Keyboard open and close listener

KeyboardListener.kt

    private val open = KeyboardState.OPEN // change value true 
    private val close = KeyboardState.CLOSE // change value false
    private var lastKeyboardState = close

    fun listener(rootView: View?, keyboardState: (KeyboardState) -> Unit) {
        rootView?.viewTreeObserver?.addOnGlobalLayoutListener {
            val rect = Rect().apply { rootView.getWindowVisibleDisplayFrame(this) }
            val screenHeight = rootView.height
            val keypadHeight = screenHeight - rect.bottom

            if (keypadHeight > screenHeight*0.15) {
                if (lastKeyboardState == close) keyboardState.invoke(open)
                lastKeyboardState = open
            } else {
                if (lastKeyboardState == open) keyboardState.invoke(close)
                lastKeyboardState = close
            }
        }
    }