gtk2/gtk/gtktextlayout.c

/* GTK - The GIMP Toolkit
 * gtktextlayout.c - calculate the layout of the text
 *
 * Copyright (c) 1992-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 2000 Red Hat, Inc.
 * Tk->Gtk port by Havoc Pennington
 * Pango support by Owen Taylor
 *
 * This file can be used under your choice of two licenses, the LGPL
 * and the original Tk license.
 *
 * LGPL:
 *
 * This 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 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Original Tk license:
 *
 * This software is copyrighted by the Regents of the University of
 * California, Sun Microsystems, Inc., and other parties.  The
 * following terms apply to all files associated with the software
 * unless explicitly disclaimed in individual files.
 *
 * The authors hereby grant permission to use, copy, modify,
 * distribute, and license this software and its documentation for any
 * purpose, provided that existing copyright notices are retained in
 * all copies and that this notice is included verbatim in any
 * distributions. No written agreement, license, or royalty fee is
 * required for any of the authorized uses.  Modifications to this
 * software may be copyrighted by their authors and need not follow
 * the licensing terms described here, provided that the new terms are
 * clearly indicated on the first page of each file where they apply.
 *
 * IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY
 * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
 * DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION,
 * OR ANY DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
 * NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS,
 * AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
 * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * GOVERNMENT USE: If you are acquiring this software on behalf of the
 * U.S. government, the Government shall have only "Restricted Rights"
 * in the software and related documentation as defined in the Federal
 * Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
 * are acquiring the software on behalf of the Department of Defense,
 * the software shall be classified as "Commercial Computer Software"
 * and the Government shall have only "Restricted Rights" as defined
 * in Clause 252.227-7013 (c) (1) of DFARs.  Notwithstanding the
 * foregoing, the authors grant the U.S. Government and others acting
 * in its behalf permission to use and distribute the software in
 * accordance with the terms specified in this license.
 *
 */
/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */

#include "gtksignal.h"
#include "gtktextlayout.h"
#include "gtktextbtree.h"
#include "gtktextiterprivate.h"

#include <stdlib.h>
#include <string.h>

static GtkTextLineData    *gtk_text_line_data_new                 (GtkTextLayout     *layout,
                                                                   GtkTextLine       *line);

static GtkTextLineData *gtk_text_layout_real_wrap (GtkTextLayout *layout,
                                                   GtkTextLine *line,
                                                   /* may be NULL */
                                                   GtkTextLineData *line_data);

static void gtk_text_layout_invalidated     (GtkTextLayout     *layout);

static void gtk_text_layout_real_invalidate     (GtkTextLayout     *layout,
                                                 const GtkTextIter *start,
                                                 const GtkTextIter *end);
static void gtk_text_layout_invalidate_cache    (GtkTextLayout     *layout,
                                                 GtkTextLine       *line);
static void gtk_text_layout_real_free_line_data (GtkTextLayout     *layout,
                                                 GtkTextLine       *line,
                                                 GtkTextLineData   *line_data);

static void gtk_text_layout_invalidate_all (GtkTextLayout *layout);

static PangoAttribute *gtk_text_attr_appearance_new (const GtkTextAppearance *appearance);

enum {
  INVALIDATED,
  CHANGED,
  ALLOCATE_CHILD,
  LAST_SIGNAL
};

enum {
  ARG_0,
  LAST_ARG
};

static void gtk_text_layout_init       (GtkTextLayout      *text_layout);
static void gtk_text_layout_class_init (GtkTextLayoutClass *klass);
static void gtk_text_layout_finalize   (GObject            *object);


static GtkObjectClass *parent_class = NULL;
static guint signals[LAST_SIGNAL] = { 0 };

PangoAttrType gtk_text_attr_appearance_type = 0;

GType
gtk_text_layout_get_type (void)
{
  static GType our_type = 0;

  if (our_type == 0)
    {
      static const GTypeInfo our_info =
      {
        sizeof (GtkTextLayoutClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc) gtk_text_layout_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data */
        sizeof (GtkTextLayout),
        0,              /* n_preallocs */
        (GInstanceInitFunc) gtk_text_layout_init
      };

      our_type = g_type_register_static (G_TYPE_OBJECT,
                                         "GtkTextLayout",
                                         &our_info,
                                         0);
    }

  return our_type;
}

static void
gtk_text_layout_class_init (GtkTextLayoutClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);
  
  object_class->finalize = gtk_text_layout_finalize;

  klass->wrap = gtk_text_layout_real_wrap;
  klass->invalidate = gtk_text_layout_real_invalidate;
  klass->free_line_data = gtk_text_layout_real_free_line_data;

  signals[INVALIDATED] =
    g_signal_newc ("invalidated",
                   G_OBJECT_CLASS_TYPE (object_class),
                   G_SIGNAL_RUN_LAST,
                   G_STRUCT_OFFSET (GtkTextLayoutClass, invalidated),
		   NULL, NULL,
		   gtk_marshal_VOID__VOID,
                   GTK_TYPE_NONE,
                   0);

  signals[CHANGED] =
    g_signal_newc ("changed",
                   G_OBJECT_CLASS_TYPE (object_class),
                   G_SIGNAL_RUN_LAST,
                   G_STRUCT_OFFSET (GtkTextLayoutClass, changed),
		   NULL, NULL,
		   gtk_marshal_VOID__INT_INT_INT,
                   GTK_TYPE_NONE,
                   3,
                   GTK_TYPE_INT,
                   GTK_TYPE_INT,
                   GTK_TYPE_INT);

  signals[ALLOCATE_CHILD] =
    g_signal_newc ("allocate_child",
                   G_OBJECT_CLASS_TYPE (object_class),
                   G_SIGNAL_RUN_LAST,
                   G_STRUCT_OFFSET (GtkTextLayoutClass, allocate_child),
		   NULL, NULL,
		   gtk_marshal_VOID__OBJECT_INT_INT,
                   GTK_TYPE_NONE,
                   3,
                   GTK_TYPE_OBJECT,
                   GTK_TYPE_INT,
                   GTK_TYPE_INT);
}

void
gtk_text_layout_init (GtkTextLayout *text_layout)
{
  text_layout->cursor_visible = TRUE;
}

GtkTextLayout*
gtk_text_layout_new (void)
{
  return GTK_TEXT_LAYOUT (g_object_new (gtk_text_layout_get_type (), NULL));
}

static void
free_style_cache (GtkTextLayout *text_layout)
{
  if (text_layout->one_style_cache)
    {
      gtk_text_attributes_unref (text_layout->one_style_cache);
      text_layout->one_style_cache = NULL;
    }
}

static void
gtk_text_layout_finalize (GObject *object)
{
  GtkTextLayout *layout;

  layout = GTK_TEXT_LAYOUT (object);

  gtk_text_layout_set_buffer (layout, NULL);

  if (layout->default_style)
    gtk_text_attributes_unref (layout->default_style);
  layout->default_style = NULL;

  if (layout->ltr_context)
    {
      g_object_unref (G_OBJECT (layout->ltr_context));
      layout->ltr_context = NULL;
    }
  if (layout->rtl_context)
    {
      g_object_unref (G_OBJECT (layout->rtl_context));
      layout->rtl_context = NULL;
    }
  
  (* G_OBJECT_CLASS (parent_class)->finalize) (object);
}

void
gtk_text_layout_set_buffer (GtkTextLayout *layout,
                            GtkTextBuffer *buffer)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (buffer == NULL || GTK_IS_TEXT_BUFFER (buffer));

  if (layout->buffer == buffer)
    return;

  free_style_cache (layout);

  if (layout->buffer)
    {
      _gtk_text_btree_remove_view (_gtk_text_buffer_get_btree (layout->buffer),
                                  layout);

      g_object_unref (G_OBJECT (layout->buffer));
      layout->buffer = NULL;
    }

  if (buffer)
    {
      layout->buffer = buffer;

      g_object_ref (G_OBJECT (buffer));

      _gtk_text_btree_add_view (_gtk_text_buffer_get_btree (buffer), layout);
    }
}

void
gtk_text_layout_default_style_changed (GtkTextLayout *layout)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));

  gtk_text_layout_invalidate_all (layout);
}

void
gtk_text_layout_set_default_style (GtkTextLayout *layout,
                                   GtkTextAttributes *values)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (values != NULL);

  if (values == layout->default_style)
    return;

  gtk_text_attributes_ref (values);

  if (layout->default_style)
    gtk_text_attributes_unref (layout->default_style);

  layout->default_style = values;

  gtk_text_layout_default_style_changed (layout);
}

void
gtk_text_layout_set_contexts (GtkTextLayout *layout,
                              PangoContext  *ltr_context,
                              PangoContext  *rtl_context)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));

  if (layout->ltr_context)
    g_object_unref (G_OBJECT (ltr_context));

  layout->ltr_context = ltr_context;
  g_object_ref (G_OBJECT (ltr_context));

  if (layout->rtl_context)
    g_object_unref (G_OBJECT (rtl_context));

  layout->rtl_context = rtl_context;
  g_object_ref (G_OBJECT (rtl_context));

  gtk_text_layout_invalidate_all (layout);
}

void
gtk_text_layout_set_screen_width (GtkTextLayout *layout, gint width)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (width >= 0);
  g_return_if_fail (layout->wrap_loop_count == 0);

  if (layout->screen_width == width)
    return;

  layout->screen_width = width;

  gtk_text_layout_invalidate_all (layout);
}

/**
 * gtk_text_layout_set_cursor_visible:
 * @layout: a #GtkTextLayout
 * @cursor_visible: If %FALSE, then the insertion cursor will not
 *   be shown, even if the text is editable.
 *
 * Sets whether the insertion cursor should be shown. Generally,
 * widgets using #GtkTextLayout will hide the cursor when the
 * widget does not have the input focus.
 **/
void
gtk_text_layout_set_cursor_visible (GtkTextLayout *layout,
                                    gboolean       cursor_visible)
{
  cursor_visible = (cursor_visible != FALSE);

  if (layout->cursor_visible != cursor_visible)
    {
      GtkTextIter iter;
      gint y, height;

      layout->cursor_visible = cursor_visible;

      /* Now queue a redraw on the paragraph containing the cursor
       */
      gtk_text_buffer_get_iter_at_mark (layout->buffer, &iter,
                                        gtk_text_buffer_get_mark (layout->buffer, "insert"));

      gtk_text_layout_get_line_yrange (layout, &iter, &y, &height);
      gtk_text_layout_changed (layout, y, height, height);

      gtk_text_layout_invalidate_cache (layout, _gtk_text_iter_get_text_line (&iter));
    }
}

