window.el 245 KB
Newer Older
1 2
;;; window.el --- GNU Emacs window commands aside from those written in C

3
;; Copyright (C) 1985, 1989, 1992-1994, 2000-2012
4
;;   Free Software Foundation, Inc.
5 6 7

;; Maintainer: FSF
;; Keywords: internal
8
;; Package: emacs
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

;; 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/>.

;;; Commentary:

;; Window tree functions.

;;; Code:

(defmacro save-selected-window (&rest body)
  "Execute BODY, then select the previously selected window.
The value returned is the value of the last form in BODY.

This macro saves and restores the selected window, as well as the
selected window in each frame.  If the previously selected window
is no longer live, then whatever window is selected at the end of
BODY remains selected.  If the previously selected window of some
frame is no longer live at the end of BODY, that frame's selected
window is left alone.

This macro saves and restores the current buffer, since otherwise
its normal operation could make a different buffer current.  The
order of recently selected windows and the buffer list ordering
are not altered by this macro (unless they are altered in BODY)."
Stefan Monnier's avatar
Stefan Monnier committed
46
  (declare (indent 0) (debug t))
47
  `(let ((save-selected-window-window (selected-window))
48 49 50 51
	 ;; We save and restore all frames' selected windows, because
	 ;; `select-window' can change the frame-selected-window of
	 ;; whatever frame that window is in.  Each text terminal's
	 ;; top-frame is preserved by putting it last in the list.
52
	 (save-selected-window-alist
53 54 55 56 57 58 59 60 61 62 63 64 65
	  (apply 'append
		 (mapcar (lambda (terminal)
			   (let ((frames (frames-on-display-list terminal))
				 (top-frame (tty-top-frame terminal))
				 alist)
			     (if top-frame
				 (setq frames
				       (cons top-frame
					     (delq top-frame frames))))
			     (dolist (f frames)
			       (push (cons f (frame-selected-window f))
				     alist))))
			 (terminal-list)))))
66 67 68 69 70 71 72 73 74 75
     (save-current-buffer
       (unwind-protect
	   (progn ,@body)
	 (dolist (elt save-selected-window-alist)
	   (and (frame-live-p (car elt))
		(window-live-p (cdr elt))
		(set-frame-selected-window (car elt) (cdr elt) 'norecord)))
	 (when (window-live-p save-selected-window-window)
	   (select-window save-selected-window-window 'norecord))))))

76 77 78 79 80
;; The following two functions are like `window-next-sibling' and
;; `window-prev-sibling' but the WINDOW argument is _not_ optional (so
;; they don't substitute the selected window for nil), and they return
;; nil when WINDOW doesn't have a parent (like a frame's root window or
;; a minibuffer window).
81
(defun window-right (window)
82 83 84
  "Return WINDOW's right sibling.
Return nil if WINDOW is the root window of its frame.  WINDOW can
be any window."
85
  (and window (window-parent window) (window-next-sibling window)))
86

87
(defun window-left (window)
88 89 90
  "Return WINDOW's left sibling.
Return nil if WINDOW is the root window of its frame.  WINDOW can
be any window."
91
  (and window (window-parent window) (window-prev-sibling window)))
92

93
(defun window-child (window)
94 95
  "Return WINDOW's first child window.
WINDOW can be any window."
96
  (or (window-top-child window) (window-left-child window)))
97 98

(defun window-child-count (window)
99 100
  "Return number of WINDOW's child windows.
WINDOW can be any window."
101 102 103 104
  (let ((count 0))
    (when (and (windowp window) (setq window (window-child window)))
      (while window
	(setq count (1+ count))
105
	(setq window (window-next-sibling window))))
106 107 108
    count))

(defun window-last-child (window)
109 110
  "Return last child window of WINDOW.
WINDOW can be any window."
111
  (when (and (windowp window) (setq window (window-child window)))
112 113
    (while (window-next-sibling window)
      (setq window (window-next-sibling window))))
114 115
  window)

116
(defun window-normalize-buffer (buffer-or-name)
117 118 119 120 121 122 123 124 125 126 127 128 129 130
  "Return buffer specified by BUFFER-OR-NAME.
BUFFER-OR-NAME must be either a buffer or a string naming a live
buffer and defaults to the current buffer."
  (cond
   ((not buffer-or-name)
    (current-buffer))
   ((bufferp buffer-or-name)
    (if (buffer-live-p buffer-or-name)
	buffer-or-name
      (error "Buffer %s is not a live buffer" buffer-or-name)))
   ((get-buffer buffer-or-name))
   (t
    (error "No such buffer %s" buffer-or-name))))

131
(defun window-normalize-frame (frame)
132 133 134 135 136 137 138 139
  "Return frame specified by FRAME.
FRAME must be a live frame and defaults to the selected frame."
  (if frame
      (if (frame-live-p frame)
	  frame
	(error "%s is not a live frame" frame))
    (selected-frame)))

140
(defun window-normalize-window (window &optional live-only)
141 142 143 144
  "Return the window specified by WINDOW.
If WINDOW is nil, return the selected window.  Otherwise, if
WINDOW is a live or an internal window, return WINDOW; if
LIVE-ONLY is non-nil, return WINDOW for a live window only.
145
Otherwise, signal an error."
146 147 148 149 150 151 152 153 154 155 156
  (cond
   ((null window)
    (selected-window))
   (live-only
    (if (window-live-p window)
	window
      (error "%s is not a live window" window)))
   ((window-valid-p window)
    window)
   (t
    (error "%s is not a valid window" window))))
157 158 159 160 161 162 163 164 165

(defvar ignore-window-parameters nil
  "If non-nil, standard functions ignore window parameters.
The functions currently affected by this are `split-window',
`delete-window', `delete-other-windows' and `other-window'.

An application may bind this to a non-nil value around calls to
these functions to inhibit processing of window parameters.")

166
(defconst window-safe-min-height 1
167
  "The absolute minimum number of lines of a window.
168 169
Anything less might crash Emacs.")

