ModifierLocalModifierNode

A androidx.compose.ui.Modifier.Node that is capable of consuming and providing ModifierLocal values.

This is the androidx.compose.ui.Modifier.Node equivalent of the ModifierLocalConsumer and ModifierLocalProvider interfaces.

import androidx.compose.ui.Modifier
import androidx.compose.ui.modifier.ModifierLocalModifierNode
import androidx.compose.ui.modifier.modifierLocalMapOf
import androidx.compose.ui.modifier.modifierLocalOf
import androidx.compose.ui.node.LayoutAwareModifierNode
import androidx.compose.ui.node.ModifierNodeElement
import androidx.compose.ui.platform.InspectorInfo
import androidx.compose.ui.unit.IntSize

class Logger { fun log(string: String) { println(string) } }

val loggerLocal = modifierLocalOf { Logger() }

class ProvideLoggerNode(logger: Logger) : ModifierLocalModifierNode, Modifier.Node() {
    override val providedValues = modifierLocalMapOf(loggerLocal to logger)
}

data class ProvideLoggerElement(
    val logger: Logger
) : ModifierNodeElement<ProvideLoggerNode>() {
    override fun create() = ProvideLoggerNode(logger)
    override fun update(node: ProvideLoggerNode) {
        node.provide(loggerLocal, logger)
    }
    override fun InspectorInfo.inspectableProperties() {
        name = "provideLogger"
        properties["logger"] = logger
    }
}

class SizeLoggerNode(
    var id: String
) : ModifierLocalModifierNode, LayoutAwareModifierNode, Modifier.Node() {
    override fun onRemeasured(size: IntSize) {
        loggerLocal.current.log("The size of $id was $size")
    }
}

data class SizeLoggerElement(
    val id: String
) : ModifierNodeElement<SizeLoggerNode>() {
    override fun create() = SizeLoggerNode(id)
    override fun update(node: SizeLoggerNode) {
        node.id = id
    }
    override fun InspectorInfo.inspectableProperties() {
        name = "logSize"
        properties["id"] = id
    }
}

fun Modifier.logSize(id: String) = this then SizeLoggerElement(id)
fun Modifier.provideLogger(logger: Logger) = this then ProvideLoggerElement(logger)

Summary

open fun <T : Any?> provide(key: ModifierLocal<T>, value: T): Unit

open val ModifierLocal<T>.current: T

open val providedValues: ModifierLocalMap