1 ;;; windmove.el --- directional window-selection routines
3 ;; Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
5 ;; Author: Hovav Shacham (hovav@cs.stanford.edu)
6 ;; Created: 17 October 1998
7 ;; Keywords: window, movement, convenience
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
26 ;; --------------------------------------------------------------------
30 ;; This package defines a set of routines, windmove-{left,up,right,
31 ;; down}, for selection of windows in a frame geometrically. For
32 ;; example, `windmove-right' selects the window immediately to the
33 ;; right of the currently-selected one. This functionality is similar
34 ;; to the window-selection controls of the BRIEF editor of yore.
36 ;; One subtle point is what happens when the window to the right has
37 ;; been split vertically; for example, consider a call to
38 ;; `windmove-right' in this setup:
44 ;; | * | | (* is point in the currently
45 ;; | | B | selected window)
49 ;; There are (at least) three reasonable things to do:
50 ;; (1) Always move to the window to the right of the top edge of the
51 ;; selected window; in this case, this policy selects A.
52 ;; (2) Always move to the window to the right of the bottom edge of
53 ;; the selected window; in this case, this policy selects B.
54 ;; (3) Move to the window to the right of point in the selected
55 ;; window. This may select either A or B, depending on the
56 ;; position of point; in the illustrated example, it would select
59 ;; Similar issues arise for all the movement functions. Windmove
60 ;; resolves this problem by allowing the user to specify behavior
61 ;; through a prefix argument. The cases are thus:
62 ;; * if no argument is given to the movement functions, or the
63 ;; argument given is zero, movement is relative to point;
64 ;; * if a positive argument is given, movement is relative to the top
65 ;; or left edge of the selected window, depending on whether the
66 ;; movement is to be horizontal or vertical;
67 ;; * if a negative argument is given, movement is relative to the
68 ;; bottom or right edge of the selected window, depending on whether
69 ;; the movement is to be horizontal or vertical.
72 ;; Another feature enables wrap-around mode when the variable
73 ;; `windmove-wrap-around' is set to a non-nil value. In this mode,
74 ;; movement that falls off the edge of the frame will wrap around to
75 ;; find the window on the opposite side of the frame. Windmove does
76 ;; the Right Thing about the minibuffer; for example, consider:
82 ;; |-----------| (* is point in the currently
83 ;; | B | C | selected window)
87 ;; With wraparound enabled, windmove-down will move to A, while
88 ;; windmove-up will move to the minibuffer if it is active, or to
89 ;; either B or C depending on the prefix argument.
92 ;; A set of default keybindings is supplied: shift-{left,up,right,down}
93 ;; invoke the corresponding Windmove function. See the installation
94 ;; section if you wish to use these keybindings.
99 ;; Put the following line in your `.emacs' file:
101 ;; (windmove-default-keybindings) ; default keybindings
104 ;; If you wish to enable wrap-around, also add a line like:
106 ;; (setq windmove-wrap-around t)
109 ;; Note: If you have an Emacs that manifests a bug that sometimes
110 ;; causes the occasional creation of a "lost column" between windows,
111 ;; so that two adjacent windows do not actually touch, you may want to
112 ;; increase the value of `windmove-window-distance-delta' to 2 or 3:
114 ;; (setq windmove-window-distance-delta 2)
119 ;; Special thanks to Julian Assange (proff@iq.org), whose
120 ;; change-windows-intuitively.el predates Windmove, and provided the
121 ;; inspiration for it. Kin Cho (kin@symmetrycomm.com) was the first
122 ;; to suggest wrap-around behavior. Thanks also to Gerd Moellmann
123 ;; (gerd@gnu.org) for his comments and suggestions.
128 ;; User configurable variables:
131 (defgroup windmove nil
132 "Directional selection of windows in a frame."
139 (defcustom windmove-wrap-around nil
140 "Whether movement off the edge of the frame wraps around.
