0;

              cursor_width = 0;
              cursor = NULL;
              while (fromg < g)
                {
                  if (fromg->type != GLYPH_BOX
                      && fromg->pos <= prev_pos && fromg->to > prev_pos)
                    {
                      if (! cursor)
                        cursor = fromg, cursor_x = x + temp_width;
                      cursor_width += fromg->width;
                    }
                  temp_width += fromg++->width;
                }
              if (cursor)
                {
                  MDrawMetric rect;

                  rect.x = cursor_x;
                  if (! (cursor->bidi_level % 2))
                    rect.x += cursor_width - 1;
                  rect.y = y - gstring->text_ascent;
                  rect.height = gstring->text_ascent + gstring->text_descent;
                  rect.width = 1;
                  mwin__fill_space (frame, win, rface, 1,
                                    rect.x, rect.y, rect.width, rect.height,
                                    control->clip_region);
                  if (! region)
                    region = mwin__region_from_rect (&rect);
                  else
                    mwin__region_add_rect (region, &rect);
                  mwin__verify_region (frame, region);
                  rect.y += rect.height - 2;
                  rect.height = 2;
                  rect.width = cursor_width < 4 ? cursor_width : 4;
                  if (! (cursor->bidi_level % 2))
                    rect.x -= rect.width - 1;
                  mwin__fill_space (frame, win, rface, 1,
                                    rect.x, rect.y, rect.width, rect.height,
                                    control->clip_region);
                  mwin__region_add_rect (region, &rect);
                  mwin__verify_region (frame, region);
                }
            }
          x += width;
          *to_idx = GLYPH_INDEX (g);
          *to_x = x;
        }
      else
        g++->enabled = 0;
    }
  return region;
}

static void
render_glyphs (MFrame *frame, MDrawWindow win, int x, int y, int width,
               MGlyphString *gstring, int from_idx, int to_idx,
               int reverse, MDrawRegion region)
{
  MGlyph *g = MGLYPH (from_idx), *gend = MGLYPH (to_idx);

  if (region)
    {
      MDrawMetric rect;

      mwin__region_to_rect (region, &rect);
      if (rect.x > x)
        {
          while (g != gend && x + g->rbearing <= rect.x)
            {
              x += g->width;
              width -= g++->width;
              while (! g->enabled && g != gend)
                g++;
            }
        }
      rect.x += rect.width;
      if (rect.x < x + width)
        {
          while (g != gend
                 && (x + width - gend[-1].width + gend[-1].lbearing >= rect.x))
            {
              width -= (--gend)->width;
              while (! gend->enabled && g != gend)
                gend--;
            }
          if (g != gend)
            while (gend[-1].to == gend->to) gend++;
        }
    }

  while (g != gend)
    {
      if (g->enabled)
        {
          MRealizedFace *rface = g->rface;
          int width = g->width;
          MGlyph *from_g = g++;

          /* Handle the glyphs of the same type/face at once.  */
          while (g != gend
                 && g->type == from_g->type
                 && g->rface == rface
                 && (g->code < 0) == (from_g->code < 0)
                 && g->enabled)
            width += g++->width;

          if (from_g->type == GLYPH_CHAR)
            {
              if (rface->rfont && from_g->code >= 0)
                (rface->rfont->driver->render) (win, x, y, gstring, from_g, g,
                                                reverse, region);
              else
                mwin__draw_empty_boxes (win, x, y, gstring, from_g, g,
                                        reverse, region);
            }
          else if (from_g->type == GLYPH_BOX)
            {
              /* Draw the left or right side of a box.  If
                 from_g->lbearing is nonzero, this is the left side,
                 else this is the right side.  */
              mwin__draw_box (frame, win, gstring, from_g, x, y, 0, region);
            }

          if (from_g->type != GLYPH_BOX)
            {
              if (rface->hline)
                mwin__draw_hline (frame, win, gstring, rface, reverse,
                                  x, y, width, region);
              if (rface->box
                  && ! reverse)
                /* Draw the top and bottom side of a box.  */
                   mwin__draw_box (frame, win, gstring, from_g,
                                   x, y, width, region);
            }
          x += width;
        }
      else
        g++;
    }
}


static int
find_overlapping_glyphs (MGlyphString *gstring, int *left, int *right,
                         int *from_x, int *to_x)
{
  MGlyph *g;
  int left_idx = *left, right_idx = *right;
  int left_x, right_x, x;

  for (g = MGLYPH (*left) - 1, x = 0; g->type != GLYPH_ANCHOR; g--)
    {
      x -= g->width;
      if (x + g->rbearing > 0)
        {
          while (g[-1].pos == g->pos && g[-1].type != GLYPH_ANCHOR)
            x -= (--g)->width;
          left_idx = GLYPH_INDEX (g);
          left_x = x;
        }
    }

  for (g = MGLYPH (*right), x = 0; g->type != GLYPH_ANCHOR; g++)
    {
      x += g->width;
      if (x - g->width + g->lbearing < 0)
        {
          while (g->pos == g[1].pos && g[1].type != GLYPH_ANCHOR)
            x += (++g)->width;
          right_idx = GLYPH_INDEX (g) + 1;
          right_x = x;
        }
    }

  if (*left == left_idx && *right == right_idx)
    return 0;

  if (*left != left_idx)
    {
      for (g = MGLYPH (*left) - 1; GLYPH_INDEX (g) >= left_idx; g--)
        g->enabled = 1;
      *left = left_idx;
      *from_x += left_x;
    }
  if (*right != right_idx)
    {
      for (g = MGLYPH (*right); GLYPH_INDEX (g) < right_idx; g++)
        g->enabled = 1;
      *right = right_idx;
      *to_x += right_x;
    }
  return 1;
}


static int
gstring_width (MGlyphString *gstring, int from, int to, int *rbearing)
{
  MGlyph *g;
  int width;

  if (from <= gstring->from && to >= gstring->to)
    {
      if (rbearing)
        *rbearing = gstring->rbearing;
      return gstring->width;
    }

  if (rbearing)
    *rbearing = 0;
  for (g = MGLYPH (1), width = 0; g->type != GLYPH_ANCHOR; g++)
    if (g->pos >= from && g->pos < to)
      {
        if (rbearing && width + g->rbearing > *rbearing)
          *rbearing = width + g->rbearing;
        width += g->width;
      }
  return width;
}


static void
render_glyph_string (MFrame *frame, MDrawWindow win, int x, int y,
                     MGlyphString *gstring, int from, int to)
{
  MDrawControl *control = &gstring->control;
  MDrawMetric rect;
  MDrawRegion clip_region, cursor_region;
  int from_idx, to_idx;
  int to_x;

  if (control->orientation_reversed)
    x -= gstring->indent + gstring_width (gstring, from, to, NULL);
  else
    x += gstring->indent;

  /* At first, draw all glyphs without cursor.  */
  cursor_region = draw_background (frame, win, x, y, gstring, from, to,
                                   &from_idx, &to_idx, &to_x);

  if (control->partial_update)
    {
      rect.x = x;
      rect.width = to_x - x;
      if (find_overlapping_glyphs (gstring, &from_idx, &to_idx, &x, &to_x))
        {
          rect.y = y - gstring->line_ascent;
          rect.height = gstring->height;
          clip_region = mwin__region_from_rect (&rect);
          if (control->clip_region)
            mwin__intersect_region (clip_region, control->clip_region);
        }
      else
        clip_region = control->clip_region;
    }
  else
    clip_region = control->clip_region;

  render_glyphs (frame, win, x, y, to_x - x, gstring, from_idx, to_idx,
                 0, clip_region);
  if (cursor_region)
    {
      if (clip_region)
        mwin__intersect_region (cursor_region, clip_region);
      render_glyphs (frame, win, x, y, to_x - x, gstring, from_idx, to_idx,
                     1, cursor_region);
    }
  if (clip_region != control->clip_region)
    mwin__free_region (clip_region);
  if (cursor_region)
    mwin__free_region (cursor_region);
  return;
}

static int gstring_num;

static void
free_gstring (void *object)
{
  MGlyphString *gstring = (MGlyphString *) object;

  if (gstring->next)
    free_gstring (gstring->next);
  if (gstring->size > 0)
    free (gstring->glyphs);
  free (gstring);
  gstring_num--;
}


static MGlyphString scratch_gstring;

static MGlyphString *
alloc_gstring (MFrame *frame, MText *mt, int pos, MDrawControl *control,
               int line, int y)
{
  MGlyphString *gstring;

  if (pos == mt->nchars)
    {
      gstring = &scratch_gstring;
    }
  else
    {
      M17N_OBJECT (gstring, free_gstring, MERROR_DRAW);
      MLIST_INIT1 (gstring, glyphs, 128);
      gstring_num++;
    }

  gstring->frame = frame;
  gstring->tick = frame->tick;
  gstring->top = gstring;
  gstring->mt = mt;
  gstring->control = *control;
  gstring->indent = gstring->width_limit = 0;
  if (control->format)
    (*control->format) (line, y, &(gstring->indent), &(gstring->width_limit));
  else
    gstring->width_limit = control->max_line_width;
  gstring->anti_alias = control->anti_alias;
  if (gstring->anti_alias
      && (unsigned) mwin__device_get_prop (frame->device, Mdepth) < 8)
    gstring->anti_alias = 0;
  return gstring;
}

/* Truncate the line width of GSTRING to GSTRING->width_limit.  */

static void
truncate_gstring (MFrame *frame, MText *mt, MGlyphString *gstring)
{
  int width;
  int i;
  int *pos_width;
  MGlyph *g;
  int pos;

