react nativeでwindow sizeを取得して画面いっぱいまで画像を拡大表示する

App.js

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

var Dimensions = require('Dimensions');
var { width, height, scale } = Dimensions.get('window'); //get window size

import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View,
  ImageBackground
} from 'react-native';

type Props = {};
export default class App extends Component<Props> {
  render() {
    return (
      <View>
        <ImageBackground style={{width: width, height: height}} source={require('./images/wallpaper.jpg')}>
          <Text style={styles.welcome}>
            Welcome to React Native!
          </Text>
        </ImageBackground>
      </View>
    );
  }
}


const styles = StyleSheet.create({
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    color: '#FFFFFF',
    margin: 10,
  },
});