141 If this variable is set to t, moving left from the leftmost window in
142 a frame will find the rightmost one, and similarly for the other
143 directions. The minibuffer is skipped over in up/down movements if it
148 ;; If your Emacs sometimes places an empty column between two adjacent
149 ;; windows, you may wish to set this delta to 2.
150 (defcustom windmove-window-distance-delta
1
151 "How far away from the current window to look for an adjacent window.
152 Measured in characters either horizontally or vertically; setting this
153 to a value larger than 1 may be useful in getting around window-
154 placement bugs in old versions of Emacs."
160 ;; Implementation overview:
162 ;; The conceptual framework behind this code is all fairly simple. We
163 ;; are on one window; we wish to move to another. The correct window
164 ;; to move to is determined by the position of point in the current
165 ;; window as well as the overall window setup.
167 ;; Early on, I made the decision to base my implementation around the
168 ;; built-in function `window-at'. This function takes a frame-based
169 ;; coordinate, and returns the window that contains it. Using this
170 ;; function, the job of the various top-level windmove functions can
171 ;; be decomposed: first, find the current frame-based location of
172 ;; point; second, manipulate it in some way to give a new location,
173 ;; that hopefully falls in the window immediately at left (or right,
174 ;; etc.); third, use `window-at' and `select-window' to select the
175 ;; window at that new location.
177 ;; This is probably not the only possible architecture, and it turns
178 ;; out to have some inherent cruftiness. (Well, okay, the third step
179 ;; is pretty clean....) We will consider each step in turn.
181 ;; A quick digression about coordinate frames: most of the functions
182 ;; in the windmove package deal with screen coordinates in one way or
183 ;; another. These coordinates are always relative to some reference
184 ;; points. Window-based coordinates have their reference point in the
185 ;; upper-left-hand corner of whatever window is being talked about;
186 ;; frame-based coordinates have their reference point in the
187 ;; upper-left-hand corner of the entire frame (of which the current
188 ;; window is a component).
190 ;; All coordinates are zero-based, which simply means that the
191 ;; reference point (whatever it is) is assigned the value (x=0, y=0).
192 ;; X-coordinates grow down the screen, and Y-coordinates grow towards
193 ;; the right of the screen.
195 ;; Okay, back to work. The first step is to gather information about
196 ;; the frame-based coordinates of point, or rather, the reference
197 ;; location. The reference location can be point, or the upper-left,
198 ;; or the lower-right corner of the window; the particular one used is
199 ;; controlled by the prefix argument to `windmove-left' and all the
202 ;; This work is done by `windmove-reference-loc'. It can figure out
203 ;; the locations of the corners by calling `window-edges', but to
204 ;; calculate the frame-based location of point, it calls the workhorse
205 ;; function `windmove-coordinates-of-position', which itself calls the
206 ;; incredibly hairy builtin `compute-motion'. There is a good deal of
207 ;; black magic in getting all the arguments to this function just right.
209 ;; The second step is more messy. Conceptually, it is fairly simple:
210 ;; if we know the reference location, and the coordinates of the
211 ;; current window, we can "throw" our reference point just over the
212 ;; appropriate edge of the window, and see what other window is
213 ;; there. More explicitly, consider this example from the user
214 ;; documentation above.
220 ;; | * | | (* is point in the currently
221 ;; | | B | selected window)
225 ;; The asterisk marks the reference point; we wish to move right.
226 ;; Since we are moving horizontally, the Y coordinate of the new
227 ;; location will be the same. The X coordinate can be such that it is
228 ;; just past the edge of the present window. Obviously, the new point
229 ;; will be inside window B. This in itself is fairly simple: using
230 ;; the result of `windmove-reference-loc' and `window-edges', all the
231 ;; necessary math can be performed. (Having said that, there is a
232 ;; good deal of room for off-by-one errors, and Emacs 19.34, at least,
233 ;; sometimes manifests a bug where two windows don't actually touch,
234 ;; so a larger skip is required.) The actual math here is done by
235 ;; `windmove-other-window-loc'.
