branch: elpa/scroll-on-jump
commit 222f9c1d33659bc367a1b507a68c0df73f9e3db8
Author: Campbell Barton <ideasma...@gmail.com>
Commit: Campbell Barton <ideasma...@gmail.com>
Add support for ease-in and ease-out curves
Also add scroll-on-jump-curve-power to control the strength of the curve.
---
changelog.rst | 3 ++
readme.rst | 20 +++++++++---
scroll-on-jump.el | 91 ++++++++++++++++++++++++++++++++++++++++---------------
3 files changed, 86 insertions(+), 28 deletions(-)
diff --git a/changelog.rst b/changelog.rst
index b336034ab1..7c32d6bb86 100644
--- a/changelog.rst
+++ b/changelog.rst
@@ -3,6 +3,9 @@
Change Log
##########
+ - Add ``scroll-on-jump-curve`` & ``scroll-on-jump-curve-power``
+ to support different kinds of curves & control their strength.
+
- Version 0.2 (2023-01-22)
- Add ``scroll-on-jump-mode-line-format`` to support overriding the
mode-line while scrolling.
diff --git a/readme.rst b/readme.rst
index a4af4efebf..9df3920e2a 100644
--- a/readme.rst
+++ b/readme.rst
@@ -162,13 +162,25 @@ Customization
While the defaults seem to work well, these values can be customized.
-``scroll-on-jump-duration``: 0.4
+``scroll-on-jump-duration``: ``0.4``
The duration for jumping to take, set to ``0.0`` to jump immediately.
-``scroll-on-jump-smooth``: t
+``scroll-on-jump-smooth``: ``t``
When not nil, use smooth scrolling (by pixels).
-``scroll-on-jump-use-curve``: t
+``scroll-on-jump-curve``: ``'smooth``
Apply a curve to the scroll speed, starting and ending slow.
-``scroll-on-jump-mode-line-format``: nil
+
+ :'smooth: Ease in/out.
+ :'smooth-in: Ease in (end slow).
+ :'smooth-out: Ease in (start slow).
+ :'linear: Linear motion (no easing).
+``scroll-on-jump-curve-power``: ``3.0``
+ The strength of the curve (when non-linear).
+
+ Values between 2 and 8 work well.
+
+ - Below 2.0 approaches a linear curve.
+ - Above 8.0 can make the motion overly abrupt.
+``scroll-on-jump-mode-line-format``: ``nil``
When non-nil, use this value for the ``mode-line-format`` while scrolling.
This can be used to temporarily override the mode-line while scrolling.
It can also help to avoid overly complex mode-lines from slowing down
scrolling.
diff --git a/scroll-on-jump.el b/scroll-on-jump.el
index 0bc11ebbdf..6cb9006caf 100644
--- a/scroll-on-jump.el
+++ b/scroll-on-jump.el
@@ -40,9 +40,19 @@
"Use smooth (pixel) scrolling, otherwise scroll by lines."
:type 'boolean)
-(defcustom scroll-on-jump-use-curve t
- "Apply a curve to the scroll speed, starting and ending slow."
- :type 'boolean)
+(defcustom scroll-on-jump-curve 'smooth
+ "The the method scrolling is calculated."
+ :type
+ '(choice
+ (const :tag "Smooth in/out, starts & ends slow" smooth)
+ (const :tag "Smooth in, starts slow" smooth-in)
+ (const :tag "Smooth out, ends slow" smooth-out)
+ (const :tag "Linear" linear)))
+
+(defcustom scroll-on-jump-curve-power 3.0
+ "The strength of the curve (when set to linear).
+A value of 1.0 is linear, values between 2 and 8 work well."
+ :type 'float)
(defcustom scroll-on-jump-mode-line-format nil
"The `mode-line-format' to use or nil to leave the `mode-line-format'
unchanged.
@@ -135,10 +145,6 @@ Argument ALSO-MOVE-POINT When non-nil, move the POINT as
well."
(t
(cons 0 0))))
-(defun scroll-on-jump--interpolate-ease (a b factor)
- "Blend FACTOR between A and B using ease style curvature."
- (+ a (* (- b a) (- (* 3.0 factor factor) (* 2.0 factor factor factor)))))
-
(defsubst scroll-on-jump--evil-visual-mode-workaround ()
"Workaround for `evil-mode' line-mode."
;; Without this, the line mode point jumps back to the origin,
@@ -155,8 +161,57 @@ Argument ALSO-MOVE-POINT When non-nil, move the POINT as
well."
;; ---------------------------------------------------------------------------
-;; Internal Logic
+;; Internal Interpolation Functions
+
+(defsubst scroll-on-jump--interp-linear-impl (a b factor)
+ "Internal macro for to blend A, B by FACTOR."
