window.el 116 KB
Newer Older
1 2
;;; window.el --- GNU Emacs window commands aside from those written in C

3
;; Copyright (C) 1985, 1989, 1992-1994, 2000-2011
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 46 47

;; 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:

(eval-when-compile (require 'cl))

(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
48
  (declare (indent 0) (debug t))
49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
  `(let ((save-selected-window-window (selected-window))
	 ;; It is necessary to save all of these, because calling
	 ;; select-window changes frame-selected-window for whatever
	 ;; frame that window is in.
	 (save-selected-window-alist
	  (mapcar (lambda (frame) (cons frame (frame-selected-window frame)))
		  (frame-list))))
     (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))))))

66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159
;; The following two functions are like `window-next' and `window-prev'
;; 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).
(defsubst window-right (window)
  "Return WINDOW's right sibling.
Return nil if WINDOW is the root window of its frame.  WINDOW can
be any window."
  (and window (window-parent window) (window-next window)))

(defsubst window-left (window)
  "Return WINDOW's left sibling.
Return nil if WINDOW is the root window of its frame.  WINDOW can
be any window."
  (and window (window-parent window) (window-prev window)))

(defsubst window-child (window)
  "Return WINDOW's first child window."
  (or (window-vchild window) (window-hchild window)))

(defun window-child-count (window)
  "Return number of WINDOW's child windows."
  (let ((count 0))
    (when (and (windowp window) (setq window (window-child window)))
      (while window
	(setq count (1+ count))
	(setq window (window-next window))))
    count))

(defun window-last-child (window)
  "Return last child window of WINDOW."
  (when (and (windowp window) (setq window (window-child window)))
    (while (window-next window)
      (setq window (window-next window))))
  window)

(defsubst window-any-p (object)
  "Return t if OBJECT denotes a live or internal window."
  (and (windowp object)
       (or (window-buffer object) (window-child object))
       t))

;; The following four functions should probably go to subr.el.
(defsubst normalize-live-buffer (buffer-or-name)
  "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))))

(defsubst normalize-live-frame (frame)
  "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)))

(defsubst normalize-any-window (window)
  "Return window specified by WINDOW.
WINDOW must be a window that has not been deleted and defaults to
the selected window."
  (if window
      (if (window-any-p window)
	  window
	(error "%s is not a window" window))
    (selected-window)))

(defsubst normalize-live-window (window)
  "Return live window specified by WINDOW.
WINDOW must be a live window and defaults to the selected one."
  (if window
      (if (and (windowp window) (window-buffer window))
	  window
	(error "%s is not a live window" window))
    (selected-window)))

(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.")

160 161 162 163 164 165 166 167
(defconst window-safe-min-height 1
  "The absolut minimum number of lines of a window.
Anything less might crash Emacs.")

(defconst window-safe-min-width 2
  "The absolut minimum number of columns of a window.
Anything less might crash Emacs.")

168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501
(defun window-iso-combination-p (&optional window horizontal)
  "If WINDOW is a vertical combination return WINDOW's first child.
WINDOW can be any window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means return WINDOW's first
child if WINDOW is a horizontal combination."
  (setq window (normalize-any-window window))
  (if horizontal
      (window-hchild window)
    (window-vchild window)))

(defsubst window-iso-combined-p (&optional window horizontal)
  "Return non-nil if and only if WINDOW is vertically combined.
WINDOW can be any window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means return non-nil if and
only if WINDOW is horizontally combined."
  (setq window (normalize-any-window window))
  (let ((parent (window-parent window)))
    (and parent (window-iso-combination-p parent horizontal))))

(defun window-iso-combinations (&optional window horizontal)
  "Return largest number of vertically arranged subwindows of WINDOW.
WINDOW can be any window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means to return the largest
number of horizontally arranged subwindows of WINDOW."
  (setq window (normalize-any-window window))
  (cond
   ((window-live-p window)
    ;; If WINDOW is live, return 1.
    1)
   ((window-iso-combination-p window horizontal)
    ;; If WINDOW is iso-combined, return the sum of the values for all
    ;; subwindows of WINDOW.
    (let ((child (window-child window))
	  (count 0))
      (while child
	(setq count
	      (+ (window-iso-combinations child horizontal)
		 count))
	(setq child (window-right child)))
      count))
   (t
    ;; If WINDOW is not iso-combined, return the maximum value of any
    ;; subwindow of WINDOW.
    (let ((child (window-child window))
	  (count 1))
      (while child
	(setq count
	      (max (window-iso-combinations child horizontal)
		   count))
	(setq child (window-right child)))
      count))))

(defun walk-window-tree-1 (proc walk-window-tree-window any &optional sub-only)
  "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)
	(funcall proc walk-window-tree-window))
      (unless walk-window-tree-buffer
	(walk-window-tree-1
	 proc (window-hchild walk-window-tree-window) any)
	(walk-window-tree-1
	 proc (window-vchild walk-window-tree-window) any))
      (if sub-only
	  (setq walk-window-tree-window nil)
	(setq walk-window-tree-window
	      (window-right walk-window-tree-window))))))

(defun walk-window-tree (proc &optional frame any)
  "Run function PROC on each live window of FRAME.
PROC must be a function with one argument - a window.  FRAME must
be a live frame and defaults to the selected one.  ANY, if
non-nil means to run PROC on all live and internal windows of
FRAME.

This function performs a pre-order, depth-first traversal of the
window tree.  If PROC changes the window tree, the result is
unpredictable."
  (let ((walk-window-tree-frame (normalize-live-frame frame)))
    (walk-window-tree-1
     proc (frame-root-window walk-window-tree-frame) any)))

(defun walk-window-subtree (proc &optional window any)
  "Run function PROC on each live subwindow of WINDOW.
WINDOW defaults to the selected window.  PROC must be a function
with one argument - a window.  ANY, if non-nil means to run PROC
on all live and internal subwindows of WINDOW.

This function performs a pre-order, depth-first traversal of the
window tree rooted at WINDOW.  If PROC changes that window tree,
the result is unpredictable."
  (setq window (normalize-any-window window))
  (walk-window-tree-1 proc window any t))

(defun windows-with-parameter (parameter &optional value frame any values)
  "Return a list of all windows on FRAME with PARAMETER non-nil.
FRAME defaults to the selected frame.  Optional argument VALUE
non-nil means only return windows whose window-parameter value of
PARAMETER equals VALUE \(comparison is done using `equal').
Optional argument ANY non-nil means consider internal windows
too.  Optional argument VALUES non-nil means return a list of cons
cells whose car is the value of the parameter and whose cdr is
the window."
  (let (this-value windows)
    (walk-window-tree
     (lambda (window)
       (when (and (setq this-value (window-parameter window parameter))
		  (or (not value) (or (equal value this-value))))
	   (setq windows
		 (if values
		     (cons (cons this-value window) windows)
		   (cons window windows)))))
     frame any)

    (nreverse windows)))

(defun window-with-parameter (parameter &optional value frame any)
  "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
for PARAMETER equals VALUE \(comparison is done with `equal').
Optional argument ANY non-nil means consider internal windows
too."
  (let (this-value windows)
    (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)))
       frame any))))

;;; Atomic windows.
(defun window-atom-root (&optional window)
  "Return root of atomic window WINDOW is a part of.
WINDOW can be any window and defaults to the selected one.
Return nil if WINDOW is not part of a atomic window."
  (setq window (normalize-any-window window))
  (let (root)
    (while (and window (window-parameter window 'window-atom))
      (setq root window)
      (setq window (window-parent window)))
    root))

(defun make-window-atom (window)
  "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))

(defun window-atom-check-1 (window)
  "Subroutine of `window-atom-check'."
  (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)
	(window-atom-check-1 (window-hchild window))
	(window-atom-check-1 (window-vchild window))))
    ;; Check right sibling
    (window-atom-check-1 (window-right window))))

(defun window-atom-check (&optional frame)
  "Check atomicity of all windows on FRAME.
FRAME defaults to the selected frame.  If an atomic window is
wrongly configured, reset the atomicity of all its subwindows to
nil.  An atomic window is wrongly configured if it has no
subwindows or one of its subwindows is not atomic."
  (window-atom-check-1 (frame-root-window frame)))

;; 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
side window slots on \(in this order) the left, top, right and
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."
  :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)

(defun window-side-check (&optional frame)
  "Check the window-side parameter of all windows on FRAME.
FRAME defaults to the selected frame.  If the configuration is
invalid, reset all window-side parameters to nil.

