From a1701b60ea83f3ad8df3dbb4f2f917a6294f8f2e Mon Sep 17 00:00:00 2001
From: Daneel <daneel@sukany.cz>
Date: Mon, 23 Feb 2026 14:11:16 +0100
Subject: [PATCH] fix(macos): enable pixel-scroll-precision-mode for smooth
 trackpad/mouse scrolling

macOS NS/Cocoa Emacs generates pixel-level scroll events from trackpad
and Magic Mouse. Without pixel-scroll-precision-mode, these events are
handled as line-based scrolling, resulting in jerky or broken scroll
behavior.

Changes:
- Enable pixel-scroll-precision-mode (Emacs 29+) in GUI mode
- Set pixel-scroll-precision-large-scroll-height to 40.0 (prevents
  trackpad fling from being interpolated frame-by-frame)
- Enable momentum scrolling (trackpad inertia from macOS)
- Keep line-based mouse-wheel-scroll-amount as fallback for physical
  scroll wheels
---
 config.el | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/config.el b/config.el
index 6f21ae1..85e96dc 100644
--- a/config.el
+++ b/config.el
@@ -178,10 +178,25 @@ Bound to cmd+v in org-mode and markdown-mode."
                  [down-mouse-1] [down-mouse-2] [down-mouse-3]))
     (global-set-key key #'ignore))
   (setq mouse-highlight nil)
-  ;; Smooth scroll wheel: 3 lines per tick, no acceleration
+
+  ;; Scroll wheel — macOS NS/Cocoa generates pixel-level scroll events from
+  ;; trackpad and Magic Mouse. pixel-scroll-precision-mode (Emacs 29+) handles
+  ;; these natively for smooth, 1:1 scrolling. Line-based mouse-wheel-scroll-amount
+  ;; is kept as fallback for physical scroll wheels that send line events.
   (setq mouse-wheel-scroll-amount '(3 ((shift) . 1) ((control) . nil))
         mouse-wheel-progressive-speed nil
-        mouse-wheel-follow-mouse t))
+        mouse-wheel-follow-mouse t)
+
+  ;; Enable pixel-precise scrolling (Emacs 29+) — essential for macOS trackpad/
+  ;; Magic Mouse. Translates pixel deltas from NS scroll events into smooth
+  ;; pixel-level buffer scrolling instead of jerky line jumps.
+  (when (fboundp 'pixel-scroll-precision-mode)
+    (pixel-scroll-precision-mode 1)
+    ;; Large scroll threshold: pixel deltas above this trigger line-based scroll
+    ;; (prevents trackpad fling from being interpolated frame-by-frame).
+    (setq pixel-scroll-precision-large-scroll-height 40.0
+          ;; Use momentum scrolling from macOS (trackpad inertia)
+          pixel-scroll-precision-use-momentum t)))