window.c

/* Window creation, deletion and examination for GNU Emacs.
   Does not include redisplay.
   Copyright (C) 1985-1987, 1993-1998, 2000-2012
                 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>
#include <stdio.h>
#include <setjmp.h>

#include "lisp.h"
#include "character.h"
#include "buffer.h"
#include "keyboard.h"
#include "keymap.h"
#include "frame.h"
#include "window.h"
#include "commands.h"
#include "indent.h"
#include "termchar.h"
#include "disptab.h"
#include "dispextern.h"
#include "blockinput.h"
#include "intervals.h"
#include "termhooks.h"		/* For FRAME_TERMINAL.  */

#ifdef HAVE_X_WINDOWS
#include "xterm.h"
#endif	/* HAVE_X_WINDOWS */
#ifdef WINDOWSNT
#include "w32term.h"
#endif
#ifdef MSDOS
#include "msdos.h"
#endif
#ifdef HAVE_NS
#include "nsterm.h"
#endif

Lisp_Object Qwindowp, Qwindow_live_p;
static Lisp_Object Qwindow_configuration_p, Qrecord_window_buffer;
static Lisp_Object Qwindow_deletable_p, Qdelete_window, Qdisplay_buffer;
static Lisp_Object Qreplace_buffer_in_windows, Qget_mru_window;
static Lisp_Object Qwindow_resize_root_window, Qwindow_resize_root_window_vertically;
static Lisp_Object Qscroll_up, Qscroll_down, Qscroll_command;
static Lisp_Object Qsafe, Qabove, Qbelow;
static Lisp_Object Qauto_buffer_name, Qclone_of;

static int displayed_window_lines (struct window *);
static struct window *decode_window (Lisp_Object);
static int count_windows (struct window *);
static int get_leaf_windows (struct window *, struct window **, int);
static void window_scroll (Lisp_Object, EMACS_INT, int, int);
static void window_scroll_pixel_based (Lisp_Object, int, int, int);
static void window_scroll_line_based (Lisp_Object, int, int, int);
static int freeze_window_start (struct window *, void *);
static Lisp_Object window_list (void);
static int add_window_to_list (struct window *, void *);
static int candidate_window_p (Lisp_Object, Lisp_Object, Lisp_Object,
                               Lisp_Object);
static Lisp_Object next_window (Lisp_Object, Lisp_Object,
                                Lisp_Object, int);
static void decode_next_window_args (Lisp_Object *, Lisp_Object *,
                                     Lisp_Object *);
static void foreach_window (struct frame *,
				 int (* fn) (struct window *, void *),
                            void *);
static int foreach_window_1 (struct window *,
                             int (* fn) (struct window *, void *),
                             void *);
static Lisp_Object window_list_1 (Lisp_Object, Lisp_Object, Lisp_Object);
static int window_resize_check (struct window *, int);
static void window_resize_apply (struct window *, int);
static Lisp_Object select_window (Lisp_Object, Lisp_Object, int);

/* This is the window in which the terminal's cursor should
   be left when nothing is being done with it.  This must
   always be a leaf window, and its buffer is selected by
   the top level editing loop at the end of each command.

   This value is always the same as
   FRAME_SELECTED_WINDOW (selected_frame).  */
Lisp_Object selected_window;

/* A list of all windows for use by next_window and Fwindow_list.
   Functions creating or deleting windows should invalidate this cache
   by setting it to nil.  */
Lisp_Object Vwindow_list;

/* The mini-buffer window of the selected frame.
   Note that you cannot test for mini-bufferness of an arbitrary window
   by comparing against this; but you can test for mini-bufferness of
   the selected window.  */
Lisp_Object minibuf_window;

/* Non-nil means it is the window whose mode line should be
   shown as the selected window when the minibuffer is selected.  */
Lisp_Object minibuf_selected_window;

/* Hook run at end of temp_output_buffer_show.  */
static Lisp_Object Qtemp_buffer_show_hook;

/* Incremented for each window created.  */
static int sequence_number;

/* Nonzero after init_window_once has finished.  */
static int window_initialized;

/* Hook to run when window config changes.  */
static Lisp_Object Qwindow_configuration_change_hook;

/* Used by the function window_scroll_pixel_based */
static int window_scroll_pixel_based_preserve_x;
static int window_scroll_pixel_based_preserve_y;

/* Same for window_scroll_line_based.  */
static EMACS_INT window_scroll_preserve_hpos;
static EMACS_INT window_scroll_preserve_vpos;

static struct window *
decode_window (register Lisp_Object window)
{
  if (NILP (window))
    return XWINDOW (selected_window);

  CHECK_LIVE_WINDOW (window);
  return XWINDOW (window);
}

static struct window *
decode_any_window (register Lisp_Object window)
{
  struct window *w;

  if (NILP (window))
    return XWINDOW (selected_window);

