workflow-ui-core-android/com.squareup.workflow1.ui/ScreenViewFactoryFinder

ScreenViewFactoryFinder

@WorkflowUiExperimentalApi
interface ScreenViewFactoryFinder

ViewEnvironment service object used by Screen.toViewFactory to find the right ScreenViewFactory to build and manage a View to display Screens of the type of the receiver. The default implementation makes AndroidScreen work, and provides default bindings for NamedScreen, EnvironmentScreen, BackStackScreen, etc.

Here is how this hook could be used to provide a custom view to handle BackStackScreen:

object MyViewFactory : ScreenViewFactory<*>>
by ScreenViewFactory(
  buildView = { environment, context, _ ->
    val view = MyBackStackContainer(context)
    ScreenViewHolder(environment, view) { rendering, environment ->
      view.update(rendering, environment)
    }
  }
)

object MyFinder : ScreenViewFactoryFinder {
  override fun  getViewFactoryForRendering(
    environment: ViewEnvironment,
    rendering: ScreenT
  ): ScreenViewFactory {
    @Suppress("UNCHECKED_CAST")
    if (rendering is BackStackScreen<*>) return MyViewFactory as ScreenViewFactory
    return super.getViewFactoryForRendering(environment, rendering)
  }
}

class MyViewModel(savedState: SavedStateHandle) : ViewModel() {
  val renderings: StateFlow by lazy {
    val env = ViewEnvironment.EMPTY + (ScreenViewFactoryFinder to MyFinder)
    renderWorkflowIn(
      workflow = MyRootWorkflow.mapRenderings { it.withEnvironment(env) },
      scope = viewModelScope,
      savedStateHandle = savedState
    )
  }
}
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