237 ;; But we can't just pass the result of `windmove-other-window-loc' to
238 ;; `window-at' directly. Why not? Suppose a move would take us off
239 ;; the edge of the screen, say to the left. We want to give a
240 ;; descriptive error message to the user. Or, suppose that a move
241 ;; would place us in the minibuffer. What if the minibuffer is
244 ;; Actually, the whole subject of the minibuffer edge of the frame is
245 ;; rather messy. It turns out that with a sufficiently large delta,
246 ;; we can fly off the bottom edge of the frame and miss the minibuffer
247 ;; altogther. This, I think, is never right: if there's a minibuffer
248 ;; and you're not in it, and you move down, the minibuffer should be
251 ;; (By the way, I'm not totally sure that the code does the right
252 ;; thing in really weird cases, like a frame with no minibuffer.)
254 ;; So, what we need is some ways to do constraining and such. The
255 ;; early versions of windmove took a fairly simplistic approach to all
256 ;; this. When I added the wrap-around option, those internals had to
257 ;; be rewritten. After a *lot* of futzing around, I came up with a
258 ;; two-step process that I think is general enough to cover the
259 ;; relevant cases. (I'm not totally happy with having to pass the
260 ;; window variable as deep as I do, but we can't have everything.)
262 ;; In the first phase, we make sure that the new location is sane.
263 ;; "Sane" means that we can only fall of the edge of the frame in the
264 ;; direction we're moving in, and that we don't miss the minibuffer if
265 ;; we're moving down and not already in the minibuffer. The function
266 ;; `windmove-constrain-loc-for-movement' takes care of all this.
268 ;; Then, we handle the wraparound, if it's enabled. The function
269 ;; `windmove-wrap-loc-for-movement' takes coordinate values (both X
270 ;; and Y) that fall off the edge of the frame, and replaces them with
271 ;; values on the other side of the frame. It also has special
272 ;; minibuffer-handling code again, because we want to wrap through the
273 ;; minibuffer if it's not enabled.
275 ;; So, that's it. Seems to work. All of this work is done by the fun
276 ;; function `windmove-find-other-window'.
278 ;; So, now we have a window to move to (or nil if something's gone
279 ;; wrong). The function `windmove-do-window-select' is the main
280 ;; driver function: it actually does the `select-window'. It is
281 ;; called by four little convenience wrappers, `windmove-left',
282 ;; `windmove-up', `windmove-right', and `windmove-down', which make
283 ;; for convenient keybinding.
286 ;; Quick & dirty utility function to add two (x . y) coords.
287 (defun windmove-coord-add (coord1 coord2
)
288 "Add the two coordinates.
289 Both COORD1 and COORD2 are coordinate cons pairs, (HPOS . VPOS). The
290 result is another coordinate cons pair."
291 (cons (+ (car coord1
) (car coord2
))
292 (+ (cdr coord1
) (cdr coord2
))))
295 (defun windmove-constrain-to-range (n min-n max-n
)
296 "Ensure that N is between MIN-N and MAX-N inclusive by constraining.
297 If N is less than MIN-N, return MIN-N; if greater than MAX-N, return
299 (max min-n
(min n max-n
)))
301 (defun windmove-constrain-around-range (n min-n max-n
)
302 "Ensure that N is between MIN-N and MAX-N inclusive by wrapping.
303 If N is less than MIN-N, return MAX-N; if greater than MAX-N, return
310 (defun windmove-frame-edges (window)
311 "Return (X-MIN Y-MIN X-MAX Y-MAX) for the frame containing WINDOW.
312 If WINDOW is nil, return the edges for the selected frame.
313 (X-MIN, Y-MIN) is the zero-based coordinate of the top-left corner
314 of the frame; (X-MAX, Y-MAX) is the zero-based coordinate of the
315 bottom-right corner of the frame.
316 For example, if a frame has 76 rows and 181 columns, the return value
317 from `windmove-frame-edges' will be the list (0 0 180 75)."
