Rocket.Chat.ReactNative/app/containers/Loading.tsx

import React from 'react';
import { Animated, Modal, StyleSheet, View } from 'react-native';

import { withTheme } from '../theme';
import { themes } from '../lib/constants';

const styles = StyleSheet.create({
	container: {
		flex: 1,
		alignItems: 'center',
		justifyContent: 'center'
	},
	image: {
		width: 100,
		height: 100,
		resizeMode: 'contain'
	}
});

interface ILoadingProps {
	visible: boolean;
	theme?: string;
}

interface ILoadingState {
	scale: Animated.Value;
	opacity: Animated.Value;
}

class Loading extends React.PureComponent<ILoadingProps, ILoadingState> {
	state = {
		scale: new Animated.Value(1),
		opacity: new Animated.Value(0)
	};

	private opacityAnimation?: Animated.CompositeAnimation;

	private scaleAnimation?: Animated.CompositeAnimation;

	componentDidMount() {
		const { opacity, scale } = this.state;
		const { visible } = this.props;

		this.opacityAnimation = Animated.timing(opacity, {
			toValue: 1,
			duration: 200,
			useNativeDriver: true
		});
		this.scaleAnimation = Animated.loop(
			Animated.sequence([
				Animated.timing(scale, {
					toValue: 0,
					duration: 1000,
					useNativeDriver: true
				}),
				Animated.timing(scale, {
					toValue: 1,
					duration: 1000,
					useNativeDriver: true
				})
			])
		);

		if (visible) {
			this.startAnimations();
		}
	}

	componentDidUpdate(prevProps: ILoadingProps) {
		const { visible } = this.props;
		if (visible && visible !== prevProps.visible) {
			this.startAnimations();
		}
	}

	componentWillUnmount() {
		if (this.opacityAnimation && this.opacityAnimation.stop) {
			this.opacityAnimation.stop();
		}
		if (this.scaleAnimation && this.scaleAnimation.stop) {
			this.scaleAnimation.stop();
		}
	}

	startAnimations() {
		if (this.opacityAnimation && this.opacityAnimation.start) {
			this.opacityAnimation.start();
		}
		if (this.scaleAnimation && this.scaleAnimation.start) {
			this.scaleAnimation.start();
		}
	}

	render() {
		const { opacity, scale } = this.state;
		const { visible, theme } = this.props;

		const scaleAnimation = scale.interpolate({
			inputRange: [0, 0.5, 1],
			outputRange: [1, 1.1, 1]
		});

		const opacityAnimation = opacity.interpolate({
			inputRange: [0, 1],
			outputRange: [0, themes[theme!].backdropOpacity],
			extrapolate: 'clamp'
		});

		return (
			<Modal visible={visible} transparent onRequestClose={() => {}}>
				<View style={styles.container} testID='loading'>
					<Animated.View
						style={[
							{
								...StyleSheet.absoluteFillObject,
								backgroundColor: themes[theme!].backdropColor,
								opacity: opacityAnimation
							}
						]}
					/>
					<Animated.Image
						source={require('../static/images/logo.png')}
						style={[
							styles.image,
							{
								transform: [
									{
										scale: scaleAnimation
									}
								]
							}
						]}
					/>
				</View>
			</Modal>
		);
	}
}

export default withTheme(Loading);