19

I have 2 screens which both have their own Scaffold and TopAppBar. When I navigate between them using the Jetpack Navigation Compose library, the app bar flashes. Why does it happen and how can I get rid of this?

enter image description here

Code:

Navigation:

@Composable
fun TodoNavHost(
    navController: NavHostController,
    modifier: Modifier = Modifier
) {
    NavHost(
        navController = navController,
        startDestination = TodoScreen.TodoList.name,
        modifier = modifier
    ) {
        composable(TodoScreen.TodoList.name) {
            TodoListScreen(
                onTodoEditClicked = { todo ->
                    navController.navigate("${TodoScreen.AddEditTodo.name}?todoId=${todo.id}")
                },
                onFabAddNewTodoClicked = {
                    navController.navigate(TodoScreen.AddEditTodo.name)
                }
            )
        }
        composable(
            "${TodoScreen.AddEditTodo.name}?todoId={todoId}", 
            arguments = listOf(
                navArgument("todoId") {
                    type = NavType.LongType
                    defaultValue = -1L
                }
            )
        ) {
            AddEditTodoScreen(
                onNavigateUp = {
                    navController.popBackStack() 
                },
                onNavigateBackWithResult = { result ->
                    navController.navigate(TodoScreen.TodoList.name)
                }
            )
        }
    }
}

Todo list screen Scaffold with TopAppBar:

@Composable
fun TodoListBody(
    todos: List<Todo>,
    todoExpandedStates: Map<Long, Boolean>,
    onTodoItemClicked: (Todo) -> Unit,
    onTodoCheckedChanged: (Todo, Boolean) -> Unit,
    onTodoEditClicked: (Todo) -> Unit,
    onFabAddNewTodoClicked: () -> Unit,
    onDeleteAllCompletedConfirmed: () -> Unit,
    modifier: Modifier = Modifier,
    errorSnackbarMessage: String = "",
    errorSnackbarShown: Boolean = false
) {

    var menuExpanded by remember { mutableStateOf(false) }
    var showDeleteAllCompletedConfirmationDialog by rememberSaveable { mutableStateOf(false) }

    Scaffold(
        modifier,
        topBar = {
            TopAppBar(
                title = { Text("My Todos") },
                actions = {
                    IconButton(
                        onClick = { menuExpanded = !menuExpanded },
                        modifier = Modifier.semantics {
                            contentDescription = "Options Menu"
                        }
                    ) {
                        Icon(Icons.Default.MoreVert, contentDescription = "Show menu")
                    }
                    DropdownMenu(
                        expanded = menuExpanded,
                        onDismissRequest = { menuExpanded = false }) {
                        DropdownMenuItem(
                            onClick = {
                                showDeleteAllCompletedConfirmationDialog = true
                                menuExpanded = false
                            },
                            modifier = Modifier.semantics {
                                contentDescription = "Option Delete All Completed"
                            }) {
                            Text("Delete all completed")
                        }
                    }
                }

            )
        },
[...]

Add/edit screen Scaffold with TopAppBar:

@Composable
fun AddEditTodoBody(
    todo: Todo?,
    todoTitle: String,
    setTitle: (String) -> Unit,
    todoImportance: Boolean,
    setImportance: (Boolean) -> Unit,
    onSaveClick: () -> Unit,
    onNavigateUp: () -> Unit,
    modifier: Modifier = Modifier
) {
    Scaffold(
        modifier,
        topBar = {
            TopAppBar(
                title = { Text(todo?.let { "Edit Todo" } ?: "Add Todo") },
                actions = {
                    IconButton(onClick = onSaveClick) {
                        Icon(Icons.Default.Save, contentDescription = "Save Todo")
                    }
                },
                navigationIcon = {
                    IconButton(onClick = onNavigateUp) {
                        Icon(Icons.Default.ArrowBack, contentDescription = "Back")
                    }
                }
            )
        },
    ) { innerPadding ->
        BodyContent(
            todoTitle = todoTitle,
            setTitle = setTitle,
            todoImportance = todoImportance,
            setImportance = setImportance,
            modifier = Modifier.padding(innerPadding)
        )
    }
}
Improve this question

10 Answers 10

Reset to default
8
+100

The flashing is caused by the default cross-fade animation in more recent versions of the navigation-compose library. The only way to get rid of it right now (without downgrading the dependency) is by using the Accompanist animation library:

implementation "com.google.accompanist:accompanist-navigation-animation:0.20.0"