318 (let ((frame (if window
319 (window-frame window
)
323 (x-max (1- (frame-width frame
))) ; 1- for last row & col here
324 (y-max (1- (frame-height frame
))))
325 (list x-min y-min x-max y-max
))))
327 ;; it turns out that constraining is always a good thing, even when
328 ;; wrapping is going to happen. this is because:
329 ;; first, since we disallow exotic diagonal-around-a-corner type
330 ;; movements, so we can always fix the unimportant direction (the one
331 ;; we're not moving in).
332 ;; second, if we're moving down and we're not in the minibuffer, then
333 ;; constraining the y coordinate to max-y is okay, because if that
334 ;; falls in the minibuffer and the minibuffer isn't active, that y
335 ;; coordinate will still be off the bottom of the frame as the
336 ;; wrapping function sees it and so will get wrapped around anyway.
337 (defun windmove-constrain-loc-for-movement (coord window dir
)
338 "Constrain COORD so that it is reasonable for the given movement.
339 This involves two things: first, make sure that the \"off\" coordinate
340 -- the one not being moved on, e.g., y for horizontal movement -- is
341 within frame boundaries; second, if the movement is down and we're not
342 moving from the minibuffer, make sure that the y coordinate does not
343 exceed the frame max-y, so that we don't overshoot the minibuffer
344 accidentally. WINDOW is the window that movement is relative to; DIR
345 is the direction of the movement, one of `left', `up', `right',
347 Returns the constrained coordinate."
348 (let ((frame-edges (windmove-frame-edges window
))
349 (in-minibuffer (window-minibuffer-p window
)))
350 (let ((min-x (nth 0 frame-edges
))
351 (min-y (nth 1 frame-edges
))
352 (max-x (nth 2 frame-edges
))
353 (max-y (nth 3 frame-edges
)))
355 (if (memq dir
'(up down
)) ; vertical movement
356 (windmove-constrain-to-range (car coord
) min-x max-x
)
359 (if (or (memq dir
'(left right
)) ; horizontal movement
361 (not in-minibuffer
))) ; don't miss minibuffer
362 ;; (technically, we shouldn't constrain on min-y in the
363 ;; second case, but this shouldn't do any harm on a
365 (windmove-constrain-to-range (cdr coord
) min-y max-y
)
367 (cons new-x new-y
)))))
369 ;; having constrained in the limited sense of windmove-constrain-loc-
370 ;; for-movement, the wrapping code is actually much simpler than it
371 ;; otherwise would be. the only complication is that we need to check
372 ;; if the minibuffer is active, and, if not, pretend that it's not
373 ;; even part of the frame.
374 (defun windmove-wrap-loc-for-movement (coord window dir
)
375 "Takes the constrained COORD and wraps it around for the movement.
376 This makes an out-of-range x or y coordinate and wraps it around the
377 frame, giving a coordinate (hopefully) in the window on the other edge
378 of the frame. WINDOW is the window that movement is relative to (nil
379 means the currently selected window); DIR is the direction of the
380 movement, one of `left', `up', `right',or `down'.
381 Returns the wrapped coordinate."
382 (let* ((frame-edges (windmove-frame-edges window
))
383 (frame-minibuffer (minibuffer-window (if window
384 (window-frame window
)
386 (minibuffer-active (minibuffer-window-active-p
388 (let ((min-x (nth 0 frame-edges
))
389 (min-y (nth 1 frame-edges
))
390 (max-x (nth 2 frame-edges
))
391 (max-y (if (not minibuffer-active
)
392 (- (nth 3 frame-edges
)
393 (window-height frame-minibuffer
))
394 (nth 3 frame-edges
))))
396 (windmove-constrain-around-range (car coord
) min-x max-x
)
397 (windmove-constrain-around-range (cdr coord
) min-y max-y
)))))
401 ;; `windmove-coordinates-of-position' is stolen and modified from the
402 ;; Emacs Lisp Reference Manual, section 27.2.5. It seems to work
403 ;; okay, although I am bothered by the fact that tab-offset (the cdr
404 ;; of the next-to- last argument) is set to 0. On the other hand, I
405 ;; can't find a single usage of `compute-motion' anywhere that doesn't
406 ;; set this component to zero, and I'm too lazy to grovel through the
407 ;; C source to figure out what's happening in the background. there
408 ;; also seems to be a good deal of fun in calculating the correct
409 ;; width of lines for telling `compute-motion' about; in particular,
410 ;; it seems we need to subtract 1 (for the continuation column) from
411 ;; the number that `window-width' gives, or continuation lines aren't
412 ;; counted correctly. I haven't seen anyone doing this before,
414 (defun windmove-coordinates-of-position (pos &optional window
)
415 "Return the coordinates of position POS in window WINDOW.
