pango-layout.c

Pango is a library for layout and rendering of text, with an emphasis on internationalization. Pang

	    }

	  pango_glyph_string_index_to_x (run->glyphs,
					 layout->text + run->item->offset,
					 run->item->length,
					 &run->item->analysis,
					 index - run->item->offset, trailing, x_pos);
	  if (x_pos)
	    *x_pos += width;

	  return;
	}

      width += pango_glyph_string_get_width (run->glyphs);

      run_list = run_list->next;
    }

  if (x_pos)
    *x_pos = width;
}

static PangoLayoutLine *
pango_layout_index_to_line (PangoLayout      *layout,
			    int               index,
			    int              *line_nr,
			    PangoLayoutLine **line_before,
			    PangoLayoutLine **line_after)
{
  GSList *tmp_list;
  GSList *line_list;
  PangoLayoutLine *line = NULL;
  PangoLayoutLine *prev_line = NULL;
  int i = -1;

  line_list = tmp_list = layout->lines;
  while (tmp_list)
    {
      PangoLayoutLine *tmp_line = tmp_list->data;

      if (tmp_line->start_index > index)
	break; /* index was in paragraph delimiters */

      prev_line = line;
      line = tmp_line;
      line_list = tmp_list;
      i++;

      if (line->start_index + line->length > index)
	break;

      tmp_list = tmp_list->next;
    }

  if (line_nr)
    *line_nr = i;

  if (line_before)
    *line_before = prev_line;

  if (line_after)
    *line_after = (line_list && line_list->next) ? line_list->next->data : NULL;

  return line;
}

static PangoLayoutLine *
pango_layout_index_to_line_and_extents (PangoLayout     *layout,
					int              index,
					PangoRectangle  *line_rect)
{
  PangoLayoutIter *iter;
  PangoLayoutLine *line = NULL;

  iter = pango_layout_get_iter (layout);

  if (!ITER_IS_INVALID (iter))
    while (TRUE)
      {
	PangoLayoutLine *tmp_line = _pango_layout_iter_get_line (iter);

	if (tmp_line->start_index > index)
	    break; /* index was in paragraph delimiters */

	line = tmp_line;

	pango_layout_iter_get_line_extents (iter, NULL, line_rect);

	if (line->start_index + line->length > index)
	  break;

	if (!pango_layout_iter_next_line (iter))
	  break; /* Use end of last line */
      }

  pango_layout_iter_free (iter);

  return line;
}

/**
 * pango_layout_index_to_line_x:
 * @layout:    a #PangoLayout
 * @index_:    the byte index of a grapheme within the layout.
 * @trailing:  an integer indicating the edge of the grapheme to retrieve the
 *             position of. If 0, the trailing edge of the grapheme, if > 0,
 *             the leading of the grapheme.
 * @line:      location to store resulting line index. (which will
 *             between 0 and pango_layout_get_line_count(layout) - 1)
 * @x_pos:     location to store resulting position within line
 *             (%PANGO_SCALE units per device unit)
 *
 * Converts from byte @index_ within the @layout to line and X position.
 * (X position is measured from the left edge of the line)
 */
void
pango_layout_index_to_line_x (PangoLayout *layout,
			      int          index,
			      gboolean     trailing,
			      int         *line,
			      int         *x_pos)
{
  int line_num;
  PangoLayoutLine *layout_line = NULL;

  g_return_if_fail (layout != NULL);
  g_return_if_fail (index >= 0);
  g_return_if_fail (index <= layout->length);

  pango_layout_check_lines (layout);

  layout_line = pango_layout_index_to_line (layout, index,
					    &line_num, NULL, NULL);

  if (layout_line)
    {
      /* use end of line if index was in the paragraph delimiters */
      if (index > layout_line->start_index + layout_line->length)
	index = layout_line->start_index + layout_line->length;

      if (line)
	*line = line_num;

      pango_layout_line_index_to_x (layout_line, index, trailing, x_pos);
    }
  else
    {
      if (line)
	*line = -1;
      if (x_pos)
	*x_pos = -1;
    }
}

