How to use animation listener for Lottie animation in Android Jetpack Compose?

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05-10-2024

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Bringing Lottie Animations to Life with Jetpack Compose: Using Animation Listeners

Lottie animations, known for their captivating visual flair, are a powerful tool to enhance user experience in Android applications. Jetpack Compose, Google's modern UI toolkit, seamlessly integrates with Lottie to bring these animations directly into your composable functions. But how do you interact with these animations in real-time, triggering actions based on their progress? This is where animation listeners come in.

The Problem:

Imagine you want to show a loading animation while your app fetches data. You'd need to know when the animation is complete to display the fetched data. Or, you might want to play a celebratory animation on successful completion of a task, coordinating it with other UI elements. This is where animation listeners provide the crucial link between your Lottie animation and your app's logic.

Illustrative Scenario:

Let's say you're building a simple app that fetches user information and displays a loading animation while it does so. Here's how you could use a Lottie animation with a listener:

@Composable
fun UserProfileScreen(viewModel: UserProfileViewModel) {
    val loadingState = viewModel.loadingState.collectAsState()
    val user = viewModel.user.collectAsState()

    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        if (loadingState.value) {
            // Lottie Animation with Listener
            val animationSpec = rememberLottieAnimationSpec(data = R.raw.loading_animation)
            val animationState = rememberLottieAnimationState(animationSpec)
            val progress by animationState.progress.collectAsState()

            // Add Listener
            LaunchedEffect(Unit) {
                animationState.play()
                animationState.addAnimationListener(object : LottieAnimationListener {
                    override fun onAnimationStart(animation: LottieAnimation) {
                        // Trigger actions when animation starts
                    }

                    override fun onAnimationRepeat(animation: LottieAnimation) {
                        // Trigger actions when animation repeats
                    }

                    override fun onAnimationEnd(animation: LottieAnimation) {
                        // Trigger actions when animation ends
                        viewModel.fetchUserData()
                    }

                    override fun onAnimationCancel(animation: LottieAnimation) {
                        // Trigger actions when animation is cancelled
                    }
                })
            }

            LottieAnimation(
                spec = animationSpec,
                animationState = animationState,
                modifier = Modifier.size(200.dp)
            )
        } else {
            // Display user data
            Text(text = "Name: ${user.value.name}")
            Text(text = "Email: ${user.value.email}")
        }
    }
}

In this example:

1. We use rememberLottieAnimationSpec to load our animation and rememberLottieAnimationState to control it.
2. We track the animation progress using animationState.progress.collectAsState().
3. An animationListener is attached to the animation state, allowing us to react to its lifecycle events (start, repeat, end, cancel).
4. In the onAnimationEnd callback, we trigger the fetchUserData function from our ViewModel. This demonstrates how the animation listener can link directly to your app's logic.

Benefits of Using Animation Listeners:

• Precise Control: Listeners provide fine-grained control over the animation's progress. You can trigger specific actions based on various stages of the animation.
• Enhanced Interactivity: Animation listeners enable you to create dynamic and engaging user interactions, responding to animation events with appropriate UI updates or data fetching.
• Clean Code Structure: By separating animation-related logic from your UI, you maintain a cleaner and more organized codebase.

Essential Considerations:

• Animation Duration: Be mindful of the animation's duration to avoid delays in your app's functionality.
• Multiple Listeners: If you're adding multiple listeners to an animation, ensure their order and execution are managed appropriately.
• Error Handling: Implement robust error handling in case animation loading fails or unexpected events occur.

Moving Forward:

Animation listeners are a powerful tool for building engaging and interactive user interfaces with Lottie animations in Jetpack Compose. By understanding their functionalities and using them effectively, you can create truly immersive and dynamic user experiences.