Fix bug #17588 with mouse highlight when an X frame is redisplayed frequently.
[emacs.git] / lisp / follow.el
blobddb25beb18216e0d1dae2a56500825828f90f11e
1 ;;; follow.el --- synchronize windows showing the same buffer
3 ;; Copyright (C) 1995-1997, 1999, 2001-2014 Free Software Foundation,
4 ;; Inc.
6 ;; Author: Anders Lindgren <andersl@andersl.com>
7 ;; Maintainer: emacs-devel@gnu.org (Anders' email bounces, Sep 2005)
8 ;; Created: 1995-05-25
9 ;; Keywords: display, window, minor-mode, convenience
11 ;; This file is part of GNU Emacs.
13 ;; GNU Emacs is free software: you can redistribute it and/or modify
14 ;; it under the terms of the GNU General Public License as published by
15 ;; the Free Software Foundation, either version 3 of the License, or
16 ;; (at your option) any later version.
18 ;; GNU Emacs is distributed in the hope that it will be useful,
19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ;; GNU General Public License for more details.
23 ;; You should have received a copy of the GNU General Public License
24 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
26 ;;; Commentary:
28 ;; `Follow mode' is a minor mode for Emacs and XEmacs that
29 ;; combines windows into one tall virtual window.
31 ;; The feeling of a "virtual window" has been accomplished by the use
32 ;; of two major techniques:
34 ;; * The windows always display adjacent sections of the buffer.
35 ;; This means that whenever one window is moved, all the
36 ;; others will follow. (Hence the name Follow mode.)
38 ;; * Should point (cursor) end up outside a window, another
39 ;; window displaying that point is selected, if possible. This
40 ;; makes it possible to walk between windows using normal cursor
41 ;; movement commands.
43 ;; Follow mode comes to its prime when a large screen and two
44 ;; side-by-side window are used. The user can, with the help of Follow
45 ;; mode, use two full-height windows as though they are one.
46 ;; Imagine yourself editing a large function, or section of text,
47 ;; and being able to use 144 lines instead of the normal 72... (your
48 ;; mileage may vary).
50 ;; To test this package, make sure `follow' is loaded, or will be
51 ;; autoloaded when activated (see below). Then do the following:
53 ;; * Find your favorite file (preferably a long one).
55 ;; * Resize Emacs so that it will be wide enough for two full size
56 ;; columns. Delete the other windows and split the window with
57 ;; the commands `C-x 1 C-x 3'.
59 ;; * Give the command:
60 ;; M-x follow-mode <RETURN>
62 ;; * Now the display should look something like (assuming the text "71"
63 ;; is on line 71):
65 ;; +----------+----------+
66 ;; |1 |73 |
67 ;; |2 |74 |
68 ;; |3 |75 |
69 ;; ... ...
70 ;; |71 |143 |
71 ;; |72 |144 |
72 ;; +----------+----------+
74 ;; As you can see, the right-hand window starts at line 73, the line
75 ;; immediately below the end of the left-hand window. As long as
76 ;; `follow-mode' is active, the two windows will follow each other!
78 ;; * Play around and enjoy! Scroll one window and watch the other.
79 ;; Jump to the beginning or end. Press `Cursor down' at the last
80 ;; line of the left-hand window. Enter new lines into the
81 ;; text. Enter long lines spanning several lines, or several
82 ;; windows.
84 ;; * Should you find `Follow' mode annoying, just type
85 ;; M-x follow-mode <RETURN>
86 ;; to turn it off.
89 ;; The command `follow-delete-other-windows-and-split' maximizes the
90 ;; visible area of the current buffer.
92 ;; I recommend adding it, and `follow-mode', to hotkeys in the global
93 ;; key map. To do so, add the following lines (replacing `[f7]' and
94 ;; `[f8]' with your favorite keys) to the init file:
96 ;; (global-set-key [f8] 'follow-mode)
97 ;; (global-set-key [f7] 'follow-delete-other-windows-and-split)
100 ;; There exist two system variables that control the appearance of
101 ;; lines wider than the window containing them. The default is to
102 ;; truncate long lines whenever a window isn't as wide as the frame.
104 ;; To make sure lines are never truncated, please place the following
105 ;; lines in your init file:
107 ;; (setq truncate-lines nil)
108 ;; (setq truncate-partial-width-windows nil)
111 ;; The correct way to configure Follow mode, or any other mode for
112 ;; that matter, is to create one or more functions that do
113 ;; whatever you would like to do. These functions are then added to
114 ;; a hook.
116 ;; The keymap `follow-key-map' contains key bindings activated by
117 ;; `follow-mode'.
119 ;; Example:
120 ;; (add-hook 'follow-mode-hook 'my-follow-mode-hook)
122 ;; (defun my-follow-mode-hook ()
123 ;; (define-key follow-mode-map "\C-ca" 'your-favorite-function)
124 ;; (define-key follow-mode-map "\C-cb" 'another-function))
127 ;; Usage:
129 ;; To activate, issue the command "M-x follow-mode"
130 ;; and press Return. To deactivate, do it again.
132 ;; The following is a list of commands useful when follow-mode is active.
134 ;; follow-scroll-up C-c . C-v
135 ;; Scroll text in a Follow mode window chain up.
137 ;; follow-scroll-down C-c . v
138 ;; Like `follow-scroll-up', but in the other direction.
140 ;; follow-delete-other-windows-and-split C-c . 1
141 ;; Maximize the visible area of the current buffer,
142 ;; and enter Follow mode. This is a very convenient
143 ;; way to start Follow mode, hence we recommend that
144 ;; this command be added to the global keymap.
146 ;; follow-recenter C-c . C-l
147 ;; Place point in the center of the middle window,
148 ;; or a specified number of lines from either top or bottom.
150 ;; follow-switch-to-buffer C-c . b
151 ;; Switch buffer in all windows displaying the current buffer
152 ;; in this frame.
154 ;; follow-switch-to-buffer-all C-c . C-b
155 ;; Switch buffer in all windows in the selected frame.
157 ;; follow-switch-to-current-buffer-all
158 ;; Show the current buffer in all windows on the current
159 ;; frame and turn on `follow-mode'.
161 ;; follow-first-window C-c . <
162 ;; Select the first window in the frame showing the same buffer.
164 ;; follow-last-window C-c . >
165 ;; Select the last window in the frame showing the same buffer.
167 ;; follow-next-window C-c . n
168 ;; Select the next window in the frame showing the same buffer.
170 ;; follow-previous-window C-c . p
171 ;; Select the previous window showing the same buffer.
174 ;; Well, it seems ok, but what if I really want to look at two different
175 ;; positions in the text? Here are two simple methods to use:
177 ;; 1) Use multiple frames; `follow' mode only affects windows displayed
178 ;; in the same frame. (My apologies to you who can't use frames.)
180 ;; 2) Bind `follow-mode' to key so you can turn it off whenever
181 ;; you want to view two locations. Of course, `follow' mode can
182 ;; be reactivated by hitting the same key again.
