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Improve momentum scrolling algorithm

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* lisp/pixel-scroll.el (pixel-scroll-precision-momentum-tick):
(pixel-scroll-precision-momentum-factor): New user options.

(pixel-scroll-kinetic-state, pixel-scroll-accumulate-velocity):
Set scroll momentum ring size to 10.

(pixel-scroll-start-momentum): Improve algorithm.
This commit is contained in:
Po Lu
2021-12-02 19:35:09 +08:00
parent aa6a05c146
commit d45e72fe5a
1 changed files with 30 additions and 15 deletions
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45
lisp/pixel-scroll.el
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@@ -109,6 +109,18 @@ This is only effective if supported by your mouse or touchpad."
:type 'boolean
:version "29.1")
(defcustom pixel-scroll-precision-momentum-tick 0.16
"Number of seconds between each momentum scroll."
:group 'mouse
:type 'float
:version "29.1")
(defcustom pixel-scroll-precision-momentum-factor 0.95
"Factor by which to reduce scroll velocity on each momentum scroll"
:group 'mouse
:type 'float
:version "29.1")
(defun pixel-scroll-in-rush-p ()
"Return non-nil if next scroll should be non-smooth.
When scrolling request is delivered soon after the previous one,
@@ -501,14 +513,14 @@ wheel."
It is a vector of the form [ VELOCITY TIME ]."
(or (window-parameter nil 'kinetic-state)
(set-window-parameter nil 'kinetic-state
(vector (make-ring 4) nil))))
(vector (make-ring 10) nil))))
(defun pixel-scroll-accumulate-velocity (delta)
"Accumulate DELTA into the current window's kinetic scroll state."
(let* ((state (pixel-scroll-kinetic-state))
(time (aref state 1)))
(when (and time (> (- (float-time) time) 0.5))
(aset state 0 (make-ring 45)))
(aset state 0 (make-ring 10)))
(ring-insert (aref state 0)
(cons (aset state 1 (float-time))
delta))))
@@ -532,23 +544,26 @@ It is a vector of the form [ VELOCITY TIME ]."
(state nil))
(with-selected-window window
(setq state (pixel-scroll-kinetic-state))
(when (aref state 1)
(when (and (aref state 1)
(listp (aref state 0)))
(unwind-protect (progn
(aset state 0
(pixel-scroll-calculate-velocity state))
(/ (pixel-scroll-calculate-velocity state) 2))
(let ((velocity (aref state 0)))
(if (> velocity 0)
(while (> velocity 0)
(pixel-scroll-precision-scroll-up 1)
(setq velocity (1- velocity))
(sit-for 0.1)
(redisplay t))
(while (< velocity 0)
(pixel-scroll-precision-scroll-down 1)
(setq velocity (1+ velocity))
(sit-for 0.1)
(redisplay t)))))
(aset state 0 (make-ring 45))
(while (> velocity 1)
(pixel-scroll-precision-scroll-up (round velocity))
(setq velocity (* velocity
pixel-scroll-precision-momentum-factor))
(redisplay t)
(sit-for pixel-scroll-precision-momentum-tick)))
(while (< velocity -1)
(pixel-scroll-precision-scroll-down (round (abs velocity)))
(setq velocity (* velocity
pixel-scroll-precision-momentum-factor))
(redisplay t)
(sit-for pixel-scroll-precision-momentum-tick))))
(aset state 0 (make-ring 10))
(aset state 1 nil)))))))
;;;###autoload