/**
 * pango_layout_move_cursor_visually:
 * @layout:       a #PangoLayout.
 * @strong:       whether the moving cursor is the strong cursor or the
 *                weak cursor. The strong cursor is the cursor corresponding
 *                to text insertion in the base direction for the layout.
 * @old_index:    the byte index of the grapheme for the old index
 * @old_trailing: if 0, the cursor was at the trailing edge of the
 *                grapheme indicated by @old_index, if > 0, the cursor
 *                was at the leading edge.
 * @direction:    direction to move cursor. A negative
 *                value indicates motion to the left.
 * @new_index:    location to store the new cursor byte index. A value of -1
 *                indicates that the cursor has been moved off the beginning
 *                of the layout. A value of %G_MAXINT indicates that
 *                the cursor has been moved off the end of the layout.
 * @new_trailing: number of characters to move forward from the location returned
 *                for @new_index to get the position where the cursor should
 *                be displayed. This allows distinguishing the position at
 *                the beginning of one line from the position at the end
 *                of the preceding line. @new_index is always on the line
 *                where the cursor should be displayed.
 *
 * Computes a new cursor position from an old position and
 * a count of positions to move visually. If @direction is positive,
 * then the new strong cursor position will be one position
 * to the right of the old cursor position. If @direction is negative,
 * then the new strong cursor position will be one position
 * to the left of the old cursor position.
 *
 * In the presence of bidirectional 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.
 *
 * Motion here is in cursor positions, not in characters, so a
 * single call to pango_layout_move_cursor_visually() may move the
 * cursor over multiple characters when multiple characters combine
 * to form a single grapheme.
 **/
void
pango_layout_move_cursor_visually (PangoLayout *layout,
				   gboolean     strong,
				   int          old_index,
				   int          old_trailing,
				   int          direction,
				   int         *new_index,
				   int         *new_trailing)
{
  PangoLayoutLine *line = NULL;
  PangoLayoutLine *prev_line;
  PangoLayoutLine *next_line;

  int *log2vis_map;
  int *vis2log_map;
  int n_vis;
  int vis_pos, vis_pos_old, log_pos;
  int start_offset;
  gboolean off_start = FALSE;
  gboolean off_end = FALSE;

  g_return_if_fail (layout != NULL);
  g_return_if_fail (old_index >= 0 && old_index <= layout->length);
  g_return_if_fail (old_index < layout->length || old_trailing == 0);
  g_return_if_fail (new_index != NULL);
  g_return_if_fail (new_trailing != NULL);

  direction = (direction >= 0 ? 1 : -1);

  pango_layout_check_lines (layout);

  /* Find the line the old cursor is on */
  line = pango_layout_index_to_line (layout, old_index,
				     NULL, &prev_line, &next_line);

  start_offset = g_utf8_pointer_to_offset (layout->text, layout->text + line->start_index);

  while (old_trailing--)
    old_index = g_utf8_next_char (layout->text + old_index) - layout->text;

  log2vis_map = pango_layout_line_get_log2vis_map (line, strong);
  n_vis = g_utf8_strlen (layout->text + line->start_index, line->length);

  /* Clamp old_index to fit on the line */
  if (old_index > (line->start_index + line->length))
    old_index = line->start_index + line->length;

  vis_pos = log2vis_map[old_index - line->start_index];

  g_free (log2vis_map);

  /* Handling movement between lines */
  if (vis_pos == 0 && direction < 0)
    {
      if (line->resolved_dir == PANGO_DIRECTION_LTR)
	off_start = TRUE;
      else
	off_end = TRUE;
    }
  else if (vis_pos == n_vis && direction > 0)
    {
      if (line->resolved_dir == PANGO_DIRECTION_LTR)
	off_end = TRUE;
      else
	off_start = TRUE;
    }

  if (off_start || off_end)
    {
      /* If we move over a paragraph boundary, count that as
       * an extra position in the motion
       */
      gboolean paragraph_boundary;

      if (off_start)
	{
	  if (!prev_line)
	    {
	      *new_index = -1;
	      *new_trailing = 0;
	      return;
	    }
	  line = prev_line;
	  paragraph_boundary = (line->start_index + line->length != old_index);
	}
      else
	{
	  if (!next_line)
	    {
	      *new_index = G_MAXINT;
	      *new_trailing = 0;
	      return;
	    }
	  line = next_line;
	  paragraph_boundary = (line->start_index != old_index);
	}

      n_vis = g_utf8_strlen (layout->text + line->start_index, line->length);
      start_offset = g_utf8_pointer_to_offset (layout->text, layout->text + line->start_index);

      if (vis_pos == 0 && direction < 0)
	{
	  vis_pos = n_vis;
	  if (paragraph_boundary)
	    vis_pos++;
	}
      else /* (vis_pos == n_vis && direction > 0) */
	{
	  vis_pos = 0;
	  if (paragraph_boundary)
	    vis_pos--;
	}
    }

  vis2log_map = pango_layout_line_get_vis2log_map (line, strong);

  vis_pos_old = vis_pos + direction;
  log_pos = g_utf8_pointer_to_offset (layout->text + line->start_index,
				      layout->text + line->start_index + vis2log_map[vis_pos_old]);
  do
    {
      vis_pos += direction;
      log_pos += g_utf8_pointer_to_offset (layout->text + line->start_index + vis2log_map[vis_pos_old],
					   layout->text + line->start_index + vis2log_map[vis_pos]);
      vis_pos_old = vis_pos;
    }
  while (vis_pos > 0 && vis_pos < n_vis &&
	 !layout->log_attrs[start_offset + log_pos].is_cursor_position);

  *new_index = line->start_index + vis2log_map[vis_pos];
  g_free (vis2log_map);