184 ;; Example from my ~/.emacs:
185 ;; (global-set-key [f8] 'follow-mode)
187 ;; Implementation:
189 ;; The main method by which Follow mode aligns windows is via the
190 ;; function `follow-post-command-hook', which is run after each
191 ;; command. This "fixes up" the alignment of other windows which are
192 ;; showing the same Follow mode buffer, on the same frame as the
193 ;; selected window. It does not try to deal with buffers other than
194 ;; the buffer of the selected frame, or windows on other frames.
196 ;; Comint mode specially calls `follow-comint-scroll-to-bottom' on
197 ;; Follow mode buffers. This function scrolls the bottom-most window
198 ;; in a window chain and aligns the other windows accordingly. Follow
199 ;; mode adds a function to `compilation-filter-hook' to align
200 ;; compilation buffers.
202 ;;; Code:
204 (require 'easymenu)
205 (eval-when-compile (require 'cl-lib))
207 ;;; Variables
209 (defgroup follow nil
210 "Synchronize windows showing the same buffer."
211 :group 'windows
212 :group 'convenience)
214 (defcustom follow-mode-hook nil
215 "Normal hook run by `follow-mode'."
216 :type 'hook
217 :group 'follow)
219 ;;; Keymap/Menu
221 ;; Define keys for the follow-mode minor mode map and replace some
222 ;; functions in the global map. All Follow mode special functions can
223 ;; be found on the `C-c .' prefix key.
225 ;; To change the prefix, redefine `follow-mode-prefix' before `follow'
226 ;; is loaded, or see the section on `follow-mode-hook' above for an
227 ;; example of how to bind the keys the way you like.
229 (defcustom follow-mode-prefix "\C-c."
230 "Prefix key to use for follow commands in Follow mode.
231 The value of this variable is checked as part of loading Follow mode.
232 After that, changing the prefix key requires manipulating keymaps."
233 :type 'string
234 :group 'follow)
236 (defvar follow-mode-map
237 (let ((mainmap (make-sparse-keymap))
238 (map (make-sparse-keymap)))
239 (define-key map "\C-v" 'follow-scroll-up)
240 (define-key map "\M-v" 'follow-scroll-down)
241 (define-key map "v" 'follow-scroll-down)
242 (define-key map "1" 'follow-delete-other-windows-and-split)
243 (define-key map "b" 'follow-switch-to-buffer)
244 (define-key map "\C-b" 'follow-switch-to-buffer-all)
245 (define-key map "\C-l" 'follow-recenter)
246 (define-key map "<" 'follow-first-window)
247 (define-key map ">" 'follow-last-window)
248 (define-key map "n" 'follow-next-window)
249 (define-key map "p" 'follow-previous-window)
251 (define-key mainmap follow-mode-prefix map)
253 ;; Replace the standard `end-of-buffer', when in Follow mode. (I
254 ;; don't see the point in trying to replace every function that
255 ;; could be enhanced in Follow mode. End-of-buffer is a special
256 ;; case since it is very simple to define and it greatly enhances
257 ;; the look and feel of Follow mode.)
258 (define-key mainmap [remap end-of-buffer] 'follow-end-of-buffer)
260 (define-key mainmap [remap scroll-bar-toolkit-scroll] 'follow-scroll-bar-toolkit-scroll)
261 (define-key mainmap [remap scroll-bar-drag] 'follow-scroll-bar-drag)
262 (define-key mainmap [remap scroll-bar-scroll-up] 'follow-scroll-bar-scroll-up)
263 (define-key mainmap [remap scroll-bar-scroll-down] 'follow-scroll-bar-scroll-down)
264 (define-key mainmap [remap mwheel-scroll] 'follow-mwheel-scroll)
266 mainmap)
267 "Minor mode keymap for Follow mode.")
269 ;; When the mode is not activated, only one item is visible to activate
270 ;; the mode.
271 (defun follow-menu-filter (menu)
272 (if (bound-and-true-p follow-mode)
273 menu
274 '(["Follow mode" follow-mode
275 :style toggle :selected follow-mode])))
277 (easy-menu-add-item nil '("Tools")
278 '("Follow"
279 :filter follow-menu-filter
280 ["Scroll Up" follow-scroll-up follow-mode]
281 ["Scroll Down" follow-scroll-down follow-mode]
282 "--"
283 ["Delete Other Windows and Split" follow-delete-other-windows-and-split follow-mode]
284 "--"
285 ["Switch To Buffer" follow-switch-to-buffer follow-mode]
286 ["Switch To Buffer (all windows)" follow-switch-to-buffer-all follow-mode]
287 "--"
288 ["First Window" follow-first-window follow-mode]
289 ["Last Window" follow-last-window follow-mode]
290 ["Next Window" follow-next-window follow-mode]
291 ["Previous Window" follow-previous-window follow-mode]
292 "--"
293 ["Recenter" follow-recenter follow-mode]
294 "--"
295 ["Follow mode" follow-mode :style toggle :selected follow-mode]))
297 (defcustom follow-mode-line-text " Follow"
298 "Text shown in the mode line when Follow mode is active.
299 Defaults to \" Follow\". Examples of other values
300 are \" Fw\", or simply \"\"."
301 :type 'string
302 :group 'follow)
304 (defcustom follow-auto nil
305 "Non-nil activates Follow mode whenever a file is loaded."
306 :type 'boolean
307 :group 'follow
308 :set (lambda (symbol value)
309 (if value
310 (add-hook 'find-file-hook 'follow-find-file-hook t)
311 (remove-hook 'find-file-hook 'follow-find-file-hook))
312 (set-default symbol value)))
314 (defvar follow-cache-command-list
315 '(next-line previous-line forward-char backward-char right-char left-char)
316 "List of commands that don't require recalculation.
318 In order to be able to use the cache, a command should not change the
319 contents of the buffer, nor should it change selected window or current
320 buffer.
322 The commands in this list are checked at load time.
324 To mark other commands as suitable for caching, set the symbol
325 property `follow-mode-use-cache' to non-nil.")
327 (defcustom follow-debug nil
328 "If non-nil, emit Follow mode debugging messages."
329 :type 'boolean
330 :group 'follow)
332 ;; Internal variables:
334 (defvar follow-internal-force-redisplay nil
335 "True when Follow mode should redisplay the windows.")
337 (defvar follow-active-menu nil
338 "The menu visible when Follow mode is active.")
340 (defvar follow-inactive-menu nil
341 "The menu visible when Follow mode is inactive.")
343 (defvar follow-inside-post-command-hook nil
344 "Non-nil when inside Follow modes `post-command-hook'.
345 Used by `follow-window-size-change'.")
347 (defvar follow-windows-start-end-cache nil
348 "Cache used by `follow-window-start-end'.")
350 ;;; Debug messages
352 ;; This inline function must be as small as possible!
353 ;; Maybe we should define a macro that expands to nil if
354 ;; the variable is not set.