/**
 * gtk_text_layout_get_cursor_visible:
 * @layout: a #GtkTextLayout
 *
 * Returns whether the insertion cursor will be shown.
 *
 * Return value: if %FALSE, the insertion cursor will not be
    shown, even if the text is editable.
 **/
gboolean
gtk_text_layout_get_cursor_visible (GtkTextLayout *layout)
{
  return layout->cursor_visible;
}

/**
 * gtk_text_layout_set_preedit_string:
 * @layout: a #PangoLayout
 * @preedit_string: a string to display at the insertion point
 * @preedit_attrs: a #PangoAttrList of attributes that apply to @preedit_string
 * @cursor_pos: position of cursor within preedit string in chars
 * 
 * Set the preedit string and attributes. The preedit string is a
 * string showing text that is currently being edited and not
 * yet committed into the buffer.
 **/
void
gtk_text_layout_set_preedit_string (GtkTextLayout *layout,
				    const gchar   *preedit_string,
				    PangoAttrList *preedit_attrs,
				    gint           cursor_pos)
{
  GtkTextIter iter;
  GtkTextLine *line;
  GtkTextLineData *line_data;

  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (preedit_attrs != NULL || preedit_string == NULL);

  if (layout->preedit_string)
    g_free (layout->preedit_string);

  if (layout->preedit_attrs)
    pango_attr_list_unref (layout->preedit_attrs);

  if (preedit_string)
    {
      layout->preedit_string = g_strdup (preedit_string);
      layout->preedit_len = strlen (layout->preedit_string);
      pango_attr_list_ref (preedit_attrs);
      layout->preedit_attrs = preedit_attrs;

      cursor_pos = CLAMP (cursor_pos, 0, g_utf8_strlen (layout->preedit_string, -1));
      layout->preedit_cursor = g_utf8_offset_to_pointer (layout->preedit_string, cursor_pos) - layout->preedit_string;
    }
  else
    {
      layout->preedit_string = NULL;
      layout->preedit_len = 0;
      layout->preedit_attrs = NULL;
      layout->preedit_cursor = 0;
    }

  /* Now invalidate the paragraph containing the cursor
   */
  gtk_text_buffer_get_iter_at_mark (layout->buffer, &iter,
				    gtk_text_buffer_get_mark (layout->buffer, "insert"));
  
  line = _gtk_text_iter_get_text_line (&iter);
  line_data = _gtk_text_line_get_data (line, layout);
  if (line_data)
    {
      gtk_text_layout_invalidate_cache (layout, line);
      _gtk_text_line_invalidate_wrap (line, line_data);
      gtk_text_layout_invalidated (layout);
    }
}

void
gtk_text_layout_get_size (GtkTextLayout *layout,
                          gint *width,
                          gint *height)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));

  if (width)
    *width = layout->width;

  if (height)
    *height = layout->height;
}

static void
gtk_text_layout_invalidated (GtkTextLayout *layout)
{
  g_signal_emit (G_OBJECT (layout), signals[INVALIDATED], 0);
}

void
gtk_text_layout_changed (GtkTextLayout *layout,
                         gint           y,
                         gint           old_height,
                         gint           new_height)
{
  g_signal_emit (G_OBJECT (layout), signals[CHANGED], 0,
                 y, old_height, new_height);
}

void
gtk_text_layout_free_line_data (GtkTextLayout     *layout,
                                GtkTextLine       *line,
                                GtkTextLineData   *line_data)
{
  (* GTK_TEXT_LAYOUT_GET_CLASS (layout)->free_line_data)
    (layout, line, line_data);
}

void
gtk_text_layout_invalidate (GtkTextLayout *layout,
                            const GtkTextIter *start_index,
                            const GtkTextIter *end_index)
{
  (* GTK_TEXT_LAYOUT_GET_CLASS (layout)->invalidate)
    (layout, start_index, end_index);
}

GtkTextLineData*
gtk_text_layout_wrap (GtkTextLayout *layout,
                      GtkTextLine  *line,
                      /* may be NULL */
                      GtkTextLineData *line_data)
{
  return (* GTK_TEXT_LAYOUT_GET_CLASS (layout)->wrap) (layout, line, line_data);
}

GSList*
gtk_text_layout_get_lines (GtkTextLayout *layout,
                           /* [top_y, bottom_y) */
                           gint top_y,
                           gint bottom_y,
                           gint *first_line_y)
{
  GtkTextLine *first_btree_line;
  GtkTextLine *last_btree_line;
  GtkTextLine *line;
  GSList *retval;

  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), NULL);
  g_return_val_if_fail (bottom_y > top_y, NULL);

  retval = NULL;

  first_btree_line =
    _gtk_text_btree_find_line_by_y (_gtk_text_buffer_get_btree (layout->buffer),
                                   layout, top_y, first_line_y);
  if (first_btree_line == NULL)
    {
      /* off the bottom */
      return NULL;
    }

  /* -1 since bottom_y is one past */
  last_btree_line =
    _gtk_text_btree_find_line_by_y (_gtk_text_buffer_get_btree (layout->buffer),
                                   layout, bottom_y - 1, NULL);

  if (!last_btree_line)
    last_btree_line =
      _gtk_text_btree_get_line (_gtk_text_buffer_get_btree (layout->buffer),
                               _gtk_text_btree_line_count (_gtk_text_buffer_get_btree (layout->buffer)) - 1,
                               NULL);

  {
    GtkTextLineData *ld = _gtk_text_line_get_data (last_btree_line, layout);
    if (ld->height == 0)
      G_BREAKPOINT ();
  }

  g_assert (last_btree_line != NULL);

  line = first_btree_line;
  while (TRUE)
    {
      retval = g_slist_prepend (retval, line);

      if (line == last_btree_line)
        break;

      line = _gtk_text_line_next (line);
    }

  retval = g_slist_reverse (retval);

  return retval;
}

static void
invalidate_cached_style (GtkTextLayout *layout)
{
  free_style_cache (layout);
}

/* These should be called around a loop which wraps a CONTIGUOUS bunch
 * of display lines. If the lines aren't contiguous you can't call
 * these.
 */
void
gtk_text_layout_wrap_loop_start (GtkTextLayout *layout)
{
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (layout->one_style_cache == NULL);

  layout->wrap_loop_count += 1;
}

void
gtk_text_layout_wrap_loop_end (GtkTextLayout *layout)
{
  g_return_if_fail (layout->wrap_loop_count > 0);

  layout->wrap_loop_count -= 1;

  if (layout->wrap_loop_count == 0)
    {
      /* We cache a some stuff if we're iterating over some lines wrapping
       * them. This cleans it up.
       */
      /* Nuke our cached style */
      invalidate_cached_style (layout);
      g_assert (layout->one_style_cache == NULL);
    }
}

static void
gtk_text_layout_invalidate_all (GtkTextLayout *layout)
{
  GtkTextIter start;
  GtkTextIter end;

  if (layout->buffer == NULL)
    return;

  gtk_text_buffer_get_bounds (layout->buffer, &start, &end);

  gtk_text_layout_invalidate (layout, &start, &end);
}

static void
gtk_text_layout_invalidate_cache (GtkTextLayout *layout,
                                  GtkTextLine   *line)
{
  if (layout->one_display_cache && line == layout->one_display_cache->line)
    {
      GtkTextLineDisplay *tmp_display = layout->one_display_cache;
      layout->one_display_cache = NULL;
      gtk_text_layout_free_line_display (layout, tmp_display);
    }
}

static void
gtk_text_layout_real_invalidate (GtkTextLayout *layout,
                                 const GtkTextIter *start,
                                 const GtkTextIter *end)
{
  GtkTextLine *line;
  GtkTextLine *last_line;

  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (layout->wrap_loop_count == 0);

#if 0
  gtk_text_view_index_spew (start_index, "invalidate start");
  gtk_text_view_index_spew (end_index, "invalidate end");
#endif

  last_line = _gtk_text_iter_get_text_line (end);
  line = _gtk_text_iter_get_text_line (start);

  while (TRUE)
    {
      GtkTextLineData *line_data = _gtk_text_line_get_data (line, layout);

      if (line_data &&
          (line != last_line || !gtk_text_iter_starts_line (end)))
        {
          gtk_text_layout_invalidate_cache (layout, line);
          _gtk_text_line_invalidate_wrap (line, line_data);
        }

      if (line == last_line)
        break;

      line = _gtk_text_line_next (line);
    }

  gtk_text_layout_invalidated (layout);
}

static void
gtk_text_layout_real_free_line_data (GtkTextLayout     *layout,
                                     GtkTextLine       *line,
                                     GtkTextLineData   *line_data)
{
  if (layout->one_display_cache && line == layout->one_display_cache->line)
    {
      GtkTextLineDisplay *tmp_display = layout->one_display_cache;
      layout->one_display_cache = NULL;
      gtk_text_layout_free_line_display (layout, tmp_display);
    }

  g_free (line_data);
}



/**
 * gtk_text_layout_is_valid:
 * @layout: a #GtkTextLayout
 *
 * Check if there are any invalid regions in a #GtkTextLayout's buffer
 *
 * Return value: #TRUE if any invalid regions were found
 **/
gboolean
gtk_text_layout_is_valid (GtkTextLayout *layout)
{
  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), FALSE);

  return _gtk_text_btree_is_valid (_gtk_text_buffer_get_btree (layout->buffer),
                                  layout);
}

static void
update_layout_size (GtkTextLayout *layout)
{
  _gtk_text_btree_get_view_size (_gtk_text_buffer_get_btree (layout->buffer),
				layout,
				&layout->width, &layout->height);
}

/**
 * gtk_text_layout_validate_yrange:
 * @layout: a #GtkTextLayout
 * @anchor: iter pointing into a line that will be used as the
 *          coordinate origin
 * @y0: offset from the top of the line pointed to by @anchor at
 *      which to begin validation. (The offset here is in pixels
 *      after validation.)
 * @y1: offset from the top of the line pointed to by @anchor at
 *      which to end validation. (The offset here is in pixels
 *      after validation.)
 *
 * Ensure that a region of a #GtkTextLayout is valid. The ::changed
 * signal will be emitted if any lines are validated.
 **/
void
gtk_text_layout_validate_yrange (GtkTextLayout *layout,
                                 GtkTextIter   *anchor,
                                 gint           y0,
                                 gint           y1)
{
  GtkTextLine *line;
  GtkTextLine *first_line = NULL;
  GtkTextLine *last_line = NULL;
  gint seen;
  gint delta_height = 0;
  gint first_line_y = 0;        /* Quiet GCC */
  gint last_line_y = 0;         /* Quiet GCC */

  g_return_if_fail (layout != NULL);
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));

  if (y0 > 0)
    y0 = 0;
  if (y1 < 0)
    y1 = 0;
  
