• Szerző: Sallai András
• Copyright © Sallai András, 2023
• Licenc: CC Attribution-Share Alike 4.0 International
• Web: https://szit.hu

A BarCodeScanner telepítése:

npx expo install expo-barcode-scanner

A következő példa egy másolat a következő oldalról, magyar nyelvre átírva:

• https://docs.expo.dev/versions/v48.0.0/sdk/bar-code-scanner/

App.js

import { BarCodeScanner } from 'expo-barcode-scanner';
import { StatusBar } from 'expo-status-bar';
import { useEffect, useState } from 'react';
import { Button, StyleSheet, Text, View } from 'react-native';
 
export default function App() {
 
  const [hasPermission, setHasPermission] = useState(null);
  const [scanned, setScanned] = useState(false);
 
  useEffect(() => {
    const getBarCodeScannerPermissions = async () => {
      const { status } = await BarCodeScanner.requestPermissionsAsync();
      setHasPermission(status === 'granted');
    };
    getBarCodeScannerPermissions();
  }, []);
 
  const handleBarCodeScanned = ({ type, data }) => {
    setScanned(true);
    alert(`A vonalkód típusa ${type}\nAz olvasott adat: ${data}`);
  };
 
  if (hasPermission === null) {
    return <Text>Szükséges a kamerához hozzáférés</Text>;
  }
  if (hasPermission === false) {
    return <Text>A kamera nem elérhető</Text>;
  }  
 
  return (
    <View style={styles.container}>
      <BarCodeScanner
        onBarCodeScanned={scanned ? undefined : handleBarCodeScanned}
        style={StyleSheet.absoluteFillObject}
      />
 
      {scanned && <Button title={'Koppints az újabb szkenneléshez'} onPress={() => setScanned(false)} />}
 
 
      <StatusBar style="auto" />
    </View>
  );
}
 
const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

A kamera-olvasó nem jelenik meg azonnal. Gombnyomásra indul.

App.js

import { BarCodeScanner } from 'expo-barcode-scanner';
import { StatusBar } from 'expo-status-bar';
import { useEffect, useState } from 'react';
import { Button, StyleSheet, Text, View } from 'react-native';
 
export default function App() {
 
  const [hasPermission, setHasPermission] = useState(null);
  const [scanned, setScanned] = useState(false);
  const [scanning, setScanning] = useState(false);
 
  useEffect(() => {
    const getBarCodeScannerPermissions = async () => {
      const { status } = await BarCodeScanner.requestPermissionsAsync();
      setHasPermission(status === 'granted');
    };
 
    getBarCodeScannerPermissions();
  }, []);
 
  const handleBarCodeScanned = ({ type, data }) => {
    setScanned(true);
    alert(`A vonalkód típusa ${type}\nAz olvasott adat: ${data}`);
  };
 
  if (hasPermission === null) {
    return <Text>Szükséges a kamerához hozzáférés</Text>;
  }
  if (hasPermission === false) {
    return <Text>A kamera nem elérhető</Text>;
  }  
 
  return (
    <View style={styles.container}>
      <Text>A "Szkennelés" gombra kattintva elindual a QR-kód szkenner.</Text>
      <Button title={'Szkennelés'} onPress={() => setScanning(true)}/>
      {
        scanning &&
        <BarCodeScanner
          onBarCodeScanned={scanned ? undefined : handleBarCodeScanned}
          style={StyleSheet.absoluteFillObject}
        />
      }
      {(scanned && scanning) && <Button title={'Tap to Scan Again'} onPress={() => setScanned(false)} />}
      {scanning && <Button title={'Bezár'} onPress={() => setScanning(false)} />}
 
      <StatusBar style="auto" />
    </View>
  );
}
 
const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

• https://www.qrcode.com/en/ (2023)