feat(x11-capture): implement X11 input capture backend#457
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Replaces the stub that always returned `NotImplemented` with a working implementation using XQueryPointer polling + XGrabPointer/XGrabKeyboard. Architecture mirrors the Windows backend: a dedicated OS thread runs the X11 event loop and communicates with the async runtime via two channels (std::sync::mpsc for requests, tokio::sync::mpsc for events). Phase 1 (no active client): polls XQueryPointer at ~1 ms to detect when the cursor crosses a screen edge towards a configured client, then calls XGrabPointer + XGrabKeyboard and sends CaptureEvent::Begin. Phase 2 (active client): drains XNextEvent. MotionNotify events compute a relative delta from the locked entry point and warp the cursor back; ButtonPress/Release and KeyPress/Release are forwarded as input events. X11 keycodes are translated to Linux evdev by subtracting 8. The right/bottom boundary detection uses `>= w-1` / `>= h-1` rather than `>= w` / `>= h` because X11 clamps cursor coordinates to the range [0, w-1] × [0, h-1] — the larger values are never returned by XQueryPointer on a single monitor. 13 unit tests cover boundary detection, coordinate clamping, and button mapping.
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Summary
Replaces the
X11InputCapturestub (which always returnedNotImplementedand fell through to theDummybackend) with a working implementation. With this change, lan-mouse on X11/Xorg sessions captures mouse and keyboard properly, allowing the cursor to cross back to the host by moving to the screen edge — no release keybind required.Fixes the root cause of #125 and #315 (Xorg users stuck on the client, needing manual release to return).
How it works
A dedicated OS thread runs the X11 event loop alongside the async runtime — the same pattern used by the Windows backend.
Phase 1 — edge detection (no active client):
Polls
XQueryPointerat ~1 ms. When the cursor crosses a screen edge toward a configured client, callsXGrabPointer+XGrabKeyboardand sendsCaptureEvent::Begin.Phase 2 — forwarding (active client):
Drains
XNextEvent.MotionNotifycomputes a relative delta from the locked entry point and warps the cursor back.ButtonPress/ButtonReleaseandKeyPress/KeyReleaseare forwarded as input events. X11 keycodes are converted to Linux evdev by subtracting 8.Key subtlety: The right/bottom boundary check uses
>= w-1/>= h-1instead of>= w/>= h. X11 clamps cursor coordinates to[0, w-1] × [0, h-1]— the larger values are never returned byXQueryPointeron a single monitor, so the original>= wcondition was dead code and the return journey never triggered.Changes
input-capture/src/x11.rsinput-capture/src/error.rsNotImplementedwithOpenDisplayFailedvariant13 unit tests cover boundary detection, coordinate clamping, and button mapping.
Tested on
Tested with one host + one client; other X11 distros and multi-client setups have not been validated yet.