  CHECK_WINDOW (window);
  w = XWINDOW (window);
  /* The following test throws up every time a tooltip frame is displayed.  */
  /* CHECK_LIVE_FRAME (w->frame); */
  return w;
}

DEFUN ("windowp", Fwindowp, Swindowp, 1, 1, 0,
       doc: /* Return t if OBJECT is a window and nil otherwise.  */)
  (Lisp_Object object)
{
  return WINDOWP (object) ? Qt : Qnil;
}

DEFUN ("window-live-p", Fwindow_live_p, Swindow_live_p, 1, 1, 0,
       doc: /* Return t if OBJECT is a live window and nil otherwise.
A live window is a window that displays a buffer.
Internal windows and deleted windows are not live.  */)
  (Lisp_Object object)
{
  return WINDOW_LIVE_P (object) ? Qt : Qnil;
}

/* Frames and windows.  */
DEFUN ("window-frame", Fwindow_frame, Swindow_frame, 1, 1, 0,
       doc: /* Return the frame that window WINDOW is on.
If WINDOW is omitted or nil, it defaults to the selected window.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), frame);
}

DEFUN ("frame-root-window", Fframe_root_window, Sframe_root_window, 0, 1, 0,
       doc: /* Return the root window of FRAME-OR-WINDOW.
If omitted, FRAME-OR-WINDOW defaults to the currently selected frame.
With a frame argument, return that frame's root window.
With a window argument, return the root window of that window's frame.  */)
  (Lisp_Object frame_or_window)
{
  Lisp_Object window;

  if (NILP (frame_or_window))
    window = FVAR (SELECTED_FRAME (), root_window);
  else if (WINDOWP (frame_or_window))
    window = FVAR (XFRAME (WINDOW_FRAME (XWINDOW (frame_or_window))), root_window);
  else
    {
      CHECK_LIVE_FRAME (frame_or_window);
      window = FVAR (XFRAME (frame_or_window), root_window);
    }

  return window;
}

DEFUN ("minibuffer-window", Fminibuffer_window, Sminibuffer_window, 0, 1, 0,
       doc: /* Return the minibuffer window for frame FRAME.
If FRAME is omitted or nil, it defaults to the selected frame.  */)
  (Lisp_Object frame)
{
  if (NILP (frame))
    frame = selected_frame;
  CHECK_LIVE_FRAME (frame);
  return FRAME_MINIBUF_WINDOW (XFRAME (frame));
}

DEFUN ("window-minibuffer-p", Fwindow_minibuffer_p,
       Swindow_minibuffer_p, 0, 1, 0,
       doc: /* Return non-nil if WINDOW is a minibuffer window.
If WINDOW is omitted or nil, it defaults to the selected window.  */)
  (Lisp_Object window)
{
  return MINI_WINDOW_P (decode_any_window (window)) ? Qt : Qnil;
}

/* Don't move this to window.el - this must be a safe routine.  */
DEFUN ("frame-first-window", Fframe_first_window, Sframe_first_window, 0, 1, 0,
       doc: /* Return the topmost, leftmost live window on FRAME-OR-WINDOW.
If omitted, FRAME-OR-WINDOW defaults to the currently selected frame.
Else if FRAME-OR-WINDOW denotes any window, return the first window of
that window's frame.  If FRAME-OR-WINDOW denotes a live frame, return
the first window of that frame.  */)
  (Lisp_Object frame_or_window)
{
  Lisp_Object window;

  if (NILP (frame_or_window))
    window = FVAR (SELECTED_FRAME (), root_window);
  else if (WINDOWP (frame_or_window))
    window = FVAR (XFRAME (WINDOW_FRAME (XWINDOW (frame_or_window))), root_window);
  else
    {
      CHECK_LIVE_FRAME (frame_or_window);
      window = FVAR (XFRAME (frame_or_window), root_window);
    }

  while (NILP (WVAR (XWINDOW (window), buffer)))
    {
      if (! NILP (WVAR (XWINDOW (window), hchild)))
	window = WVAR (XWINDOW (window), hchild);
      else if (! NILP (WVAR (XWINDOW (window), vchild)))
	window = WVAR (XWINDOW (window), vchild);
      else
	abort ();
    }

  return window;
}

DEFUN ("frame-selected-window", Fframe_selected_window,
       Sframe_selected_window, 0, 1, 0,
       doc: /* Return the selected window of FRAME-OR-WINDOW.
If omitted, FRAME-OR-WINDOW defaults to the currently selected frame.
Else if FRAME-OR-WINDOW denotes any window, return the selected window
of that window's frame.  If FRAME-OR-WINDOW denotes a live frame, return
the selected window of that frame.  */)
  (Lisp_Object frame_or_window)
{
  Lisp_Object window;

