Presenter

<init>

Presenter()

A Presenter is used to generate Views and bind Objects to them on demand. It is closely related to the concept of an , but is not position-based. The leanback framework implements the adapter concept using ObjectAdapter which refers to a Presenter (or PresenterSelector) instance.

Presenters should be stateless. Presenters typically extend ViewHolder to store all necessary view state information, such as references to child views to be used when binding to avoid expensive calls to View#findViewById(int).

A trivial Presenter that takes a string and renders it into a :

public class StringTextViewPresenter extends Presenter {
      // This class does not need a custom ViewHolder, since it does not use
      // a complex layout.
 
      @Override
      public ViewHolder onCreateViewHolder(ViewGroup parent) {
          return new ViewHolder(new TextView(parent.getContext()));
      }
 
      @Override
      public void onBindViewHolder(ViewHolder viewHolder, Object item) {
          String str = (String) item;
          TextView textView = (TextView) viewHolder.mView;
 
          textView.setText(item);
      }
 
      @Override
      public void onUnbindViewHolder(ViewHolder viewHolder) {
          // Nothing to unbind for TextView, but if this viewHolder had
          // allocated bitmaps, they can be released here.
      }
  }
  

getFacet

fun getFacet(facetClass: Class<*>!): Any!

onBindViewHolder

abstract fun onBindViewHolder(viewHolder: Presenter.ViewHolder!, item: Any!): Unit

Binds a View to an item.

onBindViewHolder

open fun onBindViewHolder(viewHolder: Presenter.ViewHolder!, item: Any!, payloads: MutableList<Any!>!): Unit

Binds a View to an item with a list of payloads.

onCreateViewHolder

abstract fun onCreateViewHolder(parent: ViewGroup!): Presenter.ViewHolder!

Creates a new View.

onUnbindViewHolder

abstract fun onUnbindViewHolder(viewHolder: Presenter.ViewHolder!): Unit

Unbinds a View from an item. Any expensive references may be released here, and any fields that are not bound for every item should be cleared here.

onViewAttachedToWindow

open fun onViewAttachedToWindow(holder: Presenter.ViewHolder!): Unit

Called when a view created by this presenter has been attached to a window.

This can be used as a reasonable signal that the view is about to be seen by the user. If the adapter previously freed any resources in onViewDetachedFromWindow(ViewHolder) those resources should be restored here.

onViewDetachedFromWindow

open fun onViewDetachedFromWindow(holder: Presenter.ViewHolder!): Unit

Called when a view created by this presenter has been detached from its window.

Becoming detached from the window is not necessarily a permanent condition; the consumer of an presenter's views may choose to cache views offscreen while they are not visible, attaching and detaching them as appropriate.

setFacet

fun setFacet(facetClass: Class<*>!, facetImpl: Any!): Unit

Sets dynamic implemented facet in addition to basic Presenter functions.

setOnClickListener

open fun setOnClickListener(holder: Presenter.ViewHolder!, listener: OnClickListener!): Unit

Called to set a click listener for the given view holder. The default implementation sets the click listener on the root view in the view holder. If the root view isn't focusable this method should be overridden to set the listener on the appropriate focusable child view(s).

cancelAnimationsRecursive

protected open static fun cancelAnimationsRecursive(view: View!): Unit

Utility method for removing all running animations on a view.