416 Return the window-based coodinates in a cons pair: (HPOS . VPOS),
417 where HPOS and VPOS are the zero-based x and y components of the
418 screen location of POS. If WINDOW is nil, return the coordinates in
419 the currently selected window.
420 As an example, if point is in the top left corner of a window, then
421 the return value from `windmove-coordinates-of-position' is (0 . 0)
422 regardless of the where point is in the buffer and where the window
423 is placed in the frame."
424 (let* ((wind (if (null window
) (selected-window) window
))
425 (usable-width (1- (window-width wind
))) ; 1- for cont. column
426 (usable-height (1- (window-height wind
))) ; 1- for mode line
427 (big-hairy-result (compute-motion
431 (cons usable-width usable-height
)
433 (cons (window-hscroll)
436 (cons (nth 1 big-hairy-result
) ; hpos, not vpos as documented
437 (nth 2 big-hairy-result
)))) ; vpos, not hpos as documented
439 ;; This calculates the reference location in the current window: the
440 ;; frame-based (x . y) of either point, the top-left, or the
441 ;; bottom-right of the window, depending on ARG.
442 (defun windmove-reference-loc (&optional arg window
)
443 "Return the reference location for directional window selection.
444 Return a coordinate (HPOS . VPOS) that is frame-based. If ARG is nil
445 or not supplied, the reference point is the buffer's point in the
446 currently-selected window, or WINDOW if supplied; otherwise, it is the
447 top-left or bottom-right corner of the selected window, or WINDOW if
448 supplied, if ARG is greater or smaller than zero, respectively."
449 (let ((effective-arg (if (null arg
) 0 (prefix-numeric-value arg
)))
450 (edges (window-edges window
)))
451 (let ((top-left (cons (nth 0 edges
)
453 ;; if 1-'s are not there, windows actually extend too far.
454 ;; actually, -2 is necessary for bottom: (nth 3 edges) is
455 ;; the height of the window; -1 because we want 0-based max,
456 ;; -1 to get rid of mode line
457 (bottom-right (cons (- (nth 2 edges
) 1)
458 (- (nth 3 edges
) 2))))
467 (windmove-coordinates-of-position (window-point window
)
470 ;; This uses the reference location in the current window (calculated
471 ;; by `windmove-reference-loc' above) to find a reference location
472 ;; that will hopefully be in the window we want to move to.
473 (defun windmove-other-window-loc (dir &optional arg window
)
474 "Return a location in the window to be moved to.
475 Return value is a frame-based (HPOS . VPOS) value that should be moved
476 to. DIR is one of `left', `up', `right', or `down'; an optional ARG
477 is handled as by `windmove-reference-loc'; WINDOW is the window that
478 movement is relative to."
479 (let ((edges (window-edges window
)) ; edges: (x0, y0, x1, y1)
480 (refpoint (windmove-reference-loc arg window
))) ; (x . y)
483 (cons (- (nth 0 edges
)
484 windmove-window-distance-delta
)
485 (cdr refpoint
))) ; (x0-d, y)
489 windmove-window-distance-delta
))) ; (x, y0-d)
491 (cons (+ (nth 2 edges
)
492 windmove-window-distance-delta
)
493 (cdr refpoint
))) ; (x1+d, y)
497 windmove-window-distance-delta
))) ; (x, y1+d)
498 (t (error "Invalid direction of movement: %s" dir
)))))
500 (defun windmove-find-other-window (dir &optional arg window
)
501 "Return the window object in direction DIR.
