window.c

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            }
          window_adjust_pagetop (prev);
          window_adjust_pagetop (next);
        }
    }
  if (prev)
    prev->flags |= W_UpdateWindow;

  if (next)
    next->flags |= W_UpdateWindow;

  window->flags |= W_UpdateWindow;
  window_adjust_pagetop (window);
}

/* Tile all of the windows currently displayed in the global variable
   WINDOWS.  If argument STYLE is TILE_INTERNALS, tile windows displaying
   internal nodes as well, otherwise do not change the height of such
   windows. */
void
window_tile_windows (style)
     int style;
{
  WINDOW *win, *last_adjusted;
  int numwins, avail, per_win_height, leftover;
  int do_internals;

  numwins = avail = 0;
  do_internals = (style == TILE_INTERNALS);

  for (win = windows; win; win = win->next)
    if (do_internals || !win->node ||
        (win->node->flags & N_IsInternal) == 0)
      {
        avail += win->height;
        numwins++;
      }

  if (numwins <= 1 || !the_screen->height)
    return;

  /* Find the size for each window.  Divide the size of the usable portion
     of the screen by the number of windows. */
  per_win_height = avail / numwins;
  leftover = avail - (per_win_height * numwins);

  last_adjusted = (WINDOW *)NULL;
  for (win = windows; win; win = win->next)
    {
      if (do_internals || !win->node ||
          (win->node->flags & N_IsInternal) == 0)
        {
          last_adjusted = win;
          win->height = per_win_height;
        }
    }

  if (last_adjusted)
    last_adjusted->height += leftover;

  /* Readjust the first_row of every window in the chain. */
  for (win = windows; win; win = win->next)
    {
      if (win->prev)
        win->first_row = win->prev->first_row + win->prev->height + 1;

      window_adjust_pagetop (win);
      win->flags |= W_UpdateWindow;
    }
}

/* Toggle the state of line wrapping in WINDOW.  This can do a bit of fancy
   redisplay. */
void
window_toggle_wrap (window)
     WINDOW *window;
{
  if (window->flags & W_NoWrap)
    window->flags &= ~W_NoWrap;
  else
    window->flags |= W_NoWrap;

  if (window != the_echo_area)
    {
      char **old_starts;
      int old_lines, old_pagetop;

      old_starts = window->line_starts;
      old_lines = window->line_count;
      old_pagetop = window->pagetop;

      calculate_line_starts (window);

      /* Make sure that point appears within this window. */
      window_adjust_pagetop (window);

      /* If the pagetop hasn't changed maybe we can do some scrolling now
         to speed up the display.  Many of the line starts will be the same,
         so scrolling here is a very good optimization.*/
      if (old_pagetop == window->pagetop)
        display_scroll_line_starts
          (window, old_pagetop, old_starts, old_lines);
      maybe_free (old_starts);
    }
  window->flags |= W_UpdateWindow;
}

/* Set WINDOW to display NODE. */
void
window_set_node_of_window (window, node)
     WINDOW *window;
     NODE *node;
{
  window->node = node;
  window->pagetop = 0;
  window->point = 0;
  recalculate_line_starts (window);
  window->flags |= W_UpdateWindow;
  window_adjust_pagetop (window);
  window_make_modeline (window);
}

/* Delete WINDOW from the list of known windows.  If this window was the
   active window, make the next window in the chain be the active window.
   If the active window is the next or previous window, choose that window
   as the recipient of the extra space.  Otherwise, prefer the next window. */
void
window_delete_window (window)
     WINDOW *window;
{
  WINDOW *next, *prev, *window_to_fix;

  next = window->next;
  prev = window->prev;