  /* Validate backwards from the anchor line to y0
   */
  line = _gtk_text_iter_get_text_line (anchor);
  seen = 0;
  while (line && seen < -y0)
    {
      GtkTextLineData *line_data = _gtk_text_line_get_data (line, layout);
      if (!line_data || !line_data->valid)
        {
          gint old_height = line_data ? line_data->height : 0;

          _gtk_text_btree_validate_line (_gtk_text_buffer_get_btree (layout->buffer),
                                         line, layout);
          line_data = _gtk_text_line_get_data (line, layout);

          delta_height += line_data->height - old_height;
          
          first_line = line;
          first_line_y = -seen;
          if (!last_line)
            {
              last_line = line;
              last_line_y = -seen + line_data->height;
            }
        }

      seen += line_data->height;
      line = _gtk_text_line_previous (line);
    }

  /* Validate forwards to y1 */
  line = _gtk_text_iter_get_text_line (anchor);
  seen = 0;
  while (line && seen < y1)
    {
      GtkTextLineData *line_data = _gtk_text_line_get_data (line, layout);
      if (!line_data || !line_data->valid)
        {
          gint old_height = line_data ? line_data->height : 0;

          _gtk_text_btree_validate_line (_gtk_text_buffer_get_btree (layout->buffer),
                                         line, layout);
          line_data = _gtk_text_line_get_data (line, layout);

          delta_height += line_data->height - old_height;
          
          if (!first_line)
            {
              first_line = line;
              first_line_y = seen;
            }
          last_line = line;
          last_line_y = seen + line_data->height;
        }

      seen += line_data->height;
      line = _gtk_text_line_next (line);
    }

  /* If we found and validated any invalid lines, update size and
   * emit the changed signal
   */
  if (first_line)
    {
      gint line_top;

      update_layout_size (layout);

      line_top = _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer),
                                                first_line, layout);

      gtk_text_layout_changed (layout,
                               line_top,
                               last_line_y - first_line_y - delta_height,
                               last_line_y - first_line_y);
    }
}

/**
 * gtk_text_layout_validate:
 * @tree: a #GtkTextLayout
 * @max_pixels: the maximum number of pixels to validate. (No more
 *              than one paragraph beyond this limit will be validated)
 *
 * Validate regions of a #GtkTextLayout. The ::changed signal will
 * be emitted for each region validated.
 **/
void
gtk_text_layout_validate (GtkTextLayout *layout,
                          gint           max_pixels)
{
  gint y, old_height, new_height;

  g_return_if_fail (layout != NULL);
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));

  while (max_pixels > 0 &&
         _gtk_text_btree_validate (_gtk_text_buffer_get_btree (layout->buffer),
                                   layout,  max_pixels,
                                   &y, &old_height, &new_height))
    {
      max_pixels -= new_height;

      update_layout_size (layout);
      gtk_text_layout_changed (layout, y, old_height, new_height);
    }
}

static GtkTextLineData*
gtk_text_layout_real_wrap (GtkTextLayout   *layout,
                           GtkTextLine     *line,
                           /* may be NULL */
                           GtkTextLineData *line_data)
{
  GtkTextLineDisplay *display;

  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), NULL);

  if (line_data == NULL)
    {
      line_data = gtk_text_line_data_new (layout, line);
      _gtk_text_line_add_data (line, line_data);
    }

  display = gtk_text_layout_get_line_display (layout, line, TRUE);
  line_data->width = display->width;
  line_data->height = display->height;
  line_data->valid = TRUE;
  gtk_text_layout_free_line_display (layout, display);

  return line_data;
}

/*
 * Layout utility functions
 */

/* If you get the style with get_style () you need to call
   release_style () to free it. */
static GtkTextAttributes*
get_style (GtkTextLayout *layout,
           const GtkTextIter *iter)
{
  GtkTextTag** tags;
  gint tag_count = 0;
  GtkTextAttributes *style;

  /* If we have the one-style cache, then it means
     that we haven't seen a toggle since we filled in the
     one-style cache.
  */
  if (layout->one_style_cache != NULL)
    {
      gtk_text_attributes_ref (layout->one_style_cache);
      return layout->one_style_cache;
    }

  g_assert (layout->one_style_cache == NULL);

  /* Get the tags at this spot */
  tags = _gtk_text_btree_get_tags (iter, &tag_count);

  /* No tags, use default style */
  if (tags == NULL || tag_count == 0)
    {
      /* One ref for the return value, one ref for the
         layout->one_style_cache reference */
      gtk_text_attributes_ref (layout->default_style);
      gtk_text_attributes_ref (layout->default_style);
      layout->one_style_cache = layout->default_style;

      if (tags)
        g_free (tags);

      return layout->default_style;
    }

  /* Sort tags in ascending order of priority */
  _gtk_text_tag_array_sort (tags, tag_count);

  style = gtk_text_attributes_new ();

  gtk_text_attributes_copy_values (layout->default_style,
                                   style);

  _gtk_text_attributes_fill_from_tags (style,
                                       tags,
                                       tag_count);

  g_free (tags);

  g_assert (style->refcount == 1);

  /* Leave this style as the last one seen */
  g_assert (layout->one_style_cache == NULL);
  gtk_text_attributes_ref (style); /* ref held by layout->one_style_cache */
  layout->one_style_cache = style;

  /* Returning yet another refcount */
  return style;
}

static void
release_style (GtkTextLayout *layout,
               GtkTextAttributes *style)
{
  g_return_if_fail (style != NULL);
  g_return_if_fail (style->refcount > 0);

  gtk_text_attributes_unref (style);
}

/*
 * Lines
 */

/* This function tries to optimize the case where a line
   is completely invisible */
static gboolean
totally_invisible_line (GtkTextLayout *layout,
                        GtkTextLine   *line,
                        GtkTextIter   *iter)
{
  GtkTextLineSegment *seg;
  int bytes = 0;

  /* If we have a cached style, then we know it does actually apply
   * and we can just see if it is invisible.
   */
  if (layout->one_style_cache &&
      !layout->one_style_cache->invisible)
    return FALSE;
  /* Without the cache, we check if the first char is visible, if so
   * we are partially visible.  Note that we have to check this since
   * we don't know the current invisible/noninvisible toggle state; this
   * function can use the whole btree to get it right.
   */
  else
    {
      _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                       iter, line, 0);

      if (!_gtk_text_btree_char_is_invisible (iter))
        return FALSE;
    }

  bytes = 0;
  seg = line->segments;

  while (seg != NULL)
    {
      if (seg->byte_count > 0)
        bytes += seg->byte_count;

      /* Note that these two tests can cause us to bail out
       * when we shouldn't, because a higher-priority tag
       * may override these settings. However the important
       * thing is to only invisible really-invisible lines, rather
       * than to invisible all really-invisible lines.
       */

      else if (seg->type == &gtk_text_toggle_on_type)
        {
          invalidate_cached_style (layout);

          /* Bail out if an elision-unsetting tag begins */
          if (seg->body.toggle.info->tag->invisible_set &&
              !seg->body.toggle.info->tag->values->invisible)
            break;
        }
      else if (seg->type == &gtk_text_toggle_off_type)
        {
          invalidate_cached_style (layout);

          /* Bail out if an elision-setting tag ends */
          if (seg->body.toggle.info->tag->invisible_set &&
              seg->body.toggle.info->tag->values->invisible)
            break;
        }

      seg = seg->next;
    }

  if (seg != NULL)       /* didn't reach line end */
    return FALSE;

  return TRUE;
}

static void
set_para_values (GtkTextLayout      *layout,
                 GtkTextAttributes *style,
                 GtkTextLineDisplay *display,
                 gdouble            *align)
{
  PangoAlignment pango_align = PANGO_ALIGN_LEFT;
  int layout_width;

  display->direction = style->direction;

  if (display->direction == GTK_TEXT_DIR_LTR)
    display->layout = pango_layout_new (layout->ltr_context);
  else
    display->layout = pango_layout_new (layout->rtl_context);

  switch (style->justification)
    {
    case GTK_JUSTIFY_LEFT:
      pango_align = (style->direction == GTK_TEXT_DIR_LTR) ? PANGO_ALIGN_LEFT : PANGO_ALIGN_RIGHT;
      break;
    case GTK_JUSTIFY_RIGHT:
      pango_align = (style->direction == GTK_TEXT_DIR_LTR) ? PANGO_ALIGN_RIGHT : PANGO_ALIGN_LEFT;
      break;
    case GTK_JUSTIFY_CENTER:
      pango_align = PANGO_ALIGN_CENTER;
      break;
    case GTK_JUSTIFY_FILL:
      g_warning ("FIXME we don't support GTK_JUSTIFY_FILL yet");
      break;
    default:
      g_assert_not_reached ();
      break;
    }

  switch (pango_align)
    {
    case PANGO_ALIGN_LEFT:
      *align = 0.0;
      break;
    case PANGO_ALIGN_RIGHT:
      *align = 1.0;
      break;
    case PANGO_ALIGN_CENTER:
      *align = 0.5;
      break;
    }

  pango_layout_set_alignment (display->layout, pango_align);
  pango_layout_set_spacing (display->layout,
                            style->pixels_inside_wrap * PANGO_SCALE);

  if (style->tabs)
    pango_layout_set_tabs (display->layout, style->tabs);

  display->top_margin = style->pixels_above_lines;
  display->height = style->pixels_above_lines + style->pixels_below_lines;
  display->bottom_margin = style->pixels_below_lines;
  display->left_margin = style->left_margin;
  display->right_margin = style->right_margin;
  
  display->x_offset = display->left_margin;

  pango_layout_set_indent (display->layout,
                           style->indent * PANGO_SCALE);

  switch (style->wrap_mode)
    {
    case GTK_WRAP_CHAR:
      layout_width = layout->screen_width - display->left_margin - display->right_margin;
      pango_layout_set_width (display->layout, layout_width * PANGO_SCALE);
      pango_layout_set_wrap (display->layout, PANGO_WRAP_CHAR);
      break;

    case GTK_WRAP_WORD:
      layout_width = layout->screen_width - display->left_margin - display->right_margin;
      pango_layout_set_width (display->layout, layout_width * PANGO_SCALE);
      pango_layout_set_wrap (display->layout, PANGO_WRAP_WORD);
      break;

