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RowPresenter

abstract class RowPresenter : Presenter
kotlin.Any
   ↳ androidx.leanback.widget.Presenter
   ↳ androidx.leanback.widget.RowPresenter

An abstract Presenter that renders an Object in RowsFragment, the object can be subclass Row or a generic one. When the object is not Row class, ViewHolder#getRow() returns null.

Customize UI widgets

When a subclass of RowPresenter adds UI widgets, it should subclass RowPresenter.ViewHolder and override createRowViewHolder(ViewGroup) and initializeRowViewHolder(ViewHolder). The subclass must use layout id "row_content" for the widget that will be aligned to the title of any HeadersFragment that may exist in the parent fragment. RowPresenter contains an optional and replaceable RowHeaderPresenter that renders the header. You can disable the default rendering or replace the Presenter with a new header presenter by calling setHeaderPresenter(RowHeaderPresenter).

UI events from fragments

RowPresenter receives calls from its parent (typically a Fragment) when:

Activated status

The activated status of a row is applied to the row view and its children via View#setActivated(boolean). The activated status is typically used to control BaseCardView info region visibility. The row's activated status can be controlled by selected status and/or expanded status. Call setSyncActivatePolicy(int) and choose one of the four policies:

User events

RowPresenter provides OnItemViewSelectedListener and OnItemViewClickedListener. If a subclass wants to add its own View.OnFocusChangeListener or View.OnClickListener, it must do that in createRowViewHolder(ViewGroup) to be properly chained by the library. Adding View listeners after createRowViewHolder(ViewGroup) is undefined and may result in incorrect behavior by the library's listeners.

Selection animation

When a user scrolls through rows, a fragment will initiate animation and call setSelectLevel(Presenter.ViewHolder, float) with float value between 0 and 1. By default, the RowPresenter draws a dim overlay on top of the row view for views that are not selected. Subclasses may override this default effect by having isUsingDefaultSelectEffect() return false and overriding onSelectLevelChanged(ViewHolder) to apply a different selection effect.

Call setSelectEffectEnabled(boolean) to enable/disable the select effect, This will not only enable/disable the default dim effect but also subclasses must respect this flag as well.

Summary

Nested classes
open

A ViewHolder for a Row.

Constants
static Int

Don't synchronize row view activated status with selected status or expanded status, application will do its own through RowPresenter.ViewHolder#setActivated(boolean).

static Int

Synchronizes row view's activated status to expand status of the row view holder.

static Int

Sets the row view's activated status to true when both expand and selected are true.

static Int

Synchronizes row view's activated status to selected status of the row view holder.

Public constructors

Constructs a RowPresenter.

Public methods
open Unit

Freezes/unfreezes the row, typically used when a transition starts/ends.

RowHeaderPresenter!

Returns the Presenter used for rendering the header, or null if none has been set.

RowPresenter.ViewHolder!