RowPresenter

abstract class RowPresenter : Presenter

kotlin.Any
↳	androidx.leanback.widget.Presenter
	↳	androidx.leanback.widget.RowPresenter

Known Direct Subclasses AbstractMediaItemPresenter, AbstractMediaListHeaderPresenter, DetailsOverviewRowPresenter, FullWidthDetailsOverviewRowPresenter, ListRowPresenter, PlaybackRowPresenter 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 Renders a DetailsOverviewRow to display an overview of an item. FullWidthDetailsOverviewRowPresenter Renders a DetailsOverviewRow to display an overview of an item. ListRowPresenter ListRowPresenter renders ListRow using a HorizontalGridView hosted in a ListRowView. PlaybackRowPresenter Subclass of RowPresenter that can define the desired behavior when the view reappears.

Known Indirect Subclasses PlaybackControlsRowPresenter, PlaybackTransportRowPresenter PlaybackControlsRowPresenter A PlaybackControlsRowPresenter renders a PlaybackControlsRow to display a series of playback control buttons. PlaybackTransportRowPresenter A PlaybackTransportRowPresenter renders a PlaybackControlsRow to display a series of playback control buttons.

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:

• A row is selected via setRowViewSelected(Presenter.ViewHolder, boolean). The event is triggered immediately when there is a row selection change before the selection animation is started. Selected status may control activated status of the row (see "Activated status" below). Subclasses of RowPresenter may override onRowViewSelected(ViewHolder, boolean).
• A row is expanded to full height via setRowViewExpanded(Presenter.ViewHolder, boolean) when BrowseFragment hides fast lane on the left. The event is triggered immediately before the expand animation is started. Row title is shown when row is expanded. Expanded status may control activated status of the row (see "Activated status" below). Subclasses of RowPresenter may override onRowViewExpanded(ViewHolder, boolean).

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:

• SYNC_ACTIVATED_TO_EXPANDED Activated status is synced with row expanded status
• SYNC_ACTIVATED_TO_SELECTED Activated status is synced with row selected status
• SYNC_ACTIVATED_TO_EXPANDED_AND_SELECTED Activated status is set to true when both expanded and selected status are true
• SYNC_ACTIVATED_CUSTOM Activated status is not controlled by selected status or expanded status, application can control activated status by its own. Application should call RowPresenter.ViewHolder#setActivated(boolean) to change activated status of row view.

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	ViewHolder A ViewHolder for a Row.

Constants
static Int	SYNC_ACTIVATED_CUSTOM 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	SYNC_ACTIVATED_TO_EXPANDED Synchronizes row view's activated status to expand status of the row view holder.
static Int	SYNC_ACTIVATED_TO_EXPANDED_AND_SELECTED Sets the row view's activated status to true when both expand and selected are true.
static Int	SYNC_ACTIVATED_TO_SELECTED Synchronizes row view's activated status to selected status of the row view holder.

Public constructors
<init>() Constructs a RowPresenter.

Public methods
open Unit	freeze(holder: RowPresenter.ViewHolder!, freeze: Boolean) Freezes/unfreezes the row, typically used when a transition starts/ends.
RowHeaderPresenter!	getHeaderPresenter() Returns the Presenter used for rendering the header, or null if none has been set.
RowPresenter.ViewHolder!	getRowViewHolder(holder: Presenter.ViewHolder!) Returns the RowPresenter.ViewHolder from the given RowPresenter ViewHolder.
Boolean	getSelectEffectEnabled() Returns true if the row selection effect is enabled.
Float	getSelectLevel(vh: Presenter.ViewHolder!) Returns the current select level.
Int	getSyncActivatePolicy() Returns the policy of updating row view activated status.
open Boolean	isUsingDefaultSelectEffect() Returns true if this RowPresenter is using the default dimming effect.
Unit	onBindViewHolder(