502 DIR, ARG, and WINDOW are handled as by `windmove-other-window-loc'."
503 (let* ((actual-current-window (or window
(selected-window)))
504 (raw-other-window-loc
505 (windmove-other-window-loc dir arg actual-current-window
))
506 (constrained-other-window-loc
507 (windmove-constrain-loc-for-movement raw-other-window-loc
508 actual-current-window
511 (if windmove-wrap-around
512 (windmove-wrap-loc-for-movement constrained-other-window-loc
513 actual-current-window
515 constrained-other-window-loc
)))
516 (window-at (car other-window-loc
)
517 (cdr other-window-loc
))))
520 ;; Selects the window that's hopefully at the location returned by
521 ;; `windmove-other-window-loc', or screams if there's no window there.
522 (defun windmove-do-window-select (dir &optional arg window
)
523 "Move to the window at direction DIR.
524 DIR, ARG, and WINDOW are handled as by `windmove-other-window-loc'.
525 If no window is at direction DIR, an error is signaled."
526 (let ((other-window (windmove-find-other-window dir arg window
)))
527 (cond ((null other-window
)
528 (error "No window at %s" dir
))
529 ((and (window-minibuffer-p other-window
)
530 (not (minibuffer-window-active-p other-window
)))
531 (error "Can't move to inactive minibuffer"))
533 (select-window other-window
)))))
536 ;;; end-user functions
537 ;; these are all simple interactive wrappers to `windmove-do-
538 ;; window-select', meant to be bound to keys.
541 (defun windmove-left (&optional arg
)
542 "Select the window to the left of the current one.
543 With no prefix argument, or with prefix argument equal to zero,
544 \"left\" is relative to the position of point in the window; otherwise
545 it is relative to the top edge (for positive ARG) or the bottom edge
546 (for negative ARG) of the current window.
547 If no window is at the desired location, an error is signaled."
549 (windmove-do-window-select 'left arg
))
552 (defun windmove-up (&optional arg
)
553 "Select the window above the current one.
554 With no prefix argument, or with prefix argument equal to zero, \"up\"
555 is relative to the position of point in the window; otherwise it is
556 relative to the left edge (for positive ARG) or the right edge (for
557 negative ARG) of the current window.
558 If no window is at the desired location, an error is signaled."
560 (windmove-do-window-select 'up arg
))
563 (defun windmove-right (&optional arg
)
564 "Select the window to the right of the current one.
565 With no prefix argument, or with prefix argument equal to zero,
566 \"right\" is relative to the position of point in the window;
567 otherwise it is relative to the top edge (for positive ARG) or the
568 bottom edge (for negative ARG) of the current window.
569 If no window is at the desired location, an error is signaled."
571 (windmove-do-window-select 'right arg
))
574 (defun windmove-down (&optional arg
)
575 "Select the window below the current one.
576 With no prefix argument, or with prefix argument equal to zero,
577 \"down\" is relative to the position of point in the window; otherwise
578 it is relative to the left edge (for positive ARG) or the right edge
579 (for negative ARG) of the current window.
580 If no window is at the desired location, an error is signaled."
582 (windmove-do-window-select 'down arg
))
585 ;;; set up keybindings
586 ;; Idea for this function is from iswitchb.el, by Stephen Eglen
587 ;; (stephen@cns.ed.ac.uk).
588 ;; I don't think these bindings will work on non-X terminals; you
589 ;; probably want to use different bindings in that case.
592 (defun windmove-default-keybindings ()
593 "Set up default keybindings for `windmove'."
595 (global-set-key [(shift left
)] 'windmove-left
)
596 (global-set-key [(shift up
)] 'windmove-up
)
597 (global-set-key [(shift right
)] 'windmove-right
)
598 (global-set-key [(shift down
)] 'windmove-down
))
603 ;;; windmove.el ends here