And then replace the normal NavHost with Accompanist's AnimatedNavHost, replace rememberNavController() with rememberAnimatedNavController() and disable the transitions animations:

AnimatedNavHost(
        navController = navController,
        startDestination = bottomNavDestinations[0].fullRoute,
        enterTransition = { _, _ -> EnterTransition.None },
        exitTransition = { _, _ -> ExitTransition.None },
        popEnterTransition = { _, _ -> EnterTransition.None },
        popExitTransition = { _, _ -> ExitTransition.None },
        modifier = modifier,
    ) {
        [...}
    }
Improve this answer
Sign up to request clarification or add additional context in comments.

3 Comments

this is not a solution. it fixes the toolbar flashing but you break the animation transition for all screens... the solution should not effect other logic
@user924 You're right. I removed my accepted solution
The proper way is to override the default animations and do that in the Navhost composable (exitTransition, popExitTransition, etc.), not to install another library.
8

I think I found an easy solution for that issue (works on Compose version 1.4.0).

My setup - blinking

All of my screens have their own toolbar wrapped in the scaffold:

// Some Composable screnn

Scaffold(
    topBar = { TopAppBar(...) }
) {
    ScreenContent()
}

Main activity which holds the nav host is defined like that:

// Activity with NavHost

setContent {
    AppTheme {
        NavHost(...) { }
    }
}

Solution - no blinking!

Wrap you NavHost in activity in a Surface:

setContent {
    AppTheme {
        Surface {
            NavHost(...) { }
        }
    }
}

Rest of the screens stay the same. No blinking and transition animation between destinations is almost the same like it was with fragments (subtle fade in/fade out). So far I haven't found any negative side effects of that.

Improve this answer

3 Comments

Did it you see it somewhere? Mb some official samples?
can you suggest how that is working in the open source project ivy wallet link - github.com/Ivy-Apps/ivy-wallet
Worked for me. Could someone please explains why this works? :)
1

I got the same issue having a "scaffold-per-screen" architecture. What helped, to my surprise, was lowering androidx.navigation:navigation-compose version to 2.4.0-alpha04.

Improve this answer

3 Comments

Right, because they haven't implemented the default transition animation there yet.
You're right, so... if it's alright to use multiple scaffolds and we don't want the default animation, AnimatedNavHost looks like a way to go?
Poplawski Right, looks like this is what we need 👍
1

With the newer library implementation "com.google.accompanist:accompanist-navigation-animation:0.24.1-alpha" you need to have the AnimatedNavHost like this

AnimatedNavHost(
            navController = navController,
            startDestination = BottomNavDestinations.TimerScreen.route,
            enterTransition = { EnterTransition.None },
            exitTransition = { ExitTransition.None },
            popEnterTransition = { EnterTransition.None },
            popExitTransition = { ExitTransition.None },
            modifier = Modifier.padding(innerPadding)

Also

Replace rememberNavController() with rememberAnimatedNavController()

Replace NavHost with AnimatedNavHost

Replace import androidx.navigation.compose.navigation with import com.google.accompanist.navigation.animation.navigation

Replace import androidx.navigation.compose.composable with import com.google.accompanist.navigation.animation.composable

Improve this answer

Comments

1

In order not to blink (or to slide if you have AnimatedNavHost) you should put the TopAppBar in the activity and outside the NavHost, otherwise the TopAppBar is just part of the screen and makes transitions like every other screen element:

// Activity with your navigation host
setContent {
    MyAppTheme {
        Scaffold(
            topBar = { TopAppBar(...) }
        ) { padding ->
            TodoNavHost(padding, ...) { }
        }
    }
}

From the Scaffold containing the TopAppBar comes the padding parameter, that you should pass to the NavHost and use it in the screen like you have done in your example

Improve this answer

Comments

1

The problem is that the view in the NavHost has a default crossfade animation. You must override it to stop the flashing, as the example below shows with noEnterTransition and noExistTransition for MainScreen.

class MainActivity : ComponentActivity() {
    private val noEnterTransition: AnimatedContentTransitionScope<NavBackStackEntry>.() -> EnterTransition =
        {
            fadeIn(
                animationSpec = tween(durationMillis = 200),
                initialAlpha = 0.99f
            )
        }

    private val noExitTransition: AnimatedContentTransitionScope<NavBackStackEntry>.() -> ExitTransition =
        {
            fadeOut(
                animationSpec = tween(durationMillis = 300),
                targetAlpha = 0.99f
            )
        }