170 171
(defcustom window-min-height 4
  "The minimum number of lines of any window.
Juanma Barranquero's avatar
Juanma Barranquero committed
172 173
The value has to accommodate a mode- or header-line if present.
A value less than `window-safe-min-height' is ignored.  The value
174 175 176 177
of this variable is honored when windows are resized or split.

Applications should never rebind this variable.  To resize a
window to a height less than the one specified here, an
178
application should instead call `window-resize' with a non-nil
179
IGNORE argument.  In order to have `split-window' make a window
Paul Eggert's avatar
Paul Eggert committed
180
shorter, explicitly specify the SIZE argument of that function."
181 182 183 184
  :type 'integer
  :version "24.1"
  :group 'windows)

185
(defconst window-safe-min-width 2
186
  "The absolute minimum number of columns of a window.
187 188
Anything less might crash Emacs.")

189 190
(defcustom window-min-width 10
  "The minimum number of columns of any window.
191
The value has to accommodate margins, fringes, or scrollbars if
192 193 194 195 196 197
present.  A value less than `window-safe-min-width' is ignored.
The value of this variable is honored when windows are resized or
split.

Applications should never rebind this variable.  To resize a
window to a width less than the one specified here, an
198
application should instead call `window-resize' with a non-nil
199
IGNORE argument.  In order to have `split-window' make a window
Paul Eggert's avatar
Paul Eggert committed
200
narrower, explicitly specify the SIZE argument of that function."
201 202 203 204
  :type 'integer
  :version "24.1"
  :group 'windows)

205
(defun window-combined-p (&optional window horizontal)
206
  "Return non-nil if WINDOW has siblings in a given direction.
207
WINDOW must be a valid window and defaults to the selected one.
208 209 210 211 212 213

HORIZONTAL determines a direction for the window combination.
If HORIZONTAL is omitted or nil, return non-nil if WINDOW is part
of a vertical window combination.
If HORIZONTAL is non-nil, return non-nil if WINDOW is part of a
horizontal window combination."
214
  (setq window (window-normalize-window window))
215
  (let ((parent (window-parent window)))
216 217 218 219
    (and parent
	 (if horizontal
	     (window-left-child parent)
	   (window-top-child parent)))))
220

221 222
(defun window-combinations (window &optional horizontal)
  "Return largest number of windows vertically arranged within WINDOW.
223
WINDOW must be a valid window and defaults to the selected one.
224
If HORIZONTAL is non-nil, return the largest number of
225
windows horizontally arranged within WINDOW."
226
  (setq window (window-normalize-window window))
227 228 229 230
  (cond
   ((window-live-p window)
    ;; If WINDOW is live, return 1.
    1)
231 232 233
   ((if horizontal
	(window-left-child window)
      (window-top-child window))
234
    ;; If WINDOW is iso-combined, return the sum of the values for all
235
    ;; child windows of WINDOW.
236 237 238 239
    (let ((child (window-child window))
	  (count 0))
      (while child
	(setq count
240
	      (+ (window-combinations child horizontal)
241 242 243 244 245
		 count))
	(setq child (window-right child)))
      count))
   (t
    ;; If WINDOW is not iso-combined, return the maximum value of any
246
    ;; child window of WINDOW.
247 248 249 250
    (let ((child (window-child window))
	  (count 1))
      (while child
	(setq count
251
	      (max (window-combinations child horizontal)
252 253 254 255
		   count))
	(setq child (window-right child)))
      count))))

256
(defun walk-window-tree-1 (fun walk-window-tree-window any &optional sub-only)
257 258 259 260 261 262
  "Helper function for `walk-window-tree' and `walk-window-subtree'."
  (let (walk-window-tree-buffer)
    (while walk-window-tree-window
      (setq walk-window-tree-buffer
	    (window-buffer walk-window-tree-window))
      (when (or walk-window-tree-buffer any)
263
	(funcall fun walk-window-tree-window))
264 265
      (unless walk-window-tree-buffer
	(walk-window-tree-1
266
	 fun (window-left-child walk-window-tree-window) any)
267
	(walk-window-tree-1
268
	 fun (window-top-child walk-window-tree-window) any))
269 270 271 272 273
      (if sub-only
	  (setq walk-window-tree-window nil)
	(setq walk-window-tree-window
	      (window-right walk-window-tree-window))))))

274
(defun walk-window-tree (fun &optional frame any minibuf)
275 276
  "Run function FUN on each live window of FRAME.
FUN must be a function with one argument - a window.  FRAME must
277
be a live frame and defaults to the selected one.  ANY, if
278
non-nil, means to run FUN on all live and internal windows of
279 280
FRAME.

281 282 283 284 285 286
Optional argument MINIBUF t means run FUN on FRAME's minibuffer
window even if it isn't active.  MINIBUF nil or omitted means run
FUN on FRAME's minibuffer window only if it's active.  In both
cases the minibuffer window must be part of FRAME.  MINIBUF
neither nil nor t means never run FUN on the minibuffer window.

287
This function performs a pre-order, depth-first traversal of the
288
window tree.  If FUN changes the window tree, the result is
289
unpredictable."
290 291 292 293 294 295 296 297 298 299
  (setq frame (window-normalize-frame frame))
  (walk-window-tree-1 fun (frame-root-window frame) any)
  (when (memq minibuf '(nil t))
    ;; Run FUN on FRAME's minibuffer window if requested.
    (let ((minibuffer-window (minibuffer-window frame)))
      (when (and (window-live-p minibuffer-window)
		 (eq (window-frame minibuffer-window) frame)
		 (or (eq minibuf t)
		     (minibuffer-window-active-p minibuffer-window)))
	(funcall fun minibuffer-window)))))
300

