Measurable

A part of the composition that can be measured. This represents a layout. The instance should never be stored.

Summary

Public functions
Placeable
measure(constraints: Constraints)

Measures the layout with constraints, returning a Placeable layout that has its new size.
Cmn

Extension properties
Any?
android
Any?
android
Any?

Retrieves the tag associated to a composable with the Modifier.layoutId modifier.
Cmn

Inherited functions
From androidx.compose.ui.layout.IntrinsicMeasurable
Int

Calculates the smallest height beyond which increasing the height never decreases the width.
Cmn
Int

Calculates the smallest width beyond which increasing the width never decreases the height.
Cmn
Int

Calculates the minimum height that the layout can be such that the content of the layout will be painted correctly.
Cmn
Int

Calculates the minimum width that the layout can be such that the content of the layout will be painted correctly.
Cmn

Inherited properties
From androidx.compose.ui.layout.IntrinsicMeasurable
Any?

Data provided by the ParentDataModifier.
Cmn

Public functions

measure

Cmn 
fun measure(constraints: Constraints): Placeable

Measures the layout with constraints, returning a Placeable layout that has its new size. A Measurable can only be measured once inside a layout pass.

Extension properties

constraintLayoutId

android 
val Measurable.constraintLayoutId: Any?

constraintLayoutTag

android 
val Measurable.constraintLayoutTag: Any?

layoutId

Cmn 
val Measurable.layoutId: Any?

Retrieves the tag associated to a composable with the Modifier.layoutId modifier. For a parent data value to be returned by this property when not using the Modifier.layoutId modifier, the parent data value should implement the LayoutIdParentData interface.

Example usage:

import androidx.compose.foundation.layout.Box
import androidx.compose.ui.Modifier
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.layout.layout
import androidx.compose.ui.layout.layoutId
import androidx.compose.ui.unit.Constraints

Layout({
    // Here the Containers are only needed to apply the modifiers. You could use the
    // modifier on header and footer directly if they are composables accepting modifiers.
    Box(Modifier.layoutId("header")) { header() }
    Box(Modifier.layoutId("footer")) { footer() }
}) { measurables, constraints ->
    val placeables =
        measurables.map { measurable ->
            when (measurable.layoutId) {
                // You should use appropriate constraints. Here we measure fake constraints.
                "header" -> measurable.measure(Constraints.fixed(100, 100))
                "footer" -> measurable.measure(constraints)
                else -> error("Unexpected tag")
            }
        }
    // Size should be derived from children measured sizes on placeables,
    // but this is simplified for the purposes of the example.
    layout(100, 100) { placeables.forEach { it.placeRelative(0, 0) } }
}