Transition Animations Between Screens in Jetpack Compose

Introduction

Smooth transitions between screens are crucial in mobile app development as they enhance user experience and provide a sense of continuity. Jetpack Compose, Google’s modern UI toolkit for Android, simplifies UI development by using a declarative approach. It also offers powerful animation APIs, making it easier to create seamless transitions between screens.

In this article, we’ll explore how to implement transition animations in Jetpack Compose, covering key concepts, essential APIs, and practical examples.

Why Use Transition Animations?

Before diving into implementation, let’s understand why transition animations are essential:

1. Enhance User Experience: Smooth transitions make the UI feel more dynamic and responsive, creating a polished experience.
2. Provide Context: They help users understand changes in the app by visually guiding them from one screen to another.
3. Improve Perceived Performance: Well-designed animations can mask delays and make the app feel faster.

Key Concepts in Jetpack Compose Animations

Jetpack Compose provides various APIs to handle animations, including:

• AnimatedVisibility: Controls visibility with animations.
• Crossfade: Creates smooth fading transitions.
• AnimatedContent: Animates content changes within the same composable.
• Navigation Animations: Defines animations between screens when using NavHost and AnimatedNavHost.
• Transitions: Enables complex animations between different states.

Setting Up Navigation in Jetpack Compose

Before implementing animations, we need a basic navigation setup. Jetpack Compose uses NavHost and NavController to handle navigation between screens.

Basic Navigation Setup

@Composable
fun MyApp() {
    val navController = rememberNavController()
    NavHost(navController, startDestination = "home") {
        composable("home") { HomeScreen(navController) }
        composable("details") { DetailScreen(navController) }
    }
}

Now, let’s add animations to this navigation flow.

Implementing Transition Animations

1. Using AnimatedNavHost

The Accompanist Navigation Animation library provides an AnimatedNavHost, allowing smooth transitions between screens. First, add the dependency to your project:

dependencies {
    implementation "com.google.accompanist:accompanist-navigation-animation:0.32.0"
}

Now, replace NavHost with AnimatedNavHost:

import com.google.accompanist.navigation.animation.*
import androidx.navigation.compose.rememberNavController

@OptIn(ExperimentalAnimationApi::class)
@Composable
fun MyAnimatedApp() {
    val navController = rememberNavController()
    AnimatedNavHost(navController, startDestination = "home") {
        composable(
            "home",
            enterTransition = { fadeIn() },
            exitTransition = { fadeOut() }
        ) {
            HomeScreen(navController)
        }
        composable(
            "details",
            enterTransition = { slideInHorizontally() },
            exitTransition = { slideOutHorizontally() }
        ) {
            DetailScreen(navController)
        }
    }
}

This implementation enables:

• Fade-in animation when entering the home screen.
• Fade-out animation when exiting the home screen.
• Slide-in animation when navigating to the details screen.
• Slide-out animation when leaving the details screen.

2. Using AnimatedContent

If you need to animate content within the same composable, use AnimatedContent.

Example:

@Composable
fun AnimatedCounter() {
    var count by remember { mutableStateOf(0) }
    
    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        AnimatedContent(targetState = count) { targetCount ->
            Text(text = "$targetCount", fontSize = 30.sp)
        }
        Button(onClick = { count++ }) {
            Text("Increase")
        }
    }
}

This smoothly animates the number change when the button is clicked.

3. Using Crossfade for Simple Transitions

Crossfade allows switching between composables with a fade effect.

Example:

@Composable
fun CrossfadeExample() {
    var isHome by remember { mutableStateOf(true) }
    
    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        Crossfade(targetState = isHome) { screen ->
            if (screen) HomeScreen() else DetailScreen()
        }
        Button(onClick = { isHome = !isHome }) {
            Text("Switch Screen")
        }
    }
}

This smoothly transitions between two screens with a fade effect.

4. Customizing Animations with updateTransition

For more control, use updateTransition to define animations between states.

Example:

@Composable
fun AnimatedBox() {
    var expanded by remember { mutableStateOf(false) }
    val transition = updateTransition(targetState = expanded, label = "Box Animation")
    
    val size by transition.animateDp(label = "Size Animation") { state ->
        if (state) 200.dp else 100.dp
    }
    
    Box(
        modifier = Modifier
            .size(size)
            .background(Color.Blue)
            .clickable { expanded = !expanded }
    )
}

This expands or shrinks a box with an animation when clicked.

Best Practices for Animations in Jetpack Compose

1. Keep animations subtle: Overuse can make UI feel cluttered.
2. Use animations to guide users: Ensure they improve UX rather than distract.
3. Optimize performance: Heavy animations may impact app performance, so use them wisely.
4. Test on real devices: Performance can vary across devices; always test on different configurations.

Conclusion

Jetpack Compose makes it easier than ever to implement smooth and elegant transition animations between screens. Whether you’re using AnimatedNavHost, AnimatedContent, Crossfade, or updateTransition, Jetpack Compose provides powerful tools to create engaging UI experiences.

By following the examples and best practices outlined in this post, you can enhance your app’s navigation experience, making it more intuitive and visually appealing.

Have you tried animations in Jetpack Compose? Share your thoughts in the comments below!