lisp/window.el

   1 ;;; window.el --- GNU Emacs window commands aside from those written in C.
   2
   3 ;;; Copyright (C) 1985, 1989, 1992, 1993, 1994 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  21 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  22
  23 ;;; Code:
  24
  25 ;;;; Window tree functions.
  26
  27 (defun one-window-p (&optional nomini all-frames)
  28   "Returns non-nil if the selected window is the only window (in its frame).
  29 Optional arg NOMINI non-nil means don't count the minibuffer
  30 even if it is active.
  31
  32 The optional arg ALL-FRAMES t means count windows on all frames.
  33 If it is `visible', count windows on all visible frames.
  34 ALL-FRAMES nil or omitted means count only the selected frame,
  35 plus the minibuffer it uses (which may be on another frame).
  36 If ALL-FRAMES is neither nil nor t, count only the selected frame."
  37   (let ((base-window (selected-window)))
  38     (if (and nomini (eq base-window (minibuffer-window)))
  39         (setq base-window (next-window base-window)))
  40     (eq base-window
  41         (next-window base-window (if nomini 'arg) all-frames))))
  42
  43 (defun walk-windows (proc &optional minibuf all-frames)
  44   "Cycle through all visible windows, calling PROC for each one.
  45 PROC is called with a window as argument.
  46
  47 Optional second arg MINIBUF t means count the minibuffer window even
  48 if not active.  MINIBUF nil or omitted means count the minibuffer iff
  49 it is active.  MINIBUF neither t nor nil means not to count the
  50 minibuffer even if it is active.
  51
  52 Several frames may share a single minibuffer; if the minibuffer
  53 counts, all windows on all frames that share that minibuffer count
  54 too.  Therefore, when a separate minibuffer frame is active,
  55 `walk-windows' includes the windows in the frame from which you
  56 entered the minibuffer, as well as the minibuffer window.  But if the
  57 minibuffer does not count, only windows from WINDOW's frame count.
  58
  59 ALL-FRAMES is the optional third argument.
  60 ALL-FRAMES nil or omitted means cycle within the frames as specified above.
  61 ALL-FRAMES = `visible' means include windows on all visible frames.
  62 ALL-FRAMES = 0 means include windows on all visible and iconified frames.
  63 ALL-FRAMES = t means include windows on all frames including invisible frames.
  64 Anything else means restrict to WINDOW's frame."
  65   ;; If we start from the minibuffer window, don't fail to come back to it.
  66   (if (window-minibuffer-p (selected-window))
  67       (setq minibuf t))
  68   (let* ((walk-windows-start (selected-window))
  69          (walk-windows-current walk-windows-start))
  70     (while (progn
  71              (setq walk-windows-current
  72                    (next-window walk-windows-current minibuf all-frames))
  73              (funcall proc walk-windows-current)
  74              (not (eq walk-windows-current walk-windows-start))))))
  75
  76 (defun minibuffer-window-active-p (window)
  77   "Return t if WINDOW (a minibuffer window) is now active."
  78   (eq window (active-minibuffer-window)))
  79 \f
  80 (defun count-windows (&optional minibuf)
  81    "Returns the number of visible windows.
  82 Optional arg NO-MINI non-nil means don't count the minibuffer
  83 even if it is active."
  84    (let ((count 0))
  85      (walk-windows (function (lambda (w)
  86                                (setq count (+ count 1))))
  87                    minibuf)
  88      count))
  89
  90 (defun balance-windows ()
  91   "Makes all visible windows the same height (approximately)."
  92   (interactive)
  93   (let ((count -1) levels newsizes size)
  94     ;; Find all the different vpos's at which windows start,
  95     ;; then count them.  But ignore levels that differ by only 1.
  96     (save-window-excursion
  97       (let (tops (prev-top -2))
  98         (walk-windows (function (lambda (w)
  99                                   (setq tops (cons (nth 1 (window-edges w))
 100                                                    tops))))
 101                       'nomini)
 102         (setq tops (sort tops '<))
 103         (while tops
 104           (if (> (car tops) (1+ prev-top))
 105               (setq prev-top (car tops)
 106                     count (1+ count)))
 107           (setq levels (cons (cons (car tops) count) levels))
 108           (setq tops (cdr tops)))
 109         (setq count (1+ count))))
 110     ;; Subdivide the frame into that many vertical levels.
 111     (setq size (/ (frame-height) count))
 112     (walk-windows (function
 113                    (lambda (w)
 114                      (select-window w)
 115                      (let ((newtop (cdr (assq (nth 1 (window-edges))
 116                                               levels)))
 117                            (newbot (or (cdr (assq (+ (window-height)
 118                                                      (nth 1 (window-edges)))
 119                                                   levels))
 120                                        count)))
 121                        (setq newsizes
 122                              (cons (cons w (* size (- newbot newtop)))
 123                                    newsizes)))))
 124                   'nomini)
 125     (walk-windows (function (lambda (w)
 126                               (select-window w)
 127                               (let ((newsize (cdr (assq w newsizes))))
 128                                 (enlarge-window (- newsize
 129                                                    (window-height))))))
 130                   'nomini)))
 131 \f
 132 ;;; I think this should be the default; I think people will prefer it--rms.
 133 (defvar split-window-keep-point t
 134   "*If non-nil, split windows keeps the original point in both children.
 135 This is often more convenient for editing.
 136 If nil, adjust point in each of the two windows to minimize redisplay.
 137 This is convenient on slow terminals, but point can move strangely.")
 138
 139 (defun split-window-vertically (&optional arg)
 140   "Split current window into two windows, one above the other.