    case GTK_WRAP_NONE:
      break;
    }
  
  display->total_width = MAX (layout->screen_width, layout->width) - display->left_margin - display->right_margin;
}

static PangoAttribute *
gtk_text_attr_appearance_copy (const PangoAttribute *attr)
{
  const GtkTextAttrAppearance *appearance_attr = (const GtkTextAttrAppearance *)attr;

  return gtk_text_attr_appearance_new (&appearance_attr->appearance);
}

static void
gtk_text_attr_appearance_destroy (PangoAttribute *attr)
{
  GtkTextAppearance *appearance = &((GtkTextAttrAppearance *)attr)->appearance;

  if (appearance->bg_stipple)
    gdk_drawable_unref (appearance->bg_stipple);
  if (appearance->fg_stipple)
    gdk_drawable_unref (appearance->fg_stipple);

  g_free (attr);
}

static gboolean
gtk_text_attr_appearance_compare (const PangoAttribute *attr1,
                                  const PangoAttribute *attr2)
{
  const GtkTextAppearance *appearance1 = &((const GtkTextAttrAppearance *)attr1)->appearance;
  const GtkTextAppearance *appearance2 = &((const GtkTextAttrAppearance *)attr2)->appearance;

  return (gdk_color_equal (&appearance1->fg_color, &appearance2->fg_color) &&
          gdk_color_equal (&appearance1->bg_color, &appearance2->bg_color) &&
          appearance1->fg_stipple ==  appearance2->fg_stipple &&
          appearance1->bg_stipple ==  appearance2->bg_stipple &&
          appearance1->underline == appearance2->underline &&
          appearance1->strikethrough == appearance2->strikethrough &&
          appearance1->draw_bg == appearance2->draw_bg);

}

/**
 * gtk_text_attr_appearance_new:
 * @desc:
 *
 * Create a new font description attribute. (This attribute
 * allows setting family, style, weight, variant, stretch,
 * and size simultaneously.)
 *
 * Return value:
 **/
static PangoAttribute *
gtk_text_attr_appearance_new (const GtkTextAppearance *appearance)
{
  static PangoAttrClass klass = {
    0,
    gtk_text_attr_appearance_copy,
    gtk_text_attr_appearance_destroy,
    gtk_text_attr_appearance_compare
  };

  GtkTextAttrAppearance *result;

  if (!klass.type)
    klass.type = gtk_text_attr_appearance_type =
      pango_attr_type_register ("GtkTextAttrAppearance");

  result = g_new (GtkTextAttrAppearance, 1);
  result->attr.klass = &klass;

  result->appearance = *appearance;

  if (appearance->bg_stipple)
    gdk_drawable_ref (appearance->bg_stipple);
  if (appearance->fg_stipple)
    gdk_drawable_ref (appearance->fg_stipple);

  return (PangoAttribute *)result;
}


static void
add_generic_attrs (GtkTextLayout      *layout,
                   GtkTextAppearance  *appearance,
                   gint                byte_count,
                   PangoAttrList      *attrs,
                   gint                start,
                   gboolean            size_only,
                   gboolean            is_text)
{
  PangoAttribute *attr;

  if (appearance->underline != PANGO_UNDERLINE_NONE)
    {
      attr = pango_attr_underline_new (appearance->underline);
      
      attr->start_index = start;
      attr->end_index = start + byte_count;
      
      pango_attr_list_insert (attrs, attr);
    }

  if (appearance->rise != 0)
    {
      attr = pango_attr_rise_new (appearance->rise);
      
      attr->start_index = start;
      attr->end_index = start + byte_count;
      
      pango_attr_list_insert (attrs, attr);
    }
  
  if (!size_only)
    {
      attr = gtk_text_attr_appearance_new (appearance);
      
      attr->start_index = start;
      attr->end_index = start + byte_count;

      ((GtkTextAttrAppearance *)attr)->appearance.is_text = is_text;
      
      pango_attr_list_insert (attrs, attr);
    }
}

static void
add_text_attrs (GtkTextLayout      *layout,
                GtkTextAttributes  *style,
                gint                byte_count,
                PangoAttrList      *attrs,
                gint                start,
                gboolean            size_only)
{
  PangoAttribute *attr;

  attr = pango_attr_font_desc_new (&style->font);
  attr->start_index = start;
  attr->end_index = start + byte_count;

  pango_attr_list_insert (attrs, attr);

  if (style->font_scale != 1.0)
    {
      attr = pango_attr_scale_new (style->font_scale);

      attr->start_index = start;
      attr->end_index = start + byte_count;
      
      pango_attr_list_insert (attrs, attr);
    }
}

static void
add_pixbuf_attrs (GtkTextLayout      *layout,
                  GtkTextLineDisplay *display,
                  GtkTextAttributes  *style,
                  GtkTextLineSegment *seg,
                  PangoAttrList      *attrs,
                  gint                start)
{
  PangoAttribute *attr;
  PangoRectangle logical_rect;
  GtkTextPixbuf *pixbuf = &seg->body.pixbuf;
  gint width, height;

  width = gdk_pixbuf_get_width (pixbuf->pixbuf);
  height = gdk_pixbuf_get_height (pixbuf->pixbuf);

  logical_rect.x = 0;
  logical_rect.y = -height * PANGO_SCALE;
  logical_rect.width = width * PANGO_SCALE;
  logical_rect.height = height * PANGO_SCALE;

  attr = pango_attr_shape_new (&logical_rect, &logical_rect);
  attr->start_index = start;
  attr->end_index = start + seg->byte_count;
  pango_attr_list_insert (attrs, attr);

  display->shaped_objects =
    g_slist_append (display->shaped_objects, pixbuf->pixbuf);
}

static void
add_child_attrs (GtkTextLayout      *layout,
                 GtkTextLineDisplay *display,
                 GtkTextAttributes  *style,
                 GtkTextLineSegment *seg,
                 PangoAttrList      *attrs,
                 gint                start)
{
  PangoAttribute *attr;
  PangoRectangle logical_rect;
  GtkTextChildAnchor *anchor;
  gint width, height;
  GSList *tmp_list;

  width = 1;
  height = 1;
  
  anchor = seg->body.child.obj;

  tmp_list = seg->body.child.widgets;
  while (tmp_list != NULL)
    {
      GtkWidget *child = tmp_list->data;

      if (_gtk_anchored_child_get_layout (child) == layout)
        {
          /* Found it */
          GtkRequisition req;

          gtk_widget_get_child_requisition (child, &req);
          
          width = req.width;
          height = req.height;

          display->shaped_objects =
            g_slist_append (display->shaped_objects, child);
          
          break;
        }
      
      tmp_list = g_slist_next (tmp_list);
    }

  if (tmp_list == NULL)
    {
      /* No widget at this anchor in this display;
       * not an error.
       */

      return;
    }

  if (layout->preedit_string)
    {
      g_free (layout->preedit_string);
      layout->preedit_string = NULL;
    }

  if (layout->preedit_attrs)
    {
      pango_attr_list_unref (layout->preedit_attrs);
      layout->preedit_attrs = NULL;
    }
  
  logical_rect.x = 0;
  logical_rect.y = -height * PANGO_SCALE;
  logical_rect.width = width * PANGO_SCALE;
  logical_rect.height = height * PANGO_SCALE;

  attr = pango_attr_shape_new (&logical_rect, &logical_rect);
  attr->start_index = start;
  attr->end_index = start + seg->byte_count;
  pango_attr_list_insert (attrs, attr);
}

static void
add_cursor (GtkTextLayout      *layout,
            GtkTextLineDisplay *display,
            GtkTextLineSegment *seg,
            gint                start)
{
  PangoRectangle strong_pos, weak_pos;
  GtkTextCursorDisplay *cursor;

  /* Hide insertion cursor when we have a selection or the layout
   * user has hidden the cursor.
   */
  if (_gtk_text_btree_mark_is_insert (_gtk_text_buffer_get_btree (layout->buffer),
                                     seg->body.mark.obj) &&
      (!layout->cursor_visible ||
       gtk_text_buffer_get_selection_bounds (layout->buffer, NULL, NULL)))
    return;

  pango_layout_get_cursor_pos (display->layout, start, &strong_pos, &weak_pos);

  cursor = g_new (GtkTextCursorDisplay, 1);

  cursor->x = PANGO_PIXELS (strong_pos.x);
  cursor->y = PANGO_PIXELS (strong_pos.y);
  cursor->height = PANGO_PIXELS (strong_pos.height);
  cursor->is_strong = TRUE;
  display->cursors = g_slist_prepend (display->cursors, cursor);

  if (weak_pos.x == strong_pos.x)
    cursor->is_weak = TRUE;
  else
    {
      cursor->is_weak = FALSE;

      cursor = g_new (GtkTextCursorDisplay, 1);

      cursor->x = PANGO_PIXELS (weak_pos.x);
      cursor->y = PANGO_PIXELS (weak_pos.y);
      cursor->height = PANGO_PIXELS (weak_pos.height);
      cursor->is_strong = FALSE;
      cursor->is_weak = TRUE;
      display->cursors = g_slist_prepend (display->cursors, cursor);
    }
}

static gboolean
is_shape (PangoLayoutRun *run)
{
  GSList *tmp_list = run->item->extra_attrs;
    
  while (tmp_list)
    {
      PangoAttribute *attr = tmp_list->data;

      if (attr->klass->type == PANGO_ATTR_SHAPE)
        return TRUE;

      tmp_list = tmp_list->next;
    }

  return FALSE;
}

static void
allocate_child_widgets (GtkTextLayout      *text_layout,
                        GtkTextLineDisplay *display)
{
  GSList *shaped = display->shaped_objects;
  PangoLayout *layout = display->layout;
  PangoLayoutIter *iter;
  
  iter = pango_layout_get_iter (layout);
  
  do
    {
      PangoLayoutRun *run = pango_layout_iter_get_run (iter);

      if (run && is_shape (run))
        {
          GObject *shaped_object = shaped->data;
          shaped = shaped->next;

          if (GTK_IS_WIDGET (shaped_object))
            {
              PangoRectangle extents;

              /* We emit "allocate_child" with the x,y of
               * the widget with respect to the top of the line
               * and the left side of the buffer
               */
              
              pango_layout_iter_get_run_extents (iter,
                                                 NULL,
                                                 &extents);
              
              g_signal_emit (G_OBJECT (text_layout),
                             signals[ALLOCATE_CHILD],
                             0,
                             shaped_object,
                             PANGO_PIXELS (extents.x) + display->x_offset,
                             PANGO_PIXELS (extents.y) + display->top_margin);
            }
        }
    }
  while (pango_layout_iter_next_run (iter));
  
  pango_layout_iter_free (iter);
}

static void
convert_color (GdkColor       *result,
	       PangoAttrColor *attr)
{
  result->red = attr->color.red;
  result->blue = attr->color.blue;
  result->green = attr->color.green;
}