  /* You cannot delete the only window or a permanent window. */
  if ((!next && !prev) || (window->flags & W_WindowIsPerm))
    return;

  if (next)
    next->prev = prev;

  if (!prev)
    windows = next;
  else
    prev->next = next;

  if (window->line_starts)
    free (window->line_starts);

  if (window->modeline)
    free (window->modeline);

  if (window == active_window)
    {
      /* If there isn't a next window, then there must be a previous one,
         since we cannot delete the last window.  If there is a next window,
         prefer to use that as the active window. */
      if (next)
        active_window = next;
      else
        active_window = prev;
    }

  if (next && active_window == next)
    window_to_fix = next;
  else if (prev && active_window == prev)
    window_to_fix = prev;
  else if (next)
    window_to_fix = next;
  else if (prev)
    window_to_fix = prev;
  else
    window_to_fix = windows;
    
  if (window_to_fix->first_row > window->first_row)
    {
      int diff;

      /* Try to adjust the visible part of the node so that as little
         text as possible has to move. */
      diff = window_to_fix->first_row - window->first_row;
      window_to_fix->first_row = window->first_row;

      window_to_fix->pagetop -= diff;
      if (window_to_fix->pagetop < 0)
        window_to_fix->pagetop = 0;
    }

  /* The `+ 1' is to offset the difference between the first_row locations.
     See the code in window_make_window (). */
  window_to_fix->height += window->height + 1;
  window_to_fix->flags |= W_UpdateWindow;

  free (window);
}

/* For every window in CHAIN, set the flags member to have FLAG set. */
void
window_mark_chain (chain, flag)
     WINDOW *chain;
     int flag;
{
  register WINDOW *win;

  for (win = chain; win; win = win->next)
    win->flags |= flag;
}

/* For every window in CHAIN, clear the flags member of FLAG. */
void
window_unmark_chain (chain, flag)
     WINDOW *chain;
     int flag;
{
  register WINDOW *win;

  for (win = chain; win; win = win->next)
    win->flags &= ~flag;
}

/* Return the number of characters it takes to display CHARACTER on the
   screen at HPOS. */
int
character_width (character, hpos)
     int character, hpos;
{
  int printable_limit = 127;
  int width = 1;

  if (ISO_Latin_p)
    printable_limit = 255;

  if (character > printable_limit)
    width = 3;
  else if (iscntrl (character))
    {
      switch (character)
        {
        case '\r':
        case '\n':
          width = the_screen->width - hpos;
          break;
        case '\t':
          width = ((hpos + 8) & 0xf8) - hpos;
          break;
        default:
          width = 2;
        }
    }
  else if (character == DEL)
    width = 2;

  return (width);
}

/* Return the number of characters it takes to display STRING on the screen
   at HPOS. */
int
string_width (string, hpos)
     char *string;
     int hpos;
{
  register int i, width, this_char_width;

  for (width = 0, i = 0; string[i]; i++)
    {
      this_char_width = character_width (string[i], hpos);
      width += this_char_width;
      hpos += this_char_width;
    }
  return (width);
}

/* Quickly guess the approximate number of lines to that NODE would
   take to display.  This really only counts carriage returns. */
int
window_physical_lines (node)
     NODE *node;
{
  register int i, lines;
  char *contents;

  if (!node)
    return (0);

  contents = node->contents;
  for (i = 0, lines = 1; i < node->nodelen; i++)
    if (contents[i] == '\n')
      lines++;

  return (lines);
}

/* Calculate a list of line starts for the node belonging to WINDOW.  The line
   starts are pointers to the actual text within WINDOW->NODE. */
void
calculate_line_starts (window)
     WINDOW *window;
{
  register int i, hpos;
  char **line_starts = (char **)NULL;
  int line_starts_index = 0, line_starts_slots = 0;
  int bump_index;
  NODE *node;

  window->line_starts = (char **)NULL;
  window->line_count = 0;
  node = window->node;

  if (!node)
    return;

  /* Grovel the node starting at the top, and for each line calculate the
     width of the characters appearing in that line.  Add each line start
     to our array. */
  i = 0;
  hpos = 0;
  bump_index = 0;

  while (i < node->nodelen)
    {
      char *line = node->contents + i;
      unsigned int cwidth, c;

      add_pointer_to_array (line, line_starts_index, line_starts,
                            line_starts_slots, 100, char *);
      if (bump_index)
        {
          i++;
          bump_index = 0;
        }

      while (1)
        {
          c = node->contents[i];
          cwidth = character_width (c, hpos);