301 302 303 304
(defun walk-window-subtree (fun &optional window any)
  "Run function FUN on the subtree of windows rooted at WINDOW.
WINDOW defaults to the selected window.  FUN must be a function
with one argument - a window.  By default, run FUN only on live
305
windows of the subtree.  If the optional argument ANY is non-nil,
306 307
run FUN on all live and internal windows of the subtree.  If
WINDOW is live, run FUN on WINDOW only.
308 309

This function performs a pre-order, depth-first traversal of the
310
subtree rooted at WINDOW.  If FUN changes that tree, the result
311
is unpredictable."
312
  (setq window (window-normalize-window window))
313
  (walk-window-tree-1 fun window any t))
314

315
(defun window-with-parameter (parameter &optional value frame any minibuf)
316 317 318
  "Return first window on FRAME with PARAMETER non-nil.
FRAME defaults to the selected frame.  Optional argument VALUE
non-nil means only return a window whose window-parameter value
Juanma Barranquero's avatar
Juanma Barranquero committed
319
for PARAMETER equals VALUE (comparison is done with `equal').
320
Optional argument ANY non-nil means consider internal windows
321 322 323 324 325 326 327
too.

Optional argument MINIBUF t means consider FRAME's minibuffer
window even if it isn't active.  MINIBUF nil or omitted means
consider FRAME's minibuffer window only if it's active.  In both
cases the minibuffer window must be part of FRAME.  MINIBUF
neither nil nor t means never consider the minibuffer window."
328
  (let (this-value)
329 330 331 332 333 334
    (catch 'found
      (walk-window-tree
       (lambda (window)
	 (when (and (setq this-value (window-parameter window parameter))
		    (or (not value) (equal value this-value)))
	   (throw 'found window)))
335
       frame any minibuf))))
336 337 338 339

;;; Atomic windows.
(defun window-atom-root (&optional window)
  "Return root of atomic window WINDOW is a part of.
340
WINDOW must be a valid window and defaults to the selected one.
Juanma Barranquero's avatar
Juanma Barranquero committed
341
Return nil if WINDOW is not part of an atomic window."
342
  (setq window (window-normalize-window window))
343 344 345 346 347 348
  (let (root)
    (while (and window (window-parameter window 'window-atom))
      (setq root window)
      (setq window (window-parent window)))
    root))

349
(defun window-make-atom (window)
350 351 352 353 354 355 356 357 358 359
  "Make WINDOW an atomic window.
WINDOW must be an internal window.  Return WINDOW."
  (if (not (window-child window))
      (error "Window %s is not an internal window" window)
    (walk-window-subtree
     (lambda (window)
       (set-window-parameter window 'window-atom t))
     window t)
    window))

360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398
(defun display-buffer-in-atom-window (buffer alist)
  "Display BUFFER in an atomic window.
This function displays BUFFER in a new window that will be
combined with an existing window to form an atomic window.  If
the existing window is already part of an atomic window, add the
new window to that atomic window.  Operations like `split-window'
or `delete-window', when applied to a constituent of an atomic
window, are applied atomically to the root of that atomic window.

ALIST is an association list of symbols and values.  The
following symbols can be used.

`window' specifies the existing window the new window shall be
  combined with.  Use `window-atom-root' to make the new window a
  sibling of an atomic window's root.  If an internal window is
  specified here, all children of that window become part of the
  atomic window too.  If no window is specified, the new window
  becomes a sibling of the selected window.

`side' denotes the side of the existing window where the new
  window shall be located.  Valid values are `below', `right',
  `above' and `left'.  The default is `below'.

The return value is the new window, nil when creating that window
failed."
  (let ((ignore-window-parameters t)
	(window-combination-limit t)
	(window (cdr (assq 'window alist)))
	(side (cdr (assq 'side alist)))
	new)
    (setq window (window-normalize-window window))
    ;; Split off new window
    (when (setq new (split-window window nil side))
      ;; Make sure we have a valid atomic window.
      (window-make-atom (window-parent window))
      ;; Display BUFFER in NEW and return NEW.
      (window--display-buffer
       buffer new 'window display-buffer-mark-dedicated))))

399 400
(defun window--atom-check-1 (window)
  "Subroutine of `window--atom-check'."
401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420
  (when window
    (if (window-parameter window 'window-atom)
	(let ((count 0))
	  (when (or (catch 'reset
		      (walk-window-subtree
		       (lambda (window)
			 (if (window-parameter window 'window-atom)
			     (setq count (1+ count))
			   (throw 'reset t)))
		       window t))
		    ;; count >= 1 must hold here.  If there's no other
		    ;; window around dissolve this atomic window.
		    (= count 1))
	    ;; Dissolve atomic window.
	    (walk-window-subtree
	     (lambda (window)
	       (set-window-parameter window 'window-atom nil))
	     window t)))
      ;; Check children.
      (unless (window-buffer window)
421 422
	(window--atom-check-1 (window-left-child window))
	(window--atom-check-1 (window-top-child window))))
423
    ;; Check right sibling
424
    (window--atom-check-1 (window-right window))))
425

426
(defun window--atom-check (&optional frame)
427 428
  "Check atomicity of all windows on FRAME.
FRAME defaults to the selected frame.  If an atomic window is
429 430 431
wrongly configured, reset the atomicity of all its windows on
FRAME to nil.  An atomic window is wrongly configured if it has
no child windows or one of its child windows is not atomic."
432
  (window--atom-check-1 (frame-root-window frame)))
433 434 435 436 437 438 439 440 441 442 443 444 445 446 447

;; Side windows.
(defvar window-sides '(left top right bottom)
  "Window sides.")

