Hi all,
I have this function (the part at issue here should be the first
line):
(defun my-recenter-after-jump (window _window-start-after)
"Recenter the point after a non-scroll command brings it out of view.
This function is meant to be called from the hook
‘window-scroll-functions’."
(with-selected-window window
(unless (or (> 0.001 (float-time (time-subtract (current-time) buffer-display-time))) ; Don’t run this function after a change of buffer. Non-nil here means the selected window displayed the current buffer less than a thousandth of a second ago, so it was most likely a change of buffer that triggered ‘window-scroll-functions’, not a scroll. See also
https://emacs.stackexchange.com/questions/63558/how-to-distinguish-a-scroll-from-a-change-of-buffer-in-a-function-called-from-w ;; Don’t recenter for these
;; - major modes
(memq major-mode '(help-mode ; ‘my-recenter-after-jump’ breaks scrolling with SPC/<backspace> in Help mode and Info mode because they don’t obey ‘scroll-preserve-screen-position’ and ‘scroll-error-top-bottom’.
Info-mode))
;; - minor modes
isearch-mode ; For Isearch, change the value of ‘scroll-conservatively’ and ‘hscroll-step’ in ‘isearch-update-post-hook’ and ‘isearch-mode-end-hook’. Doing so allows recentering the point even after a purely horizontal scroll.
(bound-and-true-p view-mode) ; ‘my-recenter-after-jump’ breaks scrolling with SPC/<backspace> in View mode because View mode doesn’t obey ‘scroll-preserve-screen-position’ and ‘scroll-error-top-bottom’.
(bound-and-true-p follow-mode)
;; - commands
(and (symbolp last-command) (get last-command 'scroll-command)) ; Don’t check the value of the ‘scroll-command’ property for anonymous commands (it can’t be t anyway).
(memq last-command '(recenter-top-bottom
query-replace query-replace-regexp ; Query replacement is taken care of by the ‘recentering-on-jump’ advice to ‘perform-replace’, which allows recentering the point after a purely horizontal scroll.
previous-line next-line ; Don’t let these commands trigger ‘my-recenter-after-jump’. It happens when Emacs has a moment of lag during which the point slips beyond the scroll margin.
previous-logical-line next-logical-line)))
(let* ((bottom-line-before (line-number-at-pos (window-end)))
(bottom-line-after (line-number-at-pos (window-end nil 'update))) ; NB: ‘window-start’ doesn’t take the ‘update’ argument.
(vertical-displacement (- bottom-line-after bottom-line-before)))
(unless (> 2 (abs vertical-displacement)) ; The purpose of having the first ‘unless’ separate from this one is to call ‘line-number-at-pos’ only when it’s needed, because it can be slow. See (2 links)
https://emacs.stackexchange.com/questions/51648/how-to-detect-the-number-of-lines-scrolled-from-scroll-up-down/51664#51664,
https://emacs.stackexchange.com/questions/3821/a-faster-method-to-obtain-line-number-at-pos-in-large-buffers (recenter)
(when truncate-lines
(my-horizontal-recenter))))))) ; REVIEW: Isn’t there a built-in function for recentering the point horizontally?
which I call from `window-scroll-functions` like this
(add-hook 'window-scroll-functions #'my-recenter-after-jump)
It's worked until I upgraded from v. 28.1 (from Fedora’s repos) to
29.0.50 (commit 6de88b6b02). Now I get
Error in window-scroll-functions (my-recenter-after-jump): (wrong-number-of-arguments (lambda (window _window-start-after) "Recenter the point after a non-scroll command brings it out of view.
This function is meant to be called from the hook
‘window-scroll-functions’." (let ((save-selected-window--state (internal--before-with-selected-window window))) (save-current-buffer (unwind-protect (progn (select-window (car save-selected-window--state) 'norecord) (if (or (> 0.001 (float-time (time-subtract (current-time) buffer-display-time))) (memq major-mode '(help-mode Info-mode)) isearch-mode (and (boundp 'view-mode) view-mode) (and (boundp 'follow-mode) follow-mode) (and (symbolp last-command) (get last-command 'scroll-command)) (memq last-command '(recenter-top-bottom query-replace query-replace-regexp previous-line next-line previous-logical-line next-logical-line))) nil (let* ((bottom-line-before (line-number-at-pos (window-end))) (bottom-line-after (line-number-at-pos (window-end nil 'update))) (vertical-displacement (- bottom-line-after bottom-line-before))) (if (> 2 (abs vertical-displacement)) nil (recenter) (if truncate-lines (progn (my-horizontal-recenter))))))) (internal--after-with-selected-window save-selected-window--state))))) 0)
All the best,
Andrea