  /* Setup the array POS_WIDTH so that POS_WIDTH[I - GSTRING->from] is
     a width of glyphs for the character at I of GSTRING->mt.  If I is
     not a beginning of a grapheme cluster, the corresponding element
     is 0.  */
  MTABLE_ALLOCA (pos_width, gstring->to - gstring->from, MERROR_DRAW);
  memset (pos_width, 0, sizeof (int) * (gstring->to - gstring->from));
  for (g = MGLYPH (1); g->type != GLYPH_ANCHOR; g++)
    pos_width[g->pos - gstring->from] += g->width;
  for (i = 0, width = 0; i < gstring->to - gstring->from; i++)
    {
      if (pos_width[i] > 0)
        {
          if (width + pos_width[i] > gstring->width_limit)
            break;
        }
      width += pos_width[i];
    }

  pos = gstring->from + i;
  if (gstring->control.line_break)
    {
      pos = (*gstring->control.line_break) (gstring->mt, gstring->from + i,
                                            gstring->from, gstring->to, 0, 0);
      if (pos <= gstring->from || pos >= gstring->to)
        return;
    }
  compose_glyph_string (frame, mt, gstring->from, pos, gstring);
  layout_glyph_string (frame, gstring);
}


/* Return a gstring that covers a character at POS.  */

static MGlyphString *
get_gstring (MFrame *frame, MText *mt, int pos, int to, MDrawControl *control)
{
  MGlyphString *gstring = NULL;

  if (pos < mtext_nchars (mt))
    {
      MTextProperty *prop = mtext_get_property (mt, pos, M_glyph_string);

      if (prop
          && ((prop->start != 0
               && mtext_ref_char (mt, prop->start - 1) != '\n')
              || (prop->end < mtext_nchars (mt)
                  && mtext_ref_char (mt, prop->end - 1) != '\n')))
        {
          mtext_detach_property (prop);
          prop = NULL;
        }
      if (prop)
        {
          gstring = prop->val;
          if (gstring->frame != frame
              || gstring->tick != frame->tick
              || memcmp (control, &gstring->control,
                         (char *) (&control->with_cursor)
                         - (char *) (control)))
            {
              mtext_detach_property (prop);
              gstring = NULL;
            }
        }
    }
  else if (! control->cursor_width)
    return NULL;

  if (gstring)
    {
      MGlyphString *gst;
      int offset;

      offset = mtext_character (mt, pos, 0, '\n');
      if (offset < 0)
        offset = 0;
      else
        offset++;
      offset -= gstring->from;
      if (offset)
        for (gst = gstring; gst; gst = gst->next)
          {
            int i;

            gst->from += offset;
            gst->to += offset;
            for (i = 0; i < gst->used; i++)
              {
                gst->glyphs[i].pos += offset;
                gst->glyphs[i].to += offset;
              }
          }
      M17N_OBJECT_REF (gstring);
    }
  else
    {
      int beg, end;
      int line = 0, y = 0;

      if (control->two_dimensional)
        {
          beg = mtext_character (mt, pos, 0, '\n');
          if (beg < 0)
            beg = 0;
          else
            beg++;
          end = mtext_nchars (mt) + (control->cursor_width != 0);
        }
      else
        {
          beg = pos;
          end = to;
        }
      gstring = alloc_gstring (frame, mt, beg, control, line, y);
      compose_glyph_string (frame, mt, beg, end, gstring);
      layout_glyph_string (frame, gstring);
      end = gstring->to;
      if (control->two_dimensional
          && gstring->width_limit
          && gstring->width > gstring->width_limit)
        {
          MGlyphString *gst = gstring;

          truncate_gstring (frame, mt, gst);
          while (gst->to < end)
            {
              line++, y += gst->height;
              gst->next = alloc_gstring (frame, mt, gst->from, control,
                                         line, y);
              gst->next->top = gstring;
              compose_glyph_string (frame, mt, gst->to, end, gst->next);
              gst = gst->next;
              layout_glyph_string (frame, gst);
              if (gst->width <= gst->width_limit)
                break;
              truncate_gstring (frame, mt, gst);
            }
        }

      if (! control->disable_caching && pos < mtext_nchars (mt))
        {
          MTextProperty *prop = mtext_property (M_glyph_string, gstring,
                                                MTEXTPROP_VOLATILE_STRONG);

          if (end > mtext_nchars (mt))
            end = mtext_nchars (mt);
          mtext_attach_property (mt, beg, end, prop);
          M17N_OBJECT_UNREF (prop);
        }
    }

  while (gstring->to <= pos)
    {
      if (! gstring->next)
        mdebug_hook ();
      gstring = gstring->next;
    }
  gstring->control = *control;

  return gstring;
}


static MDrawControl control_noop;

#define ASSURE_CONTROL(control) \
  if (! control)                \
    control = &control_noop;    \
  else


static int
draw_text (MFrame *frame, MDrawWindow win, int x, int y,
           MText *mt, int from, int to,
           MDrawControl *control)
{
  MGlyphString *gstring;

  M_CHECK_POS_X (mt, from, -1);
  ASSURE_CONTROL (control);
  if (to > mtext_nchars (mt) + (control->cursor_width != 0))
    to = mtext_nchars (mt) + (control->cursor_width != 0);
  else if (to < from)
    to = from;

  gstring = get_gstring (frame, mt, from, to, control);
  if (! gstring)
    MERROR (MERROR_DRAW, -1);
  render_glyph_string (frame, win, x, y, gstring, from, to);
  from = gstring->to;
  while (from < to)
    {
      y += gstring->line_descent;
      M17N_OBJECT_UNREF (gstring->top);
      gstring = get_gstring (frame, mt, from, to, control);
      y += gstring->line_ascent;
      render_glyph_string (frame, win, x, y, gstring, from, to);
      from = gstring->to;
    }
  M17N_OBJECT_UNREF (gstring->top);

  return 0;
}


static MGlyph *
find_glyph_in_gstring (MGlyphString *gstring, int pos, int forwardp)
{
  MGlyph *g;

  if (forwardp)
    {
      for (g = MGLYPH (1); g->type != GLYPH_ANCHOR; g++)
        if (g->pos <= pos && g->to > pos)
          break;
    }
  else
    {
      for (g = MGLYPH (gstring->used - 2); g->type != GLYPH_ANCHOR; g--)
        if (g->pos <= pos && g->to > pos)
          break;
    }
  return g;
}

\f
/* for debugging... */
char work[16];

char *
dump_combining_code (int code)
{
  char *vallign = "tcbB";
  char *hallign = "lcr";
  char *p;
  int off_x, off_y;

  if (! code)
    return "none";
  if (COMBINING_BY_CLASS_P (code))
    code = combining_code_from_class (COMBINING_CODE_CLASS (code));
  work[0] = vallign[COMBINING_CODE_BASE_Y (code)];
  work[1] = hallign[COMBINING_CODE_BASE_X (code)];
  off_y = COMBINING_CODE_OFF_Y (code) - 128;
  off_x = COMBINING_CODE_OFF_X (code) - 128;
  if (off_y > 0)
    sprintf (work + 2, "+%d", off_y);
  else if (off_y < 0)
    sprintf (work + 2, "%d", off_y);
  else if (off_x == 0)
    sprintf (work + 2, ".");
  p = work + strlen (work);
  if (off_x > 0)
    sprintf (p, ">%d", off_x);
  else if (off_x < 0)
    sprintf (p, "<%d", -off_x);
  p += strlen (p);
  p[0] = vallign[COMBINING_CODE_ADD_Y (code)];
  p[1] = hallign[COMBINING_CODE_ADD_X (code)];
  p[2] = '\0';
  return work;
}

void
dump_gstring (MGlyphString *gstring, int indent)
{
  char *prefix = (char *) alloca (indent + 1);
  MGlyph *g, *last_g = gstring->glyphs + gstring->used;

  memset (prefix, 32, indent);
  prefix[indent] = 0;

  fprintf (stderr, "(glyph-string");

  for (g = MGLYPH (0); g < last_g; g++)
    fprintf (stderr,
             "\n%s  (%02d %s pos:%d-%d c:%04X code:%04X face:%x cmb:%s w:%02d bidi:%d)",
             prefix,
             g - gstring->glyphs,
             (g->type == GLYPH_SPACE ? "SPC": g->type == GLYPH_PAD ? "PAD"
              : g->type == GLYPH_ANCHOR ? "ANC"
              : g->type == GLYPH_BOX ? "BOX" : "CHR"),
             g->pos, g->to, g->c, g->code, (unsigned) g->rface,
             dump_combining_code (g->combining_code),
             g->width, g->bidi_level);
  fprintf (stderr, ")");
}
\f

/* m17n-X internal APIs */

int
mdraw__init ()
{
  M_glyph_string = msymbol_as_managing_key ("  glyph-string");

  memset (&scratch_gstring, 0, sizeof (scratch_gstring));
  MLIST_INIT1 (&scratch_gstring, glyphs, 3);

  Mlatin = msymbol ("latin");
  Minherited = msymbol ("inherited");

  McatCc = msymbol ("Cc");
  McatCf = msymbol ("Cf");
  Mdepth = msymbol ("depth");

  MbidiR = msymbol ("R");
  MbidiAL = msymbol ("AL");
  MbidiRLE = msymbol ("RLE");
  MbidiRLO = msymbol ("RLO");
  MbidiBN = msymbol ("BN");
  MbidiS = msymbol ("S");
#ifdef HAVE_FRIBIDI
  fribidi_set_mirroring (TRUE);
#endif

  return 0;
}

void
mdraw__fini ()
{
  MLIST_FREE1 (&scratch_gstring, glyphs);
}

/*** @} */
#endif /* !FOR_DOXYGEN || DOXYGEN_INTERNAL_MODULE */

\f
/* External API */
/*** @addtogroup m17nDraw */
/*** @{ */

/*=*/
/***en
    @brief Draw an M-text on a window.

    The mdraw_text () function draws the text between $FROM and $TO of
    M-text $MT on window $WIN of frame $FRAME at coordinate ($X, $Y).

