Make scene provide an AnimatedContentScope to the composable content

This scope is the one that drives the navigation transition, which
allows callers to use it to drive other animations inside the screen
itself as it animates into or out of the NavHost.
Notably, this allows callers to use the shared element transitions.

precompose/src/commonMain/kotlin/moe/tlaster/precompose/navigation/NavHost.kt

@@ -1,6 +1,7 @@
 package moe.tlaster.precompose.navigation
 
 import androidx.compose.animation.AnimatedContent
+import androidx.compose.animation.AnimatedContentScope
 import androidx.compose.animation.AnimatedContentTransitionScope
 import androidx.compose.animation.ContentTransform
 import androidx.compose.animation.core.ExperimentalTransitionApi
@@ -258,7 +259,7 @@ fun NavHost(
 }
 
 @Composable
-private fun NavHostContent(
+private fun AnimatedContentScope.NavHostContent(
     stateHolder: SaveableStateHolder,
     entry: BackStackEntry,
 ) {
@@ -268,7 +269,7 @@ private fun NavHostContent(
             LocalSavedStateHolder provides entry.savedStateHolder,
             LocalLifecycleOwner provides entry,
             content = {
-                entry.ComposeContent()
+                entry.ComposeContent(this@NavHostContent)
             },
         )
     }
@@ -289,12 +290,12 @@ private fun GroupRoute.composeRoute(): ComposeRoute? {
 }
 
 @Composable
-private fun BackStackEntry.ComposeContent() {
+private fun BackStackEntry.ComposeContent(animatedContentScope: AnimatedContentScope) {
     if (route is GroupRoute) {
         (route as GroupRoute).composeRoute()
     } else {
         route as? ComposeRoute
-    }?.content?.invoke(this)
+    }?.content?.invoke(animatedContentScope, this)
 }
 
 @OptIn(ExperimentalFoundationApi::class)

precompose/src/commonMain/kotlin/moe/tlaster/precompose/navigation/RouteBuilder.kt

@@ -1,10 +1,12 @@
 package moe.tlaster.precompose.navigation
 
+import androidx.compose.animation.AnimatedContentScope
 import androidx.compose.runtime.Composable
 import moe.tlaster.precompose.navigation.route.FloatingRoute
 import moe.tlaster.precompose.navigation.route.GroupRoute
 import moe.tlaster.precompose.navigation.route.Route
 import moe.tlaster.precompose.navigation.route.SceneRoute
+import moe.tlaster.precompose.navigation.route.sceneRouteWithoutAnimatedContent
 import moe.tlaster.precompose.navigation.transition.NavTransition
 
 class RouteBuilder(
@@ -19,12 +21,43 @@ class RouteBuilder(
      * @param swipeProperties swipe back navigation properties for current scene
      * @param content composable for the destination
      */
+    @Deprecated(
+        message = "Deprecated in favor of scene that supports AnimatedContent",
+        level = DeprecationLevel.HIDDEN,
+    )
     fun scene(
         route: String,
         deepLinks: List<String> = emptyList(),
         navTransition: NavTransition? = null,
         swipeProperties: SwipeProperties? = null,
         content: @Composable (BackStackEntry) -> Unit,
+    ) {
+        addRoute(
+            @Suppress("DEPRECATION")
+            sceneRouteWithoutAnimatedContent(
+                route = route,
+                navTransition = navTransition,
+                deepLinks = deepLinks,
+                swipeProperties = swipeProperties,
+                content = content,
+            ),
+        )
+    }
+
+    /**
+     * Add the scene [Composable] to the [RouteBuilder]
+     * @param route route for the destination
+     * @param navTransition navigation transition for current scene
+     * @param swipeProperties swipe back navigation properties for current scene
+     * @param content composable for the destination. The AnimatedContentScope provided is the
+     *  animation that drives the scene transition. That is either entering or exiting the NavHost
+     */
+    fun scene(
+        route: String,
+        deepLinks: List<String> = emptyList(),
+        navTransition: NavTransition? = null,
+        swipeProperties: SwipeProperties? = null,
+        content: @Composable AnimatedContentScope.(BackStackEntry) -> Unit,
     ) {
         addRoute(
             SceneRoute(

precompose/src/commonMain/kotlin/moe/tlaster/precompose/navigation/route/ComposeRoute.kt

@@ -1,10 +1,11 @@
 package moe.tlaster.precompose.navigation.route
 
+import androidx.compose.animation.AnimatedContentScope
 import androidx.compose.runtime.Composable
 import moe.tlaster.precompose.navigation.BackStackEntry
 
 interface ComposeRoute : Route {
-    val content: @Composable (BackStackEntry) -> Unit
+    val content: @Composable AnimatedContentScope.(BackStackEntry) -> Unit
 }
 
 interface ComposeSceneRoute : ComposeRoute

precompose/src/commonMain/kotlin/moe/tlaster/precompose/navigation/route/FloatingRoute.kt

@@ -1,9 +1,18 @@
 package moe.tlaster.precompose.navigation.route
 
+import androidx.compose.animation.AnimatedContentScope
 import androidx.compose.runtime.Composable
 import moe.tlaster.precompose.navigation.BackStackEntry
 
 internal class FloatingRoute(
-    override val content: @Composable (BackStackEntry) -> Unit,
+    override val content: @Composable AnimatedContentScope.(BackStackEntry) -> Unit,
     override val route: String,
-) : ComposeRoute, ComposeFloatingRoute
+) : ComposeRoute, ComposeFloatingRoute {
+    internal constructor(
+        route: String,
+        content: @Composable (BackStackEntry) -> Unit
+    ) : this(
+        { entry -> content(entry) },
+        route,
+    )
+}

precompose/src/commonMain/kotlin/moe/tlaster/precompose/navigation/route/SceneRoute.kt

@@ -1,5 +1,6 @@
 package moe.tlaster.precompose.navigation.route
 
+import androidx.compose.animation.AnimatedContentScope
 import androidx.compose.runtime.Composable
 import moe.tlaster.precompose.navigation.BackStackEntry
 import moe.tlaster.precompose.navigation.SwipeProperties
@@ -10,5 +11,28 @@ internal class SceneRoute(
     val deepLinks: List<String>,
     val navTransition: NavTransition?,
     val swipeProperties: SwipeProperties?,
-    override val content: @Composable (BackStackEntry) -> Unit,
+    override val content: @Composable AnimatedContentScope.(BackStackEntry) -> Unit,
 ) : ComposeRoute, ComposeSceneRoute
+
+@Deprecated(
+    message = """
+    Used as a backwards compatible for the old RouteBuilder APIs which do not expect the content to
+    be an extension function on AnimatedContentScope        
+    """,
+    level = DeprecationLevel.WARNING,
+)
+internal fun sceneRouteWithoutAnimatedContent(
+    route: String,
+    deepLinks: List<String>,
+    navTransition: NavTransition?,
+    swipeProperties: SwipeProperties?,
+    content: @Composable (BackStackEntry) -> Unit,
+): SceneRoute {
+    return SceneRoute(
+        route,
+        deepLinks,
+        navTransition,
+        swipeProperties,
+        content = { entry -> content(entry) }
+    )
+}