356 (defsubst follow-debug-message (&rest args)
357 "Like `message', but only active when `follow-debug' is non-nil."
358 (if (and (boundp 'follow-debug) follow-debug)
359 (apply 'message args)))
361 ;;; Cache
363 (dolist (cmd follow-cache-command-list)
364 (put cmd 'follow-mode-use-cache t))
366 ;;; The mode
368 ;;;###autoload
369 (defun turn-on-follow-mode ()
370 "Turn on Follow mode. Please see the function `follow-mode'."
371 (follow-mode 1))
374 ;;;###autoload
375 (defun turn-off-follow-mode ()
376 "Turn off Follow mode. Please see the function `follow-mode'."
377 (follow-mode -1))
379 (put 'follow-mode 'permanent-local t)
380 ;;;###autoload
381 (define-minor-mode follow-mode
382 "Toggle Follow mode.
383 With a prefix argument ARG, enable Follow mode if ARG is
384 positive, and disable it otherwise. If called from Lisp, enable
385 the mode if ARG is omitted or nil.
387 Follow mode is a minor mode that combines windows into one tall
388 virtual window. This is accomplished by two main techniques:
390 * The windows always displays adjacent sections of the buffer.
391 This means that whenever one window is moved, all the
392 others will follow. (Hence the name Follow mode.)
394 * Should point (cursor) end up outside a window, another
395 window displaying that point is selected, if possible. This
396 makes it possible to walk between windows using normal cursor
397 movement commands.
399 Follow mode comes to its prime when used on a large screen and two
400 side-by-side windows are used. The user can, with the help of Follow
401 mode, use two full-height windows as though they would have been
402 one. Imagine yourself editing a large function, or section of text,
403 and being able to use 144 lines instead of the normal 72... (your
404 mileage may vary).
406 To split one large window into two side-by-side windows, the commands
407 `\\[split-window-right]' or \
408 `M-x follow-delete-other-windows-and-split' can be used.
410 Only windows displayed in the same frame follow each other.
412 This command runs the normal hook `follow-mode-hook'.
414 Keys specific to Follow mode:
415 \\{follow-mode-map}"
416 :keymap follow-mode-map
417 (if follow-mode
418 (progn
419 (add-hook 'compilation-filter-hook 'follow-align-compilation-windows t t)
420 (add-hook 'post-command-hook 'follow-post-command-hook t)
421 (add-hook 'window-size-change-functions 'follow-window-size-change t))
422 ;; Remove globally-installed hook functions only if there is no
423 ;; other Follow mode buffer.
424 (let ((buffers (buffer-list))
425 following)
426 (while (and (not following) buffers)
427 (setq following (buffer-local-value 'follow-mode (car buffers))
428 buffers (cdr buffers)))
429 (unless following
430 (remove-hook 'post-command-hook 'follow-post-command-hook)
431 (remove-hook 'window-size-change-functions 'follow-window-size-change)))
432 (remove-hook 'compilation-filter-hook 'follow-align-compilation-windows t)))
434 (defun follow-find-file-hook ()
435 "Find-file hook for Follow mode. See the variable `follow-auto'."
436 (if follow-auto (follow-mode 1)))
438 ;;; User functions
440 ;;; Scroll
442 ;; `scroll-up' and `-down', but for windows in Follow mode.
444 ;; Almost like the real thing, except when the cursor ends up outside
445 ;; the top or bottom... In our case however, we end up outside the
446 ;; window and hence we are recentered. Should we let `recenter' handle
447 ;; the point position we would never leave the selected window. To do
448 ;; it ourselves we would need to do our own redisplay, which is easier
449 ;; said than done. (Why didn't I do a real display abstraction from
450 ;; the beginning?)
452 ;; We must sometimes set `follow-internal-force-redisplay', otherwise
453 ;; our post-command-hook will move our windows back into the old
454 ;; position... (This would also be corrected if we would have had a
455 ;; good redisplay abstraction.)
457 (defun follow-scroll-up (&optional arg)
458 "Scroll text in a Follow mode window chain up.
460 If called with no ARG, the `next-screen-context-lines' last lines of
461 the bottom window in the chain will be visible in the top window.
463 If called with an argument, scroll ARG lines up.
464 Negative ARG means scroll downward.
466 Works like `scroll-up' when not in Follow mode."
467 (interactive "P")
468 (cond ((not follow-mode)
469 (scroll-up arg))
470 (arg
471 (save-excursion (scroll-up arg))
472 (setq follow-internal-force-redisplay t))
474 (let* ((windows (follow-all-followers))
475 (end (window-end (car (reverse windows)))))
476 (if (eq end (point-max))
477 (signal 'end-of-buffer nil)
478 (select-window (car windows))
479 ;; `window-end' might return nil.
480 (if end
481 (goto-char end))
482 (vertical-motion (- next-screen-context-lines))
483 (set-window-start (car windows) (point)))))))
486 (defun follow-scroll-down (&optional arg)
487 "Scroll text in a Follow mode window chain down.
489 If called with no ARG, the `next-screen-context-lines' top lines of
490 the top window in the chain will be visible in the bottom window.
492 If called with an argument, scroll ARG lines down.
493 Negative ARG means scroll upward.
495 Works like `scroll-up' when not in Follow mode."
496 (interactive "P")
497 (cond ((not follow-mode)
498 (scroll-up arg))
499 (arg
500 (save-excursion (scroll-down arg)))
502 (let* ((windows (follow-all-followers))
503 (win (car (reverse windows)))
504 (start (window-start (car windows))))
505 (if (eq start (point-min))
506 (signal 'beginning-of-buffer nil)
507 (select-window win)
508 (goto-char start)
509 (vertical-motion (- (- (window-height win)
510 (if header-line-format 2 1)
511 next-screen-context-lines)))
512 (set-window-start win (point))
513 (goto-char start)
514 (vertical-motion (- next-screen-context-lines 1))
515 (setq follow-internal-force-redisplay t))))))
517 (declare-function comint-adjust-point "comint" (window))
518 (defvar comint-scroll-show-maximum-output)
520 (defun follow-comint-scroll-to-bottom (&optional _window)
521 "Scroll the bottom-most window in the current Follow chain.
522 This is to be called by `comint-postoutput-scroll-to-bottom'."
523 (let* ((buffer (current-buffer))
524 (selected (selected-window))
525 (is-selected (eq (window-buffer) buffer))
526 some-window)
527 (when (or is-selected
528 (setq some-window (get-buffer-window)))
529 (let* ((pos (progn (comint-adjust-point nil) (point)))
530 (win (if is-selected
531 selected
532 (car (last (follow-all-followers some-window))))))
533 (select-window win)
534 (goto-char pos)
535 (setq follow-windows-start-end-cache nil)
536 (follow-adjust-window win)
537 (unless is-selected
538 (select-window selected)
539 (set-buffer buffer))))))
541 (defun follow-align-compilation-windows ()
542 "Align the windows of the current Follow mode buffer.
