如何在 React Native 中使用 expo-camera 捕捉图像
how to capture image using expo-camera in react native
我是 react-native 的新手。我创建了一个应用程序。但现在我想从这个应用程序中捕获图像。我从世博会网站上得到了代码但问题是这段代码只能打开相机。我想通过那台相机捕捉图像。所以如果可能请帮助我..
这是我的代码
import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, TouchableOpacity } from 'react-native';
import { Camera } from 'expo-camera';
import { Ionicons } from '@expo/vector-icons';
export default function App({navigation}) {
const [hasPermission, setHasPermission] = useState(null);
const [type, setType] = useState(Camera.Constants.Type.back);
useEffect(() => {
(async () => {
const { status } = await Camera.requestPermissionsAsync();
setHasPermission(status === 'granted');
})();
}, []);
if (hasPermission === null) {
return <View />;
}
if (hasPermission === false) {
return <Text>No access to camera</Text>;
}
return (
<View style={styles.container}>
<View style={styles.header}>
<Ionicons style={{paddingLeft:20}} name="arrow-back" size={40}
color="black" onPress={() => navigation.navigate("OtherInfo")} />
<Text style={{fontSize:20, paddingLeft: 70, paddingTop: 10}}>Get Image</Text>
</View>
<Camera style={styles.camera} type={type}>
<View style={styles.buttonContainer}>
<TouchableOpacity
style={styles.button}
onPress={() => {
setType(
type === Camera.Constants.Type.back
? Camera.Constants.Type.front
: Camera.Constants.Type.back
);
}}>
<Text style={styles.text}> Flip </Text>
</TouchableOpacity>
</View>
</Camera>
</View>
);
}
const styles = StyleSheet.create({
camera:{
height:500
},
header:{
flexDirection: 'row'
}
});
这是一个小应用程序的工作示例,它从相机和图库中获取照片,并在点击或选择后显示给它
工作应用程序:Expo Snack
import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, Button, Image } from 'react-native';
import { Camera } from 'expo-camera';
import * as ImagePicker from 'expo-image-picker';
export default function Add({ navigation }) {
const [cameraPermission, setCameraPermission] = useState(null);
const [galleryPermission, setGalleryPermission] = useState(null);
const [camera, setCamera] = useState(null);
const [imageUri, setImageUri] = useState(null);
const [type, setType] = useState(Camera.Constants.Type.back);
const permisionFunction = async () => {
// here is how you can get the camera permission
const cameraPermission = await Camera.requestPermissionsAsync();
setCameraPermission(cameraPermission.status === 'granted');
const imagePermission = await ImagePicker.getMediaLibraryPermissionsAsync();
console.log(imagePermission.status);
setGalleryPermission(imagePermission.status === 'granted');
if (
imagePermission.status !== 'granted' &&
cameraPermission.status !== 'granted'
) {
alert('Permission for media access needed.');
}
};
useEffect(() => {
permisionFunction();
}, []);
const takePicture = async () => {
if (camera) {
const data = await camera.takePictureAsync(null);
console.log(data.uri);
setImageUri(data.uri);
}
};
const pickImage = async () => {
let result = await ImagePicker.launchImageLibraryAsync({
mediaTypes: ImagePicker.MediaTypeOptions.Images,
allowsEditing: true,
aspect: [1, 1],
quality: 1,
});
console.log(result);
if (!result.cancelled) {
setImageUri(result.uri);
}
};
return (
<View style={styles.container}>
<View style={styles.cameraContainer}>
<Camera
ref={(ref) => setCamera(ref)}
style={styles.fixedRatio}
type={type}
ratio={'1:1'}
/>
</View>
<Button title={'Take Picture'} onPress={takePicture} />
<Button title={'Gallery'} onPress={pickImage} />
{imageUri && <Image source={{ uri: imageUri }} style={{ flex: 1 }} />}
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
},
cameraContainer: {
flex: 1,
flexDirection: 'row',
},
fixedRatio: {
flex: 1,
aspectRatio: 1,
},
button: {
flex: 0.1,
padding: 10,
alignSelf: 'flex-end',
alignItems: 'center',
},
});
我是 react-native 的新手。我创建了一个应用程序。但现在我想从这个应用程序中捕获图像。我从世博会网站上得到了代码但问题是这段代码只能打开相机。我想通过那台相机捕捉图像。所以如果可能请帮助我..
