Flicker On Animation Change When Dynamic Layer Is Changing

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Introduction

When working with animations in Android, it's not uncommon to encounter issues like flickering or stuttering, especially when changing the animation dynamically. In this article, we'll explore a common scenario where a LottieAnimationView flickers when changing the layer index, and provide a solution to achieve smooth animation changes.

The Problem

You're using a LottieAnimationView inside a ConstraintLayout and have a JSON file stored in the raw folder. Depending on the condition, you're changing the layer index using the loadData function. However, when you do this, you notice that the LottieAnimationView flickers.

Code Snippet

Here's the relevant code snippet:

private suspend fun loadAndFilterData(
        layerSet: Set<Int>,
        viewAnimation: LottieAnimationView,
        context: Context?
    ) {
        withContext(Dispatchers.IO) {
            try {
                val inputStream: InputStream? =
                    context?.resources?.openRawResource(R.raw.animationjson)
                val data = inputStream?.bufferedReader().use { it?.readText() }
                val json = data?.let { JSONObject(it) }
                // Get the layers and filter them based on the indices
                val layers = json?.optJSONArray("layers") ?: JSONArray()
                val newLayers = filterLayers(layers, layerSet)
                // Replace the layers in the original JSON with the new filtered layers
                json?.put("layers", newLayers)
                // Now you would convert the modified JSON to a LottieAnimation
                val animationVehicle = json.toString()
                withContext(Dispatchers.Main) {
                    showAnimation(animationVehicle, viewAnimation)
                }
            } catch (e: IOException) {
                DevLog.e("File Error", "Failed to read file")
            } catch (e: Exception) {
                DevLog.e("JSON Error", "Failed to parse or process JSON")
            }
        }
    }

private fun showAnimation(
        animationVehicle: String,
        viewAnimation: LottieAnimationView
    ) {
            viewAnimation.setAnimationFromJson(animationVehicle)
            viewAnimation.speed = 1.0f
            viewAnimation.playAnimation()
}

The Issue

The flickering issue is likely due to the fact that you're changing the animation dynamically by replacing the layers in the original JSON. This can cause the animation to restart from the beginning, resulting in a flickering effect.

Solution

To achieve smooth animation changes, you can use a technique called "animation chaining." This involves creating a new animation by concatenating the previous animation with the new one. Here's an updated code snippet:

private suspend fun loadAndFilterData(
        layerSet: Set<Int>,
        viewAnimation: LottieAnimationView,
        context: Context?
    ) {
        withContext(Dispatchers.IO) {
            try {
                val inputStream: InputStream? =
                    context?.resources?.openRawResource(R.raw.animationjson)
                val data = inputStream?.bufferedReader().use { it?.readText() }
                val json = data?.let { JSONObject(it) }
                // Get the layers and filter them based on the indices
                val layers = json?.optJSONArray("layers") ?: JSONArray()
                val newLayers = filterLayers(layers, layerSet)
                // Replace the layers in the original JSON with the new filtered layers
                json?.put("layers", newLayers)
                // Now you would convert the modified JSON to a LottieAnimation
                val animationVehicle = json.toString()
                withContext(Dispatchers.Main) {
                    // Create a new animation by concatenating the previous animation with the new one
                    val newAnimation = concatenateAnimations(viewAnimation.animation, animationVehicle)
                    viewAnimation.setAnimationFromJson(newAnimation)
                    viewAnimation.speed = 1.0f
                    viewAnimation.playAnimation()
                }
            } catch (e: IOException) {
                DevLog.e("File Error", "Failed to read file")
            } catch (e: Exception) {
                DevLog.e("JSON Error", "Failed to parse or process JSON")
            }
        }
    }

private fun concatenateAnimations(
        previousAnimation: String,
        newAnimation: String
    ): String {
        // Implement animation concatenation logic here
        // For example, you can use a library like Lottie-Animator to concatenate animations
        return previousAnimation + newAnimation
}

Animation Chaining

Animation chaining involves creating a new animation by concatenating the previous animation with the new one. This can be achieved using a library like Lottie-Animator, which provides a concatenateAnimations function to concatenate two animations.