(defcustom window-sides-vertical nil
  "If non-nil, left and right side windows are full height.
Otherwise, top and bottom side windows are full width."
  :type 'boolean
  :group 'windows
  :version "24.1")

(defcustom window-sides-slots '(nil nil nil nil)
  "Maximum number of side window slots.
The value is a list of four elements specifying the number of
Juanma Barranquero's avatar
Juanma Barranquero committed
448
side window slots on (in this order) the left, top, right and
449 450 451 452
bottom side of each frame.  If an element is a number, this means
to display at most that many side windows on the corresponding
side.  If an element is nil, this means there's no bound on the
number of slots on that side."
453
  :version "24.1"
454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487
  :risky t
  :type
  '(list
    :value (nil nil nil nil)
    (choice
     :tag "Left"
     :help-echo "Maximum slots of left side window."
     :value nil
     :format "%[Left%] %v\n"
     (const :tag "Unlimited" :format "%t" nil)
     (integer :tag "Number" :value 2 :size 5))
    (choice
     :tag "Top"
     :help-echo "Maximum slots of top side window."
     :value nil
     :format "%[Top%] %v\n"
     (const :tag "Unlimited" :format "%t" nil)
     (integer :tag "Number" :value 3 :size 5))
    (choice
     :tag "Right"
     :help-echo "Maximum slots of right side window."
     :value nil
     :format "%[Right%] %v\n"
     (const :tag "Unlimited" :format "%t" nil)
     (integer :tag "Number" :value 2 :size 5))
    (choice
     :tag "Bottom"
     :help-echo "Maximum slots of bottom side window."
     :value nil
     :format "%[Bottom%] %v\n"
     (const :tag "Unlimited" :format "%t" nil)
     (integer :tag "Number" :value 3 :size 5)))
  :group 'windows)

488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735
(defun window--major-non-side-window (&optional frame)
  "Return the major non-side window of frame FRAME.
The optional argument FRAME must be a live frame and defaults to
the selected one.

If FRAME has at least one side window, the major non-side window
is either an internal non-side window such that all other
non-side windows on FRAME descend from it, or the single live
non-side window of FRAME.  If FRAME has no side windows, return
its root window."
  (let ((frame (window-normalize-frame frame))
	major sibling)
    ;; Set major to the _last_ window found by `walk-window-tree' that
    ;; is not a side window but has a side window as its sibling.
    (walk-window-tree
     (lambda (window)
       (and (not (window-parameter window 'window-side))
	    (or (and (setq sibling (window-prev-sibling window))
		     (window-parameter sibling 'window-side))
		(and (setq sibling (window-next-sibling window))
		     (window-parameter sibling 'window-side)))
	    (setq major window)))
     frame t)
    (or major (frame-root-window frame))))

(defun window--major-side-window (side)
  "Return major side window on SIDE.
SIDE must be one of the symbols `left', `top', `right' or
`bottom'.  Return nil if no such window exists."
  (let ((root (frame-root-window))
	window)
    ;; (1) If a window on the opposite side exists, return that window's
    ;;     sibling.
    ;; (2) If the new window shall span the entire side, return the
    ;;     frame's root window.
    ;; (3) If a window on an orthogonal side exists, return that
    ;;     window's sibling.
    ;; (4) Otherwise return the frame's root window.
    (cond
     ((or (and (eq side 'left)
	       (setq window (window-with-parameter 'window-side 'right nil t)))
	  (and (eq side 'top)
	       (setq window (window-with-parameter 'window-side 'bottom nil t))))
      (window-prev-sibling window))
     ((or (and (eq side 'right)
	       (setq window (window-with-parameter 'window-side 'left nil t)))
	  (and (eq side 'bottom)
	       (setq window (window-with-parameter 'window-side 'top nil t))))
      (window-next-sibling window))
     ((memq side '(left right))
      (cond
       (window-sides-vertical
	root)
       ((setq window (window-with-parameter 'window-side 'top nil t))
	(window-next-sibling window))
       ((setq window (window-with-parameter 'window-side 'bottom nil t))
	(window-prev-sibling window))
       (t root)))
     ((memq side '(top bottom))
      (cond
       ((not window-sides-vertical)
	root)
       ((setq window (window-with-parameter 'window-side 'left nil t))
	(window-next-sibling window))
       ((setq window (window-with-parameter 'window-side 'right nil t))
	(window-prev-sibling window))
       (t root))))))

(defun display-buffer-in-major-side-window (buffer side slot &optional alist)
  "Display BUFFER in a new window on SIDE of the selected frame.
SIDE must be one of `left', `top', `right' or `bottom'.  SLOT
specifies the slot to use.  ALIST is an association list of
symbols and values as passed to `display-buffer-in-side-window'.
This function may be called only if no window on SIDE exists yet.
The new window automatically becomes the \"major\" side window on
SIDE.  Return the new window, nil if its creation window failed."
  (let* ((root (frame-root-window))
	 (left-or-right (memq side '(left right)))
	 (size (or (assq 'size alist)
		   (/ (window-total-size (frame-root-window) left-or-right)
		      ;; By default use a fourth of the size of the
		      ;; frame's root window.  This has to be made
		      ;; customizable via ALIST.
		      4)))
	 (major (window--major-side-window side))
	 (selected-window (selected-window))
	 (on-side (cond
		   ((eq side 'top) 'above)
		   ((eq side 'bottom) 'below)
		   (t side)))
	 ;; The following two bindings will tell `split-window' to take
	 ;; the space for the new window from `major' and not make a new
	 ;; parent window unless needed.
	 (window-combination-resize 'side)
	 (window-combination-limit nil)
	 (new (split-window major (- size) on-side))
	 fun)
    (when new
      ;; Initialize `window-side' parameter of new window to SIDE.
      (set-window-parameter new 'window-side side)
      ;; Install `window-slot' parameter of new window.
      (set-window-parameter new 'window-slot slot)
      ;; Install `delete-window' parameter thus making sure that when
      ;; the new window is deleted, a side window on the opposite side
      ;; does not get resized.
      (set-window-parameter new 'delete-window 'delete-side-window)
      ;; Install BUFFER in new window and return NEW.
      (window--display-buffer buffer new 'window 'side))))

(defun delete-side-window (window)
  "Delete side window WINDOW."
  (let ((window-combination-resize
	 (window-parameter (window-parent window) 'window-side))
	(ignore-window-parameters t))
    (delete-window window)))

(defun display-buffer-in-side-window (buffer alist)
  "Display BUFFER in a window on side SIDE of the selected frame.
ALIST is an association list of symbols and values.  The
following symbols can be used:

`side' denotes the side of the existing window where the new
  window shall be located.  Valid values are `bottom', `right',
  `top' and `left'.  The default is `bottom'.