+ (+ a (* (- b a) factor)))
+(defun scroll-on-jump--interp-linear (a b factor)
+ "Blend FACTOR between A and B using linear curvature."
+ (scroll-on-jump--interp-linear-impl a b factor))
+
+(defun scroll-on-jump--interp-ease-in (a b factor)
+ "Blend FACTOR between A and B using ease-in curvature."
+ (scroll-on-jump--interp-linear-impl a b (expt factor
scroll-on-jump-curve-power)))
+
+(defun scroll-on-jump--interp-ease-out (a b factor)
+ "Blend FACTOR between A and B using ease-in curvature."
+ (scroll-on-jump--interp-linear-impl
+ a b (- 1.0 (expt (- 1.0 factor) scroll-on-jump-curve-power))))
+
+(defun scroll-on-jump--interp-ease-in-out (a b factor)
+ "Blend FACTOR between A and B using ease-in-out curvature."
+ (cond
+ ((< factor 0.5)
+ (let ((f (* (expt (* factor 2.0) scroll-on-jump-curve-power) 0.5)))
+ (scroll-on-jump--interp-linear-impl a b f)))
+ (t
+ (let ((f (- 1.0 (* (expt (* (- 1.0 factor) 2.0)
scroll-on-jump-curve-power) 0.5))))
+ (scroll-on-jump--interp-linear-impl a b f)))))
+
+(defun scroll-on-jump--interp-fn-get (curve)
+ "Return the interpolation function associated with CURVE."
+ (cond
+ ((<= scroll-on-jump-curve-power 1.0)
+ ;; A curve of 1.0 is linear by definition,
+ ;; also catches users entering in bad values (negative numbers for e.g.)
+ ;; that will only cause problems.
+ #'scroll-on-jump--interp-linear)
+ (t
+ (pcase curve
+ ('linear #'scroll-on-jump--interp-linear)
+ ('smooth #'scroll-on-jump--interp-ease-in-out)
+ ('smooth-in #'scroll-on-jump--interp-ease-in)
+ ('smooth-out #'scroll-on-jump--interp-ease-out)
+ (_
+ (message "Unknown curve (%S), using linear" curve)
+ ;; Fall back to linear (as good an option as any).
+ #'scroll-on-jump--interp-linear)))))
+
+
+;; ---------------------------------------------------------------------------
+;; Internal Logic
(defun scroll-on-jump--immediate-scroll (window lines-scroll _dir)
"Non animated scroll for WINDOW to move LINES-SCROLL."
@@ -171,7 +226,7 @@ Moving the point when ALSO-MOVE-POINT is set."
(time-limit
(* scroll-on-jump-duration
(min 1.0 (/ (float (abs lines-scroll)) (float (window-body-height
window))))))
- (use-curve scroll-on-jump-use-curve))
+ (interp-fn (scroll-on-jump--interp-fn-get scroll-on-jump-curve)))
;; Animated scrolling (early exit on input to avoid annoying lag).
(cond
@@ -188,13 +243,7 @@ Moving the point when ALSO-MOVE-POINT is set."
(step
(let* ((time-elapsed (float-time (time-subtract
(current-time) time-init)))
(factor (min 1.0 (/ time-elapsed time-limit)))
- (lines-target
- (floor
- (cond
- (use-curve
- (scroll-on-jump--interpolate-ease 0.0
lines-scroll-abs factor))
- (t
- (* lines-scroll-abs factor)))))
+ (lines-target (floor (funcall interp-fn 0.0
lines-scroll-abs factor)))
(lines-remainder (- lines-target lines-done-abs)))
;; Step result, we must move at least one line.
(* dir (max 1 lines-remainder)))))
@@ -242,7 +291,7 @@ Argument ALSO-MOVE-POINT moves the point while scrolling."
(time-limit
(* scroll-on-jump-duration
(min 1.0 (/ (float (abs lines-scroll)) (float (window-body-height
window))))))
- (use-curve scroll-on-jump-use-curve)
+ (interp-fn (scroll-on-jump--interp-fn-get scroll-on-jump-curve))
(char-height (frame-char-height (window-frame window))))
;; Animated scrolling (early exit on input to avoid annoying lag).
@@ -270,13 +319,7 @@ Argument ALSO-MOVE-POINT moves the point while scrolling."
(step
(let* ((time-elapsed (float-time (time-subtract
(current-time) time-init)))
(factor (min 1.0 (/ time-elapsed time-limit)))
- (px-target
- (floor
- (cond
- (use-curve
- (scroll-on-jump--interpolate-ease 0.0
px-scroll-abs factor))
- (t
- (* px-scroll-abs factor)))))
+ (px-target (floor (funcall interp-fn 0.0
px-scroll-abs factor)))
(px-remainder (- px-target px-done-abs)))
(* dir px-remainder))))