 141 The uppermost window gets ARG lines and the other gets the rest.
 142 Negative arg means select the size of the lowermost window instead.
 143 With no argument, split equally or close to it.
 144 Both windows display the same buffer now current.
 145
 146 If the variable split-window-keep-point is non-nil, both new windows
 147 will get the same value of point as the current window.  This is often
 148 more convenient for editing.
 149
 150 Otherwise, we chose window starts so as to minimize the amount of
 151 redisplay; this is convenient on slow terminals.  The new selected
 152 window is the one that the current value of point appears in.  The
 153 value of point can change if the text around point is hidden by the
 154 new mode line."
 155   (interactive "P")
 156   (let ((old-w (selected-window))
 157         (old-point (point))
 158         (size (and arg (prefix-numeric-value arg)))
 159         new-w bottom switch)
 160     (and size (< size 0) (setq size (+ (window-height) size)))
 161     (setq new-w (split-window nil size))
 162     (or split-window-keep-point
 163         (progn
 164           (save-excursion
 165             (set-buffer (window-buffer))
 166             (goto-char (window-start))
 167             (vertical-motion (window-height))
 168             (set-window-start new-w (point))
 169             (if (> (point) (window-point new-w))
 170                 (set-window-point new-w (point)))
 171             (vertical-motion -1)
 172             (setq bottom (point)))
 173           (if (<= bottom (point))
 174               (set-window-point old-w (1- bottom)))
 175           (if (< (window-start new-w) old-point)
 176               (progn
 177                 (set-window-point new-w old-point)
 178                 (select-window new-w)))))
 179     new-w))
 180
 181 (defun split-window-horizontally (&optional arg)
 182   "Split current window into two windows side by side.
 183 This window becomes the leftmost of the two, and gets ARG columns.
 184 Negative arg means select the size of the rightmost window instead.
 185 No arg means split equally."
 186   (interactive "P")
 187   (let ((size (and arg (prefix-numeric-value arg))))
 188     (and size (< size 0)
 189          (setq size (+ (window-width) size)))
 190     (split-window nil size t)))
 191 \f
 192 (defun enlarge-window-horizontally (arg)
 193   "Make current window ARG columns wider."
 194   (interactive "p")
 195   (enlarge-window arg t))
 196
 197 (defun shrink-window-horizontally (arg)
 198   "Make current window ARG columns narrower."
 199   (interactive "p")
 200   (shrink-window arg t))
 201
 202 (defun shrink-window-if-larger-than-buffer (&optional window)
 203   "Shrink the WINDOW to be as small as possible to display its contents.
 204 Do not shrink to less than `window-min-height' lines.
 205 Do nothing if the buffer contains more lines than the present window height,
 206 or if some of the window's contents are scrolled out of view,
 207 or if the window is not the full width of the frame,
 208 or if the window is the only window of its frame."
 209   (interactive)
 210   (or window (setq window (selected-window)))
 211   (save-excursion
 212     (set-buffer (window-buffer window))
 213     (let* ((w (selected-window))        ;save-window-excursion can't win
 214            (buffer-file-name buffer-file-name)
 215            (p (point))
 216            (n 0)
 217            (ignore-final-newline
 218             ;; If buffer ends with a newline, ignore it when counting height
 219             ;; unless point is after it.
 220             (and (not (eobp))
 221                  (eq ?\n (char-after (1- (point-max))))))
 222            (buffer-read-only nil)
 223            (modified (buffer-modified-p))
 224            (buffer (current-buffer))
 225            (params (frame-parameters (window-frame window)))
 226            (mini (cdr (assq 'minibuffer params)))
 227            (edges (window-edges (selected-window))))
 228       (if (and (< 1 (let ((frame (selected-frame)))
 229                       (select-frame (window-frame window))
 230                       (unwind-protect
 231                           (count-windows)
 232                         (select-frame frame))))
 233                (= (window-width window) (frame-width (window-frame window)))
 234                (pos-visible-in-window-p (point-min) window)
 235                (not (eq mini 'only))
 236                (or (not mini)
 237                    (< (nth 3 edges)
 238                       (nth 1 (window-edges mini)))
 239                    (> (nth 1 edges)
 240                       (cdr (assq 'menu-bar-lines params)))))
 241           (unwind-protect
 242               (progn
 243                 (select-window (or window w))
 244                 (goto-char (point-min))
 245                 (while (pos-visible-in-window-p
 246                         (- (point-max)
 247                            (if ignore-final-newline 1 0)))
 248                   ;; defeat file locking... don't try this at home, kids!
 249                   (setq buffer-file-name nil)
 250                   (insert ?\n) (setq n (1+ n)))
 251                 (if (> n 0)
 252                     (shrink-window (min (1- n)
 253                                         (- (window-height)
 254                                            window-min-height)))))
 255             (delete-region (point-min) (point))
 256             (set-buffer-modified-p modified)
 257             (goto-char p)
 258             (select-window w)
 259             ;; Make sure we unbind buffer-read-only
 260             ;; with the proper current buffer.
 261             (set-buffer buffer))))))
 262
 263 (define-key ctl-x-map "2" 'split-window-vertically)
 264 (define-key ctl-x-map "3" 'split-window-horizontally)
 265 (define-key ctl-x-map "}" 'enlarge-window-horizontally)
 266 (define-key ctl-x-map "{" 'shrink-window-horizontally)
 267 (define-key ctl-x-map "-" 'shrink-window-if-larger-than-buffer)
 268 (define-key ctl-x-map "+" 'balance-windows)
 269
 270 ;;; windows.el ends here