Use Nav3 scene decorator for nav bars

Author: zsmb13

app/shared/src/commonMain/kotlin/org/jetbrains/kotlinconf/navigation/NavHost.kt

@@ -143,6 +143,10 @@ internal fun NavHost(
     val showGoldenKodee by remember { conferenceService.goldenKodeeData.map { it != null } }
         .collectAsStateWithLifecycle(false)
 
+    val navigationDecorator = remember(navState, navigator, showGoldenKodee) {
+        NavigationSceneDecoratorStrategy(navState, navigator, showGoldenKodee)
+    }
+
     val isGoldenKodee = navState.topLevelRoute is GoldenKodeeScreen
 
     ThemeChangeAnimation(
@@ -171,16 +175,11 @@ internal fun NavHost(
                         WindowInsets.safeDrawing.only(WindowInsetsSides.Horizontal)
                     )
             ) {
-                NavScaffold(
-                    navState = navState,
-                    navigator = navigator,
-                    showGoldenKodee = showGoldenKodee,
-                ) {
-                    NavDisplay(
-                        entries = navState.toDecoratedEntries(entryProvider),
-                        onBack = navigator::goBack,
-                    )
-                }
+                NavDisplay(
+                    entries = navState.toDecoratedEntries(entryProvider),
+                    onBack = navigator::goBack,
+                    sceneDecoratorStrategies = listOf(navigationDecorator),
+                )
 
                 val baseUrl = LocalAppGraph.current.baseUrl
                 val flagsManager = LocalAppGraph.current.flagsManager

app/shared/src/commonMain/kotlin/org/jetbrains/kotlinconf/navigation/NavScaffold.kt

@@ -26,6 +26,9 @@ import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
+import androidx.navigation3.scene.Scene
+import androidx.navigation3.scene.SceneDecoratorStrategy
+import androidx.navigation3.scene.SceneDecoratorStrategyScope
 import org.jetbrains.kotlinconf.generated.resources.Res
 import org.jetbrains.kotlinconf.generated.resources.award_28
 import org.jetbrains.kotlinconf.generated.resources.award_28_fill
@@ -88,12 +91,37 @@ private val bottomNavDestinations: List<MainNavDestination<TopLevelRoute>> = lis
     ),
 )
 
+internal class NavigationSceneDecoratorStrategy(
+    private val navState: NavState,
+    private val navigator: Navigator,
+    private val showGoldenKodee: Boolean,
+) : SceneDecoratorStrategy<AppRoute> {
+    override fun SceneDecoratorStrategyScope<AppRoute>.decorateScene(scene: Scene<AppRoute>): Scene<AppRoute> {
+        return if (navState.topLevelRoute != null) {
+            NavigationDecoratingScene(scene, navState, navigator, showGoldenKodee)
+        } else {
+            scene
+        }
+    }
+}
+
+private class NavigationDecoratingScene(
+    private val scene: Scene<AppRoute>,
+    private val navState: NavState,
+    private val navigator: Navigator,
+    private val showGoldenKodee: Boolean,
+) : Scene<AppRoute> by scene {
+    override val content: @Composable () -> Unit = {
+        NavScaffold(navState, navigator, showGoldenKodee, scene)
+    }
+}
+
 @Composable
-internal fun NavScaffold(
+private fun NavScaffold(
     navState: NavState,
     navigator: Navigator,
     showGoldenKodee: Boolean,
-    content: @Composable (() -> Unit)
+    scene: Scene<AppRoute>,
 ) {
     val onSelectRoute: (TopLevelRoute) -> Unit = { route ->
         navigator.activate(route)
@@ -137,7 +165,7 @@ internal fun NavScaffold(
 
         Column(Modifier.weight(1f)) {
             Box(Modifier.weight(1f).clipToBounds()) {
-                content()
+                scene.content()
             }
 
             NotificationBar()