Book Image

React: Cross-Platform Application Development with React Native

By : Emilio Rodriguez Martinez
Book Image

React: Cross-Platform Application Development with React Native

By: Emilio Rodriguez Martinez

Overview of this book

React Native helps web and mobile developers to build cross-platform apps that perform at the same level as any other natively developed app. The range of apps that can be built using this library is huge. From e-commerce to games, React Native is a good fit for any mobile project due to its flexibility and extendable nature. This project-based book consists of four standalone projects. Each project will help you gain a sound understanding of the framework and build mobile apps with native user experience. Starting with a simple standalone car booking app, you will progressively move on to building advanced apps by adding connectivity with external APIs, using native features, such as the camera or microphone, in the mobile device, integrating with state management libraries such as Redux or MobX, or leveraging React Native’s performance by building a full-featured game. This book is ideal for developers who want to build amazing cross-platform apps with React Native. This book is embedded with useful assessments that will help you revise the concepts you have learned in this book. This book is repurposed for this specific learning experience from the content of Packt's React Native Blueprints by Emilio Rodriguez Martinez.
Table of Contents (8 chapters)

ConfirmationModal


Our last component is a modal view, which will be opened once the user has pressed on the SET PICKUP LOCATION button on the location pin. We will display the modal and a custom activity indicator, which will use a complex animation setup to continuously rotate in its position:

/** * src/components/ConfirmationModal.js ***/

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

export default class ConfirmationModal extends React.Component {
  componentWillMount() {
    this._animatedValue = new Animated.Value(0);
  }

cycleAnimation() {
    Animated.sequence([
      Animated.timing(this._animatedValue, {
        toValue: 100,
        duration: 1000,
        easing: Easing.linear,
      }),
      Animated.timing(this._animatedValue, {
        toValue: 0,
        duration: 0,
      }),
    ]).start(() => {
      this.cycleAnimation();
    });
  }

componentDidMount() {
    this.cycleAnimation();
  }

  render() {
const interpolatedRotateAnimation = this._animatedValue.interpolate({
      inputRange: [0, 100],
      outputRange: ['0deg', '360deg'],
    });

    return (
<Modal
        animationType={'fade'}
        visible={this.props.visible}
        transparent={true}
      >
        <View style={styles.overlay}>
          <View style={styles.container}>
            <Text style={styles.title}>Contacting nearest car...</Text>
<Animated.Image
              style={[
                styles.spinner,
                { transform: [{ rotate: interpolatedRotateAnimation }] },
              ]}
              source={require('../../img/loading.png')}
            />
            <TouchableOpacity
              style={styles.closeButton}
              onPress={this.props.onClose}
            >
              <Text style={styles.closeButtonText}>X</Text>
            </TouchableOpacity>
          </View>
        </View>
      </Modal>
    );
  }
}

const styles = StyleSheet.create({
  overlay: {
    flex: 1,
    backgroundColor: '#0006',
    justifyContent: 'center',
  },
  container: {
    backgroundColor: 'white',
    alignSelf: 'center',
    padding: 20,
    borderColor: '#ccc',
    borderWidth: 1,
  },
  title: {
    textAlign: 'right',
    fontFamily: 'Blair ITC',
    paddingTop: 5,
    fontSize: 12,
  },
  spinner: {
    resizeMode: 'contain',
    height: 50,
    width: 50,
    margin: 50,
    alignSelf: 'center',
  },
  closeButton: {
    backgroundColor: '#333',
    width: 40,
    height: 40,
    borderRadius: 20,
    justifyContent: 'center',
    alignSelf: 'center',
  },
  closeButtonText: {
    color: 'white',
    alignSelf: 'center',
    fontSize: 20,
  },
});

For this component, we are using the <Modal /> component available in React Native to take advantage of its fade animation and visibility capabilities. The property this.props.visible will drive the visibility of this component as it is the parent who is aware of the pickup request from the user.

Let's focus again on animations as we want to do a more complex setup for the spinner showing activity. We want to display an endless rotating animation, so we need to systematically call our start() animation method. In order to achieve this, we created a cycleAnimation() method, which is called on the component mount (to get the animation started) and from the Animated.timing returned object as it is passed as a callback to be invoked every time the animation ends.

We are also using Animated.sequence to concatenate two animations:

  • Moving from 0 degrees to 360 (in one second using a linear easing)

  • Moving from 360 degrees to 0 (in 0 seconds)

This is required to repeat the first animation over at the end of each cycle.

Finally, we defined a variable named interpolatedRotateAnimation to store the interpolation from 0 degrees to 360, so it can be passed to the transform/rotate style defining what are going to be the available rotation values when animating our Animated.Image.

As an experiment, we can try and change loading.png with an alternative image and see how it gets animated. This can be easily achieved by replacing the source property in our <Animated.Image /> component:

...            

            <Animated.Image
              style={[
                styles.spinner,
                { transform: [{ rotate: interpolatedRotateAnimation }] },
              ]}
source={require('../../img/spinner.png')}
            />

...