这是我的代码
import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, TouchableOpacity } from 'react-native';
import { Camera } from 'expo-camera';
import { Ionicons } from '@expo/vector-icons';
export default function App({navigation}) {
const [hasPermission, setHasPermission] = useState(null);
const [type, setType] = useState(Camera.Constants.Type.back);
useEffect(() => {
(async () => {
const { status } = await Camera.requestPermissionsAsync();
setHasPermission(status === 'granted');
})();
}, []);
if (hasPermission === null) {
return <View />;
}
if (hasPermission === false) {
return <Text>No access to camera</Text>;
}
return (
<View style={styles.container}>
<View style={styles.header}>
<Ionicons style={{paddingLeft:20}} name="arrow-back" size={40}
color="black" onPress={() => navigation.navigate("OtherInfo")} />
<Text style={{fontSize:20, paddingLeft: 70, paddingTop: 10}}>Get Image</Text>
</View>
<Camera style={styles.camera} type={type}>
<View style={styles.buttonContainer}>
<TouchableOpacity
style={styles.button}
onPress={() => {
setType(
type === Camera.Constants.Type.back
? Camera.Constants.Type.front
: Camera.Constants.Type.back
);
}}>
<Text style={styles.text}> Flip </Text>
</TouchableOpacity>
</View>
</Camera>
</View>
);
}
const styles = StyleSheet.create({
camera:{
height:500
},
header:{
flexDirection: 'row'
}
});
这是一个小应用程序的工作示例,它从相机和图库中获取照片,并在点击或选择后显示给它
工作应用程序:Expo Snack
import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, Button, Image } from 'react-native';
import { Camera } from 'expo-camera';
import * as ImagePicker from 'expo-image-picker';
export default function Add({ navigation }) {
const [cameraPermission, setCameraPermission] = useState(null);
const [galleryPermission, setGalleryPermission] = useState(null);
const [camera, setCamera] = useState(null);
const [imageUri, setImageUri] = useState(null);
const [type, setType] = useState(Camera.Constants.Type.back);
const permisionFunction = async () => {
// here is how you can get the camera permission
const cameraPermission = await Camera.requestPermissionsAsync();
setCameraPermission(cameraPermission.status === 'granted');
const imagePermission = await ImagePicker.getMediaLibraryPermissionsAsync();
console.log(imagePermission.status);
setGalleryPermission(imagePermission.status === 'granted');
if (
imagePermission.status !== 'granted' &&
cameraPermission.status !== 'granted'
) {
alert('Permission for media access needed.');
}
};
useEffect(() => {
permisionFunction();
}, []);
const takePicture = async () => {
if (camera) {
const data = await camera.takePictureAsync(null);
console.log(data.uri);
setImageUri(data.uri);
}
};
const pickImage = async () => {
let result = await ImagePicker.launchImageLibraryAsync({
mediaTypes: ImagePicker.MediaTypeOptions.Images,
allowsEditing: true,
aspect: [1, 1],
quality: 1,
});
console.log(result);
if (!result.cancelled) {
setImageUri(result.uri);
}
};
return (
<View style={styles.container}>
<View style={styles.cameraContainer}>
<Camera
ref={(ref) => setCamera(ref)}
style={styles.fixedRatio}
type={type}
ratio={'1:1'}
/>
</View>
<Button title={'Take Picture'} onPress={takePicture} />
<Button title={'Gallery'} onPress={pickImage} />
{imageUri && <Image source={{ uri: imageUri }} style={{ flex: 1 }} />}
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
},
cameraContainer: {
flex: 1,
flexDirection: 'row',
},
fixedRatio: {
flex: 1,
aspectRatio: 1,
},
button: {
flex: 0.1,
padding: 10,
alignSelf: 'flex-end',
alignItems: 'center',
},
});