Recreate nested nav to work with AnimatedPane

app/dependencies/prodReleaseRuntimeClasspath.txt

@@ -17,10 +17,10 @@ androidx.compose.animation:animation-android:1.7.0-alpha06
 androidx.compose.animation:animation-core-android:1.7.0-alpha06
 androidx.compose.animation:animation-core:1.7.0-alpha06
 androidx.compose.animation:animation:1.7.0-alpha06
-androidx.compose.foundation:foundation-android:1.6.3
-androidx.compose.foundation:foundation-layout-android:1.6.3
-androidx.compose.foundation:foundation-layout:1.6.3
-androidx.compose.foundation:foundation:1.6.3
+androidx.compose.foundation:foundation-android:1.7.0-alpha06
+androidx.compose.foundation:foundation-layout-android:1.7.0-alpha06
+androidx.compose.foundation:foundation-layout:1.7.0-alpha06
+androidx.compose.foundation:foundation:1.7.0-alpha06
 androidx.compose.material3.adaptive:adaptive-android:1.0.0-alpha10
 androidx.compose.material3.adaptive:adaptive-layout-android:1.0.0-alpha10
 androidx.compose.material3.adaptive:adaptive-layout:1.0.0-alpha10
@@ -103,11 +103,11 @@ androidx.lifecycle:lifecycle-viewmodel:2.8.0-alpha04
 androidx.loader:loader:1.0.0
 androidx.localbroadcastmanager:localbroadcastmanager:1.0.0
 androidx.metrics:metrics-performance:1.0.0-alpha04
-androidx.navigation:navigation-common-ktx:2.7.7
-androidx.navigation:navigation-common:2.7.7
-androidx.navigation:navigation-compose:2.7.7
-androidx.navigation:navigation-runtime-ktx:2.7.7
-androidx.navigation:navigation-runtime:2.7.7
+androidx.navigation:navigation-common-ktx:2.8.0-alpha06
+androidx.navigation:navigation-common:2.8.0-alpha06
+androidx.navigation:navigation-compose:2.8.0-alpha06
+androidx.navigation:navigation-runtime-ktx:2.8.0-alpha06
+androidx.navigation:navigation-runtime:2.8.0-alpha06
 androidx.print:print:1.0.0
 androidx.privacysandbox.ads:ads-adservices-java:1.0.0-beta05
 androidx.privacysandbox.ads:ads-adservices:1.0.0-beta05

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/interests2pane/Interests2PaneViewModel.kt

@@ -27,7 +27,8 @@ import javax.inject.Inject
 class Interests2PaneViewModel @Inject constructor(
     private val savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
-    val selectedTopicId: StateFlow<String?> = savedStateHandle.getStateFlow(TOPIC_ID_ARG, null)
+    val selectedTopicId: StateFlow<String?> =
+        savedStateHandle.getStateFlow(TOPIC_ID_ARG, savedStateHandle[TOPIC_ID_ARG])
 
     fun onTopicClick(topicId: String?) {
         savedStateHandle[TOPIC_ID_ARG] = topicId

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/interests2pane/InterestsListDetailScreen.kt

@@ -18,14 +18,21 @@ package com.google.samples.apps.nowinandroid.ui.interests2pane
 
 import androidx.activity.compose.BackHandler
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
+import androidx.compose.material3.adaptive.layout.AnimatedPane
 import androidx.compose.material3.adaptive.layout.ListDetailPaneScaffold
 import androidx.compose.material3.adaptive.layout.ListDetailPaneScaffoldRole
 import androidx.compose.material3.adaptive.layout.PaneAdaptedValue
+import androidx.compose.material3.adaptive.layout.ThreePaneScaffoldDestinationItem
 import androidx.compose.material3.adaptive.navigation.ThreePaneScaffoldNavigator
 import androidx.compose.material3.adaptive.navigation.rememberListDetailPaneScaffoldNavigator
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.key
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.NavGraphBuilder
@@ -39,8 +46,10 @@ import com.google.samples.apps.nowinandroid.feature.interests.navigation.INTERES
 import com.google.samples.apps.nowinandroid.feature.interests.navigation.TOPIC_ID_ARG
 import com.google.samples.apps.nowinandroid.feature.topic.TopicDetailPlaceholder
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.TOPIC_ROUTE
+import com.google.samples.apps.nowinandroid.feature.topic.navigation.createTopicRoute
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.navigateToTopic
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicScreen
+import java.util.UUID
 
 private const val DETAIL_PANE_NAVHOST_ROUTE = "detail_pane_route"
 
@@ -76,17 +85,42 @@ internal fun InterestsListDetailScreen(
     selectedTopicId: String?,
     onTopicClick: (String) -> Unit,
 ) {
-    val listDetailNavigator = rememberListDetailPaneScaffoldNavigator()
+    val listDetailNavigator = rememberListDetailPaneScaffoldNavigator(
+        initialDestinationHistory = listOfNotNull(
+            ThreePaneScaffoldDestinationItem(ListDetailPaneScaffoldRole.List),
+            ThreePaneScaffoldDestinationItem<Nothing>(ListDetailPaneScaffoldRole.Detail).takeIf {
+                selectedTopicId != null
+            },
+        ),
+    )
     BackHandler(listDetailNavigator.canNavigateBack()) {
         listDetailNavigator.navigateBack()
     }
 
