Receita do LocalLifecycleOwner

Esta receita demonstra como usar LifecycleResumeEffect nas entradas de navegação 3 para pausar e retomar o trabalho com base no estado do ciclo de vida da entrada.

Como funciona

Na navegação 3, por padrão, cada NavEntry recebe o próprio LifecycleOwner via LocalLifecycleOwner.current. Isso significa que todos os componentes com reconhecimento do ciclo de vida dentro da entrada são automaticamente definidos como NavEntry.

LifecycleResumeEffect com cenas de caixa de diálogo

  1. RouteA (tela):

    • Usa LifecycleResumeEffect(Unit) definido como LocalLifecycleOwner.current da NavEntry para avançar o LinearProgressIndicator enquanto estiver no estado RESUMED.
    • Redefine automaticamente progressValue para 0f sempre que atingir 1f.
  2. RouteB (caixa de diálogo):

    • Configurado como uma caixa de diálogo usando DialogSceneStrategy.dialog().
    • Quando o usuário abre a caixa de diálogo RouteB, a RouteA permanece visível atrás da caixa de diálogo no estado STARTED (deixando RESUMED).
    • LifecycleResumeEffect chama onPauseOrDispose, pausando o indicador de progresso.
    • Quando a caixa de diálogo é dispensada, a RouteA retorna para RESUMED, e LifecycleResumeEffect retoma o indicador de progresso automaticamente.
/*
 * Copyright 2026 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.nav3recipes.lifecycleowner

import android.os.Bundle
import android.util.Log
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.animation.core.LinearEasing
import androidx.compose.animation.core.animateFloatAsState
import androidx.compose.animation.core.snap
import androidx.compose.animation.core.tween
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.Button
import androidx.compose.material3.LinearProgressIndicator
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableFloatStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.compose.LifecycleEventEffect
import androidx.lifecycle.compose.LifecycleResumeEffect
import androidx.lifecycle.compose.dropUnlessResumed
import androidx.navigation3.runtime.NavKey
import androidx.navigation3.runtime.entryProvider
import androidx.navigation3.runtime.rememberNavBackStack
import androidx.navigation3.scene.DialogSceneStrategy
import androidx.navigation3.ui.NavDisplay
import com.example.nav3recipes.content.ContentGreen
import com.example.nav3recipes.ui.setEdgeToEdgeConfig
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.serialization.Serializable
import kotlin.time.Duration.Companion.milliseconds

@Serializable
private data object RouteA : NavKey

@Serializable
private data object RouteB : NavKey

class LifecycleOwnerActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        setEdgeToEdgeConfig()
        super.onCreate(savedInstanceState)
        setContent {
            val backStack = rememberNavBackStack(RouteA)
            val dialogStrategy = remember { DialogSceneStrategy<NavKey>() }

            NavDisplay(
                backStack = backStack,
                onBack = backStack::removeLastOrNull,
                sceneStrategies = listOf(dialogStrategy),
                entryProvider = entryProvider {
                    entry<RouteA> {
                        LogLifecycleEffect("ScreenA")
                        ContentGreen("Screen A") {
                            var progressValue by remember { mutableFloatStateOf(0f) }
                            val coroutineScope = rememberCoroutineScope()

                            val animatedProgress by animateFloatAsState(
                                targetValue = progressValue,
                                animationSpec = if (progressValue == 0f) snap() else tween(durationMillis = 100, easing = LinearEasing),
                                label = "ProgressAnimation"
                            )

                            // LifecycleResumeEffect runs only while ScreenA is in the RESUMED state.
                            // When the dialog opens, ScreenA transitions to PAUSED, which calls onPauseOrDispose.
                            LifecycleResumeEffect(Unit) {
                                val job = coroutineScope.launch {
                                    while (true) {
                                        delay(100.milliseconds)
                                        progressValue += 0.01f
                                        if (progressValue >= 1f) {
                                            progressValue = 0f
                                        }
                                    }
                                }
                                onPauseOrDispose {
                                    job.cancel()
                                }
                            }

                            Column(
                                horizontalAlignment = Alignment.CenterHorizontally,
                                modifier = Modifier.padding(16.dp)
                            ) {
                                LinearProgressIndicator(progress = { animatedProgress })
                                Spacer(modifier = Modifier.height(16.dp))
                                Button(onClick = dropUnlessResumed { backStack.add(RouteB) }) {
                                    Text("Open Dialog")
                                }
                            }
                        }
                    }
                    entry<RouteB>(metadata = DialogSceneStrategy.dialog()) {
                        LogLifecycleEffect("Dialog")
                        AlertDialog(
                            onDismissRequest = backStack::removeLastOrNull,
                            title = { Text("Dialog") },
                            text = {
                                Text("Screen A is no longer in resumed state, pausing the progress indicator.")
                            },
                            confirmButton = {
                                Button(onClick = dropUnlessResumed { backStack.removeLastOrNull() }) {
                                    Text("Dismiss Dialog")
                                }
                            }
                        )
                    }
                }
            )
        }
    }
}

@Composable
private fun LogLifecycleEffect(screenName: String) {
    LifecycleEventEffect(Lifecycle.Event.ON_CREATE) {
        Log.d("LifecycleOwner", "$screenName: ON_CREATE")
    }
    LifecycleEventEffect(Lifecycle.Event.ON_START) {
        Log.d("LifecycleOwner", "$screenName: ON_START")
    }
    LifecycleEventEffect(Lifecycle.Event.ON_RESUME) {
        Log.d("LifecycleOwner", "$screenName: ON_RESUME")
    }
    LifecycleEventEffect(Lifecycle.Event.ON_PAUSE) {
        Log.d("LifecycleOwner", "$screenName: ON_PAUSE")
    }
    LifecycleEventEffect(Lifecycle.Event.ON_STOP) {
        Log.d("LifecycleOwner", "$screenName: ON_STOP")
    }
    // Note that ON_DESTROY event is not observable from composables.
}