LazyLayoutMeasureScope

Artifact: androidx.compose.foundation:foundation

Added in 1.2.0

Cmn

@ExperimentalFoundationApi
sealed interface LazyLayoutMeasureScope : MeasureScope

The receiver scope of a LazyLayout's measure lambda. The return value of the measure lambda is MeasureResult, which should be returned by layout.

Main difference from the regular flow of writing any custom layout is that you have a new function measure which accepts item index and constraints, composes the item based and then measures all the layouts emitted in the item content block.

Note: this interface is a part of LazyLayout harness that allows for building custom lazy layouts. LazyLayout and all corresponding APIs are still under development and are subject to change.

Summary

Public functions
`List<Placeable>`	`measure(index: Int, constraints: Constraints)` Subcompose and measure the item of lazy layout.	Cmn
`open Dp`	`TextUnit.toDp()` Convert Sp to `Dp`.	Cmn
`open Dp`	`Int.toDp()` Convert an `Int` pixel value to `Dp`.	Cmn
`open Dp`	`Float.toDp()` Convert a `Float` pixel value to a Dp	Cmn
`open DpSize`	`Size.toDpSize()` Convert a `Size` to a `DpSize`.	Cmn
`open Size`	`DpSize.toSize()` Convert a `DpSize` to a `Size`.	Cmn
`open TextUnit`	`Float.toSp()` Convert a `Float` pixel value to a Sp	Cmn
`open TextUnit`	`Int.toSp()` Convert an `Int` pixel value to Sp.	Cmn
`open TextUnit`	`Dp.toSp()` Convert `Dp` to Sp.	Cmn

Inherited functions

From androidx.compose.ui.unit.Density

`open Int`	`Dp.roundToPx()` Convert `Dp` to `Int` by rounding	Cmn
`open Int`	`TextUnit.roundToPx()` Convert Sp to `Int` by rounding	Cmn
`open Float`	`Dp.toPx()` Convert `Dp` to pixels.	Cmn
`open Float`	`TextUnit.toPx()` Convert Sp to pixels.	Cmn
`open Rect`	`DpRect.toRect()` Convert a `DpRect` to a `Rect`.	Cmn

From androidx.compose.ui.layout.MeasureScope

`open MeasureResult`	`layout( width: Int, height: Int, alignmentLines: Map<AlignmentLine, Int>, placementBlock: Placeable.PlacementScope.() -> Unit )` Sets the size and alignment lines of the measured layout, as well as the positioning block that defines the children positioning logic.	Cmn
`open MeasureResult`	`layout( width: Int, height: Int, alignmentLines: Map<AlignmentLine, Int>, rulers: (RulerScope.() -> Unit)?, placementBlock: Placeable.PlacementScope.() -> Unit )` Sets the size and alignment lines of the measured layout, as well as the positioning block that defines the children positioning logic.	Cmn

Inherited properties

From androidx.compose.ui.unit.Density

Float

density

The logical density of the display.

Cmn

From androidx.compose.ui.unit.FontScaling

Float

fontScale

Current user preference for the scaling factor for fonts.

Cmn

From androidx.compose.ui.layout.IntrinsicMeasureScope

`open Boolean`	`isLookingAhead` This indicates whether the ongoing measurement is for lookahead pass.	Cmn
`LayoutDirection`	`layoutDirection` The `LayoutDirection` of the `Layout` or `LayoutModifier` using the measure scope to measure their children.	Cmn

Public functions

measure

Cmn

fun measure(index: Int, constraints: Constraints): List<Placeable>

Subcompose and measure the item of lazy layout.

Parameters
`index: Int`	the item index. Should be no larger that `LazyLayoutItemProvider.itemCount`.
`constraints: Constraints`	`Constraints` to measure the children emitted into an item content composable specified via `LazyLayoutItemProvider.Item`.

Returns
`List<Placeable>`	List of `Placeable`s. Note that if you emitted multiple children into the item composable you will receive multiple placeables, each of them will be measured with the passed `constraints`.