    The appearance of the text (size, style, color, etc) is specified
    by the value of the text property whose key is @c Mface.  If the
    M-text or a part of the M-text does not have such a text property,
    the default face of $FRAME is used.

    The font used to draw a character in the M-text is selected from
    the value of the fontset property of a face by the following
    algorithm:

    <ol>

    <li> Search the text properties given to the character for the one
         whose key is @c Mcharset; its value should be either a symbol
         specifying a charset or #Mnil.  If the value is #Mnil,
         proceed to the next step.

         Otherwise, search the mapping table of the fontset for the
         charset.  If no entry is found proceed to the next step.  

         If an entry is found, use one of the fonts in the entry that
         has a glyph for the character and that matches best with the
         face properties.  If no such font exists, proceed to the next
         step.

    <li> Get the character property "script" of the character.  If it is
         inherited, get the script property from the previous
         characters.  If there is no previous character, or none of
         them has the script property other than inherited, proceed to
         the next step.

         Search the text properties given to the character for the one
         whose key is @c Mlanguage; its value should be either a
         symbol specifying a language or @c Mnil.

         Search the mapping table of the fontset for the combination
         of the script and language.  If no entry is found, proceed to
         the next step.  

        If an entry is found, use one of the fonts in the entry that
         has a glyph for the character and that matches best with the
         face properties.  If no such font exists, proceed to the next
         step.

    <li> Search the fall-back table of the fontset for a font that has
         a glyph of the character.  If such a font is found, use that
         font.

    </ol>

    If no font is found by the algorithm above, this function draws an
    empty box for the character.

    This function draws only the glyph foreground.  To specify the
    background color, use mdraw_image_text () or
    mdraw_text_with_control ().

    This function is the counterpart of <tt>XDrawString ()</tt>,
    <tt>XmbDrawString ()</tt>, and <tt>XwcDrawString ()</tt> functions
    in the X Window System.

    @return
    If the operation was successful, mdraw_text () returns 0.  If an
    error is detected, it returns -1 and assigns an error code to the
    external variable #merror_code.  */
/***ja
    @brief ¥¦¥£¥ó¥É¥¦¤Ë M-text ¤òÉÁ²è¤¹¤ë.

    ´Ø¿ô mdraw_text () ¤Ï¡¢¥Õ¥ì¡¼¥à $FRAME ¤Î¥¦¥£¥ó¥É¥¦ $WIN ¤ÎºÂɸ 
    ($X, $Y) ¤Ë¡¢M-text $MT ¤Î $FROM ¤«¤é $TO ¤Þ¤Ç¤Î¥Æ¥­¥¹¥È¤ò
    ÉÁ²è¤¹¤ë¡£

    ¥Æ¥­¥¹¥È¤Î¸«±É¤¨¡Ê¥Õ¥©¥ó¥È¡¢¥¹¥¿¥¤¥ë¡¢¿§¤Ê¤É¡Ë¤Ï¡¢¥­¡¼¤¬ @c Mface 
    ¤Ç¤¢¤ë¥Æ¥­¥¹¥È¥×¥í¥Ñ¥Æ¥£¤ÎÃͤˤè¤Ã¤Æ·è¤Þ¤ë¡£M-text ¤Î°ìÉô¤¢¤ë¤¤¤Ï
    Á´Éô¤Ë¤½¤Î¤è¤¦¤Ê¥Æ¥­¥¹¥È¥×¥í¥Ñ¥Æ¥£¤¬ÉÕ¤¤¤Æ¤¤¤Ê¤¤¾ì¹ç¤Ë¤Ï¡¢$FRAME 
    ¤Î¥Ç¥Õ¥©¥ë¥È¥Õ¥§¡¼¥¹¤¬ÍѤ¤¤é¤ì¤ë¡£

    M-text ¤Î³Æʸ»ú¤òɽ¼¨¤¹¤ë¥Õ¥©¥ó¥È¤Ï¡¢¥Õ¥§¡¼¥¹¤Î fontset ¥×¥í¥Ñ¥Æ¥£
    ¤ÎÃͤ«¤é°Ê²¼¤Î¥¢¥ë¥´¥ê¥º¥à¤ÇÁª¤Ð¤ì¤ë¡£

    <ol>

    <li> ¤½¤Îʸ»ú¤Î¥Æ¥­¥¹¥È¥×¥í¥Ñ¥Æ¥£¤Î¤¦¤Á¡¢¥­¡¼¤¬ @c Mcharset ¤Ç¤¢¤ë
         ¤â¤Î¤ÎÃͤòÄ´¤Ù¤ë¡£¤³¤ÎÃͤÏʸ»ú¥»¥Ã¥È¤òɽ¤ï¤¹¥·¥ó¥Ü¥ë¤« #Mnil 
         ¤Î¤É¤Á¤é¤«¤Ç¤¢¤ë¡£#Mnil ¤Ê¤é¤Ð¡¢¼¡¤Î¥¹¥Æ¥Ã¥×¤Ë¿Ê¤à¡£¤½¤¦¤Ç¤Ê
         ¤±¤ì¤Ð¡¢¤½¤Î¥Õ¥©¥ó¥È¥»¥Ã¥È¤Î¥Þ¥Ã¥Ô¥ó¥°¥Æ¡¼¥Ö¥ë¤«¤é¤½¤Îʸ»ú¥»¥Ã
         ¥ÈÍѤΤâ¤Î¤òõ¤¹¡£¥Õ¥©¥ó¥È¤¬¤ß¤Ä¤«¤é¤Ê¤±¤ì¤Ð¡¢¼¡¤Î¥¹¥Æ¥Ã¥×¤Ë
         ¿Ê¤à¡£
         
         ¤½¤Îʸ»ú¥»¥Ã¥ÈÍѤΥե©¥ó¥È¤¬¤ß¤Ä¤«¤ì¤Ð¡¢¤½¤ì¤é¤Î¤¦¤Á¸½ºß¤Îʸ
         »úÍѤΥ°¥ê¥Õ¤ò»ý¤Á¡¢¥Õ¥§¡¼¥¹¤Î³Æ¥×¥í¥Ñ¥Æ¥£¤ËºÇ¤â¤è¤¯¹çÃפ·¤Æ
         ¤¤¤ë¤â¤Î¤ò»È¤¦¡£¤½¤Î¤è¤¦¤Ê¥Õ¥©¥ó¥È¤¬Ìµ¤±¤ì¤Ð¼¡¤Î¥¹¥Æ¥Ã¥×¤Ë¿Ê
         ¤à¡£

    <li> ¤½¤Îʸ»ú¤Îʸ»ú¥×¥í¥Ñ¥Æ¥£ "script" ¡Ê¥¹¥¯¥ê¥×¥È¡Ë¤òÄ´¤Ù¤ë¡£·Ñ
         ¾µ¤µ¤ì¤Æ¤¤¤ë¤Ê¤é¤Ð¤½¤ì°ÊÁ°¤Îʸ»ú¤Îʸ»ú¥×¥í¥Ñ¥Æ¥£ "script" ¤ò
         Ä´¤Ù¤ë¡£Á°¤Îʸ»ú¤¬¤Ê¤«¤Ã¤¿¤ê¡¢¤½¤Îʸ»ú¥×¥í¥Ñ¥Æ¥£¤ò»ý¤Ã¤Æ¤¤¤Ê
         ¤«¤Ã¤¿¾ì¹ç¤Ë¤Ï¡¢¼¡¤Î¥¹¥Æ¥Ã¥×¤Ë¿Ê¤à¡£

         ¤½¤Îʸ»ú¤Î¥Æ¥­¥¹¥È¥×¥í¥Ñ¥Æ¥£¤Î¤¦¤Á¡¢¥­¡¼¤¬ @c Mlanguage ¤Ç¤¢
         ¤ë¤â¤Î¤ÎÃͤòÄ´¤Ù¤ë¡£¤³¤ÎÃͤϸÀ¸ì¤òɽ¤ï¤¹¥·¥ó¥Ü¥ë¤« @c Mnil ¤Î
         ¤¤¤º¤ì¤«¤Ç¤¢¤ë¡£

         ¤½¤¦¤Ç¤Ê¤±¤ì¤Ð¡¢¤½¤Î¸À¸ì¤È¥¹¥¯¥ê¥×¥È¤ÎÁȤ߹ç¤ï¤»ÍѤΥե©¥ó¥È
         ¥»¥Ã¥È¤ò¥Þ¥Ã¥Ô¥ó¥°¥Æ¡¼¥Ö¥ë¤«¤éõ¤¹¡£¸«¤Ä¤«¤é¤Ê¤±¤ì¤Ð¼¡¤Î¥¹¥Æ¥Ã
         ¥×¤Ë¿Ê¤à¡£

         ¤½¤Î¤è¤¦¤Êʸ»ú¥»¥Ã¥ÈÍѤΥե©¥ó¥È¤¬¤ß¤Ä¤«¤ì¤Ð¡¢¤½¤ì¤é¤Î¤¦¤Á¸½
         ºß¤Îʸ»úÍѤΥ°¥ê¥Õ¤ò»ý¤Á¡¢¥Õ¥§¡¼¥¹¤Î³Æ¥×¥í¥Ñ¥Æ¥£¤ËºÇ¤â¤è¤¯¹ç
         Ãפ·¤Æ¤¤¤ë¤â¤Î¤ò»È¤¦¡£¤½¤Î¤è¤¦¤Ê¥Õ¥©¥ó¥È¤¬Ìµ¤±¤ì¤Ð¼¡¤Î¥¹¥Æ¥Ã
         ¥×¤Ë¿Ê¤à¡£