543 This is to be called from `compilation-filter-hook'."
544 (let ((buffer (current-buffer))
545 (win (get-buffer-window))
546 (selected (selected-window)))
547 (when (and follow-mode (waiting-for-user-input-p) win)
548 (let ((windows (follow-all-followers win)))
549 (unless (eq (window-buffer selected) buffer)
550 (setq win (car windows))
551 (select-window win))
552 (follow-redisplay windows win t)
553 (setq follow-windows-start-end-cache nil)
554 (unless (eq selected win)
555 (select-window selected)
556 (set-buffer buffer))))))
558 ;;; Buffer
560 ;;;###autoload
561 (defun follow-delete-other-windows-and-split (&optional arg)
562 "Create two side by side windows and enter Follow mode.
564 Execute this command to display as much as possible of the text
565 in the selected window. All other windows, in the current
566 frame, are deleted and the selected window is split in two
567 side-by-side windows. Follow mode is activated, hence the
568 two windows always will display two successive pages.
569 \(If one window is moved, the other one will follow.)
571 If ARG is positive, the leftmost window is selected. If negative,
572 the rightmost is selected. If ARG is nil, the leftmost window is
573 selected if the original window is the first one in the frame."
574 (interactive "P")
575 (let ((other (or (and (null arg)
576 (not (eq (selected-window)
577 (frame-first-window))))
578 (and arg
579 (< (prefix-numeric-value arg) 0))))
580 (start (window-start)))
581 (delete-other-windows)
582 (split-window-right)
583 (if other
584 (progn
585 (other-window 1)
586 (set-window-start (selected-window) start)
587 (setq follow-internal-force-redisplay t)))
588 (follow-mode 1)))
590 (defun follow-switch-to-buffer (buffer)
591 "Show BUFFER in all windows in the current Follow mode window chain."
592 (interactive "BSwitch to Buffer: ")
593 (let ((orig-window (selected-window))
594 (windows (follow-all-followers)))
595 (while windows
596 (select-window (car windows))
597 (switch-to-buffer buffer)
598 (setq windows (cdr windows)))
599 (select-window orig-window)))
602 (defun follow-switch-to-buffer-all (&optional buffer)
603 "Show BUFFER in all windows on this frame.
604 Defaults to current buffer."
605 (interactive (list (read-buffer "Switch to Buffer: "
606 (current-buffer))))
607 (or buffer (setq buffer (current-buffer)))
608 (let ((orig-window (selected-window)))
609 (walk-windows (lambda (win)
610 (select-window win)
611 (switch-to-buffer buffer))
612 'no-minibuf)
613 (select-window orig-window)
614 (follow-redisplay)))
617 (defun follow-switch-to-current-buffer-all ()
618 "Show current buffer in all windows on this frame, and enter Follow mode."
619 (interactive)
620 (unless follow-mode
621 (follow-mode 1))
622 (follow-switch-to-buffer-all))
624 ;;; Movement
626 ;; Note, these functions are not very useful, at least not unless you
627 ;; rebind the rather cumbersome key sequence `C-c . p'.
629 (defun follow-next-window ()
630 "Select the next window showing the same buffer."
631 (interactive)
632 (let ((succ (cdr (follow-split-followers (follow-all-followers)))))
633 (if succ
634 (select-window (car succ))
635 (error "%s" "No more windows"))))
638 (defun follow-previous-window ()
639 "Select the previous window showing the same buffer."
640 (interactive)
641 (let ((pred (car (follow-split-followers (follow-all-followers)))))
642 (if pred
643 (select-window (car pred))
644 (error "%s" "No more windows"))))
647 (defun follow-first-window ()
648 "Select the first window in the frame showing the same buffer."
649 (interactive)
650 (select-window (car (follow-all-followers))))
653 (defun follow-last-window ()
654 "Select the last window in the frame showing the same buffer."
655 (interactive)
656 (select-window (car (reverse (follow-all-followers)))))
658 ;;; Redraw
660 (defun follow-recenter (&optional arg)
661 "Recenter the middle window around point.
662 Rearrange all other windows around the middle window.
664 With a positive argument, place the current line ARG lines
665 from the top. With a negative argument, place it -ARG lines
666 from the bottom."
667 (interactive "P")
668 (if arg
669 (let ((p (point))
670 (arg (prefix-numeric-value arg)))
671 (if (>= arg 0)
672 ;; Recenter relative to the top.
673 (progn
674 (follow-first-window)
675 (goto-char p)
676 (recenter arg))
677 ;; Recenter relative to the bottom.
678 (follow-last-window)
679 (goto-char p)
680 (recenter arg)
681 ;; Otherwise, our post-command-hook will move the window
682 ;; right back.
683 (setq follow-internal-force-redisplay t)))
684 ;; Recenter in the middle.
685 (let* ((dest (point))
686 (windows (follow-all-followers))
687 (win (nth (/ (- (length windows) 1) 2) windows)))
688 (select-window win)
689 (goto-char dest)
690 (recenter))))
693 (defun follow-redraw ()
694 "Arrange windows displaying the same buffer in successor order.
695 This function can be called even if the buffer is not in Follow mode.
697 Hopefully, there should be no reason to call this function when in
698 Follow mode since the windows should always be aligned."
699 (interactive)
700 (sit-for 0)
701 (follow-redisplay))
703 ;;; End of buffer
705 (defun follow-end-of-buffer (&optional arg)
706 "Move point to the end of the buffer, Follow mode style.
708 If the end is not visible, it will be displayed in the last possible
709 window in the Follow mode window chain.
711 The mark is left at the previous position. With arg N, put point N/10
712 of the way from the true end."
713 (interactive "P")
714 (let ((followers (follow-all-followers))
715 (pos (point)))
716 (cond (arg
717 (select-window (car (reverse followers))))
718 ((follow-select-if-end-visible
719 (follow-windows-start-end followers)))
721 (select-window (car (reverse followers)))))
722 (goto-char pos)
723 (with-no-warnings
724 (end-of-buffer arg))))
726 ;;; Display
728 (defun follow--window-sorter (w1 w2)
729 "Sorting function for W1 and W2 based on their positions.
730 Return non-nil if W1 is above W2; if their top-lines
731 are at the same position, return non-nil if W1 is to the
732 left of W2."
733 (let* ((edge-1 (window-pixel-edges w1))
734 (edge-2 (window-pixel-edges w2))
735 (y1 (nth 1 edge-1))
736 (y2 (nth 1 edge-2)))
737 (if (= y1 y2)
738 (< (car edge-1) (car edge-2))
739 (< y1 y2))))
741 (defun follow-all-followers (&optional win)
742 "Return all windows displaying the same buffer as the WIN.
743 The list is sorted with topmost and leftmost windows first, and
744 contains only windows in the same frame as WIN. If WIN is nil,
745 it defaults to the selected window."