A valid configuration has to preserve the following invariant:

- If a window has a non-nil window-side parameter, it must have a
  parent window and the parent window's window-side parameter
  must be either nil or the same as for window.

- If windows with non-nil window-side parameters exist, there
  must be at most one window of each side and non-side with a
  parent whose window-side parameter is nil and there must be no
  leaf window whose window-side parameter is nil."
  (let (normal none left top right bottom
	side parent parent-side code)
    (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)))
		    ;; Now check that there's more than one main window
		    ;; for any of none, left, top, right and bottom.
		    ((eq side 'none)
		     (if none
			 (throw 'reset t)
		       (setq none t)))
		    ((eq side 'left)
		     (if left
			 (throw 'reset t)
		       (setq left t)))
		    ((eq side 'top)
		     (if top
			 (throw 'reset t)
		       (setq top t)))
		    ((eq side 'right)
		     (if right
			 (throw 'reset t)
		       (setq right t)))
		    ((eq side 'bottom)
		     (if bottom
			 (throw 'reset t)
		       (setq bottom t)))
		    ((window-buffer window)
		     ;; A leaf window without window-side parameter,
		     ;; record its existence.
		     (setq normal t))))
		 frame t))
	      (if none
		  ;; At least one non-side window exists, so there must
		  ;; be at least one side-window and no normal window.
		  (or (not (or left top right bottom)) normal)
		;; No non-side window exists, so there must be no side
		;; window either.
		(or left top right bottom)))
      (walk-window-tree
       (lambda (window)
	 (set-window-parameter window 'window-side nil))
       frame t))))

(defun window-check (&optional frame)
  "Check atomic and side windows on FRAME.
FRAME defaults to the selected frame."
  (window-side-check frame)
  (window-atom-check frame))

;;; 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,
unless it has no other choice \(like when deleting a neighboring
window).")
(make-variable-buffer-local 'window-size-fixed)

502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901
(defsubst window-size-ignore (window ignore)
  "Return non-nil if IGNORE says to ignore size restrictions for WINDOW."
  (if (window-any-p ignore) (eq window ignore) ignore))

(defun window-min-size (&optional window horizontal ignore)
  "Return the minimum number of lines of WINDOW.
WINDOW can be an arbitrary window and defaults to the selected
one.  Optional argument HORIZONTAL non-nil means return the
minimum number of columns of WINDOW.

Optional argument IGNORE non-nil means ignore any restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings.  IGNORE equal `safe' means live
windows may get as small as `window-safe-min-height' lines and
`window-safe-min-width' columns.  IGNORE a window means ignore
restrictions for that window only."
  (window-min-size-1
   (normalize-any-window window) horizontal ignore))

(defun window-min-size-1 (window horizontal ignore)
  "Internal function of `window-min-size'."
  (let ((sub (window-child window)))
    (if sub
	(let ((value 0))
	  ;; WINDOW is an internal window.
	  (if (window-iso-combined-p sub horizontal)
	      ;; The minimum size of an iso-combination is the sum of
	      ;; the minimum sizes of its subwindows.
	      (while sub
		(setq value (+ value
			       (window-min-size-1 sub horizontal ignore)))
		(setq sub (window-right sub)))
	    ;; The minimum size of an ortho-combination is the maximum of
	    ;; the minimum sizes of its subwindows.
	    (while sub
	      (setq value (max value
			       (window-min-size-1 sub horizontal ignore)))
	      (setq sub (window-right sub))))
	  value)
      (with-current-buffer (window-buffer window)
	(cond
	 ((and (not (window-size-ignore window ignore))
	       (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)))
	     (if (and (not (window-size-ignore window ignore))
		      (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))
	       (if (and (not (window-size-ignore window ignore))
			(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.
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.

This function looks only at WINDOW and its subwindows.  The
function `window-resizable' looks at other windows as well.

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.

Optional argument IGNORE non-nil means ignore any restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings.  IGNORE equal `safe' means live
windows may get as small as `window-safe-min-height' lines and
`window-safe-min-width' columns.  IGNORE any window means ignore
restrictions for that window only."
  (setq window (normalize-any-window window))
  (cond
   ((< delta 0)
    (max (- (window-min-size window horizontal ignore)
	    (window-total-size window horizontal))
	 delta))
   ((window-size-ignore window ignore)
    delta)
   ((> delta 0)
    (if (window-size-fixed-p window horizontal)
	0
      delta))
   (t 0)))

(defsubst window-sizable-p (window delta &optional horizontal ignore)
  "Return t if WINDOW can be resized by DELTA lines.
For the meaning of the arguments of this function see the
doc-string of `window-sizable'."
  (setq window (normalize-any-window window))
  (if (> delta 0)
      (>= (window-sizable window delta horizontal ignore) delta)
    (<= (window-sizable window delta horizontal ignore) delta)))

(defun window-size-fixed-1 (window horizontal)
  "Internal function for `window-size-fixed-p'."
  (let ((sub (window-child window)))
    (catch 'fixed
      (if sub
	  ;; WINDOW is an internal window.
	  (if (window-iso-combined-p sub horizontal)
	      ;; An iso-combination is fixed size if all its subwindows
	      ;; are fixed-size.
	      (progn
		(while sub
		  (unless (window-size-fixed-1 sub horizontal)
		    ;; We found a non-fixed-size subwindow, so WINDOW's
		    ;; size is not fixed.
		    (throw 'fixed nil))
		  (setq sub (window-right sub)))
		;; All subwindows are fixed-size, so WINDOW's size is
		;; fixed.
		(throw 'fixed t))
	    ;; An ortho-combination is fixed-size if at least one of its
	    ;; subwindows is fixed-size.
	    (while sub
	      (when (window-size-fixed-1 sub horizontal)
		;; We found a fixed-size subwindow, so WINDOW's size is
		;; fixed.
		(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.
WINDOW can be an arbitrary window and defaults to the selected
window.  Optional argument HORIZONTAL non-nil means return
non-nil if WINDOW's width is fixed.