  if (NILP (frame_or_window))
    window = FVAR (SELECTED_FRAME (), selected_window);
  else if (WINDOWP (frame_or_window))
    window = FVAR (XFRAME (WINDOW_FRAME (XWINDOW (frame_or_window))),
                  selected_window);
  else
    {
      CHECK_LIVE_FRAME (frame_or_window);
      window = FVAR (XFRAME (frame_or_window), selected_window);
    }

  return window;
}

DEFUN ("set-frame-selected-window", Fset_frame_selected_window,
       Sset_frame_selected_window, 2, 3, 0,
       doc: /* Set selected window of FRAME to WINDOW.
FRAME must be a live frame and defaults to the selected one.  If FRAME
is the selected frame, this makes WINDOW the selected window.  Optional
argument NORECORD non-nil means to neither change the order of recently
selected windows nor the buffer list.  WINDOW must denote a live window.
Return WINDOW.  */)
  (Lisp_Object frame, Lisp_Object window, Lisp_Object norecord)
{
  if (NILP (frame))
    frame = selected_frame;

  CHECK_LIVE_FRAME (frame);
  CHECK_LIVE_WINDOW (window);

  if (! EQ (frame, WINDOW_FRAME (XWINDOW (window))))
    error ("In `set-frame-selected-window', WINDOW is not on FRAME");

  if (EQ (frame, selected_frame))
    return Fselect_window (window, norecord);
  else
    return FVAR (XFRAME (frame), selected_window) = window;
}

DEFUN ("selected-window", Fselected_window, Sselected_window, 0, 0, 0,
       doc: /* Return the selected window.
The selected window is the window in which the standard cursor for
selected windows appears and to which many commands apply.  */)
  (void)
{
  return selected_window;
}

int window_select_count;

/* If select_window is called with inhibit_point_swap non-zero it will
   not store point of the old selected window's buffer back into that
   window's pointm slot.  This is needed by Fset_window_configuration to
   avoid that the display routine is called with selected_window set to
   Qnil causing a subsequent crash.  */
static Lisp_Object
select_window (Lisp_Object window, Lisp_Object norecord, int inhibit_point_swap)
{
  register struct window *w;
  register struct window *ow;
  struct frame *sf;

  CHECK_LIVE_WINDOW (window);

  w = XWINDOW (window);
  w->frozen_window_start_p = 0;

  if (NILP (norecord))
    {
      w->use_time = ++window_select_count;
      record_buffer (WVAR (w, buffer));
    }

  if (EQ (window, selected_window) && !inhibit_point_swap)
    return window;

  sf = SELECTED_FRAME ();
  if (XFRAME (WINDOW_FRAME (w)) != sf)
    {
      FVAR (XFRAME (WINDOW_FRAME (w)), selected_window) = window;
      /* Use this rather than Fhandle_switch_frame
	 so that FRAME_FOCUS_FRAME is moved appropriately as we
	 move around in the state where a minibuffer in a separate
	 frame is active.  */
      Fselect_frame (WINDOW_FRAME (w), norecord);
      /* Fselect_frame called us back so we've done all the work already.  */
      eassert (EQ (window, selected_window));
      return window;
    }
  else
    FVAR (sf, selected_window) = window;

  /* Store the current buffer's actual point into the
     old selected window.  It belongs to that window,
     and when the window is not selected, must be in the window.  */
  if (!inhibit_point_swap)
    {
      ow = XWINDOW (selected_window);
      if (! NILP (WVAR (ow, buffer)))
	set_marker_both (WVAR (ow, pointm), WVAR (ow, buffer),
			 BUF_PT (XBUFFER (WVAR (ow, buffer))),
			 BUF_PT_BYTE (XBUFFER (WVAR (ow, buffer))));
    }

  selected_window = window;

  Fset_buffer (WVAR (w, buffer));

  BVAR (XBUFFER (WVAR (w, buffer)), last_selected_window) = window;

  /* Go to the point recorded in the window.
     This is important when the buffer is in more
     than one window.  It also matters when
     redisplay_window has altered point after scrolling,
     because it makes the change only in the window.  */
  {
    register ptrdiff_t new_point = marker_position (WVAR (w, pointm));
    if (new_point < BEGV)
      SET_PT (BEGV);
    else if (new_point > ZV)
      SET_PT (ZV);
    else
      SET_PT (new_point);
  }

  windows_or_buffers_changed++;
  return window;
}

DEFUN ("select-window", Fselect_window, Sselect_window, 1, 2, 0,
       doc: /* Select WINDOW.  Most editing will apply to WINDOW's buffer.
Also make WINDOW's buffer current and make WINDOW the frame's selected
window.  Return WINDOW.

