ActivityAsWorkflowProps.kt

@OptIn(WorkflowUiExperimentalApi::class)
class HelloWorkflowActivity : AppCompatActivity() {
  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    // This ViewModel will survive configuration changes. It's instantiated
    // by the first call to viewModels(), and that original instance is returned by
    // succeeding calls.
    val model: HelloViewModel by viewModels()
    model.init(this)
    setContentView(
      WorkflowLayout(this).apply { start(model.renderings) }
    )
  }
}

class HelloViewModel(savedState: SavedStateHandle) : ViewModel() {
  private lateinit var activities: MutableStateFlow<Activity>

  fun init(activity: Activity) {
    if (!this::activities.isInitialized) {
      activities = MutableStateFlow(activity)
    } else {
      activities.value = activity
    }
  }

  @OptIn(WorkflowUiExperimentalApi::class)
  val renderings: StateFlow<HelloRendering> by lazy {
    renderWorkflowIn(
      workflow = HelloWorkflow,
      scope = viewModelScope,
      savedStateHandle = savedState,
      props = activities
    )
  }
}