If this function returns nil, this does not necessarily mean that
WINDOW can be resized in the desired direction.  The functions
`window-resizable' and `window-resizable-p' will tell that."
  (window-size-fixed-1
   (normalize-any-window window) horizontal))

(defun window-min-delta-1 (window delta &optional horizontal ignore trail noup)
  "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
	(if (window-iso-combined-p sub horizontal)
	    ;; In an iso-combination throw DELTA if we find at least one
	    ;; subwindow and that subwindow is either not of fixed-size
	    ;; or we can ignore fixed-sizeness.
	    (let ((skip (eq trail 'after)))
	      (while sub
		(cond
		 ((eq sub window)
		  (setq skip (eq trail 'before)))
		 (skip)
		 ((and (not (window-size-ignore window ignore))
		       (window-size-fixed-p sub horizontal)))
		 (t
		  ;; We found a non-fixed-size subwindow.
		  (throw 'done delta)))
		(setq sub (window-right sub))))
	  ;; In an ortho-combination set DELTA to the minimum value by
	  ;; which other subwindows can shrink.
	  (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
	  (window-min-delta-1 parent delta horizontal ignore trail))))))

(defun window-min-delta (&optional window horizontal ignore trail noup nodown)
  "Return number of lines by which WINDOW can be shrunk.
WINDOW can be an arbitrary window and defaults to the selected
window.  Return zero if WINDOW cannot be shrunk.

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

Optional argument IGNORE non-nil means ignore any restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings.  IGNORE a window means ignore
restrictions for that window only.  IGNORE equal `safe' means
live windows may get as small as `window-safe-min-height' lines
and `window-safe-min-width' columns.

Optional argument TRAIL `before' means only windows to the left
of or above WINDOW can be enlarged.  Optional argument TRAIL
`after' means only windows to the right of or below WINDOW can be
enlarged.

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

Optional argument NODOWN non-nil means don't check whether WINDOW
itself \(and its subwindows) can be shrunk; check only whether at
least one other windows can be enlarged appropriately."
  (setq window (normalize-any-window window))
  (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.
      (window-min-delta-1 window size horizontal ignore trail noup))
     ((= 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.
      (window-min-delta-1
       window (- size minimum) horizontal ignore trail noup)))))

(defun window-max-delta-1 (window delta &optional horizontal ignore trail noup)
  "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
	(if (window-iso-combined-p sub horizontal)
	    ;; For an iso-combination calculate how much we can get from
	    ;; other subwindows.
	    (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
	  ;; subwindow is fixed-size.
	  (while sub
	    (when (and (not (eq sub window))
		       (not (window-size-ignore sub ignore))
		       (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.
	  (window-max-delta-1 parent delta horizontal ignore trail))))))

(defun window-max-delta (&optional window horizontal ignore trail noup nodown)
  "Return maximum number of lines WINDOW by which WINDOW can be enlarged.
WINDOW can be an arbitrary window and defaults to the selected
window.  The return value is zero if WINDOW cannot be enlarged.

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

Optional argument IGNORE non-nil means ignore any restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings.  IGNORE a window means ignore
restrictions for that window only.  IGNORE equal `safe' means
live windows may get as small as `window-safe-min-height' lines
and `window-safe-min-width' columns.

Optional argument TRAIL `before' means only windows to the left
of or below WINDOW can be shrunk.  Optional argument TRAIL
`after' means only windows to the right of or above WINDOW can be
shrunk.

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
WINDOW itself \(and its subwindows) can be enlarged; check only
whether other windows can be shrunk appropriately."
  (setq window (normalize-any-window window))
  (if (and (not (window-size-ignore window ignore))
	   (not nodown) (window-size-fixed-p window horizontal))
      ;; With IGNORE and NOWDON nil return zero if WINDOW has fixed
      ;; size.
      0
    ;; WINDOW has no fixed size.
    (window-max-delta-1 window 0 horizontal ignore trail noup)))

;; Make NOUP also inhibit the min-size check.
(defun window-resizable (window delta &optional horizontal ignore trail noup nodown)
  "Return DELTA if WINDOW can be resized vertically by DELTA lines.
Optional argument HORIZONTAL non-nil means return DELTA if WINDOW
can be resized horizontally by DELTA columns.  A return value of
zero means that WINDOW is not resizable.

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 that can be used
for shrinking WINDOW.

Optional argument IGNORE non-nil means ignore any restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings.  IGNORE a window means ignore
restrictions for that window only.  IGNORE equal `safe' means
live windows may get as small as `window-safe-min-height' lines
and `window-safe-min-width' columns.

Optional argument TRAIL `before' means only windows to the left
of or below WINDOW can be shrunk.  Optional argument TRAIL
`after' means only windows to the right of or above WINDOW can be
shrunk.

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

Optional argument NODOWN non-nil means don't check whether WINDOW
and its subwindows can be resized."
  (setq window (normalize-any-window window))
  (cond
   ((< delta 0)
    (max (- (window-min-delta window horizontal ignore trail noup nodown))
	 delta))
   ((> delta 0)
    (min (window-max-delta window horizontal ignore trail noup nodown)
	 delta))
   (t 0)))

(defun window-resizable-p (window delta &optional horizontal ignore trail noup nodown)
  "Return t if WINDOW can be resized vertically by DELTA lines.
For the meaning of the arguments of this function see the
doc-string of `window-resizable'."
  (setq window (normalize-any-window window))
  (if (> delta 0)
      (>= (window-resizable window delta horizontal ignore trail noup nodown)
	  delta)
    (<= (window-resizable window delta horizontal ignore trail noup nodown)
	delta)))

(defsubst window-total-height (&optional window)
  "Return the total number of lines of WINDOW.
WINDOW can be any window and defaults to the selected one.  The
return value includes WINDOW's mode line and header line, if any.
If WINDOW is internal the return value is the sum of the total
number of lines of WINDOW's child windows if these are vertically
combined and the height of WINDOW's first child otherwise.

Note: This function does not take into account the value of
`line-spacing' when calculating the number of lines in WINDOW."
  (window-total-size window))
902

903
;; See discussion in bug#4543.
904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
(defsubst window-full-height-p (&optional window)
  "Return t if WINDOW is as high as the containing frame.
More precisely, return t if and only if the total height of
WINDOW equals the total height of the root window of WINDOW's
frame.  WINDOW can be any window and defaults to the selected
one."
  (setq window (normalize-any-window window))
  (= (window-total-size window)
     (window-total-size (frame-root-window window))))

(defsubst window-total-width (&optional window)
  "Return the total number of columns of WINDOW.
WINDOW can be any window and defaults to the selected one.  The
return value includes any vertical dividers or scrollbars of
WINDOW.  If WINDOW is internal, the return value is the sum of
the total number of columns of WINDOW's child windows if these
are horizontally combined and the width of WINDOW's first child
otherwise."
  (window-total-size window t))

(defsubst window-full-width-p (&optional window)
  "Return t if WINDOW is as wide as the containing frame.
More precisely, return t if and only if the total width of WINDOW
equals the total width of the root window of WINDOW's frame.
WINDOW can be any window and defaults to the selected one."
  (setq window (normalize-any-window window))
  (= (window-total-size window t)
     (window-total-size (frame-root-window window) t)))

(defsubst window-body-height (&optional window)
  "Return the number of lines of WINDOW's body.
WINDOW must be a live window and defaults to the selected one.

The return value does not include WINDOW's mode line and header
line, if any.  If a line at the bottom of the window is only
partially visible, that line is included in the return value.  If
you do not want to include a partially visible bottom line in the
return value, use `window-text-height' instead."
  (window-body-size window))

(defsubst window-body-width (&optional window)
  "Return the number of columns of WINDOW's body.
WINDOW must be a live window and defaults to the selected one.

The return value does not include any vertical dividers or scroll
bars owned by WINDOW.  On a window-system the return value does
not include the number of columns used for WINDOW's fringes or
display margins either."
  (window-body-size window t))
953

954 955 956 957 958 959 960
(defun one-window-p (&optional nomini all-frames)
  "Return non-nil if the selected window is the only window.
Optional arg NOMINI non-nil means don't count the minibuffer
even if it is active.  Otherwise, the minibuffer is counted
when it is active.

