Add Navigation 3 ResultEventBus and result passing snippets

compose/snippets/src/main/java/com/example/compose/snippets/navigation3/decorators/DecoratorSnippets.kt

@@ -26,6 +26,8 @@ import androidx.navigation3.runtime.entryProvider
 import androidx.navigation3.runtime.rememberNavBackStack
 import androidx.navigation3.runtime.rememberSaveableStateHolderNavEntryDecorator
 import androidx.navigation3.ui.NavDisplay
+import androidx.navigation3.runtime.result.rememberResultEventBus
+import androidx.navigation3.runtime.result.rememberResultEventBusNavEntryDecorator
 import com.example.compose.snippets.navigation3.savingstate.Home
 import kotlinx.serialization.Serializable
 
@@ -62,3 +64,24 @@ fun DecoratorsBasic() {
     )
     // [END android_compose_navigation3_decorator_2]
 }
+
+@Composable
+fun DecoratorsResultEventBus() {
+    // [START android_compose_navigation3_decorator_result_hoist]
+    val resultEventBus = rememberResultEventBus()
+
+    NavDisplay(
+        /* ... */
+        // [START_EXCLUDE silent]
+        backStack = rememberNavBackStack(Home),
+        entryProvider = entryProvider<NavKey> {
+            entry<Home> { Text("Welcome to Nav3") }
+        },
+        // [END_EXCLUDE]
+        entryDecorators = listOf(
+            rememberSaveableStateHolderNavEntryDecorator(),
+            rememberResultEventBusNavEntryDecorator(resultEventBus = resultEventBus)
+        )
+    )
+    // [END android_compose_navigation3_decorator_result_hoist]
+}

compose/snippets/src/main/java/com/example/compose/snippets/navigation3/migration/NavigationMigrationAfter.kt

@@ -18,13 +18,16 @@ package com.example.compose.snippets.navigation3.migration
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.lifecycle.ViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
-import kotlinx.coroutines.flow.StateFlow
-import androidx.compose.runtime.mutableStateOf
+import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation3.runtime.EntryProviderScope
 import androidx.navigation3.runtime.NavKey
 import androidx.navigation3.runtime.entryProvider
+import androidx.navigation3.runtime.result.LocalResultEventBus
+import androidx.navigation3.runtime.result.ResultEffect
 import androidx.navigation3.scene.DialogSceneStrategy
 import androidx.navigation3.ui.NavDisplay
 import android.content.Intent
@@ -36,6 +39,7 @@ import androidx.navigation3.runtime.deeplink.DeepLinkRequest
 import androidx.navigation3.runtime.deeplink.DeepLinkUri
 import androidx.navigation3.runtime.deeplink.UriDeepLinkMatcher
 import androidx.navigation3.runtime.deeplink.invoke
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.serializer
 
@@ -152,6 +156,44 @@ private object SnippetLifecycleAfter {
     }
 }
 
+private object SnippetResultAfter {
+    @Serializable data object ContactPickerRoute : NavKey
+    data class Contact(val name: String = "")
+    class ComposeMessageViewModel : ViewModel() {
+        val recipient: Contact? = null
+        fun onRecipientSelected(contact: Contact) {}
+    }
+
+    @Composable private fun ContactPickerScreen(onContactSelected: (Contact) -> Unit) {}
+    @Composable private fun ComposeMessageContent(recipient: Contact?) {}
+
+    fun EntryProviderScope<NavKey>.entryProviderResult(navigator: Navigator) {
+        // [START android_compose_navigation3_result_after]
+        // Sender destination (in entryProvider):
+        entry<ContactPickerRoute> {
+            val resultBus = LocalResultEventBus.current
+
+            ContactPickerScreen(
+                onContactSelected = { contact ->
+                    resultBus.sendResult<Contact>(result = contact)
+                    navigator.goBack()
+                }
+            )
+        }
+
+        // Receiver destination:
+        @Composable
+        fun ComposeMessageScreen(viewModel: ComposeMessageViewModel = viewModel()) {
+            ResultEffect<Contact> { contact ->
+                viewModel.onRecipientSelected(contact)
+            }
+
+            ComposeMessageContent(recipient = viewModel.recipient)
+        }
+        // [END android_compose_navigation3_result_after]
+    }
+}
+
 private object SnippetDeepLinksAfter {
     @Serializable data class RouteA(val id: String) : NavKey
     @Serializable data object HomeKey : NavKey

compose/snippets/src/main/java/com/example/compose/snippets/navigation3/migration/NavigationMigrationBefore.kt

@@ -18,23 +18,25 @@ package com.example.compose.snippets.navigation3.migration
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
+import androidx.lifecycle.compose.LocalLifecycleOwner
+import androidx.lifecycle.ViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.NavController
-import kotlinx.coroutines.flow.StateFlow
-import androidx.navigation.NavHostController
 import androidx.navigation.NavDestination
 import androidx.navigation.NavDestination.Companion.hasRoute
 import androidx.navigation.NavDestination.Companion.hierarchy
 import androidx.navigation.NavGraphBuilder
+import androidx.navigation.NavHostController
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.dialog
 import androidx.navigation.compose.navigation
 import androidx.navigation.navDeepLink
 import androidx.navigation.toRoute
-import kotlinx.serialization.Serializable
 import kotlin.reflect.KClass
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.serialization.Serializable
 
 // Dummy screens for compilation
 @Composable private fun ScreenA(title: String) {}
@@ -126,6 +128,34 @@ private object SnippetLifecycleBefore {
     }
 }
 
+private object SnippetResultBefore {
+    data class Contact(val name: String = "")
+    class ComposeMessageViewModel : ViewModel() {
+        fun onRecipientSelected(contact: Contact) {}
+    }
+
+    @Composable
+    fun ResultBeforeSnippet(
+        navController: NavController,
+        contact: Contact,
+        viewModel: ComposeMessageViewModel
+    ) {
+        // [START android_compose_navigation3_result_before]
+        // Sender destination:
+        navController.previousBackStackEntry?.savedStateHandle?.set("contact_key", contact)
+        navController.popBackStack()
+
+        // Receiver destination:
+        val lifecycleOwner = LocalLifecycleOwner.current
+        navController.currentBackStackEntry?.savedStateHandle
+            ?.getLiveData<Contact>("contact_key")
+            ?.observe(lifecycleOwner) { contact ->
+                viewModel.onRecipientSelected(contact)
+            }
+        // [END android_compose_navigation3_result_before]
+    }
+}
+
 private object SnippetDeepLinksBefore {
     @Serializable data class RouteA(val id: String)