ui: use navigation3

So much simpler :-)
Fixes #12

Author: mrlem

app/build.gradle.kts

@@ -41,6 +41,9 @@ dependencies {
     implementation(project(":features:library:ui"))
     implementation(project(":features:overview:ui"))
     implementation(project(":theme"))
+    implementation(libs.androidx.lifecycle.viewmodel.navigation3)
+    implementation(libs.androidx.navigation3.ui)
+    implementation(libs.androidx.navigation3.runtime)
     implementation(libs.coil.compose)
     implementation(libs.coil.network)
     implementation(libs.okhttp)

app/src/main/java/org/mrlem/composesample/MainNavBar.kt

@@ -5,37 +5,30 @@ import androidx.compose.material3.NavigationBar
 import androidx.compose.material3.NavigationBarItem
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
-import androidx.navigation.NavController
-import androidx.navigation.compose.currentBackStackEntryAsState
-import org.mrlem.android.core.feature.nav.belongsTo
+import androidx.navigation3.runtime.NavBackStack
+import androidx.navigation3.runtime.NavKey
+import org.mrlem.android.core.feature.nav.Navigator
+import org.mrlem.android.core.feature.nav.Navigator.Operation
 import org.mrlem.android.core.feature.ui.NavProvider
 
 @Composable
 fun MainNavBar(
     items: List<NavProvider.BottomBarItem>,
-    navController: NavController,
+    backStack: NavBackStack<NavKey>,
+    navigator: Navigator,
     modifier: Modifier = Modifier,
 ) {
     NavigationBar(
         modifier = modifier,
     ) {
-        val navBackStackEntry by navController.currentBackStackEntryAsState()
-        val currentDestination = navBackStackEntry?.destination
-
         items.forEach { item ->
             NavigationBarItem(
                 icon = { Icon(item.icon, contentDescription = null) },
                 label = { Text(stringResource(item.labelResId)) },
-                selected = currentDestination?.belongsTo(item.route) ?: false,
-                onClick = {
-                    navController.navigate(item.route) {
-                        popUpTo(0)
-                        launchSingleTop = true
-                    }
-                },
+                selected = backStack.firstOrNull() == item.key,
+                onClick = { navigator.navigate(Operation.ReplaceAll(item.key)) },
             )
         }
     }

app/src/main/java/org/mrlem/composesample/MainWindow.kt

@@ -1,15 +1,18 @@
 package org.mrlem.composesample
 
 import androidx.compose.foundation.layout.imePadding
-import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.systemBarsPadding
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
-import androidx.navigation.compose.NavHost
-import androidx.navigation.compose.rememberNavController
+import androidx.lifecycle.viewmodel.navigation3.rememberViewModelStoreNavEntryDecorator
+import androidx.navigation3.runtime.entryProvider
+import androidx.navigation3.runtime.rememberNavBackStack
+import androidx.navigation3.runtime.rememberSaveableStateHolderNavEntryDecorator
+import androidx.navigation3.ui.NavDisplay
 import org.mrlem.android.core.feature.nav.NavigationLaunchedEffect
 import org.mrlem.android.core.feature.nav.Navigator
 import org.mrlem.android.core.feature.ui.NavProvider
@@ -19,42 +22,43 @@ fun MainWindow(
     navProviders: Set<NavProvider>,
     navigator: Navigator,
 ) {
-    val navController = rememberNavController()
+    val backStack = rememberNavBackStack(navProviders.firstNotNullOf { it.startKey })
+
     val items = navProviders
         .mapNotNull { it.navBarItem }
         .sortedBy { it.index }
     val snackbarHostState = remember { SnackbarHostState() }
 
     NavigationLaunchedEffect(
         navigator = navigator,
-        navController = navController,
+        backStack = backStack,
     )
 
     Scaffold(
         snackbarHost = { SnackbarHost(snackbarHostState) },
         bottomBar = {
             MainNavBar(
                 items = items,
-                navController = navController,
+                navigator = navigator,
+                backStack = backStack,
                 modifier = Modifier
-                    .imePadding(),
+                    .imePadding()
+                    .systemBarsPadding(),
             )
         },
     ) { innerPadding ->
-        NavHost(
-            navController = navController,
-            startDestination = navProviders.firstNotNullOfOrNull { it.startRoute }
-                ?: throw IllegalArgumentException("no start destination defined"),
-            modifier = Modifier
-                .padding(innerPadding),
-        ) {
-            navProviders.forEach { subGraph ->
-                subGraph.graph(
-                    builder = this,
-                    snackbarHostState = snackbarHostState,
-                    innerPadding = innerPadding,
-                )
-            }
-        }
+        NavDisplay(
+            backStack = backStack,
+            onBack = { backStack.removeLastOrNull() },
+            entryDecorators = listOf(
+                rememberSaveableStateHolderNavEntryDecorator(),
+                rememberViewModelStoreNavEntryDecorator(),
+            ),
+            entryProvider = entryProvider {
+                navProviders.forEach {
+                    it.entryBuilders.invoke(this, snackbarHostState, innerPadding)
+                }
+            },
+        )
     }
 }

app/src/main/java/org/mrlem/composesample/di/MainModule.kt

@@ -15,14 +15,16 @@ import javax.inject.Singleton
 @InstallIn(SingletonComponent::class)
 class MainModule {
 
-    private val applicationScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
+    private val applicationScope = CoroutineScope(context = SupervisorJob() + Dispatchers.Default)
 
     @Singleton
     @Provides
-    fun provideNavigator() = Navigator()
+    @ApplicationScope
+    fun provideApplicationScope() =
+        applicationScope
 
     @Singleton
     @Provides
-    @ApplicationScope
-    fun provideApplicationScope() = applicationScope
+    fun provideNavigator() =
+        Navigator(scope = applicationScope)
 }

build.gradle.kts

@@ -11,6 +11,7 @@ plugins {
     alias(libs.plugins.app.scripts)
     alias(libs.plugins.detekt) apply false
     alias(libs.plugins.ktlint) apply false
+    alias(libs.plugins.serialization) apply false
 }
 
 subprojects {

core/feature/nav/build.gradle.kts

@@ -8,5 +8,6 @@ android {
 }
 
 dependencies {
-    implementation(libs.androidx.navigation)
+    implementation(libs.androidx.navigation3.ui)
+    implementation(libs.androidx.navigation3.runtime)
 }