/* This function is used to convert the preedit string attributes, which are
 * standard PangoAttributes, into the custom attributes used by the text
 * widget and insert them into a attr list with a given offset.
 */
static void
add_preedit_attrs (GtkTextLayout     *layout,
		   GtkTextAttributes *style,
		   PangoAttrList     *attrs,
		   gint               offset,
		   gboolean           size_only)
{
  PangoAttrIterator *iter = pango_attr_list_get_iterator (layout->preedit_attrs);

  do
    {
      GtkTextAppearance appearance = style->appearance;
      PangoFontDescription font_desc;
      PangoAttribute *insert_attr;
      GSList *extra_attrs = NULL;
      GSList *tmp_list;
      gint start, end;

      pango_attr_iterator_range (iter, &start, &end);

      if (end == G_MAXINT)
	end = layout->preedit_len;
      
      pango_attr_iterator_get_font (iter, &style->font,
				    &font_desc, &extra_attrs);
      
      tmp_list = extra_attrs;
      while (tmp_list)
	{
	  PangoAttribute *attr = tmp_list->data;
	  
	  switch (attr->klass->type)
	    {
	    case PANGO_ATTR_FOREGROUND:
	      convert_color (&appearance.fg_color, (PangoAttrColor *)attr);
	      break;
	    case PANGO_ATTR_BACKGROUND:
	      convert_color (&appearance.bg_color, (PangoAttrColor *)attr);
	      appearance.draw_bg = TRUE;
	      break;
	    case PANGO_ATTR_UNDERLINE:
	      appearance.underline = ((PangoAttrInt *)attr)->value;
	      break;
	    case PANGO_ATTR_STRIKETHROUGH:
	      appearance.strikethrough = ((PangoAttrInt *)attr)->value;
	      break;
            case PANGO_ATTR_RISE:
              appearance.rise = ((PangoAttrInt *)attr)->value;
              break;
	    default:
	      break;
	    }
	  
	  pango_attribute_destroy (attr);
	  tmp_list = tmp_list->next;
	}
      
      g_slist_free (extra_attrs);
      
      insert_attr = pango_attr_font_desc_new (&font_desc);
      insert_attr->start_index = start + offset;
      insert_attr->end_index = end + offset;
      
      pango_attr_list_insert (attrs, insert_attr);

      add_generic_attrs (layout, &appearance, end - start,
                         attrs, start + offset,
                         size_only, TRUE);
    }
  while (pango_attr_iterator_next (iter));

  pango_attr_iterator_destroy (iter);
}

GtkTextLineDisplay *
gtk_text_layout_get_line_display (GtkTextLayout *layout,
                                  GtkTextLine   *line,
                                  gboolean       size_only)
{
  GtkTextLineDisplay *display;
  GtkTextLineSegment *seg;
  GtkTextIter iter;
  GtkTextAttributes *style;
  gchar *text;
  PangoAttrList *attrs;
  gint text_allocated, layout_byte_offset, buffer_byte_offset;
  gdouble align;
  PangoRectangle extents;
  gboolean para_values_set = FALSE;
  GSList *cursor_byte_offsets = NULL;
  GSList *cursor_segs = NULL;
  GSList *tmp_list1, *tmp_list2;
  gboolean saw_widget = FALSE;
  
  g_return_val_if_fail (line != NULL, NULL);

  if (layout->one_display_cache)
    {
      if (line == layout->one_display_cache->line &&
          (size_only || !layout->one_display_cache->size_only))
        return layout->one_display_cache;
      else
        {
          GtkTextLineDisplay *tmp_display = layout->one_display_cache;
          layout->one_display_cache = NULL;
          gtk_text_layout_free_line_display (layout, tmp_display);
        }
    }

  display = g_new0 (GtkTextLineDisplay, 1);

  display->size_only = size_only;
  display->line = line;
  display->insert_index = -1;

  _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                    &iter, line, 0);

  /* Special-case optimization for completely
   * invisible lines; makes it faster to deal
   * with sequences of invisible lines.
   */
  if (totally_invisible_line (layout, line, &iter))
    return display;

  /* Allocate space for flat text for buffer
   */
  text_allocated = _gtk_text_line_byte_count (line);
  text = g_malloc (text_allocated);

  attrs = pango_attr_list_new ();

  /* Iterate over segments, creating display chunks for them. */
  layout_byte_offset = 0; /* current length of layout text (includes preedit, does not include invisible text) */
  buffer_byte_offset = 0; /* position in the buffer line */
  seg = _gtk_text_iter_get_any_segment (&iter);
  while (seg != NULL)
    {
      /* Displayable segments */
      if (seg->type == &gtk_text_char_type ||
          seg->type == &gtk_text_pixbuf_type ||
          seg->type == &gtk_text_child_type)
        {
          _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                            &iter, line,
                                            buffer_byte_offset);
          style = get_style (layout, &iter);

          /* We have to delay setting the paragraph values until we
           * hit the first pixbuf or text segment because toggles at
           * the beginning of the paragraph should affect the
           * paragraph-global values
           */
          if (!para_values_set)
            {
              set_para_values (layout, style, display, &align);
              para_values_set = TRUE;
            }

          /* First see if the chunk is invisible, and ignore it if so. Tk
           * looked at tabs, wrap mode, etc. before doing this, but
           * that made no sense to me, so I am just skipping the
           * invisible chunks
           */
          if (!style->invisible)
            {
              if (seg->type == &gtk_text_char_type)
                {
                  /* We don't want to split segments because of marks,
                   * so we scan forward for more segments only
                   * separated from us by marks. In theory, we should
                   * also merge segments with identical styles, even
                   * if there are toggles in-between
                   */

                  gint bytes = 0;
 		  GtkTextLineSegment *prev_seg = NULL;
  
 		  while (seg)
                    {
                      if (seg->type == &gtk_text_char_type)
                        {
                          memcpy (text + layout_byte_offset, seg->body.chars, seg->byte_count);
                          layout_byte_offset += seg->byte_count;
                          buffer_byte_offset += seg->byte_count;
                          bytes += seg->byte_count;
                        }
 		      else if (seg->type == &gtk_text_right_mark_type ||
 			       seg->type == &gtk_text_left_mark_type)
                        {
 			  /* If we have preedit string, break out of this loop - we'll almost
 			   * certainly have different attributes on the preedit string
 			   */

 			  if (layout->preedit_len > 0 &&
 			      _gtk_text_btree_mark_is_insert (_gtk_text_buffer_get_btree (layout->buffer),
 							     seg->body.mark.obj))
			    break;

 			  if (seg->body.mark.visible)
 			    {
			      cursor_byte_offsets = g_slist_prepend (cursor_byte_offsets, GINT_TO_POINTER (layout_byte_offset));
			      cursor_segs = g_slist_prepend (cursor_segs, seg);
			    }
                        }
		      else
			break;

 		      prev_seg = seg;
                      seg = seg->next;
                    }

 		  seg = prev_seg; /* Back up one */
                  add_generic_attrs (layout, &style->appearance,
                                     bytes,
                                     attrs, layout_byte_offset - bytes,
                                     size_only, TRUE);
                  add_text_attrs (layout, style, bytes, attrs,
                                  layout_byte_offset - bytes, size_only);
                }
              else if (seg->type == &gtk_text_pixbuf_type)
                {
                  add_generic_attrs (layout,
                                     &style->appearance,
                                     seg->byte_count,
                                     attrs, layout_byte_offset,
                                     size_only, FALSE);
                  add_pixbuf_attrs (layout, display, style,
                                    seg, attrs, layout_byte_offset);
                  memcpy (text + layout_byte_offset, gtk_text_unknown_char_utf8,
                          seg->byte_count);
                  layout_byte_offset += seg->byte_count;
                  buffer_byte_offset += seg->byte_count;
                }
              else if (seg->type == &gtk_text_child_type)
                {
                  saw_widget = TRUE;
                  
                  add_generic_attrs (layout, &style->appearance,
                                     seg->byte_count,
                                     attrs, layout_byte_offset,
                                     size_only, FALSE);
                  add_child_attrs (layout, display, style,
                                   seg, attrs, layout_byte_offset);
                  memcpy (text + layout_byte_offset, gtk_text_unknown_char_utf8,
                          seg->byte_count);
                  layout_byte_offset += seg->byte_count;
                  buffer_byte_offset += seg->byte_count;
                }
              else
                {
                  /* We don't know this segment type */
                  g_assert_not_reached ();
                }
              
            } /* if (segment was visible) */
          else
            {
              /* Invisible segment */
              buffer_byte_offset += seg->byte_count;
            }

          release_style (layout, style);
        }

      /* Toggles */
      else if (seg->type == &gtk_text_toggle_on_type ||
               seg->type == &gtk_text_toggle_off_type)
        {
          /* Style may have changed, drop our
             current cached style */
          invalidate_cached_style (layout);
        }

      /* Marks */
      else if (seg->type == &gtk_text_right_mark_type ||
               seg->type == &gtk_text_left_mark_type)
        {
	  gint cursor_offset = 0;
 	  
	  /* At the insertion point, add the preedit string, if any */
	  
	  if (_gtk_text_btree_mark_is_insert (_gtk_text_buffer_get_btree (layout->buffer),
					     seg->body.mark.obj))
	    {
	      display->insert_index = layout_byte_offset;
	      
	      if (layout->preedit_len > 0)
		{
		  text_allocated += layout->preedit_len;
		  text = g_realloc (text, text_allocated);

		  style = get_style (layout, &iter);
		  add_preedit_attrs (layout, style, attrs, layout_byte_offset, size_only);
		  release_style (layout, style);
                  
		  memcpy (text + layout_byte_offset, layout->preedit_string, layout->preedit_len);
		  layout_byte_offset += layout->preedit_len;
                  /* DO NOT increment the buffer byte offset for preedit */
                  
		  cursor_offset = layout->preedit_cursor - layout->preedit_len;
		}
	    }
	  

          /* Display visible marks */

          if (seg->body.mark.visible)
            {
              cursor_byte_offsets = g_slist_prepend (cursor_byte_offsets,
                                                     GINT_TO_POINTER (layout_byte_offset + cursor_offset));
              cursor_segs = g_slist_prepend (cursor_segs, seg);
            }
        }

      else
        g_error ("Unknown segment type: %s", seg->type->name);

      seg = seg->next;
    }
  
  if (!para_values_set)
    {
      style = get_style (layout, &iter);
      set_para_values (layout, style, display, &align);
      release_style (layout, style);
    }
  
