package com.example.compose.snippets.state

import android.os.Bundle

import androidx.activity.ComponentActivity

import androidx.activity.compose.setContent

import androidx.compose.foundation.isSystemInDarkTheme

import androidx.compose.foundation.layout.Column

import androidx.compose.material3.Button

import androidx.compose.material3.ColorScheme

import androidx.compose.material3.LocalContentColor

import androidx.compose.material3.MaterialTheme

import androidx.compose.material3.Surface

import androidx.compose.material3.Text

import androidx.compose.material3.lightColorScheme

import androidx.compose.runtime.Composable

import androidx.compose.runtime.CompositionLocalProvider

import androidx.compose.runtime.compositionLocalOf

import androidx.compose.runtime.remember

import androidx.compose.ui.platform.LocalContext

import androidx.compose.ui.unit.Dp

import androidx.compose.ui.unit.dp

import androidx.lifecycle.ViewModel

import androidx.lifecycle.viewmodel.compose.viewModel

import com.example.compose.snippets.R

object CompositionLocalSnippets1 {

private val colors = colors()

// [START android_compose_state_compositionlocal1]

@Composable

fun MyApp() {

// Theme information tends to be defined near the root of the application

val colors = colors()

}

// Some composable deep in the hierarchy

@Composable

fun SomeTextLabel(labelText: String) {

Text(

text = labelText,

color = colors.onPrimary // ← need to access colors here

)

}

// [END android_compose_state_compositionlocal1]

}

object CompositionLocalSnippets2 {

// [START android_compose_state_compositionlocal2]

@Composable

fun MyApp() {

// Provides a Theme whose values are propagated down its `content`

MaterialTheme {

// New values for colorScheme, typography, and shapes are available

// in MaterialTheme's content lambda.

// ... content here ...

}

}

// Some composable deep in the hierarchy of MaterialTheme

@Composable

fun SomeTextLabel(labelText: String) {

Text(

text = labelText,

// `primary` is obtained from MaterialTheme's

// LocalColors CompositionLocal

color = MaterialTheme.colorScheme.primary

)

}

// [END android_compose_state_compositionlocal2]

}

object CompositionLocalSnippets3 {

// [START android_compose_state_compositionlocal3]

@Composable

fun CompositionLocalExample() {

MaterialTheme {

// Surface provides contentColorFor(MaterialTheme.colorScheme.surface) by default

// This is to automatically make text and other content contrast to the background

// correctly.

Surface {

Column {

Text("Uses Surface's provided content color")

CompositionLocalProvider(LocalContentColor provides MaterialTheme.colorScheme.primary) {

Text("Primary color provided by LocalContentColor")

Text("This Text also uses primary as textColor")

CompositionLocalProvider(LocalContentColor provides MaterialTheme.colorScheme.error) {

DescendantExample()

}

}

}

}

}

}

@Composable

fun DescendantExample() {

// CompositionLocalProviders also work across composable functions

Text("This Text uses the error color now")

}

// [END android_compose_state_compositionlocal3]

}

object CompositionLocalSnippets4 {

// [START android_compose_state_compositionlocal4]

@Composable

fun FruitText(fruitSize: Int) {

// Get `resources` from the current value of LocalContext

val resources = LocalContext.current.resources

val fruitText = remember(resources, fruitSize) {

resources.getQuantityString(R.plurals.fruit_title, fruitSize)

}

Text(text = fruitText)

}

// [END android_compose_state_compositionlocal4]

}

object CompositionLocalSnippets5_6_7 {

// [START android_compose_state_compositionlocal5]

// LocalElevations.kt file

data class Elevations(val card: Dp = 0.dp, val default: Dp = 0.dp)

// Define a CompositionLocal global object with a default

// This instance can be accessed by all composables in the app

val LocalElevations = compositionLocalOf { Elevations() }

// [END android_compose_state_compositionlocal5]

// [START android_compose_state_compositionlocal6]

// MyActivity.kt file

class MyActivity : ComponentActivity() {

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

setContent {

// Calculate elevations based on the system theme

val elevations = if (isSystemInDarkTheme()) {

Elevations(card = 1.dp, default = 1.dp)

} else {

Elevations(card = 0.dp, default = 0.dp)

}

// Bind elevation as the value for LocalElevations

CompositionLocalProvider(LocalElevations provides elevations) {

// ... Content goes here ...

// This part of Composition will see the `elevations` instance

// when accessing LocalElevations.current

}

}

}

}

// [END android_compose_state_compositionlocal6]

// [START android_compose_state_compositionlocal7]

@Composable

fun SomeComposable() {

// Access the globally defined LocalElevations variable to get the

// current Elevations in this part of the Composition

MyCard(elevation = LocalElevations.current.card) {

// Content

}

}

// [END android_compose_state_compositionlocal7]

@Composable

fun MyCard(elevation: Dp, content: @Composable () -> Unit) {

}

}

object CompositionLocalSnippets8 {

// [START android_compose_state_compositionlocal8]

@Composable

fun MyComposable(myViewModel: MyViewModel = viewModel()) {

// ...

MyDescendant(myViewModel.data)

}

// Don't pass the whole object! Just what the descendant needs.

// Also, don't pass the ViewModel as an implicit dependency using

// a CompositionLocal.

@Composable

fun MyDescendant(myViewModel: MyViewModel) { /* ... */ }

// Pass only what the descendant needs

@Composable

fun MyDescendant(data: DataToDisplay) {

// Display data

}

// [END android_compose_state_compositionlocal8]

}

object CompositionLocalSnippets9 {

// [START android_compose_state_compositionlocal9]

@Composable

fun MyComposable(myViewModel: MyViewModel = viewModel()) {

// ...

MyDescendant(myViewModel)

}

@Composable

fun MyDescendant(myViewModel: MyViewModel) {

Button(onClick = { myViewModel.loadData() }) {

Text("Load data")

}

}

// [END android_compose_state_compositionlocal9]

}

object CompositionLocalSnippets10 {

// [START android_compose_state_compositionlocal10]

@Composable

fun MyComposable(myViewModel: MyViewModel = viewModel()) {

// ...

ReusableLoadDataButton(

onLoadClick = {

myViewModel.loadData()

}

)

}

@Composable

fun ReusableLoadDataButton(onLoadClick: () -> Unit) {

Button(onClick = onLoadClick) {

Text("Load data")

}

}

// [END android_compose_state_compositionlocal10]

}

object CompositionLocalSnippets11 {

// [START android_compose_state_compositionlocal11]

@Composable

fun MyComposable(myViewModel: MyViewModel = viewModel()) {

// ...

ReusablePartOfTheScreen(

content = {

Button(

onClick = {

myViewModel.loadData()

}

) {

Text("Confirm")

}

}

)

}

@Composable

fun ReusablePartOfTheScreen(content: @Composable () -> Unit) {

Column {

// ...

content()

}

}

// [END android_compose_state_compositionlocal11]

}

fun colors(): ColorScheme = lightColorScheme()

data class DataToDisplay(val title: String)

class MyViewModel : ViewModel() {

val data = DataToDisplay("")

fun loadData() {}

}