`slot' if non-nil, specifies the window slot where to display
  BUFFER.  A value of zero or nil means use the middle slot on
  the specified side.  A negative value means use a slot
  preceding (that is, above or on the left of) the middle slot.
  A positive value means use a slot following (that is, below or
  on the right of) the middle slot.  The default is zero."
  (let ((side (or (cdr (assq 'side alist)) 'bottom))
	(slot (or (cdr (assq 'slot alist)) 0))
	new)
    (cond
     ((not (memq side '(top bottom left right)))
      (error "Invalid side %s specified" side))
     ((not (numberp slot))
      (error "Invalid slot %s specified" slot)))

    (let* ((major (window-with-parameter 'window-side side nil t))
	   ;; `major' is the major window on SIDE, `windows' the list of
	   ;; life windows on SIDE.
	   (windows
	    (when major
	      (let (windows)
		(walk-window-tree
		 (lambda (window)
		   (when (eq (window-parameter window 'window-side) side)
		     (setq windows (cons window windows)))))
		(nreverse windows))))
	   (slots (when major (max 1 (window-child-count major))))
	   (max-slots
	    (nth (cond
		  ((eq side 'left) 0)
		  ((eq side 'top) 1)
		  ((eq side 'right) 2)
		  ((eq side 'bottom) 3))
		 window-sides-slots))
	   (selected-window (selected-window))
	   window this-window this-slot prev-window next-window
	   best-window best-slot abs-slot new-window)

      (cond
       ((and (numberp max-slots) (<= max-slots 0))
	;; No side-slots available on this side.  Don't create an error,
	;; just return nil.
	nil)
       ((not windows)
	;; No major window exists on this side, make one.
	(display-buffer-in-major-side-window buffer side slot alist))
       (t
	;; Scan windows on SIDE.
	(catch 'found
	  (dolist (window windows)
	    (setq this-slot (window-parameter window 'window-slot))
	    (cond
	     ;; The following should not happen and probably be checked
	     ;; by window--side-check.
	     ((not (numberp this-slot)))
	     ((= this-slot slot)
	      ;; A window with a matching slot has been found.
	      (setq this-window window)
	      (throw 'found t))
	     (t
	      ;; Check if this window has a better slot value wrt the
	      ;; slot of the window we want.
	      (setq abs-slot
		    (if (or (and (> this-slot 0) (> slot 0))
			    (and (< this-slot 0) (< slot 0)))
			(abs (- slot this-slot))
		      (+ (abs slot) (abs this-slot))))
	      (unless (and best-slot (<= best-slot abs-slot))
		(setq best-window window)
		(setq best-slot abs-slot))
	      (cond
	       ((<= this-slot slot)
		(setq prev-window window))
	       ((not next-window)
		(setq next-window window)))))))

	;; `this-window' is the first window with the same SLOT.
	;; `prev-window' is the window with the largest slot < SLOT.  A new
	;; window will be created after it.
	;; `next-window' is the window with the smallest slot > SLOT.  A new
	;; window will be created before it.
	;; `best-window' is the window with the smallest absolute difference
	;; of its slot and SLOT.

	;; Note: We dedicate the window used softly to its buffer to
	;; avoid that "other" (non-side) buffer display functions steal
	;; it from us.  This must eventually become customizable via
	;; ALIST (or, better, avoided in the "other" functions).
	(or (and this-window
		 ;; Reuse `this-window'.
		 (window--display-buffer buffer this-window 'reuse 'side))
	    (and (or (not max-slots) (< slots max-slots))
		 (or (and next-window
			  ;; Make new window before `next-window'.
			  (let ((next-side
				 (if (memq side '(left right)) 'above 'left))
				(window-combination-resize 'side))
			    (setq window (split-window next-window nil next-side))
			    ;; When the new window is deleted, its space
			    ;; is returned to other side windows.
			    (set-window-parameter
			     window 'delete-window 'delete-side-window)
			    window))
		     (and prev-window
			  ;; Make new window after `prev-window'.
			  (let ((prev-side
				 (if (memq side '(left right)) 'below 'right))
				(window-combination-resize 'side))
			    (setq window (split-window prev-window nil prev-side))
			    ;; When the new window is deleted, its space
			    ;; is returned to other side windows.
			    (set-window-parameter
			     window 'delete-window 'delete-side-window)
			    window)))
		   (set-window-parameter window 'window-slot slot)
		   (window--display-buffer buffer window 'window 'side))
	    (and best-window
		 ;; Reuse `best-window'.
		 (progn
		   ;; Give best-window the new slot value.
		   (set-window-parameter best-window 'window-slot slot)
		   (window--display-buffer buffer best-window 'reuse 'side)))))))))

736
(defun window--side-check (&optional frame)
737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754
  "Check the side window configuration of FRAME.
FRAME defaults to the selected frame.

A valid side window configuration preserves the following two
invariants:

- If there exists a window whose window-side parameter is
  non-nil, there must exist at least one live window whose
  window-side parameter is nil.

- If a window W has a non-nil window-side parameter (i) it must
  have a parent window and that parent's window-side parameter
  must be either nil or the same as for W, and (ii) any child
  window of W must have the same window-side parameter as W.

