[英]react native bar code reader is not working correctly?
問題:
我創建了一個反應原生應用程序。 我正在使用expo-barcode-scanner。 這就是我的代碼的組織方式。
import React, { Component } from "react";
import {
View,
Text,
StyleSheet,
TouchableOpacity,
Image,
TextInput,
ScrollView,
KeyboardAvoidingView,
} from "react-native";
import Dimensions from "Dimensions";
import * as Permissions from "expo-permissions";
import { BarCodeScanner } from "expo-barcode-scanner";
class Home extends Component {
constructor(props) {
super(props);
this.state = {
QrPress: false,
hasCameraPermission: null,
};
}
componentDidMount() {
this.getPermissionsAsync();
}
getPermissionsAsync = async () => {
const { status } = await Permissions.askAsync(Permissions.CAMERA);
this.setState({ hasCameraPermission: status === "granted" });
};
_onPress_QrScan() {
this.setState({
QrPress: true
});
}
handleBarCodeScanned = ({ type, data }) => {
this.setState({ QrPress: false, scanned: true, lastScannedUrl: data });
};
renderBarcodeReader() {
const { hasCameraPermission, scanned } = this.state;
if (hasCameraPermission === null) {
return <Text>Requesting for camera permission</Text>;
}
if (hasCameraPermission === false) {
return <Text>No access to camera</Text>;
}
return (
<View
style={{
flex: 1,
flexDirection: "column",
justifyContent: "flex-end"
}}
>
<BarCodeScanner
onBarCodeScanned={scanned ? undefined : this.handleBarCodeScanned}
style={StyleSheet.absoluteFillObject}
/>
{scanned && (
<Button
title={"Tap to Scan Again"}
onPress={() => this.setState({ scanned: false })}
/>
)}
</View>
);
}
render() {
const { hasCameraPermission, scanned, QrPress } = this.state;
let marker = null;
if (this.state.locationChosen) {
marker = <MapView.Marker coordinate={this.state.focusedLocation} />;
}
return (
<View style={{}}>
<KeyboardAvoidingView behavior="padding" enabled>
<ScrollView>
<TouchableOpacity
onPress={() => {
this._onPress_QrScan();
}}
activeOpacity={3}
>
<Text style={styles.viewDetails}>Scan QR</Text>
</TouchableOpacity>
{QrPress ? (
<React.Fragment>{this.renderBarcodeReader()}</React.Fragment>
) : (
null
)}
</ScrollView>
</KeyboardAvoidingView>
</View>
);
}
}
const DEVICE_WIDTH = Dimensions.get("window").width;
const DEVICE_HEIGHT = Dimensions.get("window").height;
const styles = StyleSheet.create({
container: {
top: 0,
flex: 3
},
map: {
flex: 1,
height: 130
},
homeHeader: {
flexDirection: "column",
flex: 1
},
homeHeaderImage: {
flexDirection: "row"
},
homeHederText: {
fontSize: 18,
fontWeight: "bold",
fontStyle: "normal",
fontFamily: "sans-serif",
letterSpacing: 0.81,
color: "#000104",
marginTop: "2%",
marginLeft: "40%",
marginRight: "3%"
},
hederContentContainer: {
flexDirection: "row",
marginTop: "30%",
marginBottom: "10%"
},
qrCodeGeneraterContainer: {
alignItems: "center",
justifyContent: "center"
},
});
export default Home;
但是當我在我的 android 手機上使用 expo 客戶端打開應用程序時。 它不會呈現條形碼閱讀器。 這意味着它沒有打開相機掃描二維碼。 它只顯示一個空白的白色背景。 我嘗試了很多來找出解決這個問題的方法。 不幸的是,我對這個問題無能為力。 有人可以幫我解決這個問題嗎? 謝謝你。
你的組件有很多問題。 請使用以下代碼並根據您的要求更新樣式等。
import React, { Component } from "react";
import {
View,
Text,
StyleSheet,
TouchableOpacity,
Image,
TextInput,
ScrollView,
KeyboardAvoidingView,
Dimensions,
Button,
} from "react-native";
import MapView from 'react-native-maps';
import * as Permissions from "expo-permissions";
import { BarCodeScanner } from "expo-barcode-scanner";
class Home extends Component {
constructor(props) {
super(props);
this.state = {
QrPress: false,
hasCameraPermission: null,
};
}
componentDidMount() {
this.getPermissionsAsync();
}
getPermissionsAsync = async () => {
const { status } = await Permissions.askAsync(Permissions.CAMERA);
this.setState({ hasCameraPermission: status === "granted" });
};
_onPress_QrScan = () => {
this.setState({
QrPress: true
});
}
handleBarCodeScanned = ({ type, data }) => {
this.setState({ QrPress: false, scanned: true, lastScannedUrl: data });
};
renderBarcodeReader = () => {
const { hasCameraPermission, scanned } = this.state;
if (hasCameraPermission === null) {
return <Text>Requesting for camera permission</Text>;
}
if (hasCameraPermission === false) {
return <Text>No access to camera</Text>;
}
return (
<View
style={{
flex: 1,
flexDirection: "column",
justifyContent: "flex-end",
}}
>
<BarCodeScanner
onBarCodeScanned={scanned ? undefined : this.handleBarCodeScanned}
style={{ flex:1, ...StyleSheet.absoluteFillObject}}
/>
{scanned && (
<Button
title={"Tap to Scan Again"}
onPress={() => this.setState({ scanned: false })}
/>
)}
</View>
);
}
render() {
const { hasCameraPermission, scanned, QrPress } = this.state;
let marker = null;
if (this.state.locationChosen) {
marker = <MapView.Marker coordinate={this.state.focusedLocation} />;
}
return (
<View style={{flex:1}}>
<KeyboardAvoidingView behavior="padding" enabled style={{flex:1}}>
<ScrollView contentContainerStyle={{flexGrow: 1}} >
{QrPress ? (
<View style={{flex:1}}>
{this.renderBarcodeReader()}
</View>
) : (
<View style={{flex:1, justifyContent:'center', alignItems:'center'}}>
<TouchableOpacity
onPress={this._onPress_QrScan}
activeOpacity={3}
>
<Text style={styles.viewDetails}>Scan QR</Text>
</TouchableOpacity>
</View>
)}
</ScrollView>
</KeyboardAvoidingView>
</View>
);
}
}
const DEVICE_WIDTH = Dimensions.get("window").width;
const DEVICE_HEIGHT = Dimensions.get("window").height;
const styles = StyleSheet.create({
container: {
top: 0,
flex: 3
},
map: {
flex: 1,
height: 130
},
homeHeader: {
flexDirection: "column",
flex: 1
},
homeHeaderImage: {
flexDirection: "row"
},
homeHederText: {
fontSize: 18,
fontWeight: "bold",
fontStyle: "normal",
fontFamily: "sans-serif",
letterSpacing: 0.81,
color: "#000104",
marginTop: "2%",
marginLeft: "40%",
marginRight: "3%"
},
hederContentContainer: {
flexDirection: "row",
marginTop: "30%",
marginBottom: "10%"
},
qrCodeGeneraterContainer: {
alignItems: "center",
justifyContent: "center"
},
});
export default Home;
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