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Summary: `onHWKeyEvent` tells JS which key was pressed but not when it was pressed, so a listener can only time a press from the moment the device event reaches the JavaScript thread. That delivery is asynchronous, so any latency measured from JS silently excludes the native-to-JS hop — and excludes more of it the busier the JS thread is, which is exactly when the interaction is slowest. Add the originating `KeyEvent.getEventTime()` to the event payload. It is `SystemClock.uptimeMillis()`, the same `CLOCK_MONOTONIC` base that `performance.now()` reads in JS, so a listener can subtract the two directly with no clock conversion. The field is omitted for the focus and blur events, which have no originating hardware event. Additive and behaviour-preserving: no existing payload key changes, and nothing in the framework reads the new one. ## Changelog Changelog: [Android][Added] - Add `eventTime` to the `onHWKeyEvent` device event payload Reviewed By: rozele Differential Revision: D120451212
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Summary:
onHWKeyEventtells JS which key was pressed but not when it was pressed, so a listener can only time a press from the moment the device event reaches the JavaScript thread. That delivery is asynchronous, so any latency measured from JS silently excludes the native-to-JS hop — and excludes more of it the busier the JS thread is, which is exactly when the interaction is slowest.Add the originating
KeyEvent.getEventTime()to the event payload. It isSystemClock.uptimeMillis(), the sameCLOCK_MONOTONICbase thatperformance.now()reads in JS, so a listener can subtract the two directly with no clock conversion. The field is omitted for the focus and blur events, which have no originating hardware event.Additive and behaviour-preserving: no existing payload key changes, and nothing in the framework reads the new one.
Changelog
Changelog: [Android][Added] - Add
eventTimeto theonHWKeyEventdevice event payloadReviewed By: rozele
Differential Revision: D120451212