The optional arg ALL-FRAMES t means count windows on all frames.
961 962 963 964 965 966
If it is `visible', count windows on all visible frames on the
current terminal.  ALL-FRAMES nil or omitted means count only the
selected frame, plus the minibuffer it uses (which may be on
another frame).  ALL-FRAMES 0 means count all windows in all
visible or iconified frames on the current terminal.  If
ALL-FRAMES is anything else, count only the selected frame."
967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016
  (let ((base-window (selected-window)))
    (if (and nomini (eq base-window (minibuffer-window)))
	(setq base-window (next-window base-window)))
    (eq base-window
	(next-window base-window (if nomini 'arg) all-frames))))

(defun window-current-scroll-bars (&optional window)
  "Return the current scroll bar settings for WINDOW.
WINDOW defaults to the selected window.

The return value is a cons cell (VERTICAL . HORIZONTAL) where
VERTICAL specifies the current location of the vertical scroll
bars (`left', `right', or nil), and HORIZONTAL specifies the
current location of the horizontal scroll bars (`top', `bottom',
or nil).

Unlike `window-scroll-bars', this function reports the scroll bar
type actually used, once frame defaults and `scroll-bar-mode' are
taken into account."
  (let ((vert (nth 2 (window-scroll-bars window)))
	(hor nil))
    (when (or (eq vert t) (eq hor t))
      (let ((fcsb (frame-current-scroll-bars
		   (window-frame (or window (selected-window))))))
	(if (eq vert t)
	    (setq vert (car fcsb)))
	(if (eq hor t)
	    (setq hor (cdr fcsb)))))
    (cons vert hor)))

(defun walk-windows (proc &optional minibuf all-frames)
  "Cycle through all windows, calling PROC for each one.
PROC must specify a function with a window as its sole argument.
The optional arguments MINIBUF and ALL-FRAMES specify the set of
windows to include in the walk, see also `next-window'.

MINIBUF t means include the minibuffer window even if the
minibuffer is not active.  MINIBUF nil or omitted means include
the minibuffer window only if the minibuffer is active.  Any
other value means do not include the minibuffer window even if
the minibuffer is active.

Several frames may share a single minibuffer; if the minibuffer
is active, all windows on all frames that share that minibuffer
are included too.  Therefore, if you are using a separate
minibuffer frame and the minibuffer is active and MINIBUF says it
counts, `walk-windows' includes the windows in the frame from
which you entered the minibuffer, as well as the minibuffer
window.

1017 1018
ALL-FRAMES nil or omitted means cycle through all windows on the
 selected frame, plus the minibuffer window if specified by the
1019 1020 1021 1022 1023 1024
 MINIBUF argument, see above.  If the minibuffer counts, cycle
 through all windows on all frames that share that minibuffer
 too.
ALL-FRAMES t means cycle through all windows on all existing
 frames.
ALL-FRAMES `visible' means cycle through all windows on all
1025
 visible frames on the current terminal.
1026
ALL-FRAMES 0 means cycle through all windows on all visible and
1027
 iconified frames on the current terminal.
1028 1029
ALL-FRAMES a frame means cycle through all windows on that frame
 only.
1030 1031
Anything else means cycle through all windows on the selected
 frame and no others.
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075

This function changes neither the order of recently selected
windows nor the buffer list."
  ;; If we start from the minibuffer window, don't fail to come
  ;; back to it.
  (when (window-minibuffer-p (selected-window))
    (setq minibuf t))
  ;; Make sure to not mess up the order of recently selected
  ;; windows.  Use `save-selected-window' and `select-window'
  ;; with second argument non-nil for this purpose.
  (save-selected-window
    (when (framep all-frames)
      (select-window (frame-first-window all-frames) 'norecord))
    (let* (walk-windows-already-seen
	   (walk-windows-current (selected-window)))
      (while (progn
	       (setq walk-windows-current
		     (next-window walk-windows-current minibuf all-frames))
	       (not (memq walk-windows-current walk-windows-already-seen)))
	(setq walk-windows-already-seen
	      (cons walk-windows-current walk-windows-already-seen))
	(funcall proc walk-windows-current)))))

(defun get-window-with-predicate (predicate &optional minibuf
					    all-frames default)
  "Return a window satisfying PREDICATE.
More precisely, cycle through all windows using `walk-windows',
calling the function PREDICATE on each one of them with the
window as its sole argument.  Return the first window for which
PREDICATE returns non-nil.  If no window satisfies PREDICATE,
return DEFAULT.

The optional arguments MINIBUF and ALL-FRAMES specify the set of
windows to include.  See `walk-windows' for the meaning of these
arguments."
  (catch 'found
    (walk-windows #'(lambda (window)
		      (when (funcall predicate window)
			(throw 'found window)))
		  minibuf all-frames)
    default))

(defalias 'some-window 'get-window-with-predicate)

1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
(defun get-lru-window (&optional all-frames dedicated)
   "Return the least recently used window on frames specified by ALL-FRAMES.
Return a full-width window if possible.  A minibuffer window is
never a candidate.  A dedicated window is never a candidate
unless DEDICATED is non-nil, so if all windows are dedicated, the
value is nil.  Avoid returning the selected window if possible.

The following non-nil values of the optional argument ALL-FRAMES
have special meanings:

- t means consider all windows on all existing frames.

- `visible' means consider all windows on all visible frames on
  the current terminal.

- 0 (the number zero) means consider all windows on all visible
  and iconified frames on the current terminal.

- A frame means consider all windows on that frame only.

Any other value of ALL-FRAMES means consider all windows on the
selected frame and no others."
   (let (best-window best-time second-best-window second-best-time time)
    (dolist (window (window-list-1 nil nil all-frames))
      (when (or dedicated (not (window-dedicated-p window)))
	(setq time (window-use-time window))
	(if (or (eq window (selected-window))
		(not (window-full-width-p window)))
	    (when (or (not second-best-time) (< time second-best-time))
	      (setq second-best-time time)
	      (setq second-best-window window))
	  (when (or (not best-time) (< time best-time))
	    (setq best-time time)
	    (setq best-window window)))))
    (or best-window second-best-window)))

(defun get-largest-window (&optional all-frames dedicated)
  "Return the largest window on frames specified by ALL-FRAMES.
A minibuffer window is never a candidate.  A dedicated window is
never a candidate unless DEDICATED is non-nil, so if all windows
are dedicated, the value is nil.

The following non-nil values of the optional argument ALL-FRAMES
have special meanings:

- t means consider all windows on all existing frames.

- `visible' means consider all windows on all visible frames on
  the current terminal.

- 0 (the number zero) means consider all windows on all visible
  and iconified frames on the current terminal.

- A frame means consider all windows on that frame only.

Any other value of ALL-FRAMES means consider all windows on the
selected frame and no others."
  (let ((best-size 0)
	best-window size)
    (dolist (window (window-list-1 nil nil all-frames))
      (when (or dedicated (not (window-dedicated-p window)))
	(setq size (* (window-total-size window)
		      (window-total-size window t)))
	(when (> size best-size)
	  (setq best-size size)
	  (setq best-window window))))
    best-window))

1144 1145 1146 1147 1148
(defun get-buffer-window-list (&optional buffer-or-name minibuf all-frames)
  "Return list of all windows displaying BUFFER-OR-NAME, or nil if none.
BUFFER-OR-NAME may be a buffer or the name of an existing buffer
and defaults to the current buffer.

1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176
Any windows showing BUFFER-OR-NAME on the selected frame are listed
first.