746 (unless (window-live-p win)
747 (setq win (selected-window)))
748 (let ((windows (get-buffer-window-list
749 (window-buffer win) 'no-minibuf (window-frame win))))
750 (sort windows #'follow--window-sorter)))
752 (defun follow-split-followers (windows &optional win)
753 "Split WINDOWS into two sets: predecessors and successors.
754 Return `(PRED . SUCC)' where `PRED' and `SUCC' are ordered starting
755 from the selected window."
756 (or win
757 (setq win (selected-window)))
758 (let ((pred '()))
759 (while (not (eq (car windows) win))
760 (setq pred (cons (car windows) pred))
761 (setq windows (cdr windows)))
762 (cons pred (cdr windows))))
764 (defun follow-calc-win-end (&optional win)
765 "Calculate the end position for window WIN.
766 Return (END-POS END-OF-BUFFER).
768 Actually, the position returned is the start of the line after
769 the last fully-visible line in WIN. If WIN is nil, the selected
770 window is used."
771 (let* ((win (or win (selected-window)))
772 (edges (window-inside-pixel-edges win))
773 (ht (- (nth 3 edges) (nth 1 edges)))
774 (last-line-pos (posn-point (posn-at-x-y 0 (1- ht) win))))
775 (if (pos-visible-in-window-p last-line-pos win)
776 (let ((end (window-end win t)))
777 (list end (= end (point-max))))
778 (list last-line-pos nil))))
780 (defun follow-calc-win-start (windows pos win)
781 "Determine the start of window WIN in a Follow mode window chain.
782 WINDOWS is a list of chained windows, and POS is the starting
783 position for the first window in the list. If WIN is nil, return
784 the point below all windows."
785 (while (and windows (not (eq (car windows) win)))
786 (let ((old-start (window-start (car windows))))
787 ;; Can't use `save-window-excursion' since it triggers a redraw.
788 (set-window-start (car windows) pos 'noforce)
789 (setq pos (car (follow-calc-win-end (car windows))))
790 (set-window-start (car windows) old-start 'noforce)
791 (setq windows (cdr windows))))
792 pos)
794 ;; The result from `follow-windows-start-end' is cached when using
795 ;; a handful simple commands, like cursor movement commands.
797 (defsubst follow-cache-valid-p (windows)
798 "Test if the cached value of `follow-windows-start-end' can be used.
799 Note that this handles the case when the cache has been set to nil."
800 (let ((res t)
801 (cache follow-windows-start-end-cache))
802 (while (and res windows cache)
803 (setq res (and (eq (car windows)
804 (car (car cache)))
805 (eq (window-start (car windows))
806 (car (cdr (car cache))))))
807 (setq windows (cdr windows))
808 (setq cache (cdr cache)))
809 (and res (null windows) (null cache))))
811 (defun follow-windows-start-end (windows)
812 "Return a list of (WIN START END BUFFER-END-P) for window list WINDOWS."
813 (if (follow-cache-valid-p windows)
814 follow-windows-start-end-cache
815 (let ((orig-win (selected-window))
816 win-start-end)
817 (dolist (w windows)
818 (select-window w)
819 (push (cons w (cons (window-start) (follow-calc-win-end)))
820 win-start-end))
821 (select-window orig-win)
822 (setq follow-windows-start-end-cache (nreverse win-start-end)))))
824 (defsubst follow-pos-visible (pos win win-start-end)
825 "Non-nil when POS is visible in WIN."
826 (let ((wstart-wend-bend (cdr (assq win win-start-end))))
827 (and (>= pos (car wstart-wend-bend))
828 (or (< pos (cadr wstart-wend-bend))
829 (nth 2 wstart-wend-bend)))))
832 ;; By `aligned' we mean that for all adjacent windows, the end of the
833 ;; first is equal with the start of the successor. The first window
834 ;; should start at a full screen line.
836 (defsubst follow-windows-aligned-p (win-start-end)
837 "Non-nil if the follower windows are aligned.
838 The argument, WIN-START-END, should be a list of the form
839 returned by `follow-windows-start-end'."
840 (let ((result t))
841 (while (and win-start-end result)
842 (if (cdr win-start-end)
843 (setq result (eq (nth 2 (car win-start-end))
844 (nth 1 (cadr win-start-end)))))
845 (setq win-start-end (cdr win-start-end)))
846 result))
848 ;; Check if point is visible in all windows. (So that
849 ;; no one will be recentered.)
851 (defun follow-point-visible-all-windows-p (win-start-end)
852 "Non-nil when the `window-point' is visible in all windows."
853 (let ((res t))
854 (while (and res win-start-end)
855 (setq res (follow-pos-visible (window-point (car (car win-start-end)))
856 (car (car win-start-end))
857 win-start-end))
858 (setq win-start-end (cdr win-start-end)))
859 res))
862 ;; Make sure WIN always starts at the beginning of a whole screen
863 ;; line. If WIN is not aligned the start is updated which probably
864 ;; will lead to a redisplay of the screen later on.
866 ;; This is used with the first window in a follow chain. The reason
867 ;; is that we want to detect that point is outside the window.
868 ;; (Without the update, the start of the window will move as the
869 ;; user presses BackSpace, and the other window redisplay routines
870 ;; will move the start of the window in the wrong direction.)
872 (defun follow-update-window-start (win)
873 "Make sure that the start of WIN starts at a full screen line."
874 (save-excursion
875 (goto-char (window-start win))
876 (unless (bolp)
877 (vertical-motion 0 win)
878 (unless (eq (point) (window-start win))
879 (vertical-motion 1 win)
880 (set-window-start win (point) 'noforce)))))
882 (defun follow-select-if-visible (dest win-start-end)
883 "Select and return a window, if DEST is visible in it.
884 Return the selected window."
885 (let (win wse)
886 (while (and (not win) win-start-end)
887 ;; Don't select a window that was just moved. This makes it
888 ;; possible to later select the last window after a
889 ;; `end-of-buffer' command.
890 (setq wse (car win-start-end))
891 (when (follow-pos-visible dest (car wse) win-start-end)
892 (setq win (car wse))
893 (select-window win))
894 (setq win-start-end (cdr win-start-end)))
895 win))
897 ;; Lets select a window showing the end. Make sure we only select it if
898 ;; it wasn't just moved here. (I.e. M-> shall not unconditionally place
899 ;; point in the selected window.)
901 ;; (Compatibility kludge: in Emacs `window-end' is equal to `point-max';
902 ;; in XEmacs, it is equal to `point-max + 1'. Should I really bother
903 ;; checking `window-end' now when I check `end-of-buffer' explicitly?)
905 (defun follow-select-if-end-visible (win-start-end)
906 "Select and return a window, if end is visible in it."
907 (let ((win nil))
908 (while (and (not win) win-start-end)
909 ;; Don't select a window that was just moved. This makes it
910 ;; possible to later select the last window after a `end-of-buffer'
911 ;; command.
912 (if (and (eq (point-max) (nth 2 (car win-start-end)))
913 (nth 3 (car win-start-end))
914 ;; `window-end' might return nil.
