import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, TouchableOpacity, View } from 'react-native';
import { Magnetometer } from 'expo-sensors';
export default function Compass() {
const [data, setData] = useState({
x: 0,
y: 0,
z: 0,
});
const [subscription, setSubscription] = useState(null);
const _slow = () => {
Magnetometer.setUpdateInterval(1000);
};
const _fast = () => {
Magnetometer.setUpdateInterval(16);
};
const _subscribe = () => {
setSubscription(
Magnetometer.addListener(result => {
setData(result);
})
);
};
const _unsubscribe = () => {
subscription && subscription.remove();
setSubscription(null);
};
useEffect(() => {
_subscribe();
return () => _unsubscribe();
}, []);
const { x, y, z } = data;
return (
<View style={styles.container}>
<Text style={styles.text}>Magnetometer:</Text>
<Text style={styles.text}>
x: {round(x)} y: {round(y)} z: {round(z)}
</Text>
<View style={styles.buttonContainer}>
<TouchableOpacity onPress={subscription ? _unsubscribe : _subscribe} style={styles.button}>
<Text>{subscription ? 'On' : 'Off'}</Text>
</TouchableOpacity>
<TouchableOpacity onPress={_slow} style={[styles.button, styles.middleButton]}>
<Text>Slow</Text>
</TouchableOpacity>
<TouchableOpacity onPress={_fast} style={styles.button}>
<Text>Fast</Text>
</TouchableOpacity>
</View>
</View>
);
}
%%placeholder-start%%function round() { ... } %%placeholder-end%%function round(n) {
if (!n) {
return 0;
}
return Math.floor(n * 100) / 100;
}
%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: 'center',
paddingHorizontal: 10,
},
text: {
textAlign: 'center',
},
buttonContainer: {
flexDirection: 'row',
alignItems: 'stretch',
marginTop: 15,
},
button: {
flex: 1,
justifyContent: 'center',
alignItems: 'center',
backgroundColor: '#eee',
padding: 10,
},
middleButton: {
borderLeftWidth: 1,
borderRightWidth: 1,
borderColor: '#ccc',
},
});