Optional second arg NORECORD non-nil means do not put this buffer at the
front of the buffer list and do not make this window the most recently
selected one.

Note that the main editor command loop sets the current buffer to the
buffer of the selected window before each command.  */)
  (register Lisp_Object window, Lisp_Object norecord)
{
  return select_window (window, norecord, 0);
}

DEFUN ("window-buffer", Fwindow_buffer, Swindow_buffer, 0, 1, 0,
       doc: /* Return the buffer displayed in window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
Return nil for an internal window or a deleted window.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), buffer);
}

DEFUN ("window-parent", Fwindow_parent, Swindow_parent, 0, 1, 0,
       doc: /* Return the parent window of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
Return nil for a window with no parent (e.g. a root window).  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), parent);
}

DEFUN ("window-top-child", Fwindow_top_child, Swindow_top_child, 1, 1, 0,
       doc: /* Return the topmost child window of window WINDOW.
Return nil if WINDOW is a live window (live windows have no children).
Return nil if WINDOW is an internal window whose children form a
horizontal combination.  */)
  (Lisp_Object window)
{
  CHECK_WINDOW (window);
  return WVAR (decode_any_window (window), vchild);
}

DEFUN ("window-left-child", Fwindow_left_child, Swindow_left_child, 1, 1, 0,
       doc: /* Return the leftmost child window of window WINDOW.
Return nil if WINDOW is a live window (live windows have no children).
Return nil if WINDOW is an internal window whose children form a
vertical combination.  */)
  (Lisp_Object window)
{
  CHECK_WINDOW (window);
  return WVAR (decode_any_window (window), hchild);
}

DEFUN ("window-next-sibling", Fwindow_next_sibling, Swindow_next_sibling, 0, 1, 0,
       doc: /* Return the next sibling window of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
Return nil if WINDOW has no next sibling.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), next);
}

DEFUN ("window-prev-sibling", Fwindow_prev_sibling, Swindow_prev_sibling, 0, 1, 0,
       doc: /* Return the previous sibling window of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
Return nil if WINDOW has no previous sibling.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), prev);
}

DEFUN ("window-combination-limit", Fwindow_combination_limit, Swindow_combination_limit, 1, 1, 0,
       doc: /* Return combination limit of window WINDOW.
If the return value is nil, child windows of WINDOW can be recombined with
WINDOW's siblings.  A return value of t means that child windows of
WINDOW are never \(re-)combined with WINDOW's siblings.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), combination_limit);
}

DEFUN ("set-window-combination-limit", Fset_window_combination_limit, Sset_window_combination_limit, 2, 2, 0,
       doc: /* Set combination limit of window WINDOW to LIMIT; return LIMIT.
If LIMIT is nil, child windows of WINDOW can be recombined with
WINDOW's siblings.  LIMIT t means that child windows of WINDOW are
never \(re-)combined with WINDOW's siblings.  Other values are reserved
for future use.  */)
  (Lisp_Object window, Lisp_Object limit)
{
  register struct window *w = decode_any_window (window);
  WVAR (w, combination_limit) = limit;
  return WVAR (w, combination_limit);
}

DEFUN ("window-use-time", Fwindow_use_time, Swindow_use_time, 0, 1, 0,
       doc: /* Return the use time of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
The window with the highest use time is the most recently selected
one.  The window with the lowest use time is the least recently
selected one.  */)
  (Lisp_Object window)
{
  return make_number (decode_window (window)->use_time);
}

DEFUN ("window-total-height", Fwindow_total_height, Swindow_total_height, 0, 1, 0,
       doc: /* Return the total height, in lines, of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.

The return value includes the mode line and header line, if any.
If WINDOW is an internal window, the total height is the height
of the screen areas spanned by its children.

On a graphical display, this total height is reported as an
integer multiple of the default character height.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), total_lines);
}

DEFUN ("window-total-width", Fwindow_total_width, Swindow_total_width, 0, 1, 0,
       doc: /* Return the total width, in columns, of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.

The return value includes any vertical dividers or scroll bars
belonging to WINDOW.  If WINDOW is an internal window, the total width
is the width of the screen areas spanned by its children.