-    val nestedNavController = rememberNavController()
+    var nestedNavHostStartDestination by remember {
+        mutableStateOf(selectedTopicId?.let(::createTopicRoute) ?: TOPIC_ROUTE)
+    }
+    var nestedNavKey by rememberSaveable(
+        stateSaver = Saver({ it.toString() }, UUID::fromString),
+    ) {
+        mutableStateOf(UUID.randomUUID())
+    }
+    val nestedNavController = key(nestedNavKey) {
+        rememberNavController()
+    }
 
     fun onTopicClickShowDetailPane(topicId: String) {
         onTopicClick(topicId)
-        nestedNavController.navigateToTopic(topicId) {
-            popUpTo(DETAIL_PANE_NAVHOST_ROUTE)
+        if (listDetailNavigator.isDetailPaneVisible()) {
+            // If the detail pane was visible, then use the nestedNavController navigate call
+            // directly
+            nestedNavController.navigateToTopic(topicId) {
+                popUpTo(DETAIL_PANE_NAVHOST_ROUTE)
+            }
+        } else {
+            // Otherwise, recreate the NavHost entirely, and start at the new destination
+            nestedNavHostStartDestination = createTopicRoute(topicId)
+            nestedNavKey = UUID.randomUUID()
         }
         listDetailNavigator.navigateTo(ListDetailPaneScaffoldRole.Detail)
     }
@@ -95,34 +129,34 @@ internal fun InterestsListDetailScreen(
         value = listDetailNavigator.scaffoldValue,
         directive = listDetailNavigator.scaffoldDirective,
         listPane = {
-            InterestsRoute(
-                onTopicClick = ::onTopicClickShowDetailPane,
-                highlightSelectedTopic = listDetailNavigator.isDetailPaneVisible(),
-            )
-        },
-        detailPane = {
-            NavHost(
-                navController = nestedNavController,
-                startDestination = TOPIC_ROUTE,
-                route = DETAIL_PANE_NAVHOST_ROUTE,
-            ) {
-                topicScreen(
-                    showBackButton = !listDetailNavigator.isListPaneVisible(),
-                    onBackClick = listDetailNavigator::navigateBack,
+            AnimatedPane {
+                InterestsRoute(
                     onTopicClick = ::onTopicClickShowDetailPane,
+                    highlightSelectedTopic = listDetailNavigator.isDetailPaneVisible(),
                 )
-                composable(route = TOPIC_ROUTE) {
-                    TopicDetailPlaceholder()
+            }
+        },
+        detailPane = {
+            AnimatedPane {
+                key(nestedNavKey) {
+                    NavHost(
+                        navController = nestedNavController,
+                        startDestination = nestedNavHostStartDestination,
+                        route = DETAIL_PANE_NAVHOST_ROUTE,
+                    ) {
+                        topicScreen(
+                            showBackButton = !listDetailNavigator.isListPaneVisible(),
+                            onBackClick = listDetailNavigator::navigateBack,
+                            onTopicClick = ::onTopicClickShowDetailPane,
+                        )
+                        composable(route = TOPIC_ROUTE) {
+                            TopicDetailPlaceholder()
+                        }
+                    }
                 }
             }
         },
     )
-    LaunchedEffect(Unit) {
-        if (selectedTopicId != null) {
-            // Initial topic ID was provided when navigating to Interests, so show its details.
-            onTopicClickShowDetailPane(selectedTopicId)
-        }
-    }
 }
 
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)

feature/topic/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/topic/navigation/TopicNavigation.kt

@@ -41,13 +41,16 @@ internal class TopicArgs(val topicId: String) {
 }
 
 fun NavController.navigateToTopic(topicId: String, navOptions: NavOptionsBuilder.() -> Unit = {}) {
-    val encodedId = URLEncoder.encode(topicId, URL_CHARACTER_ENCODING)
-    val newRoute = "$TOPIC_ROUTE/$encodedId"
-    navigate(newRoute) {
+    navigate(createTopicRoute(topicId)) {
         navOptions()
     }
 }
 
+fun createTopicRoute(topicId: String): String {
+    val encodedId = URLEncoder.encode(topicId, URL_CHARACTER_ENCODING)
+    return "$TOPIC_ROUTE/$encodedId"
+}
+
 fun NavGraphBuilder.topicScreen(
     showBackButton: Boolean,
     onBackClick: () -> Unit,

gradle/libs.versions.toml

@@ -20,7 +20,7 @@ androidxHiltNavigationCompose = "1.2.0"
 androidxLifecycle = "2.7.0"
 androidxMacroBenchmark = "1.2.2"
 androidxMetrics = "1.0.0-alpha04"
-androidxNavigation = "2.7.7"
+androidxNavigation = "2.8.0-alpha06"
 androidxProfileinstaller = "1.3.1"
 androidxTestCore = "1.5.0"
 androidxTestExt = "1.1.5"