From: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
To: valentjedi@gmail.com
Cc: tkk@misasa.okayama-u.ac.jp, 29737@debbugs.gnu.org
Subject: bug#29737: 27.0.50; pixel-scroll-mode is laggy
Date: Mon, 01 Jan 2018 09:58:38 +0900 (JST) [thread overview]
Message-ID: <20180101.095838.502407685578664475.tkk@misasa.okayama-u.ac.jp> (raw)
In-Reply-To: <20171225.124845.1313473587937932282.tkk@misasa.okayama-u.ac.jp>
[-- Attachment #1: Type: Text/Plain, Size: 1152 bytes --]
I think that on scrolling of 1000 lines, smooth scroll is not
necessary. User wants smooth scrolling only for the first spin of
mouse wheel.
This patch introduces a new variable `pixel-dead-time' and
`pixel-last-scroll-time'. When another scroll request was delivered
within `pixel-dead-time', very likely user does not want smooth
scrolling.
On such situation, `scroll-down' is called instead of
`pixel-scroll-pixel-down'. On theory there should not be lag because
of smoothing.
I tested the revised pixel-scroll-mode for a week and confirmed that
works good. When `pixel-dead-time' is zero, its behavior is the same
as before. I think `pixel-dead-time' 0.1 works better.
I'm sending ChangeLog and a patch relative to the current master.
* ChangeLog
Add a new algorithm to avoid lag when scrolling is in rush
* lisp/pixel-scroll.el (pixel-scroll-up): Invoke 'scroll-up' when called within 'pixel-dead-time'.
(pixel-scroll-down): Invoke 'scroll-down' when called within 'pixel-dead-time'.
(pixel-dead-time): Interval that requires for the next smooth scrolling.
(pixel-last-scroll-time): Time when the last scrolling was made. (Bug#29737)
[-- Attachment #2: pixel-scroll.el.diff --]
[-- Type: Text/X-Patch, Size: 4570 bytes --]
diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index 70244873b4..07297d61b5 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -82,6 +82,15 @@ pixel-resolution-fine-flag
pixel scroll, typing \\[next-line] or \\[previous-line] scrolls the window to make it
fully visible, and undoes the effect of the pixel-level scroll.")
+(defvar pixel-dead-time 0.1
+ "Interval that requires for the next smooth scrolling in second.
+On another scrolling request within this period, the scrolling
+will be carried out without pixel resolution. If zero, scrolling
+is with pixel resolution always.")
+
+(defvar pixel-last-scroll-time 0
+ "Time when the last scrolling was made in second since the epoch.")
+
;;;###autoload
(define-minor-mode pixel-scroll-mode
"A minor mode to scroll text pixel-by-pixel.
@@ -104,35 +113,51 @@ pixel-scroll-up
This is an alternative of `scroll-up'. Scope moves downward."
(interactive)
(or arg (setq arg 1))
- (dotimes (ii arg) ; move scope downward
- (let ((amt (if pixel-resolution-fine-flag
- (if (integerp pixel-resolution-fine-flag)
- pixel-resolution-fine-flag
- (frame-char-height))
- (pixel-line-height))))
- (if (pixel-eob-at-top-p) ; when end-of-the-buffer is close
- (scroll-up 1) ; relay on robust method
- (while (pixel-point-at-top-p amt) ; prevent too late (multi tries)
- (vertical-motion 1)) ; move point downward
- (pixel-scroll-pixel-up amt))))) ; move scope downward
+ (if (pixel-scroll-in-rush-p)
+ (scroll-up arg)
+ (dotimes (ii arg) ; move scope downward
+ (let ((amt (if pixel-resolution-fine-flag
+ (if (integerp pixel-resolution-fine-flag)
+ pixel-resolution-fine-flag
+ (frame-char-height))
+ (pixel-line-height))))
+ (if (pixel-eob-at-top-p) ; when end-of-the-buffer is close
+ (scroll-up 1) ; relay on robust method
+ (while (pixel-point-at-top-p amt) ; prevent too late (multi tries)
+ (vertical-motion 1)) ; move point downward
+ (pixel-scroll-pixel-up amt)))))) ; move scope downward
(defun pixel-scroll-down (&optional arg)
"Scroll text of selected window down ARG lines.
This is and alternative of `scroll-down'. Scope moves upward."
(interactive)
(or arg (setq arg 1))
- (dotimes (ii arg)
- (let ((amt (if pixel-resolution-fine-flag
- (if (integerp pixel-resolution-fine-flag)
- pixel-resolution-fine-flag
- (frame-char-height))
- (pixel-line-height -1))))
- (while (pixel-point-at-bottom-p amt) ; prevent too late (multi tries)
- (vertical-motion -1)) ; move point upward
- (if (or (pixel-bob-at-top-p amt) ; when beginning-of-the-buffer is seen
- (pixel-eob-at-top-p)) ; for file with a long line
- (scroll-down 1) ; relay on robust method
- (pixel-scroll-pixel-down amt)))))
+ (if (pixel-scroll-in-rush-p)
+ (scroll-down arg)
+ (dotimes (ii arg)
+ (let ((amt (if pixel-resolution-fine-flag
+ (if (integerp pixel-resolution-fine-flag)
+ pixel-resolution-fine-flag
+ (frame-char-height))
+ (pixel-line-height -1))))
+ (while (pixel-point-at-bottom-p amt) ; prevent too late (multi tries)
+ (vertical-motion -1)) ; move point upward
+ (if (or (pixel-bob-at-top-p amt) ; when beginning-of-the-buffer is seen
+ (pixel-eob-at-top-p)) ; for file with a long line
+ (scroll-down 1) ; relay on robust method
+ (pixel-scroll-pixel-down amt))))))
+
+(defun pixel-scroll-in-rush-p ()
+ "Return non-nil if scroll is in rush.
+When scrolling request is delivered soon after the previous one,
+user is in hurry. When the interval is larger than
+`pixel-dead-time', it is ready for another smooth scroll and this
+returns nil."
+ (let* ((current-time (float-time))
+ (scroll-in-rush-p (< (- current-time pixel-last-scroll-time)
+ pixel-dead-time)))
+ (setq pixel-last-scroll-time current-time)
+ scroll-in-rush-p))
(defun pixel-bob-at-top-p (amt)
"Return non-nil if window-start is at beginning of the current buffer.
next prev parent reply other threads:[~2018-01-01 0:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-16 17:55 bug#29737: 27.0.50; pixel-scroll-mode is laggy Valentin Ignatyev
2017-12-16 18:30 ` Eli Zaretskii
[not found] ` <CAO90aWvmqMg=wkt4YyqE8kDP_BNZjAih7AEdyP-Zt74OydpUHA@mail.gmail.com>
2017-12-16 19:33 ` Eli Zaretskii
2017-12-16 19:35 ` Valentin Ignatyev
2017-12-17 2:00 ` Tak Kunihiro
2017-12-22 10:22 ` Eli Zaretskii
2017-12-23 3:18 ` Tak Kunihiro
2017-12-23 9:20 ` Eli Zaretskii
2017-12-23 11:30 ` Valentin Ignatyev
2017-12-23 11:53 ` Valentin Ignatyev
2017-12-24 2:28 ` Tak Kunihiro
2017-12-24 5:18 ` Valentin Ignatyev
2017-12-25 3:48 ` Tak Kunihiro
2018-01-01 0:58 ` Tak Kunihiro [this message]
2018-01-06 17:43 ` Eli Zaretskii
2018-01-07 2:06 ` Tak Kunihiro
2018-01-07 7:19 ` Eli Zaretskii
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