On a graphical display, this total width is reported as an
integer multiple of the default character width.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), total_cols);
}

DEFUN ("window-new-total", Fwindow_new_total, Swindow_new_total, 0, 1, 0,
       doc: /* Return the new total size of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.   */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), new_total);
}

DEFUN ("window-normal-size", Fwindow_normal_size, Swindow_normal_size, 0, 2, 0,
       doc: /* Return the normal height of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.
If HORIZONTAL is non-nil, return the normal width of WINDOW.  */)
  (Lisp_Object window, Lisp_Object horizontal)
{
  if (NILP (horizontal))
    return WVAR (decode_any_window (window), normal_lines);
  else
    return WVAR (decode_any_window (window), normal_cols);
}

DEFUN ("window-new-normal", Fwindow_new_normal, Swindow_new_normal, 0, 1, 0,
       doc: /* Return new normal size of window WINDOW.
If WINDOW is omitted or nil, it defaults to the selected window.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), new_normal);
}

DEFUN ("window-left-column", Fwindow_left_column, Swindow_left_column, 0, 1, 0,
       doc: /* Return left column of window WINDOW.
This is the distance, in columns, between the left edge of WINDOW and
the left edge of the frame's window area.  For instance, the return
value is 0 if there is no window to the left of WINDOW.

If WINDOW is omitted or nil, it defaults to the selected window.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), left_col);
}

DEFUN ("window-top-line", Fwindow_top_line, Swindow_top_line, 0, 1, 0,
       doc: /* Return top line of window WINDOW.
This is the distance, in lines, between the top of WINDOW and the top
of the frame's window area.  For instance, the return value is 0 if
there is no window above WINDOW.

If WINDOW is omitted or nil, it defaults to the selected window.  */)
  (Lisp_Object window)
{
  return WVAR (decode_any_window (window), top_line);
}

/* Return the number of lines of W's body.  Don't count any mode or
   header line of W.  */

static int
window_body_lines (struct window *w)
{
  int height = XFASTINT (WVAR (w, total_lines));

  if (!MINI_WINDOW_P (w))
    {
      if (WINDOW_WANTS_MODELINE_P (w))
	--height;
      if (WINDOW_WANTS_HEADER_LINE_P (w))
	--height;
    }

  return height;
}

/* Return the number of columns of W's body.  Don't count columns
   occupied by the scroll bar or the vertical bar separating W from its
   right sibling.  On window-systems don't count fringes or display
   margins either.  */

int
window_body_cols (struct window *w)
{
  struct frame *f = XFRAME (WINDOW_FRAME (w));
  int width = XINT (WVAR (w, total_cols));

  if (WINDOW_HAS_VERTICAL_SCROLL_BAR (w))
    /* Scroll bars occupy a few columns.  */
    width -= WINDOW_CONFIG_SCROLL_BAR_COLS (w);
  else if (!FRAME_WINDOW_P (f)
	   && !WINDOW_RIGHTMOST_P (w) && !WINDOW_FULL_WIDTH_P (w))
    /* The column of `|' characters separating side-by-side windows
       occupies one column only.  */
    width -= 1;

  if (FRAME_WINDOW_P (f))
    /* On window-systems, fringes and display margins cannot be
       used for normal text.  */
    width -= (WINDOW_FRINGE_COLS (w)
	      + WINDOW_LEFT_MARGIN_COLS (w)
	      + WINDOW_RIGHT_MARGIN_COLS (w));

  return width;
}

DEFUN ("window-body-height", Fwindow_body_height, Swindow_body_height, 0, 1, 0,
       doc: /* Return the height, in lines, of WINDOW's text area.
If WINDOW is omitted or nil, it defaults to the selected window.
Signal an error if the window is not live.

The returned height does not include the mode line or header line.
On a graphical display, the height is expressed as an integer multiple
of the default character height.  If a line at the bottom of the text
area is only partially visible, that counts as a whole line; to
exclude partially-visible lines, use `window-text-height'.  */)
  (Lisp_Object window)
{
  struct window *w = decode_window (window);
  return make_number (window_body_lines (w));
}

DEFUN ("window-body-width", Fwindow_body_width, Swindow_body_width, 0, 1, 0,
       doc: /* Return the width, in columns, of WINDOW's text area.
If WINDOW is omitted or nil, it defaults to the selected window.
Signal an error if the window is not live.

The return value does not include any vertical dividers, fringe or
marginal areas, or scroll bars.  On a graphical display, the width is
expressed as an integer multiple of the default character width.  */)
  (Lisp_Object window)
{
  struct window *w = decode_window (window);
  return make_number (window_body_cols (w));
}

DEFUN ("window-hscroll", Fwindow_hscroll, Swindow_hscroll, 0, 1, 0,
       doc: /* Return the number of columns by which WINDOW is scrolled from left margin.
WINDOW must be a live window and defaults to the selected one.  */)
  (Lisp_Object window)
{
  return make_number (decode_window (window)->hscroll);
}