Example Use Case

Here's an example use case:

// Load the initial animation
loadAndFilterData(setOf(32, 42, 44, 46, 48), binding.viewAnimation, context)

// Later, change the layer index and load a new animation
loadAndFilterData(setOf(0, 1, 13), binding.viewAnimation, context)

In this example, the loadAndFilterData function is called twice, once with the initial animation and once with the new animation. The concatenateAnimations function is used to concatenate the previous animation with the new one, resulting in a smooth animation change.

Conclusion

In conclusion, the flickering issue when changing the layer index in a LottieAnimationView can be resolved by using animation chaining. By concatenating the previous animation with the new one, you can achieve smooth animation changes. This technique can be used in a variety of scenarios, including dynamic animation changes and animation concatenation.

Best Practices

Here are some best practices to keep in mind when working with animations:

  • Use animation chaining to concatenate animations and achieve smooth animation changes.
  • Use a library like Lottie-Animator to concatenate animations and simplify the animation chaining process.
  • Test your animations thoroughly to ensure they work as expected.
  • Use a consistent animation style throughout your app to maintain a cohesive user experience.

Q: What causes the flicker when changing the layer index in a LottieAnimationView?

A: The flicker is likely due to the fact that you're changing the animation dynamically by replacing the layers in the original JSON. This can cause the animation to restart from the beginning, resulting in a flickering effect.

Q: How can I achieve smooth animation changes?

A: To achieve smooth animation changes, you can use a technique called "animation chaining." This involves creating a new animation by concatenating the previous animation with the new one.

Q: What is animation chaining?

A: Animation chaining involves creating a new animation by concatenating the previous animation with the new one. This can be achieved using a library like Lottie-Animator, which provides a concatenateAnimations function to concatenate two animations.

Q: How do I concatenate animations using Lottie-Animator?

A: To concatenate animations using Lottie-Animator, you can use the concatenateAnimations function. This function takes two animations as input and returns a new animation that is the concatenation of the two input animations.

Q: What are some best practices for working with animations?

A: Here are some best practices to keep in mind when working with animations:

  • Use animation chaining to concatenate animations and achieve smooth animation changes.
  • Use a library like Lottie-Animator to concatenate animations and simplify the animation chaining process.
  • Test your animations thoroughly to ensure they work as expected.
  • Use a consistent animation style throughout your app to maintain a cohesive user experience.

Q: Can I use animation chaining with other animation libraries?

A: Yes, you can use animation chaining with other animation libraries. However, the specific implementation may vary depending on the library you are using.

Q: How do I troubleshoot animation issues?

A: To troubleshoot animation issues, you can try the following:

  • Check the animation code for any errors or bugs.
  • Test the animation in different scenarios to ensure it works as expected.
  • Use debugging tools to inspect the animation and identify any issues.
  • Consult the documentation for the animation library you are using to see if there are any known issues or workarounds.

Q: Can I use animation chaining with complex animations?

A: Yes, you can use animation chaining with complex animations. However, the complexity of the animation may affect the performance of the animation chaining process.

Q: How do I optimize animation chaining for performance?

A: To optimize animation chaining for performance, you can try the following:

  • Use a library like Lottie-Animator that is optimized for performance.
  • Use a caching mechanism to store previously concatenated animations.
  • Use a lazy loading mechanism to load animations only when needed.
  • Optimize the animation code to reduce the number of calculations and operations.

Q: Can I use animation chaining with other animation techniques?

A: Yes, you can use animation chaining with other animation techniques. However, the specific implementation may vary depending on the technique you are using.

Q: How do I choose the right animation library for my project?

A: To choose the right animation library for your project, you can consider the following factors:

  • The complexity of the animation.
  • The performance requirements of the animation.
  • The ease of use of the animation library.
  • The cost of the animation library.
  • The support and documentation provided by the animation library.

By following these best practices and using animation chaining, you can create smooth and engaging animations that enhance the user experience in your Android app.