SecondFragment.java

class SecondFragment : Fragment() {

    override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_second, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        view.findViewById<Button>(R.id.button_second).setOnClickListener {
            findNavController().navigate(R.id.action_SecondFragment_to_FirstFragment)
        }

        val textView = view.findViewById<TextView>(R.id.textview_second)

        view.findViewById<ConstraintLayout>(R.id.root)
            .touches()
            .classifyTouches(500L)
            .filterNot { it is Touch.Other }
            .onEach {
                textView.text = it.javaClass.simpleName
                Log.w("ivan", "[SecondFragment][onViewCreated] $it")
            }
            .launchIn(lifecycleScope)
    }

    sealed class Touch(open val x: Float, open val y: Float) {
        object Click: Touch(0F, 0F)
        data class Down(override val x: Float, override val y: Float): Touch(x, y)
        data class Move(override val x: Float, override val y: Float): Touch(x, y)
        data class Up(override val x: Float, override val y: Float): Touch(x, y)
        object Other: Touch(0F, 0F)
    }

    private fun Flow<MotionEvent>.classifyTouches(clickReactionTime: Long): Flow<Touch> {
        var lastDownTime = 0L
        var lastX = 0F
        var lastY = 0F
        val xyThreshold = 3F
        return map { event ->
                when (event.action) {
                    MotionEvent.ACTION_DOWN -> {
                        lastDownTime = System.currentTimeMillis()
                        Touch.Down(event.x, event.y)
                    }
                    MotionEvent.ACTION_MOVE -> {
                        val diffX = abs(lastX - event.x)
                        val diffY = abs(lastY - event.y)
                        lastX = event.x
                        lastY = event.y
                        if (diffX <= xyThreshold && diffY <= xyThreshold) {
                            Touch.Other
                        } else {
                            Touch.Move(event.x, event.y)
                        }
                    }
                    MotionEvent.ACTION_UP -> {
                        val currentTime = System.currentTimeMillis()
                        if (currentTime - lastDownTime >= clickReactionTime) {
                            Touch.Up(event.x, event.y)
                        } else {
                            Touch.Click
                        }
                    }
                    else -> Touch.Other
                }
        }
    }
}