إعداد مسبق LocalLifecycleOwner
توضّح هذه الوصفة كيفية استخدام LifecycleResumeEffect في 3 إدخالات في Navigation لتوقيف العمل مؤقتًا واستئنافه استنادًا إلى حالة دورة حياة الإدخال.
آلية العمل
في Navigation 3، يتم تلقائيًا تزويد كل NavEntry بعنصر LifecycleOwner خاص به من خلال LocalLifecycleOwner.current. ويعني ذلك أنّه يتم تلقائيًا تحديد نطاق أي مكوّنات تراعي دورة الحياة داخل الإدخال على NavEntry.
LifecycleResumeEffect مع مشاهد مربّع الحوار
-
RouteA (شاشة):
- يستخدم
LifecycleResumeEffect(Unit)الذي تم تحديد نطاقه علىLocalLifecycleOwner.currentفيNavEntryلزيادةLinearProgressIndicatorأثناء الحالةRESUMED. - تتم إعادة ضبط
progressValueتلقائيًا إلى0fكلما وصلت إلى1f.
- يستخدم
-
RouteB (مربّع حوار):
- تمت تهيئته كمربّع حوار باستخدام
DialogSceneStrategy.dialog(). - عندما يفتح المستخدم مربّع حوار RouteB، يظل RouteA مرئيًا خلف مربّع الحوار في الحالة
STARTED(مغادرة الحالةRESUMED). - يستدعي
LifecycleResumeEffectالسمةonPauseOrDispose، ما يؤدي إلى إيقاف مؤشر التقدّم مؤقتًا. - عند إغلاق مربّع الحوار، يعود RouteA إلى الحالة
RESUMED، ويستأنفLifecycleResumeEffectمؤشر التقدّم تلقائيًا.
- تمت تهيئته كمربّع حوار باستخدام
/* * 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. }