If the configuration is invalid, reset the window-side parameters
of all windows on FRAME to nil."
  (let (left top right bottom none side parent parent-side)
755 756 757 758 759 760 761 762 763 764 765 766 767 768 769
    (when (or (catch 'reset
		(walk-window-tree
		 (lambda (window)
		   (setq side (window-parameter window 'window-side))
		   (setq parent (window-parent window))
		   (setq parent-side
			 (and parent (window-parameter parent 'window-side)))
		   ;; The following `cond' seems a bit tedious, but I'd
		   ;; rather stick to using just the stack.
		   (cond
		    (parent-side
		     (when (not (eq parent-side side))
		       ;; A parent whose window-side is non-nil must
		       ;; have a child with the same window-side.
		       (throw 'reset t)))
770 771 772 773
		    ((not side)
		     (when (window-buffer window)
		       ;; Record that we have at least one non-side,
		       ;; live window.
774
		       (setq none t)))
775 776 777 778 779 780 781 782 783
		    ((if (memq side '(left top))
			 (window-prev-sibling window)
		       (window-next-sibling window))
		     ;; Left and top major side windows must not have a
		     ;; previous sibling, right and bottom major side
		     ;; windows must not have a next sibling.
		     (throw 'reset t))
		    ;; Now check that there's no more than one major
		    ;; window for any of left, top, right and bottom.
784
		    ((eq side 'left)
785
		     (if left (throw 'reset t) (setq left t)))
786
		    ((eq side 'top)
787
		     (if top (throw 'reset t) (setq top t)))
788
		    ((eq side 'right)
789
		     (if right (throw 'reset t) (setq right t)))
790
		    ((eq side 'bottom)
791 792 793
		     (if bottom (throw 'reset t) (setq bottom t)))
		    (t 
		     (throw 'reset t))))
794
		 frame t))
795 796 797
	      ;; If there's a side window, there must be at least one
	      ;; non-side window.
	      (and (or left top right bottom) (not none)))
798 799 800 801 802
      (walk-window-tree
       (lambda (window)
	 (set-window-parameter window 'window-side nil))
       frame t))))

803
(defun window--check (&optional frame)
804 805
  "Check atomic and side windows on FRAME.
FRAME defaults to the selected frame."
806 807
  (window--side-check frame)
  (window--atom-check frame))
808 809 810 811 812 813 814 815 816

;;; Window sizes.
(defvar window-size-fixed nil
  "Non-nil in a buffer means windows displaying the buffer are fixed-size.
If the value is `height', then only the window's height is fixed.
If the value is `width', then only the window's width is fixed.
Any other non-nil value fixes both the width and the height.

Emacs won't change the size of any window displaying that buffer,
Juanma Barranquero's avatar
Juanma Barranquero committed
817
unless it has no other choice (like when deleting a neighboring
818 819 820
window).")
(make-variable-buffer-local 'window-size-fixed)

821
(defun window--size-ignore-p (window ignore)
822
  "Return non-nil if IGNORE says to ignore size restrictions for WINDOW."
823
  (if (window-valid-p ignore) (eq window ignore) ignore))
824 825

(defun window-min-size (&optional window horizontal ignore)
826
  "Return the minimum size of WINDOW.
827 828 829 830
WINDOW must be a valid window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means return the minimum
number of columns of WINDOW; otherwise return the minimum number
of WINDOW's lines.
831

832
Optional argument IGNORE, if non-nil, means ignore restrictions
833
imposed by fixed size windows, `window-min-height' or
834
`window-min-width' settings.  If IGNORE equals `safe', live
835
windows may get as small as `window-safe-min-height' lines and
836 837 838
`window-safe-min-width' columns.  If IGNORE is a window, ignore
restrictions for that window only.  Any other non-nil value
means ignore all of the above restrictions for all windows."
839
  (window--min-size-1
840
   (window-normalize-window window) horizontal ignore))
841

842
(defun window--min-size-1 (window horizontal ignore)
843 844 845 846 847
  "Internal function of `window-min-size'."
  (let ((sub (window-child window)))
    (if sub
	(let ((value 0))
	  ;; WINDOW is an internal window.
848
	  (if (window-combined-p sub horizontal)
849
	      ;; The minimum size of an iso-combination is the sum of
850
	      ;; the minimum sizes of its child windows.
851 852
	      (while sub
		(setq value (+ value
853
			       (window--min-size-1 sub horizontal ignore)))
854 855
		(setq sub (window-right sub)))
	    ;; The minimum size of an ortho-combination is the maximum of
856
	    ;; the minimum sizes of its child windows.
857 858
	    (while sub
	      (setq value (max value
859
			       (window--min-size-1 sub horizontal ignore)))
860 861 862 863
	      (setq sub (window-right sub))))
	  value)
      (with-current-buffer (window-buffer window)
	(cond
864
	 ((and (not (window--size-ignore-p window ignore))
865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892
	       (window-size-fixed-p window horizontal))
	  ;; The minimum size of a fixed size window is its size.
	  (window-total-size window horizontal))
	 ((or (eq ignore 'safe) (eq ignore window))
	  ;; If IGNORE equals `safe' or WINDOW return the safe values.
	  (if horizontal window-safe-min-width window-safe-min-height))
	 (horizontal
	  ;; For the minimum width of a window take fringes and
	  ;; scroll-bars into account.  This is questionable and should
	  ;; be removed as soon as we are able to split (and resize)
	  ;; windows such that the new (or resized) windows can get a
	  ;; size less than the user-specified `window-min-height' and
	  ;; `window-min-width'.
	  (let ((frame (window-frame window))
		(fringes (window-fringes window))
		(scroll-bars (window-scroll-bars window)))
	    (max
	     (+ window-safe-min-width
		(ceiling (car fringes) (frame-char-width frame))
		(ceiling (cadr fringes) (frame-char-width frame))
		(cond
		 ((memq (nth 2 scroll-bars) '(left right))
		  (nth 1 scroll-bars))
		 ((memq (frame-parameter frame 'vertical-scroll-bars)
			'(left right))
		  (ceiling (or (frame-parameter frame 'scroll-bar-width) 14)
			   (frame-char-width)))
		 (t 0)))
893
	     (if (and (not (window--size-ignore-p window ignore))
894 895 896 897 898 899 900 901 902
		      (numberp window-min-width))
		 window-min-width
	       0))))
	 (t
	  ;; For the minimum height of a window take any mode- or
	  ;; header-line into account.
	  (max (+ window-safe-min-height
		  (if header-line-format 1 0)
		  (if mode-line-format 1 0))
903
	       (if (and (not (window--size-ignore-p window ignore))
904 905 906 907 908 909
			(numberp window-min-height))
		   window-min-height
		 0))))))))

(defun window-sizable (window delta &optional horizontal ignore)
  "Return DELTA if DELTA lines can be added to WINDOW.
910
WINDOW must be a valid window and defaults to the selected one.
911 912 913 914
Optional argument HORIZONTAL non-nil means return DELTA if DELTA
columns can be added to WINDOW.  A return value of zero means
that no lines (or columns) can be added to WINDOW.

