feat: XI2.1 smooth scroll support via xinput driver#12
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hiroTamada merged 7 commits intomasterfrom Apr 2, 2026
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When NEKO_DESKTOP_CDP_SCROLL_URL is set, scroll events are dispatched via Chrome DevTools Protocol (Input.dispatchMouseEvent mouseWheel) instead of X11 XTestFakeButtonEvent. This enables pixel-precise, smooth scrolling for trackpads and high-resolution mice. - Add cdpscroll package with auto-discovery of browser WebSocket URL - Wire CDP scroll into DesktopManager with X11 fallback - Add new scroll payload format (length=5) with controlKey support - Existing legacy scroll format (length=4) continues to work Made-with: Cursor
Route scroll events through the xinput socket to the Xorg driver instead of using XTestFakeButtonEvent. The driver posts them as native XInput2 scroll valuator changes, giving pixel-precise smooth scrolling that Chromium handles identically to a real trackpad. Adds Scroll() method to xinput.Driver interface. DesktopManager.Scroll() uses xinput when UseInputDriver is true, falling back to XTest otherwise. Made-with: Cursor
Remove the pixelsPerNotch conversion that quantized scroll events into discrete notches. The xf86-input-neko driver now has scroll valuators (axes 3/4), so raw pixel deltas produce 1:1 smooth scrolling in Chromium. Also fix XTest fallback scroll direction (button 4/5 mapping was inverted). Made-with: Cursor
The cdpscroll package and CDPScrollURL config were from an earlier approach and are not used by the XI2.1 scroll path. Made-with: Cursor
![cursor[bot]](https://avatars.githubusercontent.com/in/1210556?s=60&v=4){kind=small}
…lback When UseInputDriver is false, the dummy driver's Scroll() previously returned nil, silently dropping all scroll events. Now it returns errNotConnected so the XTest fallback path in xorg.go is reached. Made-with: Cursor
- Remove warn-level log on every scroll when xinput driver is unavailable (dummy driver returns error by design, not worth logging) - Pass controlKey to xorg.Scroll() in the XTest fallback path so the modifier set/scroll/clear happens atomically under a single X11 lock Made-with: Cursor
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Branch on UseInputDriver to avoid dummy driver log spam while ensuring the Ctrl modifier is set before xf86-input-neko posts the motion event. The XTest fallback still handles controlKey atomically under a single lock. Made-with: Cursor
hiroTamada
commented
Apr 1, 2026
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| int ydir; | ||
| if (deltaY > 0) { | ||
| ydir = 4; // button 4 is up |
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this is needed for scrolling direction
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Summary
Enable pixel-precise smooth scrolling by sending raw pixel deltas through the
xf86-input-nekoxinput driver instead of quantizing them into discrete XTest button events.Changes
server/internal/desktop/xorg.go—Scroll()now sends raw pixel deltas directly to the xinput driver via Unix socket. Falls back to XTest if the driver connection fails.server/internal/webrtc/legacyhandler.go— SupportPayloadScrollWithCtrl(length=5) binary message format that includes acontrolKeybyte alongsidedeltaX/deltaY.server/pkg/xinput/— AddNEKO_SCROLL(0x80) message type andScroll(deltaX, deltaY int32)method to send scroll events over the Unix socket to the Xorg driver.server/pkg/xorg/xorg.c— Fix XTest fallback scroll direction (button 4/5 mapping was inverted).server/internal/config/desktop.go— AddCDPScrollURLconfig option (unused by default, for optional CDP scroll bypass).server/pkg/cdpscroll/— Optional CDP-based scroll client (gated behindCDPScrollURLconfig, not active by default).Context
Used by kernel/kernel-images#196 which extends the
xf86-input-nekoXorg driver with XI2.1 scroll valuators. Together, this achieves 1:1 pixel mapping between client trackpad deltas and browser scroll.Made with Cursor
Note
Medium Risk
Changes desktop input/scroll handling (including modifier behavior and X11 button mapping), which can impact core interaction and has platform-specific edge cases. Failover paths mitigate risk but need validation across driver/no-driver setups.
Overview
Adds XI2.1 smooth/pixel-precise scrolling support by routing scroll deltas through the
xinputUnix-socket driver whendesktop.input.enabledis set, including temporarily setting the Ctrl modifier before posting the event and falling back to XTest on driver errors.Extends the legacy WebRTC data-channel scroll payload to optionally include a Ctrl flag (
Length == 5) while keeping the existing scroll format for compatibility, and updates logging accordingly.Expands
server/pkg/xinputwith a newNEKO_SCROLLmessage andDriver.Scroll()API (dummy returns a not-connected error), and fixes the XTest fallback scroll direction mapping inserver/pkg/xorg/xorg.c.Written by Cursor Bugbot for commit ae3594a. This will update automatically on new commits. Configure here.