    /.../

    override fun onCreate(savedInstanceState: Bundle?) {
        setContent {
            val navController = rememberNavController()
            YourTheme() {

                Surface(color = MaterialTheme.colorScheme.background) {
                    NavHost(navController = navController, startDestination = "main") {
                        composable(
                            route = "main",
                            popEnterTransition = noEnterTransition,
                            exitTransition = noExitTransition,
                            popExitTransition = noExitTransition
                        ) {
                            // MainScreen(navController = navController)
                        }

                        composable(
                            route = "detail",
                            enterTransition = {
                                slideIntoContainer(
                                    towards = AnimatedContentTransitionScope.SlideDirection.Companion.Left,
                                    animationSpec = tween(200, easing = EaseOut)
                                )
                            },
                            popExitTransition = {
                                slideOutOfContainer(
                                    towards = AnimatedContentTransitionScope.SlideDirection.Companion.Right,
                                    animationSpec = tween(150, easing = EaseOut)
                                )
                            },
                        ) {
                            // DetailScreen(navController = navController)
                        }
                    }
                }
            }
        }
    }
}
Improve this answer

1 Comment

This was the only solution that helped me. Thanks!
0

Alternative to removing Animation you can change animations for example:

@Composable
private fun ScreenContent() {
    val navController = rememberAnimatedNavController()
    val springSpec = spring<IntOffset>(dampingRatio = Spring.DampingRatioMediumBouncy)
    val tweenSpec = tween<IntOffset>(durationMillis = 2000, easing = CubicBezierEasing(0.08f, 0.93f, 0.68f, 1.27f))
    ...
    ) { innerPadding ->
        AnimatedNavHost(
            navController = navController,
            startDestination = BottomNavDestinations.TimerScreen.route,
            enterTransition = { slideInHorizontally(initialOffsetX = { 1000 }, animationSpec = springSpec) },
            exitTransition = { slideOutHorizontally(targetOffsetX = { -1000 }, animationSpec = springSpec) },
            popEnterTransition = { slideInHorizontally(initialOffsetX = { 1000 }, animationSpec = tweenSpec) },
            popExitTransition = { slideOutHorizontally(targetOffsetX = { -1000 }, animationSpec = tweenSpec) },
            modifier = Modifier.padding(innerPadding)
    ) {}
Improve this answer

Comments

0

Without adding another package, as of Dec/2023, you can remove the default animation like so

NavHost(
    navController = navController,
    startDestination = HOME_ROUTE,
    route = ROOT_ROUTE,
    enterTransition = {
        EnterTransition.None // removes the blinking/fade effect
    },
    exitTransition = {
        ExitTransition.None // remove the blinking/fade effect
    }
) {
    // composables
}

Put this in your root nav host. Here is the version that I am using(as of Dec/2/2023

implementation("androidx.navigation:navigation-compose:2.7.5")
Improve this answer

1 Comment

Work for me, easy solution. And don't need for accompanist lib. Thanks
0

Updating to version 2.8.0-alpha06 solved this issue for me

Improve this answer

Comments

-1

It is the expected behaviour. You are constructing two separate app bars for both the screens so they are bound to flash. This is not the correct way. The correct way would be to actually put the scaffold in your main activity and place the NavHost as it's content. If you wish to modify the app bar, create variables to hold state. Then modify them from the Composables. Ideally, store then in a viewmodel. That is how it is done in compose. Through variables.

Thanks

Improve this answer

15 Comments

Having separate toolbars for separate screens was always a viable option in the old fragment times. Especially when you need different kinds of toolbars (like a normal one and an expandable one). What makes you think that now there should always be one single toolbar for all screens?
There are a lot of things that differ in Jetpack compose compared to the view world. Like nested layouts were a problem in the view system while they are not in compose. I guess they render in different ways so that could be it. Check the docs for not maybe
I'm not sold on this. A single Scaffold/AppBar per app seems like a nightmare to manage
It's only jarring because of the crossfade, it would not be an issue if there was slide animation support
@M.Baraka I ended up using Accompanist to disable the default crossfade animation (which causes the flash effect)
|

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.