915 (let ((end (window-end (car (car win-start-end)))))
916 (and end
917 (eq (point-max) (min (point-max) end)))))
918 (progn
919 (setq win (car (car win-start-end)))
920 (select-window win)))
921 (setq win-start-end (cdr win-start-end)))
922 win))
925 ;; Select a window that will display point if the windows would
926 ;; be redisplayed with the first window fixed. This is useful for
927 ;; example when the user has pressed return at the bottom of a window
928 ;; as point is not visible in any window.
930 (defun follow-select-if-visible-from-first (dest windows)
931 "Try to select one of WINDOWS without repositioning the topmost window.
932 If one of the windows in WINDOWS contains DEST, select it, call
933 `follow-redisplay', move point to DEST, and return that window.
934 Otherwise, return nil."
935 (let (win end-pos-end-p)
936 (save-excursion
937 (goto-char (window-start (car windows)))
938 ;; Make sure the line start in the beginning of a real screen
939 ;; line.
940 (vertical-motion 0 (car windows))
941 (when (>= dest (point))
942 ;; At or below the start. Check the windows.
943 (save-window-excursion
944 (let ((windows windows))
945 (while (and (not win) windows)
946 (set-window-start (car windows) (point) 'noforce)
947 (setq end-pos-end-p (follow-calc-win-end (car windows)))
948 (goto-char (car end-pos-end-p))
949 ;; Visible, if dest above end, or if eob is visible
950 ;; inside the window.
951 (if (or (car (cdr end-pos-end-p))
952 (< dest (point)))
953 (setq win (car windows))
954 (setq windows (cdr windows))))))))
955 (when win
956 (select-window win)
957 (follow-redisplay windows (car windows))
958 (goto-char dest))
959 win))
961 ;;; Redisplay
963 ;; Redraw all the windows on the screen, starting with the top window.
964 ;; The window used as as marker is WIN, or the selected window if WIN
965 ;; is nil. Start every window directly after the end of the previous
966 ;; window, to make sure long lines are displayed correctly.
968 (defun follow-redisplay (&optional windows win preserve-win)
969 "Reposition the WINDOWS around WIN.
970 Should point be too close to the roof we redisplay everything
971 from the top. WINDOWS should contain a list of windows to
972 redisplay; it is assumed that WIN is a member of the list.
973 Should WINDOWS be nil, the windows displaying the
974 same buffer as WIN, in the current frame, are used.
975 Should WIN be nil, the selected window is used.
976 If PRESERVE-WIN is non-nil, keep WIN itself unchanged while
977 repositioning the other windows."
978 (or win (setq win (selected-window)))
979 (or windows (setq windows (follow-all-followers win)))
980 ;; Calculate the start of the first window.
981 (let* ((old-win-start (window-start win))
982 (try-first-start (follow-estimate-first-window-start
983 windows win old-win-start))
984 (try-win-start (follow-calc-win-start
985 windows try-first-start win))
986 (start (cond ((= try-win-start old-win-start)
987 (follow-debug-message "exact")
988 try-first-start)
989 ((< try-win-start old-win-start)
990 (follow-debug-message "above")
991 (follow-calculate-first-window-start-from-above
992 windows try-first-start win old-win-start))
994 (follow-debug-message "below")
995 (follow-calculate-first-window-start-from-below
996 windows try-first-start win old-win-start)))))
997 (dolist (w windows)
998 (unless (and preserve-win (eq w win))
999 (set-window-start w start))
1000 (setq start (car (follow-calc-win-end w))))))
1002 (defun follow-estimate-first-window-start (windows win start)
1003 "Estimate the position of the first window.
1004 The estimate is computed by assuming that the window WIN, which
1005 should be a member of WINDOWS, starts at position START."
1006 (let ((windows-before (car (follow-split-followers windows win))))
1007 (save-excursion
1008 (goto-char start)
1009 (vertical-motion 0 win)
1010 (dolist (w windows-before)
1011 (vertical-motion (- 1 (window-text-height w)) w))
1012 (point))))
1015 ;; Find the starting point, start at GUESS and search downward.
1016 ;; The returned point is always a point below GUESS.
1018 (defun follow-calculate-first-window-start-from-above
1019 (windows guess win start)
1020 (save-excursion
1021 (let ((done nil)
1022 win-start
1023 res)
1024 (goto-char guess)
1025 (while (not done)
1026 (if (not (= (vertical-motion 1 (car windows)) 1))
1027 ;; Hit bottom! (Can we really do this?)
1028 ;; We'll keep it, since it ensures termination.
1029 (progn
1030 (setq done t)
1031 (setq res (point-max)))
1032 (setq win-start (follow-calc-win-start windows (point) win))
1033 (if (>= win-start start)
1034 (setq done t res (point)))))
1035 res)))
1038 ;; Find the starting point, start at GUESS and search upward. Return
1039 ;; a point on the same line as GUESS, or above.
1041 (defun follow-calculate-first-window-start-from-below
1042 (windows guess &optional win start)
1043 (setq win (or win (selected-window)))
1044 (setq start (or start (window-start win)))
1045 (save-excursion
1046 (let (done win-start res opoint)
1047 ;; Always calculate what happens when no line is displayed in the first
1048 ;; window. (The `previous' res is needed below!)
1049 (goto-char guess)
1050 (vertical-motion 0 (car windows))
1051 (setq res (point))
1052 (while (not done)
1053 (setq opoint (point))
1054 (if (not (= (vertical-motion -1 (car windows)) -1))
1055 ;; Hit roof!
1056 (setq done t res (point-min))
1057 (setq win-start (follow-calc-win-start windows (point) win))
1058 (cond ((>= (point) opoint)
1059 ;; In some pathological cases, vertical-motion may
1060 ;; return -1 even though point has not decreased. In
1061 ;; that case, avoid looping forever.
1062 (setq done t res (point)))
1063 ((= win-start start) ; Perfect match, use this value
1064 (setq done t res (point)))
1065 ((< win-start start) ; Walked to far, use previous result
1066 (setq done t))
1067 (t ; Store result for next iteration
1068 (setq res (point))))))
1069 res)))
1071 ;;; Avoid tail recenter
1073 ;; This sets the window internal flag `force_start'. The effect is
1074 ;; that windows only displaying the tail aren't recentered.
1076 ;; A window displaying only the tail, is a window whose window-start
1077 ;; position is equal to (point-max) of the buffer it displays.
1079 (defun follow-avoid-tail-recenter (&rest _rest)
1080 "Make sure windows displaying the end of a buffer aren't recentered.
1081 This is done by reading and rewriting the start position of
1082 non-first windows in Follow mode."
1083 (let* ((orig-buffer (current-buffer))
1084 (top (frame-first-window))
1085 (win top)
1086 who) ; list of (buffer . frame)
1087 ;; If the only window in the frame is a minibuffer
1088 ;; window, `next-window' will never find it again...
1089 (unless (window-minibuffer-p top)
1090 (while ;; look, no body!