          /* If this character fits within this line, just do the next one. */
          if ((hpos + cwidth) < window->width)
            {
              i++;
              hpos += cwidth;
              continue;
            }
          else
            {
              /* If this character would position the cursor at the start of
                 the next printed screen line, then do the next line. */
              if (c == '\n' || c == '\r' || c == '\t')
                {
                  i++;
                  hpos = 0;
                  break;
                }
              else
                {
                  /* This character passes the window width border.  Postion
                     the cursor after the printed character, but remember this
                     line start as where this character is.  A bit tricky. */

                  /* If this window doesn't wrap lines, proceed to the next
                     physical line here. */
                  if (window->flags & W_NoWrap)
                    {
                      hpos = 0;
                      while (i < node->nodelen && node->contents[i] != '\n')
                        i++;

                      if (node->contents[i] == '\n')
                        i++;
                    }
                  else
                    {
                      hpos = the_screen->width - hpos;
                      bump_index++;
                    }
                  break;
                }
            }
        }
    }
  window->line_starts = line_starts;
  window->line_count = line_starts_index;
}

/* Given WINDOW, recalculate the line starts for the node it displays. */
void
recalculate_line_starts (window)
     WINDOW *window;
{
  maybe_free (window->line_starts);
  calculate_line_starts (window);
}

/* Global variable control redisplay of scrolled windows.  If non-zero, it
   is the desired number of lines to scroll the window in order to make
   point visible.  A user might set this to 1 for smooth scrolling.  If
   set to zero, the line containing point is centered within the window. */
int window_scroll_step = 0;

/* Adjust the pagetop of WINDOW such that the cursor point will be visible. */
void
window_adjust_pagetop (window)
     WINDOW *window;
{
  register int line = 0;
  char *contents;

  if (!window->node)
    return;

  contents = window->node->contents;

  /* Find the first printed line start which is after WINDOW->point. */
  for (line = 0; line < window->line_count; line++)
    {
      char *line_start;

      line_start = window->line_starts[line];

      if ((line_start - contents) > window->point)
        break;
    }

  /* The line index preceding the line start which is past point is the
     one containing point. */
  line--;

  /* If this line appears in the current displayable page, do nothing.
     Otherwise, adjust the top of the page to make this line visible. */
  if ((line < window->pagetop) ||
      (line - window->pagetop > (window->height - 1)))
    {
      /* The user-settable variable "scroll-step" is used to attempt
         to make point visible, iff it is non-zero.  If that variable
         is zero, then the line containing point is centered within
         the window. */
      if (window_scroll_step < window->height)
        {
          if ((line < window->pagetop) &&
              ((window->pagetop - window_scroll_step) <= line))
            window->pagetop -= window_scroll_step;
          else if ((line - window->pagetop > (window->height - 1)) &&
                   ((line - (window->pagetop + window_scroll_step)
                     < window->height)))
            window->pagetop += window_scroll_step;
          else
            window->pagetop = line - ((window->height - 1) / 2);
        }
      else
        window->pagetop = line - ((window->height - 1) / 2);

      if (window->pagetop < 0)
        window->pagetop = 0;
      window->flags |= W_UpdateWindow;
    }
}

/* Return the index of the line containing point. */
int
window_line_of_point (window)
     WINDOW *window;
{
  register int i, start = 0;

  /* Try to optimize.  Check to see if point is past the pagetop for
     this window, and if so, start searching forward from there. */
  if ((window->pagetop > -1 && window->pagetop < window->line_count) &&
      (window->line_starts[window->pagetop] - window->node->contents)
      <= window->point)
    start = window->pagetop;

  for (i = start; i < window->line_count; i++)
    {
      if ((window->line_starts[i] - window->node->contents) > window->point)
        break;
    }

  return (i - 1);
}

/* Get and return the goal column for this window. */
int
window_get_goal_column (window)
     WINDOW *window;
{
  if (!window->node)
    return (-1);

  if (window->goal_column != -1)
    return (window->goal_column);

  /* Okay, do the work.  Find the printed offset of the cursor