Presenter

Added in 1.1.0

Kotlin |Java

abstract class Presenter : FacetProvider

Known direct subclasses

AbstractDetailsDescriptionPresenter, DetailsOverviewLogoPresenter, DividerPresenter, RowHeaderPresenter, RowPresenter, VerticalGridPresenter

`AbstractDetailsDescriptionPresenter`	An abstract `Presenter` for rendering a detailed description of an item.
`DetailsOverviewLogoPresenter`	Presenter that responsible to create a ImageView and bind to DetailsOverviewRow.
`DividerPresenter`	DividerPresenter provides a default presentation for `DividerRow` in HeadersFragment.
`RowHeaderPresenter`	RowHeaderPresenter provides a default presentation for `HeaderItem` using a `RowHeaderView` and optionally a TextView for description.
`RowPresenter`	An abstract `Presenter` that renders an Object in RowsFragment, the object can be subclass `Row` or a generic one.
`VerticalGridPresenter`	A presenter that renders objects in a `VerticalGridView`.

Known indirect subclasses

AbstractMediaItemPresenter, AbstractMediaListHeaderPresenter, DetailsOverviewRowPresenter, FullWidthDetailsOverviewRowPresenter, ListRowPresenter, PlaybackControlsRowPresenter, PlaybackRowPresenter, PlaybackTransportRowPresenter

`AbstractMediaItemPresenter`	Abstract `Presenter` class for rendering media items in a playlist format.
`AbstractMediaListHeaderPresenter`	Abstract presenter class for rendering the header for a list of media items in a playlist.
`DetailsOverviewRowPresenter`	This class is deprecated. Use `FullWidthDetailsOverviewRowPresenter`
`FullWidthDetailsOverviewRowPresenter`	Renders a `DetailsOverviewRow` to display an overview of an item.
`ListRowPresenter`	ListRowPresenter renders `ListRow` using a `HorizontalGridView` hosted in a `ListRowView`.
`PlaybackControlsRowPresenter`	A PlaybackControlsRowPresenter renders a `PlaybackControlsRow` to display a series of playback control buttons.
`PlaybackRowPresenter`	Subclass of `RowPresenter` that can define the desired behavior when the view reappears.
`PlaybackTransportRowPresenter`	A PlaybackTransportRowPresenter renders a `PlaybackControlsRow` to display a series of playback control buttons.

A Presenter is used to generate Views and bind Objects to them on demand. It is closely related to the concept of an RecyclerView.Adapter, 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 findViewById.

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

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.
    }
}

In addition to view creation and binding, Presenter allows dynamic interface (facet) to be added: setFacet. Supported facets: ItemAlignmentFacet is used by HorizontalGridView and VerticalGridView to customize child alignment.

Summary

Nested types
`class Presenter.ViewHolder : FacetProvider` 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.
`abstract class Presenter.ViewHolderTask` Base class to perform a task on Presenter.ViewHolder.

Public constructors
`Presenter()`

Public functions
`Any!`	`getFacet(facetClass: Class<Any!>!)` Queries optional implemented facet.
`abstract Unit`	`onBindViewHolder(viewHolder: Presenter.ViewHolder, item: Any?)` Binds a `View` to an item.
`Unit`	`onBindViewHolder( viewHolder: Presenter.ViewHolder, item: Any, payloads: (Mutable)List<Any!> )` Binds a `View` to an item with a list of payloads.
`abstract Presenter.ViewHolder`	`onCreateViewHolder(parent: ViewGroup)` Creates a new `View`.
`abstract Unit`	`onUnbindViewHolder(viewHolder: Presenter.ViewHolder)` Unbinds a `View` from an item.
`Unit`	`onViewAttachedToWindow(holder: Presenter.ViewHolder)` Called when a view created by this presenter has been attached to a window.
`Unit`	`onViewDetachedFromWindow(holder: Presenter.ViewHolder)` Called when a view created by this presenter has been detached from its window.
`Unit`	`setFacet(facetClass: Class<Any!>!, facetImpl: Any!)` Sets dynamic implemented facet in addition to basic Presenter functions.
`Unit`	`setOnClickListener( holder: Presenter.ViewHolder!, listener: View.OnClickListener! )` Called to set a click listener for the given view holder.

Protected functions
`java-static Unit`	`cancelAnimationsRecursive(view: View!)` Utility method for removing all running animations on a view.

Public constructors

Presenter

Added in 1.1.0

Presenter()

Public functions

getFacet

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

Queries optional implemented facet.

Parameters
`facetClass: Class<Any!>!`	Facet classes to query, examples are: class of `ItemAlignmentFacet`.

Returns
`Any!`	Facet implementation for the facetClass or null if feature not implemented.

Added in 1.1.0

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

Binds a View to an item.

Added in 1.1.0

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

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

Parameters
`viewHolder: Presenter.ViewHolder`	The ViewHolder which should be updated to represent the contents of the item at the given position in the data set.
`item: Any`	The item which should be bound to view holder.
`payloads: (Mutable)List<Any!>`	A non-null list of merged payloads. Can be empty list if requires full update.

onCreateViewHolder

Added in 1.1.0

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

Creates a new View.

Added in 1.1.0

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.

Added in 1.1.0

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 those resources should be restored here.

Parameters
`holder: Presenter.ViewHolder`	Holder of the view being attached

Added in 1.1.0

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.

Any view property animations should be cancelled here or the view may fail to be recycled.

Parameters
`holder: Presenter.ViewHolder`	Holder of the view being detached

setFacet

Added in 1.1.0

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

Sets dynamic implemented facet in addition to basic Presenter functions.

Parameters
`facetClass: Class<Any!>!`	Facet classes to query, can be class of `ItemAlignmentFacet`.
`facetImpl: Any!`	Facet implementation.

Added in 1.1.0

fun setOnClickListener(
    holder: Presenter.ViewHolder!,
    listener: View.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).

Parameters
`holder: Presenter.ViewHolder!`	The view holder containing the view(s) on which the listener should be set.
`listener: View.OnClickListener!`	The click listener to be set.

Protected functions

cancelAnimationsRecursive

Added in 1.1.0

protected java-static fun cancelAnimationsRecursive(view: View!): Unit

Utility method for removing all running animations on a view.

Presenter

Summary

Nested types

Public constructors

Public functions

Protected functions

Public constructors

Presenter

Public functions

getFacet

onBindViewHolder

onBindViewHolder

onCreateViewHolder

onUnbindViewHolder

onViewAttachedToWindow

onViewDetachedFromWindow

setFacet

setOnClickListener

Protected functions

cancelAnimationsRecursive