1091 (let ((start (window-start win))
1092 (pair (cons (window-buffer win) (window-frame win))))
1093 (set-buffer (window-buffer win))
1094 (cond ((null (member pair who))
1095 (setq who (cons pair who)))
1096 ((and follow-mode (eq (point-max) start))
1097 ;; Write the same window start back, but don't
1098 ;; set the NOFORCE flag.
1099 (set-window-start win start)))
1100 (setq win (next-window win 'not t))
1101 (not (eq win top)))) ;; Loop while this is true.
1102 (set-buffer orig-buffer))))
1104 ;;; Post Command Hook
1106 ;; The magic little box. This function is called after every command.
1108 ;; This is not as complicated as it seems. It is simply a list of common
1109 ;; display situations and the actions to take, plus commands for redrawing
1110 ;; the screen if it should be unaligned.
1112 ;; We divide the check into two parts; whether we are at the end or not.
1113 ;; This is due to the fact that the end can actually be visible
1114 ;; in several window even though they are aligned.
1116 (defun follow-post-command-hook ()
1117 "Ensure that the windows in Follow mode are adjacent after each command."
1118 (unless (input-pending-p)
1119 (let ((follow-inside-post-command-hook t)
1120 (win (selected-window)))
1121 ;; Work in the selected window, not in the current buffer.
1122 (with-current-buffer (window-buffer win)
1123 (unless (and (symbolp this-command)
1124 (get this-command 'follow-mode-use-cache))
1125 (setq follow-windows-start-end-cache nil))
1126 (follow-adjust-window win)))))
1128 (defun follow-adjust-window (win)
1129 ;; Adjust the window WIN and its followers.
1130 (cl-assert (eq (window-buffer win) (current-buffer)))
1131 (when (and follow-mode
1132 (not (window-minibuffer-p win)))
1133 (let* ((dest (point))
1134 (windows (follow-all-followers win))
1135 (win-start-end (progn
1136 (follow-update-window-start (car windows))
1137 (follow-windows-start-end windows)))
1138 (aligned (follow-windows-aligned-p win-start-end))
1139 (visible (follow-pos-visible dest win win-start-end))
1140 selected-window-up-to-date)
1141 (unless (and aligned visible)
1142 (setq follow-windows-start-end-cache nil))
1144 ;; Select a window to display point.
1145 (unless follow-internal-force-redisplay
1146 (if (eq dest (point-max))
1147 ;; Be careful at point-max: the display can be aligned
1148 ;; while DEST can be visible in several windows.
1149 (cond
1150 ;; Select the current window, but only when the display
1151 ;; is correct. (When inserting characters in a tail
1152 ;; window, the display is not correct, as they are
1153 ;; shown twice.)
1155 ;; Never stick to the current window after a deletion.
1156 ;; Otherwise, when typing `DEL' in a window showing
1157 ;; only the end of the file, a character would be
1158 ;; removed from the window above, which is very
1159 ;; unintuitive.
1160 ((and visible
1161 aligned
1162 (not (memq this-command
1163 '(backward-delete-char
1164 delete-backward-char
1165 backward-delete-char-untabify
1166 kill-region))))
1167 (follow-debug-message "Max: same"))
1168 ;; If the end is visible, and the window doesn't
1169 ;; seems like it just has been moved, select it.
1170 ((follow-select-if-end-visible win-start-end)
1171 (follow-debug-message "Max: end visible")
1172 (setq visible t aligned nil)
1173 (goto-char dest))
1174 ;; Just show the end...
1176 (follow-debug-message "Max: default")
1177 (select-window (car (last windows)))
1178 (goto-char dest)
1179 (setq visible nil aligned nil)))
1181 ;; We're not at the end, here life is much simpler.
1182 (cond
1183 ;; This is the normal case!
1184 ;; It should be optimized for speed.
1185 ((and visible aligned)
1186 (follow-debug-message "same"))
1187 ;; Pick a position in any window. If the display is ok,
1188 ;; this picks the `correct' window.
1189 ((follow-select-if-visible dest win-start-end)
1190 (follow-debug-message "visible")
1191 (goto-char dest)
1192 ;; Perform redisplay, in case line is partially visible.
1193 (setq visible nil))
1194 ;; Not visible anywhere else, lets pick this one.
1195 (visible
1196 (follow-debug-message "visible in selected."))
1197 ;; If DEST is before the first window start, select the
1198 ;; first window.
1199 ((< dest (nth 1 (car win-start-end)))
1200 (follow-debug-message "before first")
1201 (select-window (car windows))
1202 (goto-char dest)
1203 (setq visible nil aligned nil))
1204 ;; If we can position the cursor without moving the first
1205 ;; window, do it. This is the case that catches `RET' at
1206 ;; the bottom of a window.
1207 ((follow-select-if-visible-from-first dest windows)
1208 (follow-debug-message "Below first")
1209 (setq visible t aligned t))
1210 ;; None of the above. Stick to the selected window.
1212 (follow-debug-message "None")
1213 (setq visible nil aligned nil))))
1215 ;; If a new window was selected, make sure that the old is
1216 ;; not scrolled when point is outside the window.
1217 (unless (eq win (selected-window))
1218 (let ((p (window-point win)))
1219 (set-window-start win (window-start win) nil)
1220 (set-window-point win p))))
1222 (unless visible
1223 ;; If point may not be visible in the selected window,
1224 ;; perform a redisplay; this ensures scrolling.
1225 (let ((opoint (point)))
1226 (redisplay)
1227 ;; If this `redisplay' moved point, we got clobbered by a
1228 ;; previous call to `set-window-start'. Try again.
1229 (when (/= (point) opoint)
1230 (goto-char opoint)
1231 (redisplay)))
1233 (setq selected-window-up-to-date t)
1234 (follow-avoid-tail-recenter)
1235 (setq win-start-end (follow-windows-start-end windows)
1236 follow-windows-start-end-cache nil
1237 aligned nil))
1239 ;; Now redraw the windows around the selected window.
1240 (unless (and (not follow-internal-force-redisplay)
1241 (or aligned
1242 (follow-windows-aligned-p win-start-end))
1243 (follow-point-visible-all-windows-p win-start-end))
1244 (setq follow-internal-force-redisplay nil)
1245 (follow-redisplay windows (selected-window)
1246 selected-window-up-to-date)
1247 (setq win-start-end (follow-windows-start-end windows)
1248 follow-windows-start-end-cache nil)
1249 ;; Point can end up in another window when DEST is at
1250 ;; the beginning of the buffer and the selected window is
1251 ;; not the first. It can also happen when long lines are
1252 ;; used and there is a big difference between the width of
1253 ;; the windows. (When scrolling one line in a wide window
1254 ;; which will cause a move larger that an entire small
1255 ;; window.)
1256 (unless (follow-pos-visible dest win win-start-end)
1257 (follow-select-if-visible dest win-start-end)
1258 (goto-char dest)))
1260 ;; If the region is visible, make it look good when spanning
1261 ;; multiple windows.