/* Set W's horizontal scroll amount to HSCROLL clipped to a reasonable
   range, returning the new amount as a fixnum.  */
static Lisp_Object
set_window_hscroll (struct window *w, EMACS_INT hscroll)
{
  /* Horizontal scrolling has problems with large scroll amounts.
     It's too slow with long lines, and even with small lines the
     display can be messed up.  For now, though, impose only the limits
     required by the internal representation: horizontal scrolling must
     fit in fixnum (since it's visible to Elisp) and into ptrdiff_t
     (since it's stored in a ptrdiff_t).  */
  ptrdiff_t hscroll_max = min (MOST_POSITIVE_FIXNUM, PTRDIFF_MAX);
  ptrdiff_t new_hscroll = clip_to_bounds (0, hscroll, hscroll_max);

  /* Prevent redisplay shortcuts when changing the hscroll.  */
  if (w->hscroll != new_hscroll)
    XBUFFER (WVAR (w, buffer))->prevent_redisplay_optimizations_p = 1;

  w->hscroll = new_hscroll;
  return make_number (new_hscroll);
}

DEFUN ("set-window-hscroll", Fset_window_hscroll, Sset_window_hscroll, 2, 2, 0,
       doc: /* Set number of columns WINDOW is scrolled from left margin to NCOL.
If WINDOW is nil, the selected window is used.
Clip the number to a reasonable value if out of range.
Return the new number.  NCOL should be zero or positive.

Note that if `automatic-hscrolling' is non-nil, you cannot scroll the
window so that the location of point moves off-window.  */)
  (Lisp_Object window, Lisp_Object ncol)
{
  struct window *w = decode_window (window);

  CHECK_NUMBER (ncol);
  return set_window_hscroll (w, XINT (ncol));
}

DEFUN ("window-redisplay-end-trigger", Fwindow_redisplay_end_trigger,
       Swindow_redisplay_end_trigger, 0, 1, 0,
       doc: /* Return WINDOW's redisplay end trigger value.
WINDOW defaults to the selected window.
See `set-window-redisplay-end-trigger' for more information.  */)
  (Lisp_Object window)
{
  return WVAR (decode_window (window), redisplay_end_trigger);
}

DEFUN ("set-window-redisplay-end-trigger", Fset_window_redisplay_end_trigger,
       Sset_window_redisplay_end_trigger, 2, 2, 0,
       doc: /* Set WINDOW's redisplay end trigger value to VALUE.
VALUE should be a buffer position (typically a marker) or nil.
If it is a buffer position, then if redisplay in WINDOW reaches a position
beyond VALUE, the functions in `redisplay-end-trigger-functions' are called
with two arguments: WINDOW, and the end trigger value.
Afterwards the end-trigger value is reset to nil.  */)
  (register Lisp_Object window, Lisp_Object value)
{
  register struct window *w;

  w = decode_window (window);
  WVAR (w, redisplay_end_trigger) = value;
  return value;
}

DEFUN ("window-edges", Fwindow_edges, Swindow_edges, 0, 1, 0,
       doc: /* Return a list of the edge coordinates of WINDOW.
The list has the form (LEFT TOP RIGHT BOTTOM).
TOP and BOTTOM count by lines, and LEFT and RIGHT count by columns,
all relative to 0, 0 at top left corner of frame.

RIGHT is one more than the rightmost column occupied by WINDOW.
BOTTOM is one more than the bottommost row occupied by WINDOW.
The edges include the space used by WINDOW's scroll bar, display
margins, fringes, header line, and/or mode line.  For the edges of
just the text area, use `window-inside-edges'.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_any_window (window);

  return Fcons (make_number (WINDOW_LEFT_EDGE_COL (w)),
	 Fcons (make_number (WINDOW_TOP_EDGE_LINE (w)),
	 Fcons (make_number (WINDOW_RIGHT_EDGE_COL (w)),
	 Fcons (make_number (WINDOW_BOTTOM_EDGE_LINE (w)),
		Qnil))));
}

DEFUN ("window-pixel-edges", Fwindow_pixel_edges, Swindow_pixel_edges, 0, 1, 0,
       doc: /* Return a list of the edge pixel coordinates of WINDOW.
The list has the form (LEFT TOP RIGHT BOTTOM), all relative to 0, 0 at
the top left corner of the frame.

RIGHT is one more than the rightmost x position occupied by WINDOW.
BOTTOM is one more than the bottommost y position occupied by WINDOW.
The pixel edges include the space used by WINDOW's scroll bar, display
margins, fringes, header line, and/or mode line.  For the pixel edges
of just the text area, use `window-inside-pixel-edges'.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_any_window (window);

  return Fcons (make_number (WINDOW_LEFT_EDGE_X (w)),
	 Fcons (make_number (WINDOW_TOP_EDGE_Y (w)),
	 Fcons (make_number (WINDOW_RIGHT_EDGE_X (w)),
	 Fcons (make_number (WINDOW_BOTTOM_EDGE_Y (w)),
		Qnil))));
}

