Animations in React Native with layoutAnimation

April 2 2017

Using LayoutAnimation to perform css transition like animations. I've been working with React Native since early 2016.The majority of the Apps that I've published have been fairly straightforward in their UI and presentation. Recently, I was tasked with doing some basic animations when a user interacts with UI. The React Native documentation can be pretty verbose at times and beat around the most basic features of a component, library, or api.

In this article I'll discuss the basics of LayoutAnimation, how it differs from the Animated library, and provide some examples of LayoutAnimation.

I'll also be providing an example repository.

Also, note that according the documentation LayoutAnimation requires some extra configuration for Android. The examples in this post will all be geared towards iOS.

LayoutAnimation vs Animated

React Native offers two animation utilities. The Animated library is a more full featured tool for doing parallel and sequenced animations. The LayoutAnimation API provides a way easily animate the frames between renders and it works much the same way as a css transition would. Providing a previous layout state and the next layout state.

App

This app does as simple left and right animation of a TouchableOpacity with a Text child.

First, take note of the initial state. Here next will toggle the animation either to the left or right (depending on the previous state). The TouchableOpacity that will be animated gets its left position from the state, and the onPress event calls the component's onPress method.

With LayoutAnimation you specify one of a few tweening options. Here easeInEaseOut() will provide easing tweens. The onPress function checks to see if it should be adding or subtracting 50 with the state's left. LayoutAnimation takes care of the rest and the frames between the renders will be animated.

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  TouchableOpacity,
  LayoutAnimation,
} from 'react-native';

export default class layoutanimation extends Component {
  constructor(props) {
    super(props);

    this.state = {
      next: 'left',
      left: 0,
    };
  }

  onPress() {
    LayoutAnimation.easeInEaseOut();
    if (this.state.next === 'left') {
      this.setState({ left: this.state.left - 50, next: 'right' });
    } else {
      this.setState({ left: this.state.left + 50, next: 'left' });
    }
  }

  render() {
    return (
      <View style={styles.container}>
        <TouchableOpacity
          style={{ left: this.state.left }}
          onPress={() => this.onPress()}
        >
          <Text>LayoutAnimation</Text>
        </TouchableOpacity>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});

AppRegistry.registerComponent('layoutanimation', () => layoutanimation);

Summary

LayoutAnimation works well in situations where you are animating against a single change.

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