    <li> ¤½¤Îʸ»ú¤Î¥°¥ê¥Õ¤ò»ý¤Ä¥Õ¥©¥ó¥È¤ò¡¢¥Õ¥©¥ó¥È¥»¥Ã¥È¤Îfall-back¥Æ¡¼
         ¥Ö¥ë¤«¤éõ¤¹¡£¥Õ¥©¥ó¥È¤¬¸«¤Ä¤«¤ì¤Ð¤½¤ì¤ò»È¤¦¡£

    </ol>

    °Ê¾å¤Î¥¢¥ë¥´¥ê¥º¥à¤Ç¥Õ¥©¥ó¥È¤¬¸«¤Ä¤«¤é¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤Ï¤½¤Îʸ»ú
    ¤È¤·¤Æ¶õ¤Î»Í³Ñ·Á¤òɽ¼¨¤¹¤ë¡£

    ¤³¤Î´Ø¿ô¤¬ÉÁ²è¤¹¤ë¤Î¤Ï¥°¥ê¥Õ¤ÎÁ°·Ê¤À¤±¤Ç¤¢¤ë¡£ÇØ·Ê¿§¤ò»ØÄꤹ¤ë¤Ë¤Ï¡¢
    ´Ø¿ô mdraw_image_text () ¤«´Ø¿ô mdraw_text_with_control () ¤ò»È¤¦
    ¤³¤È¡£

    ¤³¤Î´Ø¿ô¤Ï¡¢X ¥¦¥£¥ó¥É¥¦¤Ë¤ª¤±¤ë´Ø¿ô <tt>XDrawString ()</tt>,
    <tt>XmbDrawString ()</tt>, <tt>XwcDrawString ()</tt> ¤ËÁêÅö¤¹¤ë¡£

    @return
    ½èÍý¤¬À®¸ù¤·¤¿¾ì¹ç¡¢mdraw_text () ¤Ï 0 ÊÖ¤¹¡£¥¨¥é¡¼¤¬¸¡½Ð¤µ¤ì¤¿¾ì
    ¹ç¤Ï -1 ¤òÊÖ¤·¡¢³°ÉôÊÑ¿ô #merror_code ¤Ë¥¨¥é¡¼¥³¡¼¥É¤òÀßÄꤹ¤ë¡£

    @latexonly \IPAlabel{mdraw_text} @endlatexonly  */

/***
    @errors
    @c MERROR_RANGE

    @seealso
    mdraw_image_text ()  */

int
mdraw_text (MFrame *frame, MDrawWindow win, int x, int y,
            MText *mt, int from, int to)
{
  MDrawControl control;

  memset (&control, 0, sizeof control);
  control.as_image = 0;
  return draw_text (frame, win, x, y, mt, from, to, &control);
}

/*=*/


/***en
    @brief Draw an M-text on a window as an image.

    The mdraw_image_text () function draws the text between $FROM and
    $TO of M-text $MT as image on window $WIN of frame $FRAME at
    coordinate ($X, $Y).

    The way to draw a text is the same as in mdraw_text () except that
    this function also draws the background with the color specified
    by faces.

    This function is the counterpart of <tt>XDrawImageString ()</tt>,
    <tt>XmbDrawImageString ()</tt>, and <tt>XwcDrawImageString ()</tt>
    functions in the X Window System.

    @return
    If the operation was successful, mdraw_image_text () returns 0.
    If an error is detected, it returns -1 and assigns an error code
    to the external variable #merror_code.  */

/***ja
    @brief ¥Ç¥£¥¹¥×¥ì¥¤¤ËM-text ¤ò²èÁü¤È¤·¤ÆÉÁ¤¯.
  
    ´Ø¿ô mdraw_image_text () ¤Ï¡¢¥Õ¥ì¡¼¥à $FRAME ¤Î¥¦¥£¥ó¥É¥¦ $WIN ¤Î
    ºÂɸ ($X, $Y) ¤Ë¡¢M-text $MT ¤Î $FROM ¤«¤é $TO ¤Þ¤Ç¤Î¥Æ¥­¥¹¥È¤ò²è
    Áü¤È¤·¤ÆÉÁ¤¯¡£

    ¥Æ¥­¥¹¥È¤ÎÉÁ²èÊýË¡¤Ï mdraw_text () ¤È¤Û¤ÜƱ¤¸¤Ç¤¢¤ë¤¬¡¢¤³¤Î´Ø¿ô¤Ç
    ¤Ï¥Õ¥§¡¼¥¹¤Ç»ØÄꤵ¤ì¤¿¿§¤ÇÇطʤâÉÁ¤¯ÅÀ¤¬°Û¤Ê¤Ã¤Æ¤¤¤ë¡£

    ¤³¤Î´Ø¿ô¤Ï¡¢X ¥¦¥£¥ó¥É¥¦¤Ë¤ª¤±¤ë <tt>XDrawImageString ()</tt>,
    <tt>XmbDrawImageString ()</tt>, <tt>XwcDrawImageString ()</tt> ¤Ë
    ÁêÅö¤¹¤ë¡£

    @return
    ½èÍý¤¬À®¸ù¤·¤¿¾ì¹ç¡¢mdraw_image_text () ¤Ï 0 ¤òÊÖ¤¹¡£¥¨¥é¡¼¤¬¸¡½Ð
    ¤µ¤ì¤¿¾ì¹ç¤Ï -1 ¤òÊÖ¤·¡¢³°ÉôÊÑ¿ô #m_errro ¤Ë¥¨¥é¡¼¥³¡¼¥É¤òÀßÄꤹ
    ¤ë¡£

    @latexonly \IPAlabel{mdraw_image_text} @endlatexonly   */

/***
    @errors
    @c MERROR_RANGE

    @seealso
    mdraw_text ()  */

int
mdraw_image_text (MFrame *frame, MDrawWindow win, int x, int y,
                  MText *mt, int from, int to)
{
  MDrawControl control;

  memset (&control, 0, sizeof control);
  control.as_image = 1;
  return draw_text (frame, win, x, y, mt, from, to, &control);
}

/*=*/

/***en
    @brief Draw an M-text on a window with fine control.

    The mdraw_text_with_control () function draws the text between
    $FROM and $TO of M-text $MT on windows $WIN of frame $FRAME at
    coordinate ($X, $Y).

    The way to draw a text is the same as in mdraw_text () except that
    this function also follows what specified in the drawing control
    object $CONTROL.

    For instance, if <two_dimensional> of $CONTROL is nonzero, this
    function draw an M-text 2-dimensionally, i.e., newlines in M-text
    breaks lines and the following characters are drawn in the next
    line.  See the documentation of the structure @ MDrawControl for
    more detail.  */

/***ja
    @brief ¥Ç¥£¥¹¥×¥ì¥¤¤ËM-text ¤òÉÁ¤¯¡Ê¾ÜºÙ¤ÊÀ©¸æ¤Ä¤­¡Ë.

    ´Ø¿ô mdraw_text_with_control () ¤Ï¡¢¥Õ¥ì¡¼¥à $FRAME ¤Î¥¦¥£¥ó¥É¥¦ 
    $WIN ¤ÎºÂɸ ($X, $Y) ¤Ë¡¢M-text $MT ¤Î $FROM ¤«¤é $TO ¤Þ¤Ç¤Î¥Æ¥­¥¹
    ¥È¤òÉÁ¤¯¡£

    ¥Æ¥­¥¹¥È¤ÎÉÁ²èÊýË¡¤Ï mdraw_text () ¤È¤Û¤ÜƱ¤¸¤Ç¤¢¤ë¤¬¡¢¤³¤Î´Ø¿ô¤Ï
    ÉÁ²èÀ©¸æÍѤΥª¥Ö¥¸¥§¥¯¥È $CONTROL ¤Ç¤Î»Ø¼¨¤Ë¤â½¾¤¦ÅÀ¤¬°Û¤Ê¤Ã¤Æ¤¤¤ë¡£

    ¤¿¤È¤¨¤Ð $CONTROL ¤Î <two_dimensional> ¤¬¥¼¥í¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô
    ¤ÏM-text ¤ò2¼¡¸µÅª¤ËÉÁ¤¯¡£¤¹¤Ê¤ï¤Á M-text Ãæ¤Î²þ¹Ô¤Ç¹Ô¤ò²þ¤á¡¢Â³¤¯
    ʸ»ú¤Ï¼¡¤Î¹Ô¤ËÉÁ¤¯¡£¾ÜºÙ¤Ï¹½Â¤ÂÎ @ MDrawControl ¤ÎÀâÌÀ¤ò»²¾È¤¹¤ë¤³
    ¤È¡£*/

int
mdraw_text_with_control (MFrame *frame, MDrawWindow win, int x, int y,
                         MText *mt, int from, int to, MDrawControl *control)
{
  return draw_text (frame, win, x, y, mt, from, to, control);
}

/*=*/

/***en
    @brief Compute text pixel width.

    The mdraw_text_extents () function computes the width of text
    between $FROM and $TO of M-text $MT when it is drawn on a window
    of frame $FRAME using the mdraw_text_with_control () function with
    the drawing control object $CONTROL.

    If $OVERALL_INK_RETURN is not @c NULL, this function also computes
    the bounding box of character ink of the M-text, and stores the
    results in the members of the structure pointed to by
    $OVERALL_INK_RETURN.  If the M-text has a face specifying a
    surrounding box, the box is included in the bounding box.

    If $OVERALL_LOGICAL_RETURN is not @c NULL, this function also
    computes the bounding box that provides mininum spacing to other
    graphical features (such as surrounding box) for the M-text, and
    stores the results in the members of the structure pointed to by
    $OVERALL_LOGICAL_RETURN.

