🌈 react-native-rlottie

Features

• ▶️ Uses rlottie to run lottie animations
• 🌠 rlottie creates rasterized bitmaps for each frame of the animation (instead of using the platform's animation API to continuisly run the animation).
  • This also gives us the possibility to pre-render the animation into cache, so even complex animation can start and run in 60 FPS
• ✅ Compatible with the new architecture (Fabric)
• 🤖 Especially on android, using rlottie can be more performant than lottie-android (which is used by lottie-react-native):
  • 📉 Using less CPU and RAM
  • 🏃‍♂️ Puts less pressure on the UI/main Thread, ensuring 60 FPS even on low end devices
  • Read more in Performance Comparison

Usage

We try to be as close to the lottie-react-native implementation API, so you can use this library as drop-in replacement/complement.

So loading a local animation really is the same:

import React from 'react';
import {View} from 'react-native';
import RLottieView from 'react-native-rlottie';

const lottieAnim = require('./assets/icon_trophy.json');

const App = () => {
  return (
    <View>
      <RLottieView source={lottieAnim} style={styles.animation} />
    </View>
  );
};

const styles = StyleSheet.create({
  animation: {
    height: 700,
    width: 700,
  },
});

export default App;

Performance Comparison

All data for the comparison can be found here: https://docs.google.com/spreadsheets/d/1Akz2As7HSJ7n9kmpIMYG966GY4QybOkJth5nNewYZhs/edit?usp=sharing

We compared react-native-rlottie with lottie-react-native:

🤖 Android

Key observations

• Running the animation consumes less CPU (-76%) and memory (-41%).
• The animation runs fluently in 60 FPS, whereas lottie-android causes the FPS to drop.
  • This is due to the fact that the animation used for testing is a "complex" one, and running the animation with the platform's animated/art API is more expensive then to render the animation as bitmaps.

🍎 iOS

// TODO: Comparison for ios

Key observations

• Running the animation with lottie-react-native adds CPU pressure. Using the example with an iPhone 7+ there is a ~10% CPU pressure during running the animation with lottie-rn, whereas with rlottie its 0%

Overall key points

• Constantly running an animation with rlottie is in general more resource-saving, thus it can ensure more stable FPS, specially on low end devices.
• HOWEVER, the first time you render the animation rlottie will use more resources than lottie-rn, as it needs to decode all frames for the first time. For large and complex animations this can be a severe factor. That's why, especially on iOS, its recommanded to pre-load an animation.
• In general, you should check the performance implications for each animation you are using, and test yourself if you are getting better results with lottie-rn or rlottie.

Note: The performance results have been recorded with react-native-performance-stats.

How to test yourself

Installation

yarn add react-native-rlottie@alpha

npm i react-native-rlottie@alpha

iOS

Run pod install:

npx pod-install

Android

No additional steps for android are required, except when using the new react native architecture:

Supported After Effects Features

This has full feature parity with rlottie, so check their supported features here

Caveats

In our testing, on iOS, there is a blocking of the UI thread and it takes some time until the animation is ready (for our most complex animation its 2s!). On iOS we are still missing some of the optimziation that we have already on android such as async/threaded frame decoding on the fly. Once we add those features we believe the performance can be similar to android. However, more development/research is needed. If you are an iOS dev, we welcome you to take on the challenge and improve or provide wisdom 🙌

Development

We are open for and welcoming contribution of any kind!

To develop this library use the example/. Simply install the dependencies in the root dir with yarn and then install the dependencies in the example/.

As this library is compatible with the old and the new arch, it can be useful to check both versions during development.

🤖 Switching arch:

In example/android/gradle.properties you can simply toggle the newArchEnabled variable.

🍎 Switching arch:

Go into example/ios and run the following command setting RCT_NEW_ARCH_ENABLED to 1 or 0 depending on which arch you want to test:

cd ios && RCT_NEW_ARCH_ENABLED=1 pod install && cd ..

References / Used libraries / Thanks

• https://github.com/Aghajari/AXrLottie - Used for android implementation, does all the heavy lifting, thx <3
• https://github.com/SDWebImage/librlottie-Xcode - Providing rlottie as cocoapods package, ready to be consumed by XCode, thx <3