为什么 LazyColumn 不能使用鼠标滚动，但回收器视图可以？

Question

This is a question of Why rather than How .

I am using scrcpy to mirror and control my physical test mobile device using my desktop.

I am migrating an app from views to jetpack compose.
This is something I observed and I am curious why this happens so.

Using the desktop mouse scroll wheel, I am able to scroll a RecyclerView .

But I am not able to do so in a LazyColumn .

Note: I am able to scroll the LazyColumn using the mouse by click and drag.
Only the scroll wheel is not working.

Code (which I feel is really not relevant)

bookingsState?.let { bookings ->
    LazyColumn(
        modifier = Modifier.fillMaxWidth(),
    ) {
        items(bookings) { booking: BookingEntity ->
            BookingView(booking)
        }
    }
}

Answer 1

( scrcpy author here)

scrcpy just injects scroll events , which are handled by the system: https://github.com/Genymobile/scrcpy/blob/c96f5c70e9c6fe82da059c7d24e77d9730aa7f86/server/src/main/java/com/genymobile/scrcpy/Controller.java#L225-L246

However, the problem might still be explained by incorrect parameters in the scroll event, which happen to work in many case but not all. Such problems already occurred in the past: https://github.com/Genymobile/scrcpy/issues/2169

In particular, scroll events are injected with a touchscreen as input device, which is probably incorrect. Could you please try with this fix: https://github.com/Genymobile/scrcpy/commit/13b8fc0ad9376409a1c93194c6f7c491e51c533d

Here is a binary to replace in your v1.18 release so you can test easily:scrcpy-server (SHA256: a1db961faf8f567737373f1fa9f39609fede8955b5b28c3f31a06256f54d33d1)

Thank you for your feedback.

---

The problem is the same with a mouse (connected via bluetooth), without scrcpy being involved at all: https://github.com/Genymobile/scrcpy/issues/2602#issuecomment-907686669