    If $OVERALL_LINE_RETURN is not @c NULL, this function also
    computes the bounding box that provides mininum spacing to the
    other M-text drawn, and stores the results in the members of the
    structure pointed to by $OVERALL_LINE_RETURN.  This is a union of
    $OVERALL_INK_RETURN and $OVERALL_LOGICAL_RETURN if the members
    min_line_ascent, min_line_descent, max_line_ascent, and
    max_line_descent of $CONTROL are all zero.

    @return
    This function returns the width of the text to be drawn in the
    unit of pixels.  If $CONTROL->two_dimensional is nonzero and the
    text is drawn in multiple physical lines, it returns the width of
    the widest line.  If an error occurs, it returns -1 and assigns an
    error code to the external variable #merror_code.  */


/***ja 
    @brief ¥Æ¥­¥¹¥È¤ÎÉý¡Ê¥Ô¥¯¥»¥ëñ°Ì¡Ë¤ò·×»»¤¹¤ë.

    ´Ø¿ô mdraw_text_extents () ¤Ï¡¢´Ø¿ô mdraw_text_with_control () ¤¬
    ÉÁ²èÀ©¸æ¥ª¥Ö¥¸¥§¥¯¥È $CONTROL ¤òÍѤ¤¤Æ M-text $MT ¤Î $FROM ¤«¤é $TO 
    ¤Þ¤Ç¤ò¥Õ¥ì¡¼¥à $FRAME ¤Ëɽ¼¨¤¹¤ëºÝ¤ËɬÍפȤʤëÉý¤òÊÖ¤¹¡£

    $OVERALL_INK_RETURN ¤¬ @c NULL ¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤Ï M-text ¤Îʸ
    »ú¤Î¥¤¥ó¥¯¤Î¥Ð¥¦¥ó¥Ç¥£¥ó¥°¥Ü¥Ã¥¯¥¹¤â·×»»¤·¡¢$OVERALL_INK_RETURN ¤¬
    »Ø¤¹¹½Â¤ÂΤΥá¥ó¥Ð¤Ë¤½¤Î·ë²Ì¤òÀßÄꤹ¤ë¡£M-text ¤Ë°Ï¤ßÏÈ(surrounding box)
    ¤ò»ØÄꤹ¤ë¥Õ¥§¡¼¥¹¤¬¤¢¤ì¤Ð¡¢¤½¤ì¤â¥Ð¥¦¥ó¥Ç¥£¥ó¥°¥Ü¥Ã¥¯¥¹¤Ë´Þ¤à¡£

    $OVERALL_LOGICAL_RETURN ¤¬ @c NULL ¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤Ï M-text 
    ¤È¾¤Î graphical feature ¡Ê°Ï¤ßÏȤʤɡˤȤδ֤κǾ®¤Î¥¹¥Ú¡¼¥¹¤ò¼¨
    ¤¹¥Ð¥¦¥ó¥Ç¥£¥ó¥°¥Ü¥Ã¥¯¥¹¤â·×»»¤·¡¢$OVERALL_LOGICAL_RETURN ¤¬»Ø¤¹¹½
    ¤ÂΤΥá¥ó¥Ð¤Ë¤½¤Î·ë²Ì¤òÀßÄꤹ¤ë¡£

    $OVERALL_LINE_RETURN ¤¬ @c NULL ¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤Ï¾¤Î M-text 
    ¤È¤Î´Ö¤ÎºÇ¾®¤Î¥¹¥Ú¡¼¥¹¤ò¼¨¤¹¥Ð¥¦¥ó¥Ç¥£¥ó¥°¥Ü¥Ã¥¯¥¹¤â·×»»¤·¡¢
    $OVERALL_LINE_RETURN ¤¬»Ø¤¹¹½Â¤ÂΤΥá¥ó¥Ð¤Ë¤½¤Î·ë²Ì¤òÀßÄꤹ¤ë¡£¥ª
    ¥Ö¥¸¥§¥¯¥È $CONTROL ¤Î¥á¥ó¥Ð min_line_ascent, min_line_descent,
    max_line_ascent, max_line_descent ¤¬¤¹¤Ù¤Æ0¤Î»þ¤Ë¤Ï¡¢¤³¤ÎÃÍ¤Ï 
    $OVERALL_INK_RETURN ¤È$OVERALL_LOGICAL_RETURN ¤ÎϤȤʤ롣

    @return ¤³¤Î´Ø¿ô¤Ïɽ¼¨¤ËɬÍפʥƥ­¥¹¥È¤ÎÉý¤ò¥Ô¥¯¥»¥ëñ°Ì¤ÇÊÖ¤¹¡£
    $CONTROL->two_dimensional ¤¬0¤Ç¤Ê¤¯¡¢¥Æ¥­¥¹¥È¤¬Ê£¿ô¤Î¹Ô¤ËÅϤäÆÉÁ
    ¤«¤ì¤ë¾ì¹ç¤Ë¤Ï¡¢ºÇÂç¤ÎÉý¤òÊÖ¤¹¡£¥¨¥é¡¼¤¬À¸¤¸¤¿¾ì¹ç¤Ï -1 ¤òÊÖ¤·¡¢³°
    ÉôÊÑ¿ô #merror_code ¤Ë¥¨¥é¡¼¥³¡¼¥É¤òÀßÄꤹ¤ë¡£

    @latexonly \IPAlabel{mdraw_text_extents} @endlatexonly  */

/***
    @errors
    @c MERROR_RANGE  */

int
mdraw_text_extents (MFrame *frame,
                    MText *mt, int from, int to, MDrawControl *control,
                    MDrawMetric *overall_ink_return,
                    MDrawMetric *overall_logical_return,
                    MDrawMetric *overall_line_return)
{
  MGlyphString *gstring;
  int y = 0;
  int width, rbearing;

  ASSURE_CONTROL (control);
  M_CHECK_POS_X (mt, from, -1);
  if (to > mtext_nchars (mt) + (control->cursor_width != 0))
    to = mtext_nchars (mt) + (control->cursor_width != 0);
  else if (to < from)
    to = from;

  gstring = get_gstring (frame, mt, from, to, control);
  if (! gstring)
    MERROR (MERROR_DRAW, -1);
  width = gstring_width (gstring, from, to, &rbearing);
  if (overall_ink_return)
    {
      overall_ink_return->y = - gstring->physical_ascent;
      overall_ink_return->x = gstring->lbearing;
    }
  if (overall_logical_return)
    {
      overall_logical_return->y = - gstring->ascent;
      overall_logical_return->x = 0;
    }
  if (overall_line_return)
    {
      overall_line_return->y = - gstring->line_ascent;
      overall_line_return->x = gstring->lbearing;
    }

  for (from = gstring->to; from < to; from = gstring->to)
    {
      int this_width, this_rbearing;

      y += gstring->line_descent;
      M17N_OBJECT_UNREF (gstring->top);
      gstring = get_gstring (frame, mt, from, to, control);
      this_width = gstring_width (gstring, from, to, &this_rbearing);
      y += gstring->line_ascent;
      if (width < this_width)
        width = this_width;
      if (rbearing < this_rbearing)
        rbearing = this_rbearing;
    }
  if (overall_ink_return)
    {
      overall_ink_return->width = rbearing;
      overall_ink_return->height
        = y + gstring->physical_descent - overall_ink_return->y;
    }
  if (overall_logical_return)
    {
      overall_logical_return->width = width;
      overall_logical_return->height
        = y + gstring->descent - overall_logical_return->y;
    }
  if (overall_line_return)
    {
      overall_line_return->width = MAX (width, rbearing);
      overall_line_return->height
        = y + gstring->line_descent - overall_line_return->y;
    }

  M17N_OBJECT_UNREF (gstring->top);
  return width;
}

/*=*/

/***en
    @brief Compute the text dimensions of each character of M-text.

    The mdraw_text_per_char_extents () function computes the drawn
    metric of each character between $FROM and $TO of M-text $MT
    assuming that they are drawn on a window of frame $FRAME using the
    mdraw_text_with_control () function with the drawing control
    object $CONTROL.

    $ARRAY_SIZE specifies the size of $INK_ARRAY_RETURN and
    $LOGICAL_ARRAY_RETURN.  Each successive element of
    $INK_ARRAY_RETURN and $LOGICAL_ARRAY_RETURN are set to the drawn
    ink and logical metrics of successive characters respectively,
    relative to the drawing origin of the M-text.  The number of
    elements of $INK_ARRAY_RETURN and $LOGICAL_ARRAY_RETURN that have
    been set is returned to $NUM_CHARS_RETURN.

    If $ARRAY_SIZE is too small to return all metrics, the function
    returns -1 and store the requested size in $NUM_CHARS_RETURN.
    Otherwise, it returns zero.

    If pointer $OVERALL_INK_RETURN and $OVERALL_LOGICAL_RETURN are not
    @c NULL, this function also computes the metrics of the overall
    text and stores the results in the members of the structure
    pointed to by $OVERALL_INK_RETURN and $OVERALL_LOGICAL_RETURN.

    If $CONTROL->two_dimensional is nonzero, this function computes
    only the metrics of characters in the first line.  */
/***ja
    @brief  M-text ¤Î³Æʸ»ú¤Îɽ¼¨ÈϰϤò·×»»¤¹¤ë.