915 916 917
This function looks only at WINDOW and, recursively, its child
windows.  The function `window-resizable' looks at other windows
as well.
918 919 920 921 922 923 924 925 926 927 928

DELTA positive means WINDOW shall be enlarged by DELTA lines or
columns.  If WINDOW cannot be enlarged by DELTA lines or columns
return the maximum value in the range 0..DELTA by which WINDOW
can be enlarged.

DELTA negative means WINDOW shall be shrunk by -DELTA lines or
columns.  If WINDOW cannot be shrunk by -DELTA lines or columns,
return the minimum value in the range DELTA..0 by which WINDOW
can be shrunk.

929
Optional argument IGNORE non-nil means ignore restrictions
930
imposed by fixed size windows, `window-min-height' or
931
`window-min-width' settings.  If IGNORE equals `safe', live
932
windows may get as small as `window-safe-min-height' lines and
933 934 935
`window-safe-min-width' columns.  If IGNORE is a window, ignore
restrictions for that window only.  Any other non-nil value means
ignore all of the above restrictions for all windows."
936
  (setq window (window-normalize-window window))
937 938 939 940 941
  (cond
   ((< delta 0)
    (max (- (window-min-size window horizontal ignore)
	    (window-total-size window horizontal))
	 delta))
942
   ((window--size-ignore-p window ignore)
943 944 945 946 947 948 949
    delta)
   ((> delta 0)
    (if (window-size-fixed-p window horizontal)
	0
      delta))
   (t 0)))

950
(defun window-sizable-p (window delta &optional horizontal ignore)
951
  "Return t if WINDOW can be resized by DELTA lines.
952
WINDOW must be a valid window and defaults to the selected one.
953 954
For the meaning of the arguments of this function see the
doc-string of `window-sizable'."
955
  (setq window (window-normalize-window window))
956 957 958 959
  (if (> delta 0)
      (>= (window-sizable window delta horizontal ignore) delta)
    (<= (window-sizable window delta horizontal ignore) delta)))

960
(defun window--size-fixed-1 (window horizontal)
961 962 963 964 965
  "Internal function for `window-size-fixed-p'."
  (let ((sub (window-child window)))
    (catch 'fixed
      (if sub
	  ;; WINDOW is an internal window.
966
	  (if (window-combined-p sub horizontal)
967 968
	      ;; An iso-combination is fixed size if all its child
	      ;; windows are fixed-size.
969 970
	      (progn
		(while sub
971
		  (unless (window--size-fixed-1 sub horizontal)
972 973
		    ;; We found a non-fixed-size child window, so
		    ;; WINDOW's size is not fixed.
974 975
		    (throw 'fixed nil))
		  (setq sub (window-right sub)))
976
		;; All child windows are fixed-size, so WINDOW's size is
977 978 979
		;; fixed.
		(throw 'fixed t))
	    ;; An ortho-combination is fixed-size if at least one of its
980
	    ;; child windows is fixed-size.
981
	    (while sub
982
	      (when (window--size-fixed-1 sub horizontal)
983 984
		;; We found a fixed-size child window, so WINDOW's size
		;; is fixed.
985 986 987 988 989 990 991 992 993 994
		(throw 'fixed t))
	      (setq sub (window-right sub))))
	;; WINDOW is a live window.
	(with-current-buffer (window-buffer window)
	  (if horizontal
	      (memq window-size-fixed '(width t))
	    (memq window-size-fixed '(height t))))))))

(defun window-size-fixed-p (&optional window horizontal)
  "Return non-nil if WINDOW's height is fixed.
995 996 997
WINDOW must be a valid window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means return non-nil if
WINDOW's width is fixed.
998 999

If this function returns nil, this does not necessarily mean that
Martin Rudalics's avatar
Martin Rudalics committed
1000 1001
WINDOW can be resized in the desired direction.  The function
`window-resizable' can tell that."
1002
  (window--size-fixed-1
1003
   (window-normalize-window window) horizontal))
1004

1005
(defun window--min-delta-1 (window delta &optional horizontal ignore trail noup)
1006 1007 1008 1009 1010 1011 1012 1013
  "Internal function for `window-min-delta'."
  (if (not (window-parent window))
      ;; If we can't go up, return zero.
      0
    ;; Else try to find a non-fixed-size sibling of WINDOW.
    (let* ((parent (window-parent window))
	   (sub (window-child parent)))
      (catch 'done
1014
	(if (window-combined-p sub horizontal)
1015
	    ;; In an iso-combination throw DELTA if we find at least one
1016 1017
	    ;; child window and that window is either not fixed-size or
	    ;; we can ignore fixed-sizeness.
1018 1019 1020 1021 1022 1023
	    (let ((skip (eq trail 'after)))
	      (while sub
		(cond
		 ((eq sub window)
		  (setq skip (eq trail 'before)))
		 (skip)
1024
		 ((and (not (window--size-ignore-p window ignore))
1025 1026
		       (window-size-fixed-p sub horizontal)))
		 (t
1027
		  ;; We found a non-fixed-size child window.
1028 1029 1030
		  (throw 'done delta)))
		(setq sub (window-right sub))))
	  ;; In an ortho-combination set DELTA to the minimum value by
1031
	  ;; which other child windows can shrink.
1032 1033 1034 1035 1036 1037 1038 1039 1040
	  (while sub
	    (unless (eq sub window)
	      (setq delta
		    (min delta
			 (- (window-total-size sub horizontal)
			    (window-min-size sub horizontal ignore)))))
	    (setq sub (window-right sub))))
	(if noup
	    delta
1041
	  (window--min-delta-1 parent delta horizontal ignore trail))))))
1042 1043 1044