  /* Pango doesn't want the trailing paragraph delimiters */

  {
    /* Only one character has type G_UNICODE_PARAGRAPH_SEPARATOR in
     * Unicode 3.0; update this if that changes.
     */
#define PARAGRAPH_SEPARATOR 0x2029
    gunichar ch = 0;

    if (layout_byte_offset > 0)
      {
        const char *prev = g_utf8_prev_char (text + layout_byte_offset);
        ch = g_utf8_get_char (prev);
        if (ch == PARAGRAPH_SEPARATOR || ch == '\r' || ch == '\n')
          layout_byte_offset = prev - text; /* chop off */

        if (ch == '\n' && layout_byte_offset > 0)
          {
            /* Possibly chop a CR as well */
            prev = g_utf8_prev_char (text + layout_byte_offset);
            if (*prev == '\r')
              --layout_byte_offset;
          }
      }
  }
  
  pango_layout_set_text (display->layout, text, layout_byte_offset);
  pango_layout_set_attributes (display->layout, attrs);

  tmp_list1 = cursor_byte_offsets;
  tmp_list2 = cursor_segs;
  while (tmp_list1)
    {
      add_cursor (layout, display, tmp_list2->data,
                  GPOINTER_TO_INT (tmp_list1->data));
      tmp_list1 = tmp_list1->next;
      tmp_list2 = tmp_list2->next;
    }
  g_slist_free (cursor_byte_offsets);
  g_slist_free (cursor_segs);

  pango_layout_get_extents (display->layout, NULL, &extents);

  display->x_offset += (display->total_width - PANGO_PIXELS (extents.x + extents.width)) * align;

  display->width = PANGO_PIXELS (extents.width) + display->left_margin + display->right_margin;
  display->height += PANGO_PIXELS (extents.height);
  
  /* Free this if we aren't in a loop */
  if (layout->wrap_loop_count == 0)
    invalidate_cached_style (layout);

  g_free (text);
  pango_attr_list_unref (attrs);

  layout->one_display_cache = display;

  if (saw_widget)
    allocate_child_widgets (layout, display);
  
  return display;
}

void
gtk_text_layout_free_line_display (GtkTextLayout      *layout,
                                   GtkTextLineDisplay *display)
{
  if (display != layout->one_display_cache)
    {
      if (display->layout)
        g_object_unref (G_OBJECT (display->layout));

      if (display->cursors)
        {
          g_slist_foreach (display->cursors, (GFunc)g_free, NULL);
          g_slist_free (display->cursors);
        }
      g_slist_free (display->shaped_objects);

      g_free (display);
    }
}

/* Functions to convert iter <=> index for the line of a GtkTextLineDisplay
 * taking into account the preedit string and invisible text if necessary.
 */
static gint
line_display_iter_to_index (GtkTextLayout      *layout,
			    GtkTextLineDisplay *display,
			    const GtkTextIter  *iter)
{
  gint index;

  g_return_val_if_fail (_gtk_text_iter_get_text_line (iter) == display->line, 0);

  index = gtk_text_iter_get_visible_line_index (iter);
  
  if (index >= display->insert_index)
    index += layout->preedit_len;

  return index;
}

static void
line_display_index_to_iter (GtkTextLayout      *layout,
			    GtkTextLineDisplay *display,
			    GtkTextIter        *iter,
			    gint                index,
			    gint                trailing)
{
  if (index >= display->insert_index + layout->preedit_len)
    index -= layout->preedit_len;
  else if (index > display->insert_index)
    {
      index = display->insert_index;
      trailing = 0;
    }

  _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                    iter, display->line, 0);

  gtk_text_iter_set_visible_line_index (iter, index);
  
  if (_gtk_text_iter_get_text_line (iter) != display->line)
    {
      /* Clamp to end of line - really this clamping should have been done
       * before here, maybe in Pango, this is a broken band-aid I think
       */
      _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                        iter, display->line, 0);

      if (!gtk_text_iter_ends_line (iter))
        gtk_text_iter_forward_to_line_end (iter);
    }
  
  gtk_text_iter_forward_chars (iter, trailing);
}

/* FIXME: This really doesn't belong in this file ... */
static GtkTextLineData*
gtk_text_line_data_new (GtkTextLayout *layout,
                        GtkTextLine   *line)
{
  GtkTextLineData *line_data;

  line_data = g_new (GtkTextLineData, 1);

  line_data->view_id = layout;
  line_data->next = NULL;
  line_data->width = 0;
  line_data->height = 0;
  line_data->valid = FALSE;

  return line_data;
}

static void
get_line_at_y (GtkTextLayout *layout,
               gint           y,
               GtkTextLine  **line,
               gint          *line_top)
{
  if (y < 0)
    y = 0;
  if (y > layout->height)
    y = layout->height;

  *line = _gtk_text_btree_find_line_by_y (_gtk_text_buffer_get_btree (layout->buffer),
                                         layout, y, line_top);
  if (*line == NULL)
    {
      *line = _gtk_text_btree_get_line (_gtk_text_buffer_get_btree (layout->buffer),
                                       _gtk_text_btree_line_count (_gtk_text_buffer_get_btree (layout->buffer)) - 1, NULL);
      if (line_top)
        *line_top =
          _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer),
                                        *line, layout);
    }
}

/**
 * gtk_text_layout_get_line_at_y:
 * @layout: a #GtkLayout
 * @target_iter: the iterator in which the result is stored
 * @y: the y positition
 * @line_top: location to store the y coordinate of the
 *            top of the line. (Can by %NULL.)
 *
 * Get the iter at the beginning of the line which is displayed
 * at the given y.
 **/
void
gtk_text_layout_get_line_at_y (GtkTextLayout *layout,
                               GtkTextIter   *target_iter,
                               gint           y,
                               gint          *line_top)
{
  GtkTextLine *line;

  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (target_iter != NULL);

  get_line_at_y (layout, y, &line, line_top);
  _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                   target_iter, line, 0);
}

void
gtk_text_layout_get_iter_at_pixel (GtkTextLayout *layout,
                                   GtkTextIter *target_iter,
                                   gint x, gint y)
{
  GtkTextLine *line;
  gint byte_index, trailing;
  gint line_top;
  GtkTextLineDisplay *display;

  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (target_iter != NULL);

  /* Adjust pixels to be on-screen. This gives nice
     behavior if the user is dragging with a pointer grab.
  */
  if (x < 0)
    x = 0;
  if (x > layout->width)
    x = layout->width;

  get_line_at_y (layout, y, &line, &line_top);

  display = gtk_text_layout_get_line_display (layout, line, FALSE);

  x -= display->x_offset;
  y -= line_top + display->top_margin;

  /* We clamp y to the area of the actual layout so that the layouts
   * hit testing works OK on the space above and below the layout
   */
  y = CLAMP (y, 0, display->height - display->top_margin - display->bottom_margin - 1);

  if (!pango_layout_xy_to_index (display->layout, x * PANGO_SCALE, y * PANGO_SCALE,
                                 &byte_index, &trailing))
    {
      byte_index = _gtk_text_line_byte_count (line);
      trailing = 0;
    }

  line_display_index_to_iter (layout, display, target_iter, byte_index, trailing);

  gtk_text_layout_free_line_display (layout, display);
}

/**
 * gtk_text_layout_get_cursor_locations
 * @layout: a #GtkTextLayout
 * @iter: a #GtkTextIter
 * @strong_pos: location to store the strong cursor position (may be %NULL)
 * @weak_pos: location to store the weak cursor position (may be %NULL)
 *
 * Given an iterator within a text laout, determine the positions that of the
 * strong and weak cursors if the insertion point is at that
 * iterator. The position of each cursor is stored as a zero-width
 * rectangle. The strong cursor location is the location where
 * characters of the directionality equal to the base direction of the
 * paragraph are inserted.  The weak cursor location is the location
 * where characters of the directionality opposite to the base
 * direction of the paragraph are inserted.
 **/
void
gtk_text_layout_get_cursor_locations (GtkTextLayout  *layout,
                                      GtkTextIter    *iter,
                                      GdkRectangle   *strong_pos,
                                      GdkRectangle   *weak_pos)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_top;
  gint index;

  PangoRectangle pango_strong_pos;
  PangoRectangle pango_weak_pos;

  g_return_if_fail (layout != NULL);
  g_return_if_fail (iter != NULL);

  line = _gtk_text_iter_get_text_line (iter);
  display = gtk_text_layout_get_line_display (layout, line, FALSE);
  index = line_display_iter_to_index (layout, display, iter);
  
  line_top = _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer),
                                           line, layout);
  
  pango_layout_get_cursor_pos (display->layout, index,
                               strong_pos ? &pango_strong_pos : NULL,
                               weak_pos ? &pango_weak_pos : NULL);

  if (strong_pos)
    {
      strong_pos->x = display->x_offset + pango_strong_pos.x / PANGO_SCALE;
      strong_pos->y = line_top + display->top_margin + pango_strong_pos.y / PANGO_SCALE;
      strong_pos->width = 0;
      strong_pos->height = pango_strong_pos.height / PANGO_SCALE;
    }

  if (weak_pos)
    {
      weak_pos->x = display->x_offset + pango_weak_pos.x / PANGO_SCALE;
      weak_pos->y = line_top + display->top_margin + pango_weak_pos.y / PANGO_SCALE;
      weak_pos->width = 0;
      weak_pos->height = pango_weak_pos.height / PANGO_SCALE;
    }

  gtk_text_layout_free_line_display (layout, display);
}

/**
 * gtk_text_layout_get_line_yrange:
 * @layout: a #GtkTextLayout
 * @iter:   a #GtkTextIter
 * @y:      location to store the top of the paragraph in pixels,
 *          or %NULL.
 * @height  location to store the height of the paragraph in pixels,
 *          or %NULL.
 *
 * Find the range of y coordinates for the paragraph containing
 * the given iter.
 **/
void
gtk_text_layout_get_line_yrange (GtkTextLayout     *layout,
                                 const GtkTextIter *iter,
                                 gint              *y,
                                 gint              *height)
{
  GtkTextLine *line;

