MainActivity.kt

override fun onResume() {
    super.onResume()
    camera_view.onResume()
}
override fun onPause() {
    super.onPause()
    camera_view.onPause()
}
override fun onStart() {
    super.onStart()
    camera_view.onStart()
}
override fun onStop() {
    super.onStop()
    camera_view.onStop()
}