How to snap pictures using expo react native camera? - react-native

Question

I have just started using React Native with Expo so I am kind of confused. So, I have made a camera component which I imported in the main screen. Everything looks good. But I can't take pictures. I cannot click the snap icon and save the image. Is there a component that I missed?
I have only posted the CameraComponent class below.
Camera.js
class CameraComponent extends Component {
state = {
hasCameraPermission: null,
type: Camera.Constants.Type.back
}
async componentWillMount() {
const { status } = await Permissions.askAsync(Permissions.CAMERA);
this.setState({ hasCameraPermission: status === 'granted' })
}
render() {
const { hasCameraPermission } = this.state
if (hasCameraPermission === null) {
return <View />
}
else if (hasCameraPermission === false) {
return <Text> No access to camera</Text>
}
else {
return (
<View style={{ flex: 1 }}>
<Camera
style={{ flex: 1, justifyContent: 'space-between' }}
type={this.state.type}
>
<Header
searchBar
rounded
style={{
position: 'absolute',
backgroundColor: 'transparent',
left: 0,
top: 0,
right: 0,
zIndex: 100,
alignItems: 'center'
}}
>
<View style={{ flexDirection: 'row', flex: 4 }}>
<Ionicons name="md-camera" style={{ color: 'white' }} />
<Item style={{ backgroundColor: 'transparent' }}>
<Icon name="ios-search" style={{ color: 'white', fontSize: 24, fontWeight: 'bold' }}></Icon>
</Item>
</View>
<View style={{ flexDirection: 'row', flex: 2, justifyContent: 'space-around' }}>
<Icon name="ios-flash" style={{ color: 'white', fontWeight: 'bold' }} />
<Icon
onPress={() => {
this.setState({
type: this.state.type === Camera.Constants.Type.back ?
Camera.Constants.Type.front :
Camera.Constants.Type.back
})
}}
name="ios-reverse-camera"
style={{ color: 'white', fontWeight: 'bold' }}
/>
</View>
</Header>
<View style={{ flexDirection: 'row', justifyContent: 'space-between', paddingHorizontal: 30, marginBottom: 15, alignItems: 'flex-end' }}>
<Ionicons name="ios-map" style={{ color: 'white', fontSize: 36 }}></Ionicons>
<View></View>
<View style={{ alignItems: 'center' }}>
<MaterialCommunityIcons name="circle-outline" // This is the icon which should take and save image
style={{ color: 'white', fontSize: 100 }}
></MaterialCommunityIcons>
<Icon name="ios-images" style={{ color: 'white', fontSize: 36 }} />
</View>
</View>
</Camera>
</View>
)
}
}
}
export default CameraComponent;
The icon in the center i;e circle icon should automatically take and save image.

Answer 1

You can use "onPictureSaved" when the asynchronous takePictureAsync function returns so that you can grab the photo object:
takePicture = () => {
if (this.camera) {
this.camera.takePictureAsync({ onPictureSaved: this.onPictureSaved });
}
};
onPictureSaved = photo => {
console.log(photo);
}
In the view you would have a Camera component that has a ref:
<Camera style={styles.camera} type={this.state.type} ref={(ref) => { this.camera = ref }} >
As well as a button that will call the takePicture function on press:
<TouchableOpacity style={styles.captureButton} onPress={this.takePicture} />

Answer 2

So you need to tell your 'circle icon' to take the picture. First I would add a reference to your camera like so
<Camera style={{ flex: 1 }}
ref={ (ref) => {this.camera = ref} }
type={this.state.type}>
then create a function that actually tells your app to take the photo:
async snapPhoto() {
console.log('Button Pressed');
if (this.camera) {
console.log('Taking photo');
const options = { quality: 1, base64: true, fixOrientation: true,
exif: true};
await this.camera.takePictureAsync(options).then(photo => {
photo.exif.Orientation = 1;
console.log(photo);
});
}
}
Now make your icon have an onPress() to take the photo. I did something like this.
<TouchableOpacity style={styles.captureButton} onPress={this.snapPhoto.bind(this)}>
<Image style={{width: 100, height: 100}} source={require('../assets/capture.png')}
/>
</TouchableOpacity>
You may also want to create a view that renders an image preview or something similar. The Expo documentation has a fairly good example on getting started. Note that Expo creates a cached folder called 'Camera' and that's where the image initially is.

Answer 3

You can do this in a functional component as well using a ref created via a React Hook. Here is an example based on the expo SDK 38 Camera component https://docs.expo.io/versions/v38.0.0/sdk/camera/
import React, { useState, useEffect, useRef } from 'react';
import { Text, View, TouchableOpacity } from 'react-native';
import { Camera } from 'expo-camera';
export default function App() {
const [hasPermission, setHasPermission] = useState(null);
const [type, setType] = useState(Camera.Constants.Type.back);
const ref = useRef(null)
useEffect(() => {
(async () => {
const { status } = await Camera.requestPermissionsAsync();
setHasPermission(status === 'granted');
})();
}, []);
_takePhoto = async () => {
const photo = await ref.current.takePictureAsync()
console.debug(photo)
}
if (hasPermission === null) {
return <View />;
}
if (hasPermission === false) {
return <Text>No access to camera</Text>;
}
return (
<View style={{ flex: 1 }}>
<Camera style={{ flex: 1 }} type={type} ref={ref}>
<View
style={{
flex: 1,
backgroundColor: 'transparent',
flexDirection: 'row',
}}>
<TouchableOpacity
style={{
flex: 0.1,
alignSelf: 'flex-end',
alignItems: 'center',
}}
onPress={() => {
setType(
type === Camera.Constants.Type.back
? Camera.Constants.Type.front
: Camera.Constants.Type.back
);
}}>
<Text style={{ fontSize: 18, marginBottom: 10, color: 'white' }}> Flip </Text>
</TouchableOpacity>
<TouchableOpacity
onPress={_takePhoto}
>
<Text>Snap Photo</Text>
</TouchableOpacity>
</View>
</Camera>
</View>
);
}
I did not check what the UI for that looks like but the main point is to utilize React.useRef and attach the ref to your <Camera/> component. Then you may call ref.current.takePictureAsync to capture and access a new image. Look below to see the important relevant snippets for capturing a photo.
import React from 'react'
/* ... other imports
*/
export default CameraScene = () => {
/* ... other state and permission logic
*/
const ref = useRef(null)
const _takePhoto = async () => {
const photo = await ref.current.takePictureAsync()
console.debug(photo)
}
return (
<Camera style={{flex: 1}} ref={ref}> /* ...
... other ui logic
*/
</Camera>
)
}
Learn more about useRef here https://reactjs.org/docs/hooks-reference.html#useref)

Answer 4

You'll need to add a ref to the Camera class to be able to call it's takePictureAsync function within your own 'handle' method.
cameraRef = React.createRef();
<Camera ref={this.cameraRef}>...</Camera>
Don't forget ".current" when calling the method of the referenced camera.
handlePhoto = async () => {
if(this.cameraRef){
let photo = await this.cameraRef.current.takePictureAsync();
console.log(photo);
}
}
Then simply call your 'handle' method on a touchable element acting as the photo-snap button.
<TouchableOpacity
style={{width:60, height:60, borderRadius:30, backgroundColor:"#fff"}}
onPress={this.handlePhoto} />
You should be able to see the photo logged in your console.

Answer 5

Are you trying to do this on an actual physical device? You can't shoot pictures with an emulator.