MINIBUF t means include the minibuffer window even if the
minibuffer is not active.  MINIBUF nil or omitted means include
the minibuffer window only if the minibuffer is active.  Any
other value means do not include the minibuffer window even if
the minibuffer is active.

ALL-FRAMES nil or omitted means consider all windows on the
selected frame, plus the minibuffer window if specified by the
MINIBUF argument.  If the minibuffer counts, consider all windows
on all frames that share that minibuffer too.  The following
non-nil values of ALL-FRAMES have special meanings:

- t means consider all windows on all existing frames.

- `visible' means consider all windows on all visible frames on
  the current terminal.

- 0 (the number zero) means consider all windows on all visible
  and iconified frames on the current terminal.

- A frame means consider all windows on that frame only.

Anything else means consider all windows on the selected frame
and no others."
  (let ((buffer (normalize-live-buffer buffer-or-name))
1177
	windows)
1178 1179 1180 1181
    (dolist (window (window-list-1 (frame-first-window) minibuf all-frames))
      (when (eq (window-buffer window) buffer)
	(setq windows (cons window windows))))
    (nreverse windows)))
1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192

(defun minibuffer-window-active-p (window)
  "Return t if WINDOW is the currently active minibuffer window."
  (eq window (active-minibuffer-window)))

(defun count-windows (&optional minibuf)
   "Return the number of visible windows.
The optional argument MINIBUF specifies whether the minibuffer
window shall be counted.  See `walk-windows' for the precise
meaning of this argument."
   (let ((count 0))
1193
     (walk-windows (lambda (_w) (setq count (+ count 1)))
1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364
		   minibuf)
     count))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; `balance-windows' subroutines using `window-tree'

;;; Translate from internal window tree format

(defun bw-get-tree (&optional window-or-frame)
  "Get a window split tree in our format.

WINDOW-OR-FRAME must be nil, a frame, or a window.  If it is nil,
then the whole window split tree for `selected-frame' is returned.
If it is a frame, then this is used instead.  If it is a window,
then the smallest tree containing that window is returned."
  (when window-or-frame
    (unless (or (framep window-or-frame)
                (windowp window-or-frame))
      (error "Not a frame or window: %s" window-or-frame)))
  (let ((subtree (bw-find-tree-sub window-or-frame)))
    (when subtree
      (if (integerp subtree)
	  nil
	(bw-get-tree-1 subtree)))))

(defun bw-get-tree-1 (split)
  (if (windowp split)
      split
    (let ((dir (car split))
          (edges (car (cdr split)))
          (childs (cdr (cdr split))))
      (list
       (cons 'dir (if dir 'ver 'hor))
       (cons 'b (nth 3 edges))
       (cons 'r (nth 2 edges))
       (cons 't (nth 1 edges))
       (cons 'l (nth 0 edges))
       (cons 'childs (mapcar #'bw-get-tree-1 childs))))))

(defun bw-find-tree-sub (window-or-frame &optional get-parent)
  (let* ((window (when (windowp window-or-frame) window-or-frame))
         (frame (when (windowp window) (window-frame window)))
         (wt (car (window-tree frame))))
    (when (< 1 (length (window-list frame 0)))
      (if window
          (bw-find-tree-sub-1 wt window get-parent)
        wt))))

(defun bw-find-tree-sub-1 (tree win &optional get-parent)
  (unless (windowp win) (error "Not a window: %s" win))
  (if (memq win tree)
      (if get-parent
          get-parent
        tree)
    (let ((childs (cdr (cdr tree)))
          child
          subtree)
      (while (and childs (not subtree))
        (setq child (car childs))
        (setq childs (cdr childs))
        (when (and child (listp child))
          (setq subtree (bw-find-tree-sub-1 child win get-parent))))
      (if (integerp subtree)
          (progn
            (if (= 1 subtree)
                tree
              (1- subtree)))
        subtree
        ))))

;;; Window or object edges

(defun bw-l (obj)
  "Left edge of OBJ."
  (if (windowp obj) (nth 0 (window-edges obj)) (cdr (assq 'l obj))))
(defun bw-t (obj)
  "Top edge of OBJ."
  (if (windowp obj) (nth 1 (window-edges obj)) (cdr (assq 't obj))))
(defun bw-r (obj)
  "Right edge of OBJ."
  (if (windowp obj) (nth 2 (window-edges obj)) (cdr (assq 'r obj))))
(defun bw-b (obj)
  "Bottom edge of OBJ."
  (if (windowp obj) (nth 3 (window-edges obj)) (cdr (assq 'b obj))))

;;; Split directions

(defun bw-dir (obj)
  "Return window split tree direction if OBJ.
If OBJ is a window return 'both.  If it is a window split tree
then return its direction."
  (if (symbolp obj)
      obj
    (if (windowp obj)
        'both
      (let ((dir (cdr (assq 'dir obj))))
        (unless (memq dir '(hor ver both))
          (error "Can't find dir in %s" obj))
        dir))))

(defun bw-eqdir (obj1 obj2)
  "Return t if window split tree directions are equal.
OBJ1 and OBJ2 should be either windows or window split trees in
our format.  The directions returned by `bw-dir' are compared and
t is returned if they are `eq' or one of them is 'both."
  (let ((dir1 (bw-dir obj1))
        (dir2 (bw-dir obj2)))
    (or (eq dir1 dir2)
        (eq dir1 'both)
        (eq dir2 'both))))

;;; Building split tree

(defun bw-refresh-edges (obj)
  "Refresh the edge information of OBJ and return OBJ."
  (unless (windowp obj)
    (let ((childs (cdr (assq 'childs obj)))
          (ol 1000)
          (ot 1000)
          (or -1)
          (ob -1))
      (dolist (o childs)
        (when (> ol (bw-l o)) (setq ol (bw-l o)))
        (when (> ot (bw-t o)) (setq ot (bw-t o)))
        (when (< or (bw-r o)) (setq or (bw-r o)))
        (when (< ob (bw-b o)) (setq ob (bw-b o))))
      (setq obj (delq 'l obj))
      (setq obj (delq 't obj))
      (setq obj (delq 'r obj))
      (setq obj (delq 'b obj))
      (add-to-list 'obj (cons 'l ol))
      (add-to-list 'obj (cons 't ot))
      (add-to-list 'obj (cons 'r or))
      (add-to-list 'obj (cons 'b ob))
      ))
  obj)

;;; Balance windows

(defun balance-windows (&optional window-or-frame)
  "Make windows the same heights or widths in window split subtrees.