static void
calc_absolute_offset (struct window *w, int *add_x, int *add_y)
{
  struct frame *f = XFRAME (WVAR (w, frame));
  *add_y = f->top_pos;
#ifdef FRAME_MENUBAR_HEIGHT
  *add_y += FRAME_MENUBAR_HEIGHT (f);
#endif
#ifdef FRAME_TOOLBAR_TOP_HEIGHT
  *add_y += FRAME_TOOLBAR_TOP_HEIGHT (f);
#elif FRAME_TOOLBAR_HEIGHT
  *add_y += FRAME_TOOLBAR_HEIGHT (f);
#endif
#ifdef FRAME_NS_TITLEBAR_HEIGHT
  *add_y += FRAME_NS_TITLEBAR_HEIGHT (f);
#endif
  *add_x = f->left_pos;
#ifdef FRAME_TOOLBAR_LEFT_WIDTH
  *add_x += FRAME_TOOLBAR_LEFT_WIDTH (f);
#endif
}

DEFUN ("window-absolute-pixel-edges", Fwindow_absolute_pixel_edges,
       Swindow_absolute_pixel_edges, 0, 1, 0,
       doc: /* Return a list of the edge pixel coordinates of WINDOW.
The list has the form (LEFT TOP RIGHT BOTTOM), all relative to 0, 0 at
the top left corner of the display.

RIGHT is one more than the rightmost x position occupied by WINDOW.
BOTTOM is one more than the bottommost y position occupied by WINDOW.
The pixel edges include the space used by WINDOW's scroll bar, display
margins, fringes, header line, and/or mode line.  For the pixel edges
of just the text area, use `window-inside-absolute-pixel-edges'.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_any_window (window);
  int add_x, add_y;
  calc_absolute_offset (w, &add_x, &add_y);

  return Fcons (make_number (WINDOW_LEFT_EDGE_X (w) + add_x),
         Fcons (make_number (WINDOW_TOP_EDGE_Y (w) + add_y),
	 Fcons (make_number (WINDOW_RIGHT_EDGE_X (w) + add_x),
	 Fcons (make_number (WINDOW_BOTTOM_EDGE_Y (w) + add_y),
		Qnil))));
}

DEFUN ("window-inside-edges", Fwindow_inside_edges, Swindow_inside_edges, 0, 1, 0,
       doc: /* Return a list of the edge coordinates of WINDOW.
The list has the form (LEFT TOP RIGHT BOTTOM).
TOP and BOTTOM count by lines, and LEFT and RIGHT count by columns,
all relative to 0, 0 at top left corner of frame.

RIGHT is one more than the rightmost column of WINDOW's text area.
BOTTOM is one more than the bottommost row of WINDOW's text area.
The inside edges do not include the space used by the WINDOW's scroll
bar, display margins, fringes, header line, and/or mode line.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_window (window);

  return list4 (make_number (WINDOW_BOX_LEFT_EDGE_COL (w)
			     + WINDOW_LEFT_MARGIN_COLS (w)
			     + WINDOW_LEFT_FRINGE_COLS (w)),
		make_number (WINDOW_TOP_EDGE_LINE (w)
			     + WINDOW_HEADER_LINE_LINES (w)),
		make_number (WINDOW_BOX_RIGHT_EDGE_COL (w)
			     - WINDOW_RIGHT_MARGIN_COLS (w)
			     - WINDOW_RIGHT_FRINGE_COLS (w)),
		make_number (WINDOW_BOTTOM_EDGE_LINE (w)
			     - WINDOW_MODE_LINE_LINES (w)));
}

DEFUN ("window-inside-pixel-edges", Fwindow_inside_pixel_edges, Swindow_inside_pixel_edges, 0, 1, 0,
       doc: /* Return a list of the edge pixel coordinates of WINDOW's text area.
The list has the form (LEFT TOP RIGHT BOTTOM), all relative to (0,0)
at the top left corner of the frame's window area.

RIGHT is one more than the rightmost x position of WINDOW's text area.
BOTTOM is one more than the bottommost y position of WINDOW's text area.
The inside edges do not include the space used by WINDOW's scroll bar,
display margins, fringes, header line, and/or mode line.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_window (window);

  return list4 (make_number (WINDOW_BOX_LEFT_EDGE_X (w)
			     + WINDOW_LEFT_MARGIN_WIDTH (w)
			     + WINDOW_LEFT_FRINGE_WIDTH (w)),
		make_number (WINDOW_TOP_EDGE_Y (w)
			     + WINDOW_HEADER_LINE_HEIGHT (w)),
		make_number (WINDOW_BOX_RIGHT_EDGE_X (w)
			     - WINDOW_RIGHT_MARGIN_WIDTH (w)
			     - WINDOW_RIGHT_FRINGE_WIDTH (w)),
		make_number (WINDOW_BOTTOM_EDGE_Y (w)
			     - WINDOW_MODE_LINE_HEIGHT (w)));
}

DEFUN ("window-inside-absolute-pixel-edges",
       Fwindow_inside_absolute_pixel_edges,
       Swindow_inside_absolute_pixel_edges, 0, 1, 0,
       doc: /* Return a list of the edge pixel coordinates of WINDOW's text area.
The list has the form (LEFT TOP RIGHT BOTTOM), all relative to (0,0)
at the top left corner of the frame's window area.