  *new_trailing = 0;

  if (*new_index == line->start_index + line->length && line->length > 0)
    {
      do
	{
	  log_pos--;
	  *new_index = g_utf8_prev_char (layout->text + *new_index) - layout->text;
	  (*new_trailing)++;
	}
      while (log_pos > 0 && !layout->log_attrs[start_offset + log_pos].is_cursor_position);
    }
}

/**
 * pango_layout_xy_to_index:
 * @layout:    a #PangoLayout
 * @x:         the X offset (in Pango units)
 *             from the left edge of the layout.
 * @y:         the Y offset (in Pango units)
 *             from the top edge of the layout
 * @index_:    location to store calculated byte index
 * @trailing:  location to store a integer indicating where
 *             in the grapheme the user clicked. It will either
 *             be zero, or the number of characters in the
 *             grapheme. 0 represents the trailing edge of the grapheme.
 *
 * Converts from X and Y position within a layout to the byte
 * index to the character at that logical position. If the
 * Y position is not inside the layout, the closest position is chosen
 * (the position will be clamped inside the layout). If the
 * X position is not within the layout, then the start or the
 * end of the line is chosen as  described for pango_layout_x_to_index().
 * If either the X or Y positions were not inside the layout, then the
 * function returns %FALSE; on an exact hit, it returns %TRUE.
 *
 * Return value: %TRUE if the coordinates were inside text, %FALSE otherwise.
 **/
gboolean
pango_layout_xy_to_index (PangoLayout *layout,
			  int          x,
			  int          y,
			  int         *index,
			  gint        *trailing)
{
  PangoLayoutIter *iter;
  PangoLayoutLine *prev_line = NULL;
  PangoLayoutLine *found = NULL;
  int found_line_x = 0;
  int prev_last = 0;
  int prev_line_x = 0;
  gboolean retval = FALSE;
  gboolean outside = FALSE;

  g_return_val_if_fail (PANGO_IS_LAYOUT (layout), FALSE);

  iter = pango_layout_get_iter (layout);

  do
    {
      PangoRectangle line_logical;
      int first_y, last_y;

      pango_layout_iter_get_line_extents (iter, NULL, &line_logical);
      pango_layout_iter_get_line_yrange (iter, &first_y, &last_y);

      if (y < first_y)
	{
	  if (prev_line && y < (prev_last + (first_y - prev_last) / 2))
	    {
	      found = prev_line;
	      found_line_x = prev_line_x;
	    }
	  else
	    {
	      if (prev_line == NULL)
		outside = TRUE; /* off the top */

	      found = _pango_layout_iter_get_line (iter);
	      found_line_x = x - line_logical.x;
	    }
	}
      else if (y >= first_y &&
	       y < last_y)
	{
	  found = _pango_layout_iter_get_line (iter);
	  found_line_x = x - line_logical.x;
	}

      prev_line = _pango_layout_iter_get_line (iter);
      prev_last = last_y;
      prev_line_x = x - line_logical.x;

      if (found != NULL)
	break;
    }
  while (pango_layout_iter_next_line (iter));

  pango_layout_iter_free (iter);

  if (found == NULL)
    {
      /* Off the bottom of the layout */
      outside = TRUE;

      found = prev_line;
      found_line_x = prev_line_x;
    }

  retval = pango_layout_line_x_to_index (found,
					 found_line_x,
					 index, trailing);

  if (outside)
    retval = FALSE;

  return retval;
}

/**
 * pango_layout_index_to_pos:
 * @layout: a #PangoLayout
 * @index_: byte index within @layout
 * @pos: rectangle in which to store the position of the grapheme
 *
 * Converts from an index within a #PangoLayout to the onscreen position
 * corresponding to the grapheme at that index, which is represented
 * as rectangle.  Note that <literal>pos->x</literal> is always the leading
 * edge of the grapheme and <literal>pos->x + pos->width</literal> the trailing
 * edge of the grapheme. If the directionality of the grapheme is right-to-left,
 * then <literal>pos->width</literal> will be negative.
 **/
void
pango_layout_index_to_pos (PangoLayout    *layout,
			   int             index,
			   PangoRectangle *pos)
{
  PangoRectangle logical_rect;
  PangoLayoutIter *iter;
  PangoLayoutLine *layout_line = NULL;
  int x_pos;

  g_return_if_fail (layout != NULL);
  g_return_if_fail (index >= 0);
  g_return_if_fail (pos != NULL);

  iter = pango_layout_get_iter (layout);

  if (!ITER_IS_INVALID (iter))
    {
      while (TRUE)
	{
	  PangoLayoutLine *tmp_line = _pango_layout_iter_get_line (iter);

	  if (tmp_line->start_index > index)
	    {
	      /* index is in the paragraph delimiters, move to
	       * end of previous line
	       */
	      index = layout_line->start_index + layout_line->length;
	      break;
	    }

	  layout_line = tmp_line;

	  pango_layout_iter_get_line_extents (iter, NULL, &logical_rect);