    ´Ø¿ô mdraw_text_per_char_extents () ¤Ï¡¢´Ø¿ô 
    mdraw_text_with_control () ¤¬ÉÁ²èÀ©¸æ¥ª¥Ö¥¸¥§¥¯¥È $CONTROL ¤òÍѤ¤
    ¤Æ M-text $MT ¤Î $FROM ¤«¤é $TO ¤Þ¤Ç¤ò¥Õ¥ì¡¼¥à $FRAME ¤Ëɽ¼¨¤¹¤ëºÝ
    ¤Î³Æʸ»ú¤Î¥µ¥¤¥º¤ò·×»»¤¹¤ë¡£

    $ARRAY_SIZE ¤Ë¤è¤Ã¤Æ $INK_ARRAY_RETURN ¤È$LOGICAL_ARRAY_RETURN ¤Î
    ¥µ¥¤¥º¤ò»ØÄꤹ¤ë¡£$INK_ARRAY_RETURN ¤È$LOGICAL_ARRAY_RETURN ¤Î³ÆÍ×
    ÁǤϡ¢¤½¤ì¤¾¤ìʸ»ú¤ÎÉÁ²è¥¤¥ó¥¯¤ÈÏÀÍý¥µ¥¤¥º¡ÊM-text¤Îɽ¼¨¸¶ÅÀ¤«¤é¤Î
    ÁêÂаÌÃ͡ˤˤè¤Ã¤Æ½ç¤ËËä¤á¤é¤ì¤ë¡£ÀßÄꤵ¤ì¤¿ $INK_ARRAY_RETURN ¤È 
    $LOGICAL_ARRAY_RETURN ¤ÎÍ×ÁǤοô¤Ï¡¢$NUM_CHARS_RETURN ¤ËÌᤵ¤ì¤ë¡£
   
    $ARRAY_SIZE ¤¬¤¹¤Ù¤Æ¤ÎÀ£Ë¡¤òÌ᤻¤Ê¤¤¤Û¤É¾®¤µ¤¤¾ì¹ç¤Ë¤Ï¡¢´Ø¿ô¤Ï -1 
    ¤òÊÖ¤·¡¢É¬ÍפÊÂ礭¤µ¤ò $NUM_CHARS_RETURN ¤ËÊÖ¤¹¡£¤½¤¦¤Ç¤Ê¤±¤ì¤Ð 0 
    ¤òÊÖ¤¹¡£

    ¥Ý¥¤¥ó¥¿ $OVERALL_INK_RETURN ¤È $OVERALL_LOGICAL_RETURN ¤¬@c NULL 
    ¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤Ï¥Æ¥­¥¹¥ÈÁ´ÂΤΥµ¥¤¥º¤â·×»»¤·¡¢·ë²Ì¤ò
    $OVERALL_INK_RETURN ¤È $OVERALL_LOGICAL_RETURN ¤Ç»Ø¤µ¤ì¤ë¹½Â¤¤Î¥á
    ¥ó¥Ð¤ËÊݸ¤¹¤ë¡£

    $CONTROL->two_dimensional ¤¬0¤Ç¤Ê¤±¤ì¤Ð¡¢¤³¤Î´Ø¿ô¤ÏºÇ½é¤Î¹Ô¤Îʸ»ú
    ¤Î¥µ¥¤¥º¤À¤±¤ò·×»»¤¹¤ë¡£ */

int
mdraw_text_per_char_extents (MFrame *frame,
                             MText *mt, int from, int to,
                             MDrawControl *control,
                             MDrawMetric *ink_array_return,
                             MDrawMetric *logical_array_return,
                             int array_size,
                             int *num_chars_return,
                             MDrawMetric *overall_ink_return,
                             MDrawMetric *overall_logical_return)
{
  MGlyphString *gstring;
  MGlyph *g;
  int x;

  ASSURE_CONTROL (control);
  *num_chars_return = to - from;
  if (array_size < *num_chars_return)
    return 0;
  if (overall_logical_return)
    memset (overall_logical_return, 0, sizeof (MDrawMetric));
  if (overall_ink_return)
    memset (overall_ink_return, 0, sizeof (MDrawMetric));

  M_CHECK_RANGE (mt, from, to, -1, 0);
  gstring = get_gstring (frame, mt, from, to, control);
  if (! gstring)
    {
      *num_chars_return = 0;
      return 0;
    }

  for (g = MGLYPH (1), x = 0; g->type != GLYPH_ANCHOR;)
    if (g->pos >= from && g->pos < to)
      {
        int start = g->pos;
        int end = g->to;
        int width = g->width;
        int lbearing = g->lbearing;
        int rbearing = g->rbearing;
        int ascent = g->ascent;
        int descent = g->descent;
        int logical_ascent = g->rface->rfont->ascent;
        int logical_descent = g->rface->rfont->descent;

        for (g++; g->type != GLYPH_ANCHOR && g->pos == start; g++)
          {
            if (lbearing < width + g->lbearing)
              lbearing = width + g->lbearing;
            if (rbearing < width + g->rbearing)
              rbearing = width + g->rbearing;
            width += g->width;
            if (ascent < g->ascent)
              ascent = g->ascent;
            if (descent < g->descent)
              descent = g->descent;
          }

        if (end > to)
          end = to;
        while (start < end)
          {
            ink_array_return[start - from].x = x + lbearing;
            ink_array_return[start - from].y = - ascent;
            ink_array_return[start - from].width = rbearing - lbearing;
            ink_array_return[start - from].height = ascent + descent;
            logical_array_return[start - from].x = x;
            logical_array_return[start - from].y = - logical_descent;
            logical_array_return[start - from].height
              = logical_ascent + logical_descent;
            logical_array_return[start - from].width = width;
            start++;
          }
        x += width;
      }

  if (overall_ink_return)
    {
      overall_ink_return->y = - gstring->line_ascent;
      overall_ink_return->x = gstring->lbearing;
      overall_ink_return->width = x - gstring->lbearing;
      overall_ink_return->height = gstring->height;
    }
  if (overall_logical_return)
    {
      overall_logical_return->y = - gstring->ascent;
      overall_logical_return->x = 0;
      overall_logical_return->width = x;
      overall_logical_return->height = gstring->ascent + gstring->descent;
    }

  M17N_OBJECT_UNREF (gstring->top);
  return 1;
}

/*=*/

/***en
    @brief Return the character position nearest to the coordinates.

    The mdraw_coordinates_position () function checks which character
    is to be drawn at coordinate ($X, $Y) when the text between $FROM
    and $TO of M-text $MT is drawn at the coordinate (0, 0) using the
    mdraw_text_with_control () function with the drawing control
    object $CONTROL.  Here, the character position means the number of
    characters that precede the character in question in $MT, that is,
    the character position of the first character is 0.

    $FRAME is used only to get the default face information.

    @return
    If the glyph image of a character covers coordinate ($X, $Y),
    mdraw_coordinates_position () returns the character position of
    that character.\n\n
    If $Y is less than the minimum Y-coordinate of the drawn area, it
    returns $FROM.\n\n\n
    If $Y is greater than the maximum Y-coordinate of the drawn area,
    it returns $TO.\n\n\n
    If $Y fits in with the drawn area but $X is less than the minimum
    X-coordinate, it returns the character position of the first
    character drawn on the line $Y.\n\n\n
    If $Y fits in with the drawn area but $X is greater than the
    maximum X-coordinate, it returns the character position of the
    last character drawn on the line $Y.  */

/***ja
    @brief »ØÄꤷ¤¿ºÂɸ¤ËºÇ¤â¶á¤¤Ê¸»ú¤Îʸ»ú°ÌÃÖ¤òÆÀ¤ë.

    ´Ø¿ô mdraw_coordinates_position () ¤Ï¡¢´Ø¿ô 
    mdraw_text_with_control () ¤¬ÉÁ²èÀ©¸æ¥ª¥Ö¥¸¥§¥¯¥È $CONTROL ¤òÍѤ¤
    ¤ÆM-text $MT ¤Î $FROM ¤«¤é $TO ¤Þ¤Ç¤òºÂɸ (0, 0) ¤òµ¯ÅÀ¤È¤·¤ÆÉÁ²è
    ¤·¤¿¾ì¹ç¤Ë¡¢ºÂɸ ($X, $Y) ¤ËÉÁ²è¤µ¤ì¤ëʸ»ú¤Îʸ»ú°ÌÃÖ¤òÊÖ¤¹¡£¤³¤³¤Ç
    ʸ»ú°ÌÃ֤Ȥϡ¢Åö³º M-text Ãæ¤Ë¤ª¤¤¤Æ¤½¤Îʸ»ú¤¬ºÇ½é¤«¤é²¿ÈÖÌܤ«¤ò¼¨
    ¤¹À°¿ô¤Ç¤¢¤ë¡£¤¿¤À¤·ºÇ½é¤Îʸ»ú¤Îʸ»ú°ÌÃÖ¤Ï0¤È¤¹¤ë¡£

    $FRAME ¤Ï¥Ç¥Õ¥©¥ë¥È¤Î¥Õ¥§¡¼¥¹¤Î¾ðÊó¤òÆÀ¤ë¤¿¤á¤À¤±¤ËÍѤ¤¤é¤ì¤ë¡£

    @return
    ºÂɸ ($X, $Y) ¤¬¤¢¤ëʸ»ú¤Î¥°¥ê¥Õ¤Çʤ¤ï¤ì¤ë¾ì¹ç¡¢ ´Ø¿ô 
    mdraw_coordinates_position () ¤Ï¤½¤Îʸ»ú¤Îʸ»ú°ÌÃÖ¤òÊÖ¤¹¡£

    ¤â¤· $Y ¤¬ÉÁ²èÎΰè¤ÎºÇ¾®YºÂɸ¤è¤ê¤â¾®¤µ¤¤¤Ê¤é¤Ð $FROM ¤òÊÖ¤¹¡£

    ¤â¤· $Y ¤¬ÉÁ²èÎΰè¤ÎºÇÂçYºÂɸ¤è¤ê¤âÂ礭¤¤¤Ê¤é¤Ð $TO ¤òÊÖ¤¹¡£

    ¤â¤· $Y ¤¬ÉÁ²èÎΰè¤Ë¾è¤Ã¤Æ¤¤¤Æ¤«¤Ä $X ¤¬ÉÁ²èÎΰè¤ÎºÇ¾®XºÂɸ¤è¤ê¤â
    ¾®¤µ¤¤¾ì¹ç¤Ï¡¢Ä¾Àþ y = $Y ¾å¤ËÉÁ²è¤µ¤ì¤ëºÇ½é¤Îʸ»ú¤Îʸ»ú°ÌÃÖ¤òÊÖ¤¹¡£

