From: Stefan Monnier <monnier@iro.umontreal.ca>
To: JD Smith <jdtsmith@gmail.com>
Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: Temporarily select-window, without updating mode-line face and cursor fill?
Date: Sun, 02 May 2021 22:25:14 -0400 [thread overview]
Message-ID: <jwvlf8wwogv.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <81F181EB-D3C1-4619-B42A-1F49321EC544@gmail.com> (JD Smith's message of "Sun, 2 May 2021 22:08:49 -0400")
> If you had any concrete suggestions for calculating window positions
> (like window-start and window-end, not just buffer positions) in
> a non-active window without selecting it, which is superior to my
> approach, I’d be happy to hear.
We really should simply speed up `line-number-at-pos`.
It shouldn't be hard. See below what I do in nlinum.el.
Stefan
(defvar nlinum--line-number-cache nil)
(make-variable-buffer-local 'nlinum--line-number-cache)
;; We could try and avoid flushing the cache at every change, e.g. with:
;; (defun nlinum--before-change (start _end)
;; (if (and nlinum--line-number-cache
;; (< start (car nlinum--line-number-cache)))
;; (save-excursion (goto-char start) (nlinum--line-number-at-pos))))
;; But it's far from clear that it's worth the trouble. The current simplistic
;; approach seems to be good enough in practice.
(defun nlinum--after-change (&rest _args)
(setq nlinum--line-number-cache nil))
(defun nlinum--line-number-at-pos ()
"Like `line-number-at-pos' but sped up with a cache.
Only works right if point is at BOL."
;; (cl-assert (bolp))
(if nlinum-widen
(save-excursion
(save-restriction
(widen)
(forward-line 0) ;In case (point-min) was not at BOL.
(let ((nlinum-widen nil))
(nlinum--line-number-at-pos))))
(let ((pos
(if (and nlinum--line-number-cache
(> (- (point) (point-min))
(abs (- (point) (car nlinum--line-number-cache)))))
(funcall (if (> (point) (car nlinum--line-number-cache))
#'+ #'-)
(cdr nlinum--line-number-cache)
(count-lines (point) (car nlinum--line-number-cache)))
(line-number-at-pos))))
;;(assert (= pos (line-number-at-pos)))
(add-hook 'after-change-functions #'nlinum--after-change nil :local)
(setq nlinum--line-number-cache (cons (point) pos))
pos)))
next prev parent reply other threads:[~2021-05-03 2:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 18:46 Temporarily select-window, without updating mode-line face and cursor fill? JD Smith
2021-05-01 19:31 ` Eli Zaretskii
2021-05-01 20:32 ` JD Smith
2021-05-02 6:49 ` Eli Zaretskii
2021-05-03 2:15 ` JD Smith
2021-05-03 7:50 ` martin rudalics
2021-05-03 16:16 ` JD Smith
2021-05-03 17:32 ` martin rudalics
2021-05-02 7:40 ` martin rudalics
2021-05-03 2:23 ` JD Smith
2021-05-01 22:17 ` JD Smith
2021-05-02 6:55 ` Eli Zaretskii
2021-05-03 2:08 ` JD Smith
2021-05-03 2:25 ` Stefan Monnier [this message]
2021-05-03 2:49 ` JD Smith
2021-05-04 19:28 ` JD Smith
2021-05-04 19:40 ` Stefan Monnier
2021-05-05 0:49 ` Stefan Kangas
2021-05-05 11:54 ` Eli Zaretskii
2021-05-05 19:32 ` Stefan Kangas
2021-05-05 19:47 ` Stefan Monnier
2021-05-06 0:16 ` JD Smith
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