1262 (when (region-active-p)
1263 (follow-maximize-region
1264 (selected-window) windows win-start-end)))
1266 ;; Whether or not the buffer was in follow mode, update windows
1267 ;; displaying the tail so that Emacs won't recenter them.
1268 (follow-avoid-tail-recenter)))
1270 ;;; The region
1272 ;; Tries to make the highlighted area representing the region look
1273 ;; good when spanning several windows.
1275 ;; Not perfect, as point can't be placed at window end, only at
1276 ;; end-1. This will highlight a little bit in windows above
1277 ;; the current.
1279 (defun follow-maximize-region (win windows win-start-end)
1280 "Make a highlighted region stretching multiple windows look good."
1281 (let* ((all (follow-split-followers windows win))
1282 (pred (car all))
1283 (succ (cdr all))
1284 data)
1285 (while pred
1286 (setq data (assq (car pred) win-start-end))
1287 (set-window-point (car pred) (max (nth 1 data) (- (nth 2 data) 1)))
1288 (setq pred (cdr pred)))
1289 (while succ
1290 (set-window-point (car succ) (nth 1 (assq (car succ) win-start-end)))
1291 (setq succ (cdr succ)))))
1293 ;;; Scroll bar
1295 ;;;; Scroll-bar support code.
1297 ;; This handles the case where the user drags the scroll bar of a
1298 ;; non-selected window whose buffer is in Follow mode.
1300 (declare-function scroll-bar-toolkit-scroll "scroll-bar" (event))
1301 (declare-function scroll-bar-drag "scroll-bar" (event))
1302 (declare-function scroll-bar-scroll-up "scroll-bar" (event))
1303 (declare-function scroll-bar-scroll-down "scroll-bar" (event))
1304 (declare-function mwheel-scroll "mwheel" (event))
1306 (defun follow-scroll-bar-toolkit-scroll (event)
1307 (interactive "e")
1308 (scroll-bar-toolkit-scroll event)
1309 (follow-redraw-after-event event))
1311 (defun follow-scroll-bar-drag (event)
1312 (interactive "e")
1313 (scroll-bar-drag event)
1314 (follow-redraw-after-event event))
1316 (defun follow-scroll-bar-scroll-up (event)
1317 (interactive "e")
1318 (scroll-bar-scroll-up event)
1319 (follow-redraw-after-event event))
1321 (defun follow-scroll-bar-scroll-down (event)
1322 (interactive "e")
1323 (scroll-bar-scroll-down event)
1324 (follow-redraw-after-event event))
1326 (defun follow-mwheel-scroll (event)
1327 (interactive "e")
1328 (mwheel-scroll event)
1329 (follow-redraw-after-event event))
1331 (defun follow-redraw-after-event (event)
1332 "Re-align the Follow mode windows affected by EVENT."
1333 (let* ((window (nth 0 (event-end event)))
1334 (buffer (window-buffer window))
1335 (orig-win (selected-window)))
1336 (when (and (buffer-local-value 'follow-mode buffer)
1337 ;; Ignore the case where we scroll the selected window;
1338 ;; that is handled by the post-command hook function.
1339 (not (eq window (selected-window))))
1340 (select-window window)
1341 (follow-redisplay)
1342 (unless (eq (window-buffer orig-win) buffer)
1343 (select-window orig-win)))))
1345 ;;; Window size change
1347 ;; The functions in `window-size-change-functions' are called every
1348 ;; time a window in a frame changes size, most notably after the frame
1349 ;; has been resized. We call `follow-post-command-hook' for every
1350 ;; Follow mode buffer visible in any window in the resized frame.
1352 ;; Since `follow-window-size-change' can be called indirectly from
1353 ;; `follow-post-command-hook' we have a potential infinite loop. To
1354 ;; avoid this, we simply do not do anything in this situation. The
1355 ;; variable `follow-inside-post-command-hook' contains information
1356 ;; about whether the execution actually is inside the
1357 ;; post-command-hook or not.
1359 (defun follow-window-size-change (frame)
1360 "Redraw all windows in FRAME, when in Follow mode."
1361 ;; Below, we call `post-command-hook'. Avoid an infloop.
1362 (unless follow-inside-post-command-hook
1363 (let ((buffers '())
1364 (orig-window (selected-window))
1365 (orig-buffer (current-buffer))
1366 (orig-frame (selected-frame))
1367 windows
1368 buf)
1369 (select-frame frame)
1370 (unwind-protect
1371 (walk-windows
1372 (lambda (win)
1373 (setq buf (window-buffer win))
1374 (unless (memq buf buffers)
1375 (set-buffer buf)
1376 (when follow-mode
1377 (setq windows (follow-all-followers win))
1378 (if (not (memq orig-window windows))
1379 (follow-redisplay windows win)
1380 ;; Make sure we're redrawing around the selected
1381 ;; window.
1382 (select-window orig-window)
1383 (follow-post-command-hook)
1384 (setq orig-window (selected-window)))
1385 (setq buffers (cons buf buffers)))))
1386 'no-minibuf)
1387 (select-frame orig-frame)
1388 (set-buffer orig-buffer)
1389 (select-window orig-window)))))
1391 (add-hook 'window-scroll-functions 'follow-avoid-tail-recenter t)
1393 ;;; Profile support
1395 ;; The following (non-evaluated) section can be used to
1396 ;; profile this package using `elp'.
1398 ;; Invalid indentation on purpose!
1400 ;; (setq elp-function-list
1401 ;; '(window-end
1402 ;; vertical-motion
1403 ;; follow-mode
1404 ;; follow-all-followers
1405 ;; follow-split-followers
1406 ;; follow-redisplay
1407 ;; follow-estimate-first-window-start
1408 ;; follow-calculate-first-window-start-from-above
1409 ;; follow-calculate-first-window-start-from-below
1410 ;; follow-calc-win-end
1411 ;; follow-calc-win-start
1412 ;; follow-pos-visible
1413 ;; follow-windows-start-end
1414 ;; follow-cache-valid-p
1415 ;; follow-select-if-visible
1416 ;; follow-select-if-visible-from-first
1417 ;; follow-windows-aligned-p
1418 ;; follow-point-visible-all-windows-p
1419 ;; follow-avoid-tail-recenter
1420 ;; follow-update-window-start
1421 ;; follow-post-command-hook))
1423 (provide 'follow)
1425 ;; /------------------------------------------------------------------------\
1426 ;; | "I [..] am rarely happier then when spending an entire day programming |
1427 ;; | my computer to perform automatically a task that it would otherwise |
1428 ;; | take me a good ten seconds to do by hand. Ten seconds, I tell myself, |
1429 ;; | is ten seconds. Time is valuable and ten seconds' worth of it is well |
1430 ;; | worth the investment of a day's happy activity working out a way to |
1431 ;; | save it". -- Douglas Adams, "Last Chance to See" |
1432 ;; \------------------------------------------------------------------------/
1434 ;;; follow.el ends here