Keep RecyclerView vertical scroll offset after layout resizing due to the keyboard being shown.

recyclerview_fixed_scroll.kt

private var verticalScrollOffset = AtomicInteger(0)

recyclerView.addOnLayoutChangeListener { _, _, _, _, bottom, _, _, _, oldBottom ->
    val y = oldBottom - bottom
    if (y.absoluteValue > 0) {
        recyclerView.post {
            if (y > 0 || verticalScrollOffset.get().absoluteValue >= y.absoluteValue) {
                recyclerView.scrollBy(0, y)
            } else {
                recyclerView.scrollBy(0, verticalScrollOffset.get())
            }
        }
    }
}

recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
    var state = AtomicInteger(RecyclerView.SCROLL_STATE_IDLE)

    override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
        state.compareAndSet(RecyclerView.SCROLL_STATE_IDLE, newState)
        when (newState) {
            RecyclerView.SCROLL_STATE_IDLE -> {
                if (!state.compareAndSet(RecyclerView.SCROLL_STATE_SETTLING, newState)) {
                    state.compareAndSet(RecyclerView.SCROLL_STATE_DRAGGING, newState)
                }
            }
            RecyclerView.SCROLL_STATE_DRAGGING -> {
                state.compareAndSet(RecyclerView.SCROLL_STATE_IDLE, newState)
            }
            RecyclerView.SCROLL_STATE_SETTLING -> {
                state.compareAndSet(RecyclerView.SCROLL_STATE_DRAGGING, newState)
            }
        }
    }

    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        if (state.get() != RecyclerView.SCROLL_STATE_IDLE) {
            verticalScrollOffset.getAndAdd(dy)
        }
    }
})