  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (_gtk_text_iter_get_btree (iter) == _gtk_text_buffer_get_btree (layout->buffer));

  line = _gtk_text_iter_get_text_line (iter);

  if (y)
    *y = _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer),
                                       line, layout);
  if (height)
    {
      GtkTextLineData *line_data = _gtk_text_line_get_data (line, layout);
      if (line_data)
        *height = line_data->height;
      else
        *height = 0;
    }
}

void
gtk_text_layout_get_iter_location (GtkTextLayout     *layout,
                                   const GtkTextIter *iter,
                                   GdkRectangle      *rect)
{
  PangoRectangle pango_rect;
  GtkTextLine *line;
  GtkTextBTree *tree;
  GtkTextLineDisplay *display;
  gint byte_index;
  gint x_offset;
  
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (_gtk_text_iter_get_btree (iter) == _gtk_text_buffer_get_btree (layout->buffer));
  g_return_if_fail (rect != NULL);

  tree = _gtk_text_iter_get_btree (iter);
  line = _gtk_text_iter_get_text_line (iter);

  display = gtk_text_layout_get_line_display (layout, line, FALSE);

  rect->y = _gtk_text_btree_find_line_top (tree, line, layout);

  x_offset = display->x_offset * PANGO_SCALE;

  byte_index = gtk_text_iter_get_line_index (iter);
  
  pango_layout_index_to_pos (display->layout, byte_index, &pango_rect);
  
  rect->x = PANGO_PIXELS (x_offset + pango_rect.x);
  rect->y += PANGO_PIXELS (pango_rect.y) + display->top_margin;
  rect->width = PANGO_PIXELS (pango_rect.width);
  rect->height = PANGO_PIXELS (pango_rect.height);

  gtk_text_layout_free_line_display (layout, display);
}

/* FFIXX */

/* Find the iter for the logical beginning of the first display line whose
 * top y is >= y. If none exists, move the iter to the logical beginning
 * of the last line in the buffer.
 */
static void
find_display_line_below (GtkTextLayout *layout,
                         GtkTextIter   *iter,
                         gint           y)
{
  GtkTextLine *line, *next;
  GtkTextLine *found_line = NULL;
  gint line_top;
  gint found_byte = 0;

  line = _gtk_text_btree_find_line_by_y (_gtk_text_buffer_get_btree (layout->buffer),
                                        layout, y, &line_top);
  if (!line)
    {
      line =
        _gtk_text_btree_get_line (_gtk_text_buffer_get_btree (layout->buffer),
                                 _gtk_text_btree_line_count (_gtk_text_buffer_get_btree (layout->buffer)) - 1,
                                 NULL);
      line_top =
        _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer),
                                      line, layout);
    }

  while (line && !found_line)
    {
      GtkTextLineDisplay *display = gtk_text_layout_get_line_display (layout, line, FALSE);
      PangoLayoutIter *layout_iter;

      layout_iter = pango_layout_get_iter (display->layout);

      line_top += display->top_margin;

      do
        {
          gint first_y, last_y;
          PangoLayoutLine *layout_line = pango_layout_iter_get_line (layout_iter);

          found_byte = layout_line->start_index;
          
          if (line_top >= y)
            {
              found_line = line;
              break;
            }

          pango_layout_iter_get_line_yrange (layout_iter, &first_y, &last_y);
          line_top += (last_y - first_y) / PANGO_SCALE;
        }
      while (pango_layout_iter_next_line (layout_iter));

      pango_layout_iter_free (layout_iter);
      
      line_top += display->bottom_margin;
      gtk_text_layout_free_line_display (layout, display);

      next = _gtk_text_line_next (line);
      if (!next)
        found_line = line;

      line = next;
    }

  _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                   iter, found_line, found_byte);
}

/* Find the iter for the logical beginning of the last display line whose
 * top y is >= y. If none exists, move the iter to the logical beginning
 * of the first line in the buffer.
 */
static void
find_display_line_above (GtkTextLayout *layout,
                         GtkTextIter   *iter,
                         gint           y)
{
  GtkTextLine *line;
  GtkTextLine *found_line = NULL;
  gint line_top;
  gint found_byte = 0;

  line = _gtk_text_btree_find_line_by_y (_gtk_text_buffer_get_btree (layout->buffer), layout, y, &line_top);
  if (!line)
    {
      line = _gtk_text_btree_get_line (_gtk_text_buffer_get_btree (layout->buffer),
                                      _gtk_text_btree_line_count (_gtk_text_buffer_get_btree (layout->buffer)) - 1, NULL);
      line_top = _gtk_text_btree_find_line_top (_gtk_text_buffer_get_btree (layout->buffer), line, layout);
    }

  while (line && !found_line)
    {
      GtkTextLineDisplay *display = gtk_text_layout_get_line_display (layout, line, FALSE);
      PangoRectangle logical_rect;
      PangoLayoutIter *layout_iter;
      gint tmp_top;

      layout_iter = pango_layout_get_iter (display->layout);
      
      line_top -= display->top_margin + display->bottom_margin;
      pango_layout_iter_get_layout_extents (layout_iter, NULL, &logical_rect);
      line_top -= logical_rect.height / PANGO_SCALE;

      tmp_top = line_top + display->top_margin;

      do
        {
          gint first_y, last_y;
          PangoLayoutLine *layout_line = pango_layout_iter_get_line (layout_iter);

          found_byte = layout_line->start_index;

          pango_layout_iter_get_line_yrange (layout_iter, &first_y, &last_y);
          
          tmp_top -= (last_y - first_y) / PANGO_SCALE;

          if (tmp_top < y)
            {
              found_line = line;
              goto done;
            }
        }
      while (pango_layout_iter_next_line (layout_iter));

      pango_layout_iter_free (layout_iter);
      
      gtk_text_layout_free_line_display (layout, display);

      line = _gtk_text_line_previous (line);
    }

 done:
  
  if (found_line)
    _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                     iter, found_line, found_byte);
  else
    gtk_text_buffer_get_iter_at_offset (layout->buffer, iter, 0);
}

/**
 * gtk_text_layout_clamp_iter_to_vrange:
 * @layout: a #GtkTextLayout
 * @iter:   a #GtkTextIter
 * @top:    the top of the range
 * @bottom: the bottom the range
 *
 * If the iterator is not fully in the range @top <= y < @bottom,
 * then, if possible, move it the minimum distance so that the
 * iterator in this range.
 *
 * Returns: %TRUE if the iterator was moved, otherwise %FALSE.
 **/
gboolean
gtk_text_layout_clamp_iter_to_vrange (GtkTextLayout *layout,
                                      GtkTextIter   *iter,
                                      gint           top,
                                      gint           bottom)
{
  GdkRectangle iter_rect;

  gtk_text_layout_get_iter_location (layout, iter, &iter_rect);

  /* If the iter is at least partially above the range, put the iter
   * at the first fully visible line after the range.
   */
  if (iter_rect.y < top)
    {
      find_display_line_below (layout, iter, top);

      return TRUE;
    }
  /* Otherwise, if the iter is at least partially below the screen, put the
   * iter on the last logical position of the last completely visible
   * line on screen
   */
  else if (iter_rect.y + iter_rect.height > bottom)
    {
      find_display_line_above (layout, iter, bottom);

      return TRUE;
    }
  else
    return FALSE;
}

/**
 * gtk_text_layout_move_iter_to_previous_line:
 * @layout: a #GtkLayout
 * @iter:   a #GtkTextIter
 *
 * Move the iterator to the beginning of the previous line. The lines
 * of a wrapped paragraph are treated as distinct for this operation.
 **/
gboolean
gtk_text_layout_move_iter_to_previous_line (GtkTextLayout *layout,
                                            GtkTextIter   *iter)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_byte;
  GSList *tmp_list;
  PangoLayoutLine *layout_line;
  GtkTextIter orig;
  gboolean update_byte = FALSE;
  
  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);

  orig = *iter;


  line = _gtk_text_iter_get_text_line (iter);
  display = gtk_text_layout_get_line_display (layout, line, FALSE);
  line_byte = line_display_iter_to_index (layout, display, iter);

  /* If display->height == 0 then the line is invisible, so don't
   * move onto it.
   */
  while (display->height == 0)
    {
      GtkTextLine *prev_line;

      prev_line = _gtk_text_line_previous (line);

      if (prev_line == NULL)
        {
          line_display_index_to_iter (layout, display, iter, 0, 0);
          goto out;
        }

      gtk_text_layout_free_line_display (layout, display);

      line = prev_line;
      display = gtk_text_layout_get_line_display (layout, prev_line, FALSE);
      update_byte = TRUE;
    }
  
  tmp_list = pango_layout_get_lines (display->layout);
  layout_line = tmp_list->data;

  if (update_byte)
    {
      line_byte = layout_line->start_index + layout_line->length;
    }
  
  if (line_byte < layout_line->length || !tmp_list->next) /* first line of paragraph */
    {
      GtkTextLine *prev_line;

      prev_line = _gtk_text_line_previous (line);
      while (prev_line)
        {
          gtk_text_layout_free_line_display (layout, display);

          display = gtk_text_layout_get_line_display (layout, prev_line, FALSE);

          if (display->height > 0)
            {
              tmp_list = g_slist_last (pango_layout_get_lines (display->layout));
              layout_line = tmp_list->data;

              line_display_index_to_iter (layout, display, iter,
                                          layout_line->start_index + layout_line->length, 0);
              break;
            }

          prev_line = _gtk_text_line_previous (prev_line);
        }

      if (prev_line == NULL)
 	line_display_index_to_iter (layout, display, iter, 0, 0);
    }
  else
    {
      gint prev_offset = layout_line->start_index;

      tmp_list = tmp_list->next;
      while (tmp_list)
        {
          layout_line = tmp_list->data;

          if (line_byte < layout_line->start_index + layout_line->length ||
              !tmp_list->next)
            {
 	      line_display_index_to_iter (layout, display, iter, prev_offset, 0);
              break;
            }

          prev_offset = layout_line->start_index;
          tmp_list = tmp_list->next;
        }
    }

 out:
  
  gtk_text_layout_free_line_display (layout, display);

  return
    !gtk_text_iter_equal (iter, &orig) &&
    !gtk_text_iter_is_end (iter);
}

/**
 * gtk_text_layout_move_iter_to_next_line:
 * @layout: a #GtkLayout
 * @iter:   a #GtkTextIter
 *
 * Move the iterator to the beginning of the next line. The
 * lines of a wrapped paragraph are treated as distinct for
 * this operation.
 **/
gboolean
gtk_text_layout_move_iter_to_next_line (GtkTextLayout *layout,
                                        GtkTextIter   *iter)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_byte;
  GtkTextIter orig;
  gboolean found = FALSE;
  gboolean found_after = FALSE;
  gboolean first = TRUE;