When called non-interactively WINDOW-OR-FRAME may be either a
window or a frame.  It then balances the windows on the implied
frame.  If the parameter is a window only the corresponding window
subtree is balanced."
  (interactive)
  (let (
        (wt (bw-get-tree window-or-frame))
        (w)
        (h)
        (tried-sizes)
        (last-sizes)
        (windows (window-list nil 0)))
    (when wt
      (while (not (member last-sizes tried-sizes))
        (when last-sizes (setq tried-sizes (cons last-sizes tried-sizes)))
        (setq last-sizes (mapcar (lambda (w)
                                   (window-edges w))
                                 windows))
        (when (eq 'hor (bw-dir wt))
          (setq w (- (bw-r wt) (bw-l wt))))
        (when (eq 'ver (bw-dir wt))
          (setq h (- (bw-b wt) (bw-t wt))))
        (bw-balance-sub wt w h)))))

(defun bw-adjust-window (window delta horizontal)
  "Wrapper around `adjust-window-trailing-edge' with error checking.
Arguments WINDOW, DELTA and HORIZONTAL are passed on to that function."
  ;; `adjust-window-trailing-edge' may fail if delta is too large.
  (while (>= (abs delta) 1)
1365
    (condition-case nil
1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502
        (progn
          (adjust-window-trailing-edge window delta horizontal)
          (setq delta 0))
      (error
       ;;(message "adjust: %s" (error-message-string err))
       (setq delta (/ delta 2))))))

(defun bw-balance-sub (wt w h)
  (setq wt (bw-refresh-edges wt))
  (unless w (setq w (- (bw-r wt) (bw-l wt))))
  (unless h (setq h (- (bw-b wt) (bw-t wt))))
  (if (windowp wt)
      (progn
        (when w
          (let ((dw (- w (- (bw-r wt) (bw-l wt)))))
            (when (/= 0 dw)
              (bw-adjust-window wt dw t))))
        (when h
          (let ((dh (- h (- (bw-b wt) (bw-t wt)))))
            (when (/= 0 dh)
              (bw-adjust-window wt dh nil)))))
    (let* ((childs (cdr (assq 'childs wt)))
           (cw (when w (/ w (if (bw-eqdir 'hor wt) (length childs) 1))))
           (ch (when h (/ h (if (bw-eqdir 'ver wt) (length childs) 1)))))
      (dolist (c childs)
        (bw-balance-sub c cw ch)))))

(defun window-fixed-size-p (&optional window direction)
  "Return t if WINDOW cannot be resized in DIRECTION.
WINDOW defaults to the selected window.  DIRECTION can be
nil (i.e. any), `height' or `width'."
  (with-current-buffer (window-buffer window)
    (when (and (boundp 'window-size-fixed) window-size-fixed)
      (not (and direction
		(member (cons direction window-size-fixed)
			'((height . width) (width . height))))))))

;;; A different solution to balance-windows.

(defvar window-area-factor 1
  "Factor by which the window area should be over-estimated.
This is used by `balance-windows-area'.
Changing this globally has no effect.")
(make-variable-buffer-local 'window-area-factor)

(defun balance-windows-area ()
  "Make all visible windows the same area (approximately).
See also `window-area-factor' to change the relative size of
specific buffers."
  (interactive)
  (let* ((unchanged 0) (carry 0) (round 0)
         ;; Remove fixed-size windows.
         (wins (delq nil (mapcar (lambda (win)
                                   (if (not (window-fixed-size-p win)) win))
                                 (window-list nil 'nomini))))
         (changelog nil)
         next)
    ;; Resizing a window changes the size of surrounding windows in complex
    ;; ways, so it's difficult to balance them all.  The introduction of
    ;; `adjust-window-trailing-edge' made it a bit easier, but it is still
    ;; very difficult to do.  `balance-window' above takes an off-line
    ;; approach: get the whole window tree, then balance it, then try to
    ;; adjust the windows so they fit the result.
    ;; Here, instead, we take a "local optimization" approach, where we just
    ;; go through all the windows several times until nothing needs to be
    ;; changed.  The main problem with this approach is that it's difficult
    ;; to make sure it terminates, so we use some heuristic to try and break
    ;; off infinite loops.
    ;; After a round without any change, we allow a second, to give a chance
    ;; to the carry to propagate a minor imbalance from the end back to
    ;; the beginning.
    (while (< unchanged 2)
      ;; (message "New round")
      (setq unchanged (1+ unchanged) round (1+ round))
      (dolist (win wins)
        (setq next win)
        (while (progn (setq next (next-window next))
                      (window-fixed-size-p next)))
        ;; (assert (eq next (or (cadr (member win wins)) (car wins))))
        (let* ((horiz
                (< (car (window-edges win)) (car (window-edges next))))
               (areadiff (/ (- (* (window-height next) (window-width next)
                                  (buffer-local-value 'window-area-factor
                                                      (window-buffer next)))
                               (* (window-height win) (window-width win)
                                  (buffer-local-value 'window-area-factor
                                                      (window-buffer win))))
                            (max (buffer-local-value 'window-area-factor
                                                     (window-buffer win))
                                 (buffer-local-value 'window-area-factor
                                                     (window-buffer next)))))
               (edgesize (if horiz
                             (+ (window-height win) (window-height next))
                           (+ (window-width win) (window-width next))))
               (diff (/ areadiff edgesize)))
          (when (zerop diff)
            ;; Maybe diff is actually closer to 1 than to 0.
            (setq diff (/ (* 3 areadiff) (* 2 edgesize))))
          (when (and (zerop diff) (not (zerop areadiff)))
            (setq diff (/ (+ areadiff carry) edgesize))
            ;; Change things smoothly.
            (if (or (> diff 1) (< diff -1)) (setq diff (/ diff 2))))
          (if (zerop diff)
              ;; Make sure negligible differences don't accumulate to
              ;; become significant.
              (setq carry (+ carry areadiff))
            (bw-adjust-window win diff horiz)
            ;; (sit-for 0.5)
            (let ((change (cons win (window-edges win))))
              ;; If the same change has been seen already for this window,
              ;; we're most likely in an endless loop, so don't count it as
              ;; a change.
              (unless (member change changelog)
                (push change changelog)
                (setq unchanged 0 carry 0)))))))
    ;; We've now basically balanced all the windows.
    ;; But there may be some minor off-by-one imbalance left over,
    ;; so let's do some fine tuning.
    ;; (bw-finetune wins)
    ;; (message "Done in %d rounds" round)
    ))


(defcustom display-buffer-function nil
  "If non-nil, function to call to handle `display-buffer'.
It will receive two args, the buffer and a flag which if non-nil
means that the currently selected window is not acceptable.  It
should choose or create a window, display the specified buffer in
it, and return the window.

Commands such as `switch-to-buffer-other-window' and
`find-file-other-window' work using this function."
  :type '(choice
	  (const nil)
	  (function :tag "function"))
  :group 'windows)

1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566
(defcustom special-display-buffer-names nil
  "List of names of buffers that should be displayed specially.
Displaying a buffer with `display-buffer' or `pop-to-buffer', if
its name is in this list, displays the buffer in a way specified
by `special-display-function'.  `special-display-popup-frame'
\(the default for `special-display-function') usually displays
the buffer in a separate frame made with the parameters specified
by `special-display-frame-alist'.  If `special-display-function'
has been set to some other function, that function is called with
the buffer as first, and nil as second argument.

Alternatively, an element of this list can be specified as
\(BUFFER-NAME FRAME-PARAMETERS), where BUFFER-NAME is a buffer
name and FRAME-PARAMETERS an alist of \(PARAMETER . VALUE) pairs.
`special-display-popup-frame' will interpret such pairs as frame
parameters when it creates a special frame, overriding the
corresponding values from `special-display-frame-alist'.

As a special case, if FRAME-PARAMETERS contains (same-window . t)
`special-display-popup-frame' displays that buffer in the
selected window.  If FRAME-PARAMETERS contains (same-frame . t),
it displays that buffer in a window on the selected frame.

If `special-display-function' specifies some other function than
`special-display-popup-frame', that function is called with the
buffer named BUFFER-NAME as first, and FRAME-PARAMETERS as second
argument.

Finally, an element of this list can be also specified as
\(BUFFER-NAME FUNCTION OTHER-ARGS).  In that case,
`special-display-popup-frame' will call FUNCTION with the buffer
named BUFFER-NAME as first argument, and OTHER-ARGS as the
second.  If `special-display-function' specifies some other
function, that function is called with the buffer named
BUFFER-NAME as first, and the element's cdr as second argument.

