Class

ScalingLazyListState

A state object that can be hoisted to control and observe scrolling.

Source set: Android

Deprecated

Was moved to androidx.wear.compose.foundation.lazy package. Please use it instead

public class ScalingLazyListState
constructor(
    private var initialCenterItemIndex: Int = 1,
    private var initialCenterItemScrollOffset: Int = 0,
) : ScrollableState

A state object that can be hoisted to control and observe scrolling.

In most cases, this will be created via rememberScalingLazyListState.

If the developer wants custom control over position and spacing they can switch off autoCentering and provide contentPadding.

Note that it is not always possible for the values provided by initialCenterItemIndex and initialCenterItemScrollOffset to be honored, e.g. If initialCenterItemIndex is set to a value larger than the number of items initially in the list, or to an index that can not be placed in the middle of the screen due to the contentPadding or autoCentering properties provided to the ScalingLazyColumn. After the ScalingLazyColumn is initially drawn the actual values for the centerItemIndex and centerItemScrollOffset can be read from the state.

Parameters
initialCenterItemIndex the initial value for ScalingLazyListState.centerItemIndex, defaults to 1. This will place the 2nd list item (index == 1) in the center of the viewport and the first item (index == 0) before it.
initialCenterItemScrollOffset the initial value for ScalingLazyListState.centerItemScrollOffset

Properties

centerItemIndex

Source set: Android
public val centerItemIndex: Int

The index of the item positioned closest to the viewport center

centerItemScrollOffset

Source set: Android
public val centerItemScrollOffset: Int

The offset of the item closest to the viewport center. Depending on the ScalingLazyListAnchorType of the ScalingLazyColumn the offset will be relative to either the items Edge or Center.

A positive value indicates that the center item's anchor point is above the viewport center-line, a negative value indicates that the center item anchor point is below the viewport center-line.

layoutInfo

Source set: Android
public val layoutInfo: ScalingLazyListLayoutInfo

The object of ScalingLazyListLayoutInfo calculated during the last layout pass. For example, you can use it to calculate what items are currently visible.

Functions

scrollToItem

public suspend fun scrollToItem(
        /*@IntRange(from = 0)*/
        index: Int,
        /*@IntRange(from = 0)*/
        scrollOffset: Int = 0,
    )

Instantly brings the item at index to the center of the viewport and positions it based on the anchorType and applies the scrollOffset pixels.

Parameters
index the index to which to scroll. Must be non-negative.
scrollOffset the offset that the item should end up after the scroll. Note that positive offset refers to forward scroll, so in a top-to-bottom list, positive offset will scroll the item further upward (taking it partly offscreen).

animateScrollToItem

public suspend fun animateScrollToItem(
        /*@IntRange(from = 0)*/
        index: Int,
        /*@IntRange(from = 0)*/
        scrollOffset: Int = 0,
    )

Animate (smooth scroll) the given item at index to the center of the viewport and position it based on the anchorType and applies the scrollOffset pixels.

Parameters
index the index to which to scroll. Must be non-negative.
scrollOffset the offset that the item should end up after the scroll (same as scrollToItem) - note that positive offset refers to forward scroll, so in a top-to-bottom list, positive offset will scroll the item further upward (taking it partly offscreen)

Companion Object

Properties

Source set: Android
public val Saver: Saver<ScalingLazyListState, Any>

The default Saver implementation for ScalingLazyListState.

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