  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);

  orig = *iter;
  
  line = _gtk_text_iter_get_text_line (iter);

  while (line && !found_after)
    {
      GSList *tmp_list;

      display = gtk_text_layout_get_line_display (layout, line, FALSE);

      if (display->height == 0)
        goto next;
      
      if (first)
	{
	  line_byte = line_display_iter_to_index (layout, display, iter);
	  first = FALSE;
	}
      else
	line_byte = 0;
	
      tmp_list = pango_layout_get_lines (display->layout);
      while (tmp_list && !found_after)
        {
          PangoLayoutLine *layout_line = tmp_list->data;

          if (found)
            {
	      line_display_index_to_iter (layout, display, iter,
                                          layout_line->start_index, 0);
              found_after = TRUE;
            }
          else if (line_byte < layout_line->start_index + layout_line->length || !tmp_list->next)
            found = TRUE;
          
          tmp_list = tmp_list->next;
        }

    next:
      
      gtk_text_layout_free_line_display (layout, display);

      line = _gtk_text_line_next (line);
    }

  return
    !gtk_text_iter_equal (iter, &orig) &&
    !gtk_text_iter_is_end (iter);
}

/**
 * gtk_text_layout_move_iter_to_line_end:
 * @layout: a #GtkTextLayout
 * @direction: if negative, move to beginning of line, otherwise
               move to end of line.
 *
 * Move to the beginning or end of a display line.
 **/
gboolean
gtk_text_layout_move_iter_to_line_end (GtkTextLayout *layout,
                                       GtkTextIter   *iter,
                                       gint           direction)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_byte;
  GSList *tmp_list;
  GtkTextIter orig;
  
  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);

  orig = *iter;
  
  line = _gtk_text_iter_get_text_line (iter);
  display = gtk_text_layout_get_line_display (layout, line, FALSE);
  line_byte = line_display_iter_to_index (layout, display, iter);

  tmp_list = pango_layout_get_lines (display->layout);
  while (tmp_list)
    {
      PangoLayoutLine *layout_line = tmp_list->data;

      if (line_byte < layout_line->start_index + layout_line->length || !tmp_list->next)
        {
 	  line_display_index_to_iter (layout, display, iter,
 				      direction < 0 ? layout_line->start_index : layout_line->start_index + layout_line->length,
 				      0);

          /* FIXME: As a bad hack, we move back one position when we
	   * are inside a paragraph to avoid going to next line on a
	   * forced break not at whitespace. Real fix is to keep track
	   * of whether marks are at leading or trailing edge?  */
          if (direction > 0 && layout_line->length > 0 && !gtk_text_iter_ends_line (iter))
            gtk_text_iter_backward_char (iter);

          break;
        }
      
      tmp_list = tmp_list->next;
    }

  gtk_text_layout_free_line_display (layout, display);

  return
    !gtk_text_iter_equal (iter, &orig) &&
    !gtk_text_iter_is_end (iter);
}


/**
 * gtk_text_layout_iter_starts_line:
 * @layout: a #GtkTextLayout
 * @iter: iterator to test
 *
 * Tests whether an iterator is at the start of a display line.
 **/
gboolean
gtk_text_layout_iter_starts_line (GtkTextLayout       *layout,
                                  const GtkTextIter   *iter)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_byte;
  GSList *tmp_list;
  
  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (GTK_IS_TEXT_LAYOUT (layout), FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);

  line = _gtk_text_iter_get_text_line (iter);
  display = gtk_text_layout_get_line_display (layout, line, FALSE);
  line_byte = line_display_iter_to_index (layout, display, iter);

  tmp_list = pango_layout_get_lines (display->layout);
  while (tmp_list)
    {
      PangoLayoutLine *layout_line = tmp_list->data;

      if (line_byte < layout_line->start_index + layout_line->length ||
          !tmp_list->next)
        {
          /* We're located on this line or the para delimiters before
           * it
           */
          gtk_text_layout_free_line_display (layout, display);
          
          if (line_byte == layout_line->start_index)
            return TRUE;
          else
            return FALSE;
        }
      
      tmp_list = tmp_list->next;
    }

  g_assert_not_reached ();
  return FALSE;
}

void
gtk_text_layout_get_iter_at_line (GtkTextLayout  *layout,
                                  GtkTextIter    *iter,
                                  GtkTextLine    *line,
                                  gint            byte_offset)
{
  _gtk_text_btree_get_iter_at_line (_gtk_text_buffer_get_btree (layout->buffer),
                                    iter, line, byte_offset);
}


/**
 * gtk_text_layout_move_iter_to_x:
 * @layout: a #GtkTextLayout
 * @iter:   a #GtkTextIter
 * @x:      X coordinate
 *
 * Keeping the iterator on the same line of the layout, move it to the
 * specified X coordinate. The lines of a wrapped paragraph are
 * treated as distinct for this operation.
 **/
void
gtk_text_layout_move_iter_to_x (GtkTextLayout *layout,
                                GtkTextIter   *iter,
                                gint           x)
{
  GtkTextLine *line;
  GtkTextLineDisplay *display;
  gint line_byte;
  PangoLayoutIter *layout_iter;
  
  g_return_if_fail (layout != NULL);
  g_return_if_fail (GTK_IS_TEXT_LAYOUT (layout));
  g_return_if_fail (iter != NULL);

  line = _gtk_text_iter_get_text_line (iter);

  display = gtk_text_layout_get_line_display (layout, line, FALSE);
  line_byte = line_display_iter_to_index (layout, display, iter);

  layout_iter = pango_layout_get_iter (display->layout);

  do
    {
      PangoLayoutLine *layout_line = pango_layout_iter_get_line (layout_iter);

      if (line_byte < layout_line->start_index + layout_line->length ||
          pango_layout_iter_at_last_line (layout_iter))
        {
          PangoRectangle logical_rect;
          gint byte_index, trailing;
          gint x_offset = display->x_offset * PANGO_SCALE;

          pango_layout_iter_get_line_extents (layout_iter, NULL, &logical_rect);

          pango_layout_line_x_to_index (layout_line,
                                        x * PANGO_SCALE - x_offset - logical_rect.x,
                                        &byte_index, &trailing);

 	  line_display_index_to_iter (layout, display, iter, byte_index, trailing);

          break;
        }
    }
  while (pango_layout_iter_next_line (layout_iter));

  pango_layout_iter_free (layout_iter);
  
  gtk_text_layout_free_line_display (layout, display);
}

/**
 * gtk_text_layout_move_iter_visually:
 * @layout:  a #GtkTextLayout
 * @iter:    a #GtkTextIter
 * @count:   number of characters to move (negative moves left, positive moves right)
 *
 * Move the iterator a given number of characters visually, treating
 * it as the strong cursor position. If @count is positive, then the
 * new strong cursor position will be @count positions to the right of
 * the old cursor position. If @count is negative then the new strong
 * cursor position will be @count positions to the left of the old
 * cursor position.
 *
 * In the presence of bidirection text, the correspondence
 * between logical and visual order will depend on the direction
 * of the current run, and there may be jumps when the cursor
 * is moved off of the end of a run.
 **/

gboolean
gtk_text_layout_move_iter_visually (GtkTextLayout *layout,
                                    GtkTextIter   *iter,
                                    gint           count)
{
  GtkTextLineDisplay *display = NULL;
  GtkTextIter orig;
  
  g_return_val_if_fail (layout != NULL, FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);

  orig = *iter;
  
  while (count != 0)
    {
      GtkTextLine *line = _gtk_text_iter_get_text_line (iter);
      gint line_byte;
      gint extra_back = 0;

      int byte_count = _gtk_text_line_byte_count (line);

      int new_index;
      int new_trailing;

 
      if (!display)
	display = gtk_text_layout_get_line_display (layout, line, FALSE);
      line_byte = line_display_iter_to_index (layout, display, iter);

      if (count > 0)
        {
          pango_layout_move_cursor_visually (display->layout, line_byte, 0, 1, &new_index, &new_trailing);
          count--;
        }
      else
        {
          pango_layout_move_cursor_visually (display->layout, line_byte, 0, -1, &new_index, &new_trailing);
          count++;
        }

      /* We need to handle the preedit string specially. Well, we don't really need to
       * handle it specially, since hopefully calling gtk_im_context_reset() will
       * remove the preedit string; but if we start off in front of the preedit
       * string (logically) and end up in or on the back edge of the preedit string,
       * we should move the iter one place farther.
       */
      if (layout->preedit_len > 0 && display->insert_index >= 0)
	{
	  if (line_byte == display->insert_index + layout->preedit_len &&
	      new_index < display->insert_index + layout->preedit_len)
	    {
	      line_byte = display->insert_index;
	      extra_back = 1;
	    }
	}
      
      if (new_index < 0 || (new_index == 0 && extra_back))
        {
          line = _gtk_text_line_previous (line);

          if (!line)
            goto done;
          
 	  gtk_text_layout_free_line_display (layout, display);
 	  display = gtk_text_layout_get_line_display (layout, line, FALSE);
          new_index = _gtk_text_line_byte_count (line);
        }
      else if (new_index > byte_count)
        {
          line = _gtk_text_line_next (line);
          if (!line)
            goto done;

 	  gtk_text_layout_free_line_display (layout, display);
 	  display = gtk_text_layout_get_line_display (layout, line, FALSE);
          new_index = 0;
        }
      
       line_display_index_to_iter (layout, display, iter, new_index, new_trailing);
       if (extra_back)
	 gtk_text_iter_backward_char (iter);
    }

  gtk_text_layout_free_line_display (layout, display);

 done:
  
  return
    !gtk_text_iter_equal (iter, &orig) &&
    !gtk_text_iter_is_end (iter);
}

void
gtk_text_layout_spew (GtkTextLayout *layout)
{
#if 0
  GtkTextDisplayLine *iter;
  guint wrapped = 0;
  guint paragraphs = 0;
  GtkTextLine *last_line = NULL;

  iter = layout->line_list;
  while (iter != NULL)
    {
      if (iter->line != last_line)
        {
          printf ("%5u  paragraph (%p)\n", paragraphs, iter->line);
          ++paragraphs;
          last_line = iter->line;
        }

      printf ("  %5u  y: %d len: %d start: %d bytes: %d\n",
              wrapped, iter->y, iter->length, iter->byte_offset,
              iter->byte_count);

      ++wrapped;
      iter = iter->next;
    }

  printf ("Layout %s recompute\n",
          layout->need_recompute ? "needs" : "doesn't need");

  printf ("Layout pars: %u lines: %u size: %d x %d Screen width: %d\n",
          paragraphs, wrapped, layout->width,
          layout->height, layout->screen_width);
#endif
}