If this variable appears \"not to work\", because you added a
name to it but the corresponding buffer is displayed in the
selected window, look at the values of `same-window-buffer-names'
and `same-window-regexps'.  Those variables take precedence over
this one.

See also `special-display-regexps'."
  :type '(repeat
	  (choice :tag "Buffer"
		  :value ""
		  (string :format "%v")
		  (cons :tag "With parameters"
			:format "%v"
			:value ("" . nil)
			(string :format "%v")
			(repeat :tag "Parameters"
				(cons :format "%v"
				      (symbol :tag "Parameter")
				      (sexp :tag "Value"))))
		  (list :tag "With function"
			:format "%v"
			:value ("" . nil)
			(string :format "%v")
			(function :tag "Function")
			(repeat :tag "Arguments" (sexp)))))
  :group 'windows
  :group 'frames)

1567 1568 1569
;;;###autoload
(put 'special-display-buffer-names 'risky-local-variable t)

1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634
(defcustom special-display-regexps nil
  "List of regexps saying which buffers should be displayed specially.
Displaying a buffer with `display-buffer' or `pop-to-buffer', if
any regexp in this list matches its name, displays it specially
using `special-display-function'.  `special-display-popup-frame'
\(the default for `special-display-function') usually displays
the buffer in a separate frame made with the parameters specified
by `special-display-frame-alist'.  If `special-display-function'
has been set to some other function, that function is called with
the buffer as first, and nil as second argument.

Alternatively, an element of this list can be specified as
\(REGEXP FRAME-PARAMETERS), where REGEXP is a regexp as above and
FRAME-PARAMETERS an alist of (PARAMETER . VALUE) pairs.
`special-display-popup-frame' will then interpret these pairs as
frame parameters when creating a special frame for a buffer whose
name matches REGEXP, overriding the corresponding values from
`special-display-frame-alist'.

As a special case, if FRAME-PARAMETERS contains (same-window . t)
`special-display-popup-frame' displays buffers matching REGEXP in
the selected window.  \(same-frame . t) in FRAME-PARAMETERS means
to display such buffers in a window on the selected frame.

If `special-display-function' specifies some other function than
`special-display-popup-frame', that function is called with the
buffer whose name matched REGEXP as first, and FRAME-PARAMETERS
as second argument.

Finally, an element of this list can be also specified as
\(REGEXP FUNCTION OTHER-ARGS).  `special-display-popup-frame'
will then call FUNCTION with the buffer whose name matched
REGEXP as first, and OTHER-ARGS as second argument.  If
`special-display-function' specifies some other function, that
function is called with the buffer whose name matched REGEXP
as first, and the element's cdr as second argument.

If this variable appears \"not to work\", because you added a
name to it but the corresponding buffer is displayed in the
selected window, look at the values of `same-window-buffer-names'
and `same-window-regexps'.  Those variables take precedence over
this one.

See also `special-display-buffer-names'."
  :type '(repeat
	  (choice :tag "Buffer"
		  :value ""
		  (regexp :format "%v")
		  (cons :tag "With parameters"
			:format "%v"
			:value ("" . nil)
			(regexp :format "%v")
			(repeat :tag "Parameters"
				(cons :format "%v"
				      (symbol :tag "Parameter")
				      (sexp :tag "Value"))))
		  (list :tag "With function"
			:format "%v"
			:value ("" . nil)
			(regexp :format "%v")
			(function :tag "Function")
			(repeat :tag "Arguments" (sexp)))))
  :group 'windows
  :group 'frames)

1635 1636
(defun special-display-p (buffer-name)
  "Return non-nil if a buffer named BUFFER-NAME gets a special frame.
1637 1638 1639 1640 1641 1642
More precisely, return t if `special-display-buffer-names' or
`special-display-regexps' contain a string entry equaling or
matching BUFFER-NAME.  If `special-display-buffer-names' or
`special-display-regexps' contain a list entry whose car equals
or matches BUFFER-NAME, the return value is the cdr of that
entry."
1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658
  (let (tmp)
    (cond
     ((not (stringp buffer-name)))
     ((member buffer-name special-display-buffer-names)
      t)
     ((setq tmp (assoc buffer-name special-display-buffer-names))
      (cdr tmp))
     ((catch 'found
	(dolist (regexp special-display-regexps)
	  (cond
	   ((stringp regexp)
	    (when (string-match-p regexp buffer-name)
	      (throw 'found t)))
	   ((and (consp regexp) (stringp (car regexp))
		 (string-match-p (car regexp) buffer-name))
	    (throw 'found (cdr regexp))))))))))
1659 1660

(defcustom special-display-function 'special-display-popup-frame
1661 1662 1663 1664 1665 1666 1667 1668 1669
  "Function to call for displaying special buffers.
This function is called with two arguments - the buffer and,
optionally, a list - and should return a window displaying that
buffer.  The default value usually makes a separate frame for the
buffer using `special-display-frame-alist' to specify the frame
parameters.  See the definition of `special-display-popup-frame'
for how to specify such a function.

A buffer is special when its name is either listed in
1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680
`special-display-buffer-names' or matches a regexp in
`special-display-regexps'."
  :type 'function
  :group 'frames)

(defcustom same-window-buffer-names nil
  "List of names of buffers that should appear in the \"same\" window.
`display-buffer' and `pop-to-buffer' show a buffer whose name is
on this list in the selected rather than some other window.

An element of this list can be a cons cell instead of just a
1681 1682
string.  In that case, the cell's car must be a string specifying
the buffer name.  This is for compatibility with
1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696
`special-display-buffer-names'; the cdr of the cons cell is
ignored.

See also `same-window-regexps'."
 :type '(repeat (string :format "%v"))
 :group 'windows)

(defcustom same-window-regexps nil
  "List of regexps saying which buffers should appear in the \"same\" window.
`display-buffer' and `pop-to-buffer' show a buffer whose name
matches a regexp on this list in the selected rather than some
other window.

An element of this list can be a cons cell instead of just a
1697
string.  In that case, the cell's car must be a regexp matching
1698
the buffer name.  This is for compatibility with
1699
`special-display-regexps'; the cdr of the cons cell is ignored.
1700 1701 1702 1703 1704

See also `same-window-buffer-names'."
  :type '(repeat (regexp :format "%v"))
  :group 'windows)

1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726
(defun same-window-p (buffer-name)
  "Return non-nil if a buffer named BUFFER-NAME would be shown in the \"same\" window.
This function returns non-nil if `display-buffer' or
`pop-to-buffer' would show a buffer named BUFFER-NAME in the
selected rather than \(as usual\) some other window.  See
`same-window-buffer-names' and `same-window-regexps'."
  (cond
   ((not (stringp buffer-name)))
   ;; The elements of `same-window-buffer-names' can be buffer
   ;; names or cons cells whose cars are buffer names.
   ((member buffer-name same-window-buffer-names))
   ((assoc buffer-name same-window-buffer-names))
   ((catch 'found
      (dolist (regexp same-window-regexps)
	;; The elements of `same-window-regexps' can be regexps
	;; or cons cells whose cars are regexps.
	(when (or (and (stringp regexp)
		       (string-match regexp buffer-name))
		  (and (consp regexp) (stringp (car regexp))
		       (string-match-p (car regexp) buffer-name)))
	  (throw 'found t)))))))

1727 1728
(defcustom pop-up-frames nil
  "Whether `display-buffer' should make a separate frame.
Juanma Barranquero's avatar
Juanma Barranquero committed
1729
If nil, never make a separate frame.
1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751
If the value is `graphic-only', make a separate frame
on graphic displays only.
Any other non-nil value means always make a separate frame."
  :type '(choice
	  (const :tag "Never" nil)
	  (const :tag "On graphic displays only" graphic-only)
	  (const :tag "Always" t))
  :group 'windows)

(defcustom display-buffer-reuse-frames nil
  "Non-nil means `display-buffer' should reuse frames.
If the buffer in question is already displayed in a frame, raise
that frame."
  :type 'boolean
  :version "21.1"
  :group 'windows)

(defcustom pop-up-windows t
  "Non-nil means `display-buffer' should make a new window."
  :type 'boolean
  :group 'windows)

1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776
(defcustom split-window-preferred-function 'split-window-sensibly
  "Function called by `display-buffer' routines to split a window.
This function is called with a window as single argument and is
supposed to split that window and return the new window.  If the
window can (or shall) not be split, it is supposed to return nil.
The default is to call the function `split-window-sensibly' which
tries to split the window in a way which seems most suitable.
You can customize the options `split-height-threshold' and/or
`split-width-threshold' in order to have `split-window-sensibly'
prefer either vertical or horizontal splitting.