(defun window-min-delta (&optional window horizontal ignore trail noup nodown)
  "Return number of lines by which WINDOW can be shrunk.
1045 1046
WINDOW must be a valid window and defaults to the selected one.
Return zero if WINDOW cannot be shrunk.
1047 1048 1049 1050

Optional argument HORIZONTAL non-nil means return number of
columns by which WINDOW can be shrunk.

1051
Optional argument IGNORE non-nil means ignore restrictions
1052
imposed by fixed size windows, `window-min-height' or
1053 1054
`window-min-width' settings.  If IGNORE is a window, ignore
restrictions for that window only.  If IGNORE equals `safe',
1055
live windows may get as small as `window-safe-min-height' lines
1056 1057
and `window-safe-min-width' columns.  Any other non-nil value
means ignore all of the above restrictions for all windows.
1058

1059 1060 1061 1062
Optional argument TRAIL restricts the windows that can be enlarged.
If its value is `before', only windows to the left of or above WINDOW
can be enlarged.  If it is `after', only windows to the right of or
below WINDOW can be enlarged.
1063 1064

Optional argument NOUP non-nil means don't go up in the window
1065
tree, but try to enlarge windows within WINDOW's combination only.
1066 1067

Optional argument NODOWN non-nil means don't check whether WINDOW
Juanma Barranquero's avatar
Juanma Barranquero committed
1068
itself (and its child windows) can be shrunk; check only whether
1069
at least one other window can be enlarged appropriately."
1070
  (setq window (window-normalize-window window))
1071 1072 1073 1074 1075
  (let ((size (window-total-size window horizontal))
	(minimum (window-min-size window horizontal ignore)))
    (cond
     (nodown
      ;; If NODOWN is t, try to recover the entire size of WINDOW.
1076
      (window--min-delta-1 window size horizontal ignore trail noup))
1077 1078 1079 1080 1081 1082 1083
     ((= size minimum)
      ;; If NODOWN is nil and WINDOW's size is already at its minimum,
      ;; there's nothing to recover.
      0)
     (t
      ;; Otherwise, try to recover whatever WINDOW is larger than its
      ;; minimum size.
1084
      (window--min-delta-1
1085 1086
       window (- size minimum) horizontal ignore trail noup)))))

1087
(defun window--max-delta-1 (window delta &optional horizontal ignore trail noup)
1088 1089 1090 1091 1092 1093 1094
  "Internal function of `window-max-delta'."
  (if (not (window-parent window))
      ;; Can't go up.  Return DELTA.
      delta
    (let* ((parent (window-parent window))
	   (sub (window-child parent)))
      (catch 'fixed
1095
	(if (window-combined-p sub horizontal)
1096
	    ;; For an iso-combination calculate how much we can get from
1097
	    ;; other child windows.
1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
	    (let ((skip (eq trail 'after)))
	      (while sub
		(cond
		 ((eq sub window)
		  (setq skip (eq trail 'before)))
		 (skip)
		 (t
		  (setq delta
			(+ delta
			   (- (window-total-size sub horizontal)
			      (window-min-size sub horizontal ignore))))))
		(setq sub (window-right sub))))
	  ;; For an ortho-combination throw DELTA when at least one
1111
	  ;; child window is fixed-size.
1112 1113
	  (while sub
	    (when (and (not (eq sub window))
1114
		       (not (window--size-ignore-p sub ignore))
1115 1116 1117 1118 1119 1120 1121 1122
		       (window-size-fixed-p sub horizontal))
	      (throw 'fixed delta))
	    (setq sub (window-right sub))))
	(if noup
	    ;; When NOUP is nil, DELTA is all we can get.
	    delta
	  ;; Else try with parent of WINDOW, passing the DELTA we
	  ;; recovered so far.
1123
	  (window--max-delta-1 parent delta horizontal ignore trail))))))
1124 1125

(defun window-max-delta (&optional window horizontal ignore trail noup nodown)
1126
  "Return maximum number of lines by which WINDOW can be enlarged.
1127 1128
WINDOW must be a valid window and defaults to the selected one.
The return value is zero if WINDOW cannot be enlarged.
1129 1130 1131 1132

Optional argument HORIZONTAL non-nil means return maximum number
of columns by which WINDOW can be enlarged.

1133
Optional argument IGNORE non-nil means ignore restrictions
1134
imposed by fixed size windows, `window-min-height' or
1135 1136
`window-min-width' settings.  If IGNORE is a window, ignore
restrictions for that window only.  If IGNORE equals `safe',
1137
live windows may get as small as `window-safe-min-height' lines
1138 1139
and `window-safe-min-width' columns.  Any other non-nil value means
ignore all of the above restrictions for all windows.
1140

1141 1142 1143 1144
Optional argument TRAIL restricts the windows that can be enlarged.
If its value is `before', only windows to the left of or above WINDOW
can be enlarged.  If it is `after', only windows to the right of or
below WINDOW can be enlarged.
1145 1146 1147 1148 1149 1150

Optional argument NOUP non-nil means don't go up in the window
tree but try to obtain the entire space from windows within
WINDOW's combination.

Optional argument NODOWN non-nil means do not check whether
Juanma Barranquero's avatar
Juanma Barranquero committed
1151
WINDOW itself (and its child windows) can be enlarged; check
1152
only whether other windows can be shrunk appropriately."
1153
  (setq window (window-normalize-window window))
1154
  (if (and (not (