Package: emacs;
Reported by: Drew Adams <drew.adams <at> oracle.com>
Date: Fri, 17 Jan 2014 04:43:01 UTC
Severity: wishlist
Found in version 24.3.50
View this message in rfc822 format
From: Keith David Bershatsky <esq <at> lawlist.com> To: 16475 <at> debbugs.gnu.org Cc: Eli Zaretskii <eliz <at> gnu.org>, Drew Adams <drew.adams <at> oracle.com> Subject: bug#16475: 24.3.50; enhancement request: remove vertical scroll bar automatically when not needed Date: Thu, 11 Feb 2016 18:46:22 -0800
If and when feature request 22404 ever comes to fruition (to accurately calculate window-start/window-end every command loop under all circumstances), the following is a minor mode that demonstrates how to add/remove scroll bars depending upon the length of the buffer. It can undoubtedly use some improvements, but I am already successfully using it for my own personal setup with the latest draft/patch for the `window-start-end-hook`.
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22404
[NOTE: Eli has indicated that a `post-redisplay-hook' (which does not introduce user Lisp into the redisplay mix) would be a better alternative to the proposed `window-start-end-hook`, and I completely respect Eli's opinion in that regard. However, I wanted to get something working for my own personal use and I am enjoying familiarizing myself with some basic C language coding relating to feature 22404.]
Thanks,
Keith
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; sb-mode
;; https://github.com/kentaro/auto-save-buffers-enhanced
;; `sb-regexp-match-p` function modified by @sds on stackoverflow
;; http://stackoverflow.com/a/20343715/2112489
(defun sb-regexp-match-p (regexps string)
(and string
(catch 'matched
(let ((inhibit-changing-match-data t)) ; small optimization
(dolist (regexp regexps)
(when (string-match regexp string)
(throw 'matched t)))))))
(defgroup sb nil
"A group for the lawlist scroll-bar."
:tag "Scroll Bar"
:group 'convenience)
(defvar regexp-always-scroll-bar '("\\.yes" "\\*Scroll-Bar\\*")
"Regexp matching buffer names that will always have scroll bars.")
(defvar regexp-never-scroll-bar '("\\.off" "\\.not" "\\*Calendar\\*")
"Regexp matching buffer names that will never have scroll bars.")
(defun lawlist-scroll-bar-fn (win start end pbol-start peol-end fully-p)
(when
(and
(window-live-p win)
(not (minibufferp)))
(let* (
(buffer-size (buffer-size))
(point-min (point-min))
(point-max (point-max))
(window-scroll-bars (window-scroll-bars))
(buffer-name (buffer-name)))
(cond
;; not regexp matches | not narrow-to-region
((and
(not (sb-regexp-match-p regexp-always-scroll-bar buffer-name))
(not (sb-regexp-match-p regexp-never-scroll-bar buffer-name))
(equal (- point-max point-min) buffer-size))
(cond
;; Lines of text are less-than or equal-to window height,
;; and scroll bars are present (which need to be removed).
((and
(<= (- point-max point-min) (- end start))
(or
(equal window-scroll-bars '(15 2 right nil)) ;; GNU Emacs 24.5.1 of 2015-04-10 on builder10-6.porkrind.org
(equal window-scroll-bars '(15 2 right 0 0 nil)) ;; 10/01/2014
(equal window-scroll-bars '(15 2 right nil 0 nil)) )) ;; 11/19/2014
(set-window-scroll-bars win 0 'right nil))
;; Lines of text are greater-than window height, and
;; scroll bars are not present (which need to be added).
((and
(> (- point-max point-min) (- end start))
(or
(equal window-scroll-bars '(0 0 nil nil)) ;; GNU Emacs 24.5.1 of 2015-04-10 on builder10-6.porkrind.org
(equal window-scroll-bars '(0 0 t nil)) ;; GNU Emacs 24.5.1 of 2015-04-10 on builder10-6.porkrind.org
(equal window-scroll-bars '(0 0 t 0 0 t)) ;; windows-nt (default)
(equal window-scroll-bars '(nil 0 t nil 0 nil)) ;; darwin (default) ;; 11/19/2014
(equal window-scroll-bars '(0 0 t 0 0 nil)) ;; darwin (default) ;; 10/01/2014
(equal window-scroll-bars '(0 0 nil nil 0 nil)) ;; 11/19/2014 (after scroll bars are removed)
(equal window-scroll-bars '(0 0 nil 0 0 nil)))) ;; windows-nt / darwin
(set-window-scroll-bars win 15 'right nil))))
;; Narrow-to-region is active, and scroll bars are present
;; (which need to be removed).
((and
(buffer-narrowed-p)
(or
(equal window-scroll-bars '(15 2 right nil)) ;; GNU Emacs 24.5.1 of 2015-04-10 on builder10-6.porkrind.org
(equal window-scroll-bars '(15 2 right 0 0 nil)) ;; 10/01/2014
(equal window-scroll-bars '(15 2 right nil 0 nil)) )) ;; 11/19/2014
(set-window-scroll-bars win 0 'right nil))
;; not narrow-to-region | regexp always scroll-bars
((and
(equal (- point-max point-min) buffer-size)
(eq major-mode 'calendar-mode)
(sb-regexp-match-p regexp-always-scroll-bar buffer-name))
(set-window-scroll-bars win 15 'right nil))
;; not narrow-to-region | regexp never scroll-bars
((and
(equal (- point-max point-min) buffer-size)
(sb-regexp-match-p regexp-never-scroll-bar buffer-name))
(set-window-scroll-bars win 0 'right nil))))))
(defvar sb-mode-display-hook nil
"Hook used primarily for `lawlist-scroll-bar-fn'.")
(define-minor-mode sb-mode
"This is a minor-mode for lawlist-scroll-bar."
:init-value nil
:lighter " SB"
:keymap nil
:global nil
:group 'sb
(cond
(sb-mode
(add-hook 'window-start-end-hook 'lawlist-scroll-bar-fn nil t)
(when (called-interactively-p 'any)
(message "Globally turned ON `sb-mode`.")))
(t
(remove-hook 'window-start-end-hook 'lawlist-scroll-bar-fn t)
(set-window-scroll-bars (selected-window) 0 'right nil)
(when (called-interactively-p 'any)
(message "Globally turned OFF `sb-mode`.") ))))
(provide 'lawlist-sb)
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.