    ¤â¤· $Y ¤¬ÉÁ²èÎΰè¤Ë¾è¤Ã¤Æ¤¤¤Æ¤«¤Ä $X ¤¬ÉÁ²èÎΰè¤ÎºÇÂçXºÂɸ¤è¤ê¤â
    Â礭¤¤¾ì¹ç¤Ï¡¢Ä¾Àþ y = $Y ¾å¤ËÉÁ²è¤µ¤ì¤ëºÇ¸å¤Îʸ»ú¤Îʸ»ú°ÌÃÖ¤òÊÖ¤¹¡£ */

int
mdraw_coordinates_position (MFrame *frame, MText *mt, int from, int to,
                            int x_offset, int y_offset, MDrawControl *control)
{
  MGlyphString *gstring;
  int y = 0;
  int width;
  MGlyph *g;

  M_CHECK_POS_X (mt, from, -1);
  if (to > mtext_nchars (mt) + (control->cursor_width != 0))
    to = mtext_nchars (mt) + (control->cursor_width != 0);
  else if (to < from)
    to = from;

  if (from == to)
    return from;
  ASSURE_CONTROL (control);
  gstring = get_gstring (frame, mt, from, to, control);
  while (y + gstring->line_descent <= y_offset
         && gstring->to < to)
    {
      from = gstring->to;
      y += gstring->line_descent;
      M17N_OBJECT_UNREF (gstring->top);
      gstring = get_gstring (frame, mt, from, to, control);
      y += gstring->line_ascent;
    }

  /* Accumulate width of glyphs in WIDTH until it exceeds X. */
  if (! control->orientation_reversed)
    {
      width = gstring->indent;
      for (g = MGLYPH (1); g[1].type != GLYPH_ANCHOR; g++)
        if (g->pos >= from && g->pos < to)
          {
            width += g->width;
            if (width > x_offset)
              break;
          }
    }
  else
    {
      width = - gstring->indent;
      for (g = MGLYPH (gstring->used - 2); g->type != GLYPH_ANCHOR; g--)
        if (g->pos >= from && g->pos < to)
          {
            width -= g->width;
            if (width < x_offset)
              break;
          }
    }
  from = g->pos;
  M17N_OBJECT_UNREF (gstring->top);

  return from;
}

/*=*/

/***en
    @brief Compute information about a glyph.

    The mdraw_glyph_info () function computes information about a
    glyph that covers a character at position $POS of the M-text $MT
    assuming that the text is drawn from the character at $FROM of $MT
    on a window of frame $FRAME using the mdraw_text_with_control ()
    function with the drawing control object $CONTROL.

    The information is stored in the members of $INFO.  */
/***ja
    @brief ¥°¥ê¥Õ¤Ë´Ø¤¹¤ë¾ðÊó¤ò·×»»¤¹¤ë.

    ´Ø¿ô mdraw_glyph_info () ¤Ï¡¢´Ø¿ô mdraw_text_with_control () ¤¬ÉÁ
    ²èÀ©¸æ¥ª¥Ö¥¸¥§¥¯¥È $CONTROL ¤òÍѤ¤¤ÆM-text $MT ¤Î $FROM ¤«¤é $TO 
    ¤Þ¤Ç¤ò¥Õ¥ì¡¼¥à $FRAME ¤ËÉÁ²è¤·¤¿¾ì¹ç¡¢M-text ¤Îʸ»ú°ÌÃÖ $POS ¤Îʸ
    »ú¤òʤ¤¦¥°¥ê¥Õ¤Ë´Ø¤¹¤ë¾ðÊó¤ò·×»»¤¹¤ë¡£

    ¾ðÊó¤Ï$INFO ¤Î¥á¥ó¥Ð¤ËÊÝ»ý¤µ¤ì¤ë¡£  */

/***
    @seealso
    MDrawGlyphInfo
*/

int
mdraw_glyph_info (MFrame *frame, MText *mt, int from, int pos,
                  MDrawControl *control, MDrawGlyphInfo *info)
{
  MGlyphString *gstring;
  MGlyph *g;
  int y = 0;

  M_CHECK_RANGE_X (mt, from, pos, -1);

  ASSURE_CONTROL (control);
  gstring = get_gstring (frame, mt, from, pos + 1, control);
  if (! gstring)
    MERROR (MERROR_DRAW, -1);
  while (gstring->to <= pos)
    {
      y += gstring->line_descent;
      M17N_OBJECT_UNREF (gstring->top);
      gstring = get_gstring (frame, mt, gstring->to, pos + 1, control);
      y += gstring->line_ascent;
    }
  info->line_from = gstring->from;
  if (info->line_from < from)
    info->line_from = from;
  info->line_to = gstring->to;

  info->y = y;
  if (! control->orientation_reversed)
    {
      info->x = gstring->indent;
      for (g = MGLYPH (1); g->pos > pos || g->to <= pos; g++)
        info->x += g->width;
    }
  else
    {
      info->x = - gstring->indent;
      for (g = MGLYPH (gstring->used - 2); g->pos > pos || g->to <= pos; g--)
        info->x -= g->width;
      while (g[-1].to == g->to)
        g--;
    }
  info->from = g->pos;
  info->to = g->to;
  info->this.x = g->lbearing;
  info->this.y = - gstring->line_ascent;
  info->this.height = gstring->height;
  if (g->rface->rfont)
    info->font = &g->rface->rfont->font;
  else
    info->font = NULL;
  /* info->this.width is calculated later.  */

  if (info->from > info->line_from)
    {
      /* The logically previous glyph is on this line.  */
      MGlyph *g_tmp = find_glyph_in_gstring (gstring, info->from - 1, 1);

      info->prev_from = g_tmp->pos;
    }
  else if (info->line_from > 0)
    {
      /* The logically previous glyph is on the previous line.  */
      MGlyphString *gst = get_gstring (frame, mt, gstring->from - 1,
                                       gstring->from, control);
      MGlyph *g_tmp = find_glyph_in_gstring (gst, info->from - 1, 1);

      info->prev_from = g_tmp->pos;
      M17N_OBJECT_UNREF (gst->top);
    }
  else
    info->prev_from = -1;

  if (GLYPH_INDEX (g) > 1)
    info->left_from = g[-1].pos, info->left_to = g[-1].to;
  else if (! control->orientation_reversed)
    {
      if (info->line_from > 0)
        {
          MGlyph *g_tmp;
          MGlyphString *gst;
          int p = gstring->from - 1;

          gst = get_gstring (frame, mt, p, gstring->from, control);
          g_tmp = gst->glyphs + (gst->used - 2);
          info->left_from = g_tmp->pos, info->left_to = g_tmp->to;
          M17N_OBJECT_UNREF (gst->top);
        }
      else
        info->left_from = info->left_to = -1;
    }
  else
    {
      if (gstring->to + (control->cursor_width == 0) <= mtext_nchars (mt))
        {
          MGlyph *g_tmp;
          MGlyphString *gst;
          int p = gstring->to;

          gst = get_gstring (frame, mt, p, p + 1, control);
          g_tmp = gst->glyphs + (gst->used - 2);
          info->left_from = g_tmp->pos, info->left_to = g_tmp->to;
          M17N_OBJECT_UNREF (gst->top);
        }
      else
        info->left_from = info->left_to = -1;
    }

  if (info->to < gstring->to)
    {
      /* The logically next glyph is on this line.   */
      MGlyph *g_tmp = find_glyph_in_gstring (gstring, info->to, 0);

      info->next_to = g_tmp->to;
    }
  else if (info->to + (control->cursor_width == 0) <= mtext_nchars (mt))
    {
      /* The logically next glyph is on the next line.   */
      int p = info->to;
      MGlyphString *gst = get_gstring (frame, mt, p, p + 1, control);
      MGlyph *g_tmp = find_glyph_in_gstring (gst, p, 0);

      info->next_to = g_tmp->to;
      M17N_OBJECT_UNREF (gst->top);
    }
  else
    info->next_to = -1;

  for (info->this.width = (g++)->width;
       g->pos == pos && g->type != GLYPH_ANCHOR;
       info->this.width += (g++)->width);

  if (g->type != GLYPH_ANCHOR)
    info->right_from = g->pos, info->right_to = g->to;
  else if (! control->orientation_reversed)
    {
      if (gstring->to + (control->cursor_width == 0) <= mtext_nchars (mt))
        {
          pos = gstring->to;
          M17N_OBJECT_UNREF (gstring->top);
          gstring = get_gstring (frame, mt, pos, pos + 1, control);
          g = MGLYPH (1);
          info->right_from = g->pos, info->right_to = g->to;
        }
      else
        info->right_from = info->right_to = -1;
    }
  else
    {
      if (info->line_from > 0)
        {
          pos = gstring->from - 1;
          M17N_OBJECT_UNREF (gstring->top);
          gstring = get_gstring (frame, mt, pos, pos + 1, control);
          g = MGLYPH (1);
          info->right_from = g->pos, info->right_to = g->to;
        }
      else
        info->right_from = info->right_to = -1;
    }

  M17N_OBJECT_UNREF (gstring->top);
  return 0;
}

/*=*/

/***en
    @brief Draw one or more textitems.

    The mdraw_text_items () function draws one or more M-texts on
    window $WIN of $FRAME at coordinate ($X, $Y).  $ITEMS is an array
    of the textitems to be drawn and $NITEMS is the number of
    textimtems in the array.  */

/***ja
    @brief textitem ¤òɽ¼¨¤¹¤ë.

