litho-widget/com.facebook.litho.widget/ViewportManager

ViewportManager

@ThreadSafe

class ViewportManager(currentFirstVisiblePosition: Int, currentLastVisiblePosition: Int, layoutInfo: LayoutInfo)

This class will handle all viewport changes due to both scrolling and ViewHolder removal that is not related to scrolling.

Classes that are interested to have its viewport changes handled by ViewportManager should set the OnScrollListener returned from ViewportManager.getScrollListener in the RecyclerView

Constructors

ViewportManager

constructor(currentFirstVisiblePosition: Int, currentLastVisiblePosition: Int, layoutInfo: LayoutInfo)

Types

ViewportScrollListener

inner class ViewportScrollListener : RecyclerView.OnScrollListener

Properties

scrollListener

@get:UiThread

val scrollListener: ViewportManager.ViewportScrollListener

Functions

addViewportChangedListener

@AnyThread

fun addViewportChangedListener(viewportChangedListener: ViewportInfo.ViewportChanged?)

insertAffectsVisibleRange

@UiThread

fun insertAffectsVisibleRange(position: Int, size: Int, viewportCount: Int): Boolean

moveAffectsVisibleRange

@UiThread

fun moveAffectsVisibleRange(fromPosition: Int, toPosition: Int, viewportCount: Int): Boolean

onViewportChanged

@UiThread

fun onViewportChanged(state: Int)

Handles a change in viewport. This method should not be called outside of the method OnScrollListener.onScrolled

removeAffectsVisibleRange

@UiThread

fun removeAffectsVisibleRange(position: Int, size: Int): Boolean

removeViewportChangedListener

@AnyThread

fun removeViewportChangedListener(viewportChangedListener: ViewportInfo.ViewportChanged?)

resetShouldUpdate

@UiThread

fun resetShouldUpdate()

setShouldUpdate

@UiThread

fun setShouldUpdate(shouldUpdate: Boolean)

shouldUpdate

@UiThread

fun shouldUpdate(): Boolean

Whether first/last visible positions should be updated. If this returns true, we should not do any computations based on current first/last visible positions until they are updated.

updateAffectsVisibleRange

@UiThread

fun updateAffectsVisibleRange(position: Int, size: Int): Boolean