Allows to hide and show keyboard with notification after successful hiding or showing

RxKeyboardManager.kt

@Reusable
class RxKeyboardManager(private val activity: Activity, private val mainThread: Scheduler, private val imm: InputMethodManager) {
    val keyboardStates = Observable.create<Boolean>({
        val globalLayoutListener = ViewTreeObserver.OnGlobalLayoutListener { it.onNext(isKeyboardShown()) }
        it.setCancellation { activity.window.decorView.viewTreeObserver.removeOnGlobalLayoutListener(globalLayoutListener) }
        activity.window.decorView.viewTreeObserver.addOnGlobalLayoutListener(globalLayoutListener)
    }, Emitter.BackpressureMode.LATEST)
            .distinctUntilChanged()
            .subscribeOn(mainThread)
            .share()

    fun isKeyboardShown(): Boolean {
        val rootView = activity.window.decorView
        /* 128dp = 32dp * 4, minimum button height 32dp and generic 4 rows soft keyboard */
        val SOFT_KEYBOARD_HEIGHT_DP_THRESHOLD = 128

        val r = Rect()
        rootView.getWindowVisibleDisplayFrame(r)
        val dm = rootView.resources.displayMetrics
        /* heightDiff = rootView height - status bar height (r.top) - visible frame height (r.bottom - r.top) */
        val heightDiff = rootView.bottom - r.bottom
        /* Threshold size: dp to pixels, multiply with display density */
        return heightDiff > SOFT_KEYBOARD_HEIGHT_DP_THRESHOLD * dm.density
    }

    @CheckResult
    fun showKeyboard(viewForInput: View): Completable = if (isKeyboardShown()) {
        Completable.complete()
    } else {
        Completable.fromAction { imm.showSoftInput(viewForInput, 0) }
                .concatWith(keyboardReacted(visibility = true))
    }

    @CheckResult
    @JvmOverloads
    fun hideKeyboard(view: View = activity.window.decorView): Completable = if (isKeyboardShown()) {
        Completable.fromAction { imm.hideSoftInputFromWindow(view.windowToken, 0) }
                .concatWith(keyboardReacted(visibility = false))
    } else {
        Completable.complete()
    }

    private fun keyboardReacted(visibility: Boolean): Completable = keyboardStates
            .first { it == visibility }
            .observeOn(mainThread)// Wait when UI reflected (a small delay because of post())
            .toCompletable()
}