Summary: Methods

FacetProvider

Kotlin |Java

public interface FacetProvider

androidx.leanback.widget.FacetProvider

Known indirect subclasses AbstractDetailsDescriptionPresenter, AbstractDetailsDescriptionPresenter.ViewHolder, AbstractMediaItemPresenter, AbstractMediaItemPresenter.ViewHolder, AbstractMediaListHeaderPresenter, AbstractMediaListHeaderPresenter.ViewHolder, DetailsOverviewLogoPresenter, DetailsOverviewLogoPresenter.ViewHolder, DetailsOverviewRowPresenter, DetailsOverviewRowPresenter.ViewHolder, DividerPresenter, FullWidthDetailsOverviewRowPresenter, FullWidthDetailsOverviewRowPresenter.ViewHolder, GuidedActionsStylist.ViewHolder, and 16 others. AbstractDetailsDescriptionPresenter An abstract Presenter for rendering a detailed description of an item.  AbstractDetailsDescriptionPresenter.ViewHolder The ViewHolder for the AbstractDetailsDescriptionPresenter.  AbstractMediaItemPresenter Abstract Presenter class for rendering media items in a playlist format.  AbstractMediaItemPresenter.ViewHolder The ViewHolder for the AbstractMediaItemPresenter.  AbstractMediaListHeaderPresenter Abstract presenter class for rendering the header for a list of media items in a playlist.  AbstractMediaListHeaderPresenter.ViewHolder The ViewHolder for the AbstractMediaListHeaderPresenter.  DetailsOverviewLogoPresenter Presenter that responsible to create a ImageView and bind to DetailsOverviewRow.  DetailsOverviewLogoPresenter.ViewHolder ViewHolder for Logo view of DetailsOverviewRow.  DetailsOverviewRowPresenter This class is deprecated. Use FullWidthDetailsOverviewRowPresenter   DetailsOverviewRowPresenter.ViewHolder A ViewHolder for the DetailsOverviewRow.  DividerPresenter DividerPresenter provides a default presentation for DividerRow in HeadersFragment.  FullWidthDetailsOverviewRowPresenter Renders a DetailsOverviewRow to display an overview of an item.  FullWidthDetailsOverviewRowPresenter.ViewHolder A ViewHolder for the DetailsOverviewRow.  GuidedActionsStylist.ViewHolder ViewHolder caches information about the action item layouts' subviews.  ItemBridgeAdapter.ViewHolder ViewHolder for the ItemBridgeAdapter.  ListRowPresenter ListRowPresenter renders ListRow using a HorizontalGridView hosted in a ListRowView.  ListRowPresenter.ViewHolder ViewHolder for the ListRowPresenter.  PlaybackControlsRowPresenter A PlaybackControlsRowPresenter renders a PlaybackControlsRow to display a series of playback control buttons.  PlaybackControlsRowPresenter.ViewHolder A ViewHolder for the PlaybackControlsRow.  PlaybackRowPresenter Subclass of RowPresenter that can define the desired behavior when the view reappears.  PlaybackRowPresenter.ViewHolder This container is used for trapping click events and passing them to the playback controls.  PlaybackTransportRowPresenter A PlaybackTransportRowPresenter renders a PlaybackControlsRow to display a series of playback control buttons.  PlaybackTransportRowPresenter.ViewHolder A ViewHolder for the PlaybackControlsRow supporting seek UI.  Presenter A Presenter is used to generate Views and bind Objects to them on demand.  Presenter.ViewHolder ViewHolder can be subclassed and used to cache any view accessors needed to improve binding performance (for example, results of findViewById) without needing to subclass a View.  RowHeaderPresenter RowHeaderPresenter provides a default presentation for HeaderItem using a RowHeaderView and optionally a TextView for description.  RowHeaderPresenter.ViewHolder A ViewHolder for the RowHeaderPresenter.  RowPresenter An abstract Presenter that renders an Object in RowsFragment, the object can be subclass Row or a generic one.  RowPresenter.ViewHolder A ViewHolder for a Row.  VerticalGridPresenter A presenter that renders objects in a VerticalGridView.  VerticalGridPresenter.ViewHolder ViewHolder for the VerticalGridPresenter.

---

This is the query interface to supply optional features(aka facets) on an object without the need of letting the object to subclass or implement java interfaces. Facets allow leanback to re-compose optional features from leanback ViewHolder to RecyclerView ViewHolder. A typical "facet" class is ItemAlignmentFacet that defines how to align a ViewHolder inside VerticalGridView or HorizontalGridView. A FacetProvider could be retrieved from two sources by VerticalGridView/HorizontalGridView in the following order.

ViewHolder based facet:

RecyclerView.ViewHolder can implement FacetProvider. If app uses leanback Presenter.ViewHolder, the facet of Presenter.ViewHolder will be relayed by ItemBridgeAdapter.ViewHolder which is a wrapper of Presenter.ViewHolder. ViewHolder based facet is used less frequently than item view type based facet because in most cases ViewHolders of same type share the same alignment definition.

For example, app calls viewHolder.setFacet(ItemAlignmentFacet.class, itemAlignmentFacet) to set alignment of the ViewHolder instance.

RecyclerView item view type based facet:

RecyclerView.Adapter can implement FacetProviderAdapter which returns FacetProvider for each item view type. If app uses leanback ObjectAdapter and Presenter, app wraps the ObjectAdapter and Presenter using ItemBridgeAdapter. The implementation of ItemBridgeAdapter.getFacetProvider(int) will return the FacetProvider implemented by Presenter which is mapped to the item view type.

For example, app calls presenter.setFacet(ItemAlignmentFacet.class, itemAlignmentFacet) to set alignment of all ViewHolders created by this Presenter.

Summary

Public methods
abstract Object	getFacet(Class<?> facetClass) Queries optional implemented facet.

Public methods

getFacet

public abstract Object getFacet (Class<?> facetClass)

Queries optional implemented facet.

Parameters
facetClass	Class: Facet classes to query, examples are: class of ItemAlignmentFacet.

Returns
Object	Facet implementation for the facetClass or null if feature not implemented.