If you set this to any other function, bear in mind that the
`display-buffer' routines may call this function two times.  The
argument of the first call is the largest window on its frame.
If that call fails to return a live window, the function is
called again with the least recently used window as argument.  If
that call fails too, `display-buffer' will use an existing window
to display its buffer.

The window selected at the time `display-buffer' was invoked is
still selected when this function is called.  Hence you can
compare the window argument with the value of `selected-window'
if you intend to split the selected window instead or if you do
not want to split the selected window."
  :type 'function
1777 1778 1779
  :version "23.1"
  :group 'windows)

1780 1781 1782 1783 1784 1785 1786 1787 1788
(defcustom split-height-threshold 80
  "Minimum height for splitting windows sensibly.
If this is an integer, `split-window-sensibly' may split a window
vertically only if it has at least this many lines.  If this is
nil, `split-window-sensibly' is not allowed to split a window
vertically.  If, however, a window is the only window on its
frame, `split-window-sensibly' may split it vertically
disregarding the value of this variable."
  :type '(choice (const nil) (integer :tag "lines"))
1789 1790 1791
  :version "23.1"
  :group 'windows)

1792 1793 1794 1795 1796 1797 1798
(defcustom split-width-threshold 160
  "Minimum width for splitting windows sensibly.
If this is an integer, `split-window-sensibly' may split a window
horizontally only if it has at least this many columns.  If this
is nil, `split-window-sensibly' is not allowed to split a window
horizontally."
  :type '(choice (const nil) (integer :tag "columns"))
1799 1800 1801
  :version "23.1"
  :group 'windows)

1802 1803 1804 1805 1806
(defun window-splittable-p (window &optional horizontal)
  "Return non-nil if `split-window-sensibly' may split WINDOW.
Optional argument HORIZONTAL nil or omitted means check whether
`split-window-sensibly' may split WINDOW vertically.  HORIZONTAL
non-nil means check whether WINDOW may be split horizontally.
1807

1808
WINDOW may be split vertically when the following conditions
1809 1810 1811
hold:
- `window-size-fixed' is either nil or equals `width' for the
  buffer of WINDOW.
1812
- `split-height-threshold' is an integer and WINDOW is at least as
1813 1814 1815 1816 1817
  high as `split-height-threshold'.
- When WINDOW is split evenly, the emanating windows are at least
  `window-min-height' lines tall and can accommodate at least one
  line plus - if WINDOW has one - a mode line.

1818
WINDOW may be split horizontally when the following conditions
1819 1820 1821
hold:
- `window-size-fixed' is either nil or equals `height' for the
  buffer of WINDOW.
1822
- `split-width-threshold' is an integer and WINDOW is at least as
1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851
  wide as `split-width-threshold'.
- When WINDOW is split evenly, the emanating windows are at least
  `window-min-width' or two (whichever is larger) columns wide."
  (when (window-live-p window)
    (with-current-buffer (window-buffer window)
      (if horizontal
	  ;; A window can be split horizontally when its width is not
	  ;; fixed, it is at least `split-width-threshold' columns wide
	  ;; and at least twice as wide as `window-min-width' and 2 (the
	  ;; latter value is hardcoded).
	  (and (memq window-size-fixed '(nil height))
	       ;; Testing `window-full-width-p' here hardly makes any
	       ;; sense nowadays.  This can be done more intuitively by
	       ;; setting up `split-width-threshold' appropriately.
	       (numberp split-width-threshold)
	       (>= (window-width window)
		   (max split-width-threshold
			(* 2 (max window-min-width 2)))))
	;; A window can be split vertically when its height is not
	;; fixed, it is at least `split-height-threshold' lines high,
	;; and it is at least twice as high as `window-min-height' and 2
	;; if it has a modeline or 1.
	(and (memq window-size-fixed '(nil width))
	     (numberp split-height-threshold)
	     (>= (window-height window)
		 (max split-height-threshold
		      (* 2 (max window-min-height
				(if mode-line-format 2 1))))))))))

1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900
(defun split-window-sensibly (window)
  "Split WINDOW in a way suitable for `display-buffer'.
If `split-height-threshold' specifies an integer, WINDOW is at
least `split-height-threshold' lines tall and can be split
vertically, split WINDOW into two windows one above the other and
return the lower window.  Otherwise, if `split-width-threshold'
specifies an integer, WINDOW is at least `split-width-threshold'
columns wide and can be split horizontally, split WINDOW into two
windows side by side and return the window on the right.  If this
can't be done either and WINDOW is the only window on its frame,
try to split WINDOW vertically disregarding any value specified
by `split-height-threshold'.  If that succeeds, return the lower
window.  Return nil otherwise.

By default `display-buffer' routines call this function to split
the largest or least recently used window.  To change the default
customize the option `split-window-preferred-function'.

You can enforce this function to not split WINDOW horizontally,
by setting \(or binding) the variable `split-width-threshold' to
nil.  If, in addition, you set `split-height-threshold' to zero,
chances increase that this function does split WINDOW vertically.

In order to not split WINDOW vertically, set \(or bind) the
variable `split-height-threshold' to nil.  Additionally, you can
set `split-width-threshold' to zero to make a horizontal split
more likely to occur.

Have a look at the function `window-splittable-p' if you want to
know how `split-window-sensibly' determines whether WINDOW can be
split."
  (or (and (window-splittable-p window)
	   ;; Split window vertically.
	   (with-selected-window window
	     (split-window-vertically)))
      (and (window-splittable-p window t)
	   ;; Split window horizontally.
	   (with-selected-window window
	     (split-window-horizontally)))
      (and (eq window (frame-root-window (window-frame window)))
	   (not (window-minibuffer-p window))
	   ;; If WINDOW is the only window on its frame and is not the
	   ;; minibuffer window, try to split it vertically disregarding
	   ;; the value of `split-height-threshold'.
	   (let ((split-height-threshold 0))
	     (when (window-splittable-p window)
	       (with-selected-window window
		 (split-window-vertically)))))))

1901
(defun window--try-to-split-window (window)
1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913
  "Try to split WINDOW.
Return value returned by `split-window-preferred-function' if it
represents a live window, nil otherwise."
      (and (window-live-p window)
	   (not (frame-parameter (window-frame window) 'unsplittable))
	   (let ((new-window
		  ;; Since `split-window-preferred-function' might
		  ;; throw an error use `condition-case'.
		  (condition-case nil
		      (funcall split-window-preferred-function window)
		    (error nil))))
	     (and