feat: XI2.1 smooth scrolling via xf86-input-neko scroll valuators#196
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hiroTamada wants to merge 6 commits intomainfrom
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feat: XI2.1 smooth scrolling via xf86-input-neko scroll valuators#196hiroTamada wants to merge 6 commits intomainfrom
hiroTamada wants to merge 6 commits intomainfrom
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Replace the XTest button-event scroll path (fixed ~100px quantum per click) with XInput2.1 scroll valuators on the xf86-input-neko driver. This gives pixel-precise 1:1 mapping between client trackpad deltas and browser scroll pixels, eliminating the jumpiness of discrete scroll notches. Changes: - neko.c: add vertical/horizontal scroll valuator axes (3, 4) with SetScrollValuator; handle NEKO_SCROLL messages via xf86PostMotionEventM instead of button events; change device type from XI_TOUCHSCREEN to XI_MOUSE so Chromium respects valuators - video.vue: remove PIXELS_PER_TICK quantization and 100ms throttle; send raw pixel deltas batched per rAF; use document-level wheel listener with passive:false for reliable preventDefault - base.ts: extend wheel binary message to include controlKey byte (PayloadScrollWithCtrl, length=5) - neko.yaml: enable xinput driver with socket path - Dockerfile: use neko base image with XI2 scroll support Requires: kernel/neko branch hiro/xi2-scroll Made-with: Cursor
![cursor[bot]](https://avatars.githubusercontent.com/in/1210556?s=60&v=4){kind=small}
- Scope wheel listener to overlay element instead of document to avoid blocking scrolling in chat/emoji/files panels - Store handler reference and remove it in beforeDestroy to prevent leaks - Re-integrate scroll sensitivity setting (1-100 range, 50 = 1x) - Remove unused scroll_x/scroll_y fields from xf86-input-neko driver - Revert Dockerfile FROM to existing neko base tag for CI (pending neko#12) Made-with: Cursor
hiroTamada
commented
Apr 1, 2026
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| FROM ghcr.io/kernel/neko/base:3.0.8-v1.4.0 AS neko | ||
| # ^--- now has event.SYSTEM_PONG with legacy support to keepalive | ||
| # TODO: update to xi2-scroll tag once kernel/neko#12 is merged and tagged |
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I will update this once neko PR is merged
- Cancel any pending requestAnimationFrame in beforeDestroy to prevent accessing torn-down Vue instance - Restore sendMousePos call in onWheel so cursor position is synced before scroll events (trackpad scrolling doesn't fire mousemove) Made-with: Cursor
The default scroll setting is 10, so the divisor should be 10 (not 50) to produce 1x sensitivity at the default value. Range: 1=0.1x to 100=10x. Made-with: Cursor
Call preventDefault() before the locked check so the page doesn't scroll underneath the video overlay when hosting but locked. Made-with: Cursor
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- Subtract sent dx/dy from accumulators instead of resetting to zero, preserving fractional remainders for accurate sensitivity scaling - Use assignment for ctrl flag to reflect latest event state, avoiding false positives from transient ctrl events within a RAF batch Made-with: Cursor
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Checklist
ghcr.io/kernel/neko/base:xi2-scrollimage to be publishedSummary
Replace the XTest button-event scroll path with XInput2.1 smooth scroll valuators on the
xf86-input-nekoXorg driver. This fixes the fundamental scrolling problem: XTest could only fire discrete "notch" events (~100px per click in Chromium), making it impossible to achieve smooth trackpad scrolling. With XI2.1, we get pixel-precise 1:1 mapping between client trackpad deltas and browser scroll pixels.Problem
The old XTest approach (
xf86PostButtonEventwith buttons 4/5) had a fixed scroll quantum — each button press scrolled ~100px in Chromium with no sub-notch precision. This meant:pixelsPerNotchtoo low → fires many button clicks → scrolls too fastpixelsPerNotchtoo high → needs lots of delta before firing → feels jumpy/unresponsiveSolution
Use XInput2.1 scroll valuators which provide continuous, sub-pixel scroll precision:
xf86-input-neko driver (
neko.c):SetScrollValuatorNEKO_SCROLL(0x80) messages viaxf86PostMotionEventMinstead of button eventsXI_TOUCHSCREENtoXI_MOUSEso Chromium respects scroll valuatorsClient (
video.vue/base.ts):PIXELS_PER_TICKquantization and 100ms throttlerequestAnimationFramepassive: falsefor reliablepreventDefault()controlKeybyte (length=5)Config:
neko.yamlwith socket pathTest results
Programmatic tests confirm exact 1:1 pixel mapping:
Depends on
kernel/neko@hiro/xi2-scroll— server-side changes to send raw pixel deltas to xinput driverMade with Cursor
Note
Medium Risk
Changes the low-level mouse wheel pipeline end-to-end (client event handling, binary protocol, and Xorg input driver), so regressions could break scrolling or input behavior across browsers/hosts.
Overview
Adds an XI2.1 smooth-scrolling path by extending
xf86-input-nekowith vertical/horizontal scroll valuators and handling a newNEKO_SCROLLmessage type via motion events, including switching the device type toXI_MOUSE.Updates the web client wheel handling to prevent default scrolling via a non-passive wheel listener, batch raw deltas per
requestAnimationFrame(removing quantization/throttle), and sends an updated wheel payload including acontrolKeybyte.Enables the new input driver via
neko.yamlconfiguration (input socket), and annotates the container build to track the required upstreamneko/baseimage tag.Written by Cursor Bugbot for commit 11c1ba1. This will update automatically on new commits. Configure here.