    ´Ø¿ô mdraw_text_items () ¤Ï¡¢°ì¸Ä°Ê¾å¤Î¥Æ¥­¥¹¥È¥¢¥¤¥Æ¥à¤ò¡¢¥Õ¥ì¡¼
    ¥à $FRAME ¤Î¥¦¥£¥ó¥É¥¦ $WIN ¤ÎºÂɸ ($X, $Y) ¤Ëɽ¼¨¤¹¤ë¡£$ITEMS ¤Ï
    ɽ¼¨¤¹¤Ù¤­¥Æ¥­¥¹¥È¥¢¥¤¥Æ¥à¤ÎÇÛÎó¤Ø¤Î¥Ý¥¤¥ó¥¿¤Ç¤¢¤ê¡¢$NITEMS ¤Ï¤½¤Î
    ¸Ä¿ô¤Ç¤¢¤ë¡£

    @latexonly \IPAlabel{mdraw_text_items} @endlatexonly  */

/***
    @seealso
    MTextItem, mdraw_text ().  */

void
mdraw_text_items (MFrame *frame, MDrawWindow win, int x, int y,
                  MDrawTextItem *items, int nitems)
{
  while (nitems-- > 0)
    {
      if (items->face)
        mtext_push_prop (items->mt, 0, mtext_nchars (items->mt), Mface,
                         items->face);
      mdraw_text_with_control (frame, win, x, y,
                               items->mt, 0, mtext_nchars (items->mt),
                               items->control);
      x += mdraw_text_extents (frame, items->mt, 0, mtext_nchars (items->mt),
                               items->control, NULL, NULL, NULL);
      x += items->delta;
      if (items->face)
        mtext_pop_prop (items->mt, 0, mtext_nchars (items->mt), Mface);
    }
}

/*=*/
/***en 
      @brief   calculate a line breaking position.

      The function mdraw_default_line_break () calculates a line
      breaking position based on the line number $LINE and the
      coordinate $Y, when a line is too long to fit within the width
      limit.  $POS is the position of the character next to the last
      one that fits within the limit.  $FROM is the position of the
      first character of the line, and TO is the position of the last
      character displayed on the line if there were not width limit.
      LINE and Y are reset to 0 when a line is broken by a newline
      character, and incremented each time when a long line is broken
      because of the width limit.  

      @return 
      This function returns a character position to break the
      line.

*/
/***ja 
      @brief ²þ¹Ô°ÌÃÖ¤ò·×»»¤¹¤ë.

      ´Ø¿ô mdraw_default_line_break () ¤Ï¡¢¹Ô¤¬ºÇÂçÉýÃæ¤Ë¼ý¤Þ¤é¤Ê¤¤¾ì
      ¹ç¤Ë¹Ô¤ò²þ¤á¤ë°ÌÃÖ¤ò¡¢¹ÔÈÖ¹æ LINE ¤ÈºÂɸ Y ¤Ë´ð¤Å¤¤¤Æ·×»»¤¹¤ë¡£
      $POS ¤ÏºÇÂçÉý¤Ë¼ý¤Þ¤ëºÇ¸å¤Îʸ»ú¤Î¼¡¤Îʸ»ú¤Î°ÌÃ֤Ǥ¢¤ë¡£$FROM ¤Ï
      ¹Ô¤ÎºÇ½é¤Îʸ»ú¤Î°ÌÃÖ¡¢$TO ¤ÏºÇÂçÉý¤¬»ØÄꤵ¤ì¤Æ¤¤¤Ê¤±¤ì¤Ð¤½¤Î¹Ô¤Ë
      ɽ¼¨¤µ¤ì¤ëºÇ¸å¤Îʸ»ú¤Î°ÌÃ֤Ǥ¢¤ë¡£ LINE ¤È Y ¤Ï²þ¹Ôʸ»ú¤Ë¤è¤Ã¤Æ
      ¹Ô¤¬²þ¤Þ¤Ã¤¿ºÝ¤Ë¤Ï 0 ¤Ë¥ê¥»¥Ã¥È¤µ¤ì¡¢ºÇÂçÉý¤Ë¤è¤Ã¤Æ¹Ô¤¬²þ¤Þ¤Ã¤¿
      ¾ì¹ç¤Ë¤Ï 1 ¤Å¤ÄÁý¤ä¤µ¤ì¤ë¡£

      @return 
      ¤³¤Î´Ø¿ô¤Ï¹Ô¤ò²þ¤á¤ëʸ»ú°ÌÃÖ¤òÊÖ¤¹¡£
*/

int
mdraw_default_line_break (MText *mt, int pos,
                          int from, int to, int line, int y)
{
  int c = mtext_ref_char (mt, pos);
  int orig_pos = pos;

  if (c == ' ' || c == '\t')
    {
      pos++;
      while (pos < to
             && ((c = mtext_ref_char (mt, pos)) == ' ' || c == '\t'))
        pos++;
    }
  else
    {
      while (pos > from)
        {
          if (c == ' ' || c == '\t')
            break;
          pos--;
          c = mtext_ref_char (mt, pos);
        }
      if (pos == from)
        pos = orig_pos;
      else
        pos++;
    }
  return pos;
}

/*=*/

/***en
    @brief Obtain per character dimension information.

    The mdraw_per_char_extents () function computes the text dimension
    of each character in M-text $MT.  The faces given as text
    properties in $MT and the default face of frame $FRAME determine
    the fonts to draw the text.  Each successive element in
    $ARRAY_RETURN is set to the drawn metrics of successive
    characters, which is relative to the origin of the drawing, and a
    rectangle for each character in $MT.  The number of elements of
    $ARRAY_RETURN must be equal to or greater than the number of
    characters in $MT.

    If pointer $OVERALL_RETURN is not @c NULL, this function also
    computes the extents of the overall text and stores the results in
    the members of the structure pointed to by $OVERALL_RETURN  */

/***ja
    @brief M-text ¤Îʸ»úËè¤Îɽ¼¨ÈϰϾðÊó¤òÆÀ¤ë.

    ´Ø¿ô mdraw_per_char_extents () ¤Ï¡¢M-text $MT Ãæ¤Î³Æʸ»ú¤Îɽ¼¨ÈÏ°Ï
    ¤ò·×»»¤¹¤ë¡£¤³¤Î·×»»¤ËÍѤ¤¤ë¥Õ¥©¥ó¥È¤Ï¡¢$MT ¤Î¥Æ¥­¥¹¥È¥×¥í¥Ñ¥Æ¥£¤Ç
    »ØÄꤵ¤ì¤¿¥Õ¥§¡¼¥¹¤È¡¢¥Õ¥ì¡¼¥à $FRAME ¤Î¥Ç¥Õ¥©¥ë¥È¥Õ¥§¡¼¥¹¤Ë¤è¤Ã¤Æ·è
    ¤Þ¤ë¡£$ARRAY_RETURN ¤Î³ÆÍ×ÁǤϡ¢Åö³º M-text Ãæ¤Î³Æʸ»ú¤Îɽ¼¨ÈÏ°Ï
    ¾ðÊó¤Ë¤è¤Ã¤Æ½ç¤ËËä¤á¤é¤ì¤ë¡£¤³¤Îɽ¼¨ÈϰϾðÊó¤Ï¡¢M-text ¤Îɽ¼¨¸¶ÅÀ
    ¤«¤é¤ÎÁêÂаÌÃ֤Ǥ¢¤ë¡£$ARRAY_RETURN ¤ÎÍ×ÁÇ¿ô¤Ï¡¢M-text ¤Îʸ»ú¿ô°Ê
    ¾å¤Ç¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£

    ¥Ý¥¤¥ó¥¿ $OVERALL_RETURN ¤¬ @c NULL ¤Ç¤Ê¤¤¾ì¹ç¤Ï¡¢¥Æ¥­¥¹¥ÈÁ´ÂΤÎɽ
    ¼¨ÈϰϾðÊó¤â·×»»¤·¡¢¤½¤Î·ë²Ì¤ò $OVERALL_RETURN ¤Î»Ø¤¹¹½Â¤ÂΤ˳ÊǼ
    ¤¹¤ë¡£

    @latexonly \IPAlabel{mdraw_per_char_extents} @endlatexonly  */

void
mdraw_per_char_extents (MFrame *frame, MText *mt,
  MDrawMetric *array_return,
  MDrawMetric *overall_return)
{
}

/***en 
    @brief clear cached information.    

    The mdraw_clear_cache () function clear cached information
    on M-text $MT that was attached by any of the drawing functions.
    When the behaviour of `format' or `line_break'
    member functions of MDrawControl is changed, the cache must be cleared.

    @seealso
    MDrawControl */
/***ja 
    @brief ¥­¥ã¥Ã¥·¥å¾ðÊó¤ò¾Ã¤¹.

    ´Ø¿ô mdraw_clear_cache () ¤ÏÉÁ²è´Ø¿ô¤Ë¤è¤Ã¤Æ M-text $MT ¤ËÉÕ²Ã
    ¤µ¤ì¤¿¥­¥ã¥Ã¥·¥å¾ðÊó¤ò¤¹¤Ù¤Æ¾Ãµî¤¹¤ë¡£MDrawControl ¤Î `format' ¤¢
    ¤ë¤¤¤Ï `line_break' ¥á¥ó¥Ð´Ø¿ô¤Î¿¶Éñ¤¤¤¬ÊѤï¤Ã¤¿¾ì¹ç¤Ë¤Ï¥­¥ã¥Ã¥·¥å
    ¤ò¾Ãµî¤·¤Ê¤¯¤Æ¤Ï¤Ê¤é¤Ê¤¤¡£
    @seealso
    MDrawControl */

void
mdraw_clear_cache (MText *mt)
{
  mtext_pop_prop (mt, 0, mtext_nchars (mt), M_glyph_string);
}

/*** @} */

/*
  Local Variables:
  coding: euc-japan
  End:
*/