unidirectional-view-impl.kt

class FooViewImpl @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyle: Int = 0,
    private val events: PublishRelay<Event> = PublishRelay.create<Event>()
) : LinearLayout(context, attrs, defStyle),
    FooView,
    // delegate implementing ObservableSource to our Relay
    ObservableSource<Event> by events {
     
    // 1. find the views
    private val title: TextView by lazy { findViewById<TextView>(R.id.title)}
    private val panel: ViewGroup by lazy { findViewById<ViewGroup>(R.id.panel)}
    private val button: Button by lazy { findViewById<Button>(R.id.button)}
    private val editText: EditText by lazy { findViewById<EditText>(R.id.editText)}
     
    // 2. set listeners to trigger Events
    override fun onFinishInflate() {
        super.onFinishInflate()
        button.setOnClickListener { events.accept(Event.ButtonClicked) }
        editText.setOnFocusChangeListener { _, hasFocus -> events.accept(Event.TextFocusChanged(hasFocus)) }
    }
     
    // 3. render the ViewModel
    override fun accept(vm: ViewModel) {
        title.text = vm.title
        panel.setBackgroundColor(ContextCompat.getColor(context, vm.bgColor))
    }
}