RIGHT is one more than the rightmost x position of WINDOW's text area.
BOTTOM is one more than the bottommost y position of WINDOW's text area.
The inside edges do not include the space used by WINDOW's scroll bar,
display margins, fringes, header line, and/or mode line.  */)
  (Lisp_Object window)
{
  register struct window *w = decode_window (window);
  int add_x, add_y;
  calc_absolute_offset (w, &add_x, &add_y);

  return list4 (make_number (WINDOW_BOX_LEFT_EDGE_X (w)
			     + WINDOW_LEFT_MARGIN_WIDTH (w)
			     + WINDOW_LEFT_FRINGE_WIDTH (w) + add_x),
		make_number (WINDOW_TOP_EDGE_Y (w)
			     + WINDOW_HEADER_LINE_HEIGHT (w) + add_y),
		make_number (WINDOW_BOX_RIGHT_EDGE_X (w)
			     - WINDOW_RIGHT_MARGIN_WIDTH (w)
			     - WINDOW_RIGHT_FRINGE_WIDTH (w) + add_x),
		make_number (WINDOW_BOTTOM_EDGE_Y (w)
			     - WINDOW_MODE_LINE_HEIGHT (w) + add_y));
}

/* Test if the character at column X, row Y is within window W.
   If it is not, return ON_NOTHING;
   if it is in the window's text area, return ON_TEXT;
   if it is on the window's modeline, return ON_MODE_LINE;
   if it is on the border between the window and its right sibling,
      return ON_VERTICAL_BORDER.
   if it is on a scroll bar, return ON_SCROLL_BAR.
   if it is on the window's top line, return ON_HEADER_LINE;
   if it is in left or right fringe of the window,
      return ON_LEFT_FRINGE or ON_RIGHT_FRINGE;
   if it is in the marginal area to the left/right of the window,
      return ON_LEFT_MARGIN or ON_RIGHT_MARGIN.

   X and Y are frame relative pixel coordinates.  */

static enum window_part
coordinates_in_window (register struct window *w, int x, int y)
{
  struct frame *f = XFRAME (WINDOW_FRAME (w));
  enum window_part part;
  int ux = FRAME_COLUMN_WIDTH (f);
  int left_x = WINDOW_LEFT_EDGE_X (w);
  int right_x = WINDOW_RIGHT_EDGE_X (w);
  int top_y = WINDOW_TOP_EDGE_Y (w);
  int bottom_y = WINDOW_BOTTOM_EDGE_Y (w);
  /* The width of the area where the vertical line can be dragged.
     (Between mode lines for instance.  */
  int grabbable_width = ux;
  int lmargin_width, rmargin_width, text_left, text_right;

  /* Outside any interesting row or column?  */
  if (y < top_y || y >= bottom_y || x < left_x || x >= right_x)
    return ON_NOTHING;

  /* On the mode line or header line?   */
  if ((WINDOW_WANTS_MODELINE_P (w)
       && y >= bottom_y - CURRENT_MODE_LINE_HEIGHT (w)
       && (part = ON_MODE_LINE))
      || (WINDOW_WANTS_HEADER_LINE_P (w)
	  && y < top_y + CURRENT_HEADER_LINE_HEIGHT (w)
	  && (part = ON_HEADER_LINE)))
    {
      /* If it's under/over the scroll bar portion of the mode/header
	 line, say it's on the vertical line.  That's to be able to
	 resize windows horizontally in case we're using toolkit scroll
	 bars.  Note: If scrollbars are on the left, the window that
	 must be eventually resized is that on the left of WINDOW.  */
      if ((WINDOW_HAS_VERTICAL_SCROLL_BAR_ON_LEFT (w)
	   && !WINDOW_LEFTMOST_P (w)
	   && eabs (x - left_x) < grabbable_width)
	  || (!WINDOW_HAS_VERTICAL_SCROLL_BAR_ON_LEFT (w)
	      && !WINDOW_RIGHTMOST_P (w)
	      && eabs (x - right_x) < grabbable_width))
	return ON_VERTICAL_BORDER;
      else
	return part;
    }

  /* In what's below, we subtract 1 when computing right_x because we
     want the rightmost pixel, which is given by left_pixel+width-1.  */