Expo CameraA React component that renders a preview for the device's front or back camera.
expo-camera provides a React component that renders a preview of the device's front or back camera. The camera's parameters such as zoom, torch, and flash mode are adjustable. Using CameraView, you can take photos and record videos that are saved to the app's cache. The component is also capable of detecting bar codes appearing in the preview. Run the example on your device to see all these features working together.
Installation
- npx expo install expo-cameraIf you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.
Configuration in app.json/app.config.js
You can configure expo-camera using its built-in config plugin if you use config plugins in your project (EAS Build or npx expo run:[android|ios]). The plugin allows you to configure various properties that cannot be set at runtime and require building a new app binary to take effect.
Example app.json with config plugin
{
"expo": {
"plugins": [
[
"expo-camera",
{
"cameraPermission": "Allow $(PRODUCT_NAME) to access your camera",
"microphonePermission": "Allow $(PRODUCT_NAME) to access your microphone",
"recordAudioAndroid": true
}
]
]
}
}
Configurable properties
| Name | Default | Description |
|---|---|---|
cameraPermission | "Allow $(PRODUCT_NAME) to access your camera" | Only for: iOS A string to set the |
microphonePermission | "Allow $(PRODUCT_NAME) to access your microphone" | Only for: iOS A string to set the |
recordAudioAndroid | true | Only for: Android A boolean that determines whether to enable the |
Are you using this library in a bare React Native app?
Learn how to configure the native projects in the installation instructions in the expo-camera repository.
Usage
Only one Camera preview can be active at any given time. If you have multiple screens in your app, you should unmountCameracomponents whenever a screen is unfocused.
import { CameraView, CameraType, useCameraPermissions } from 'expo-camera';
import { useState } from 'react';
import { Button, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
export default function App() {
const [facing, setFacing] = useState<CameraType>('back');
const [permission, requestPermission] = useCameraPermissions();
if (!permission) {
// Camera permissions are still loading.
return <View />;
}
if (!permission.granted) {
// Camera permissions are not granted yet.
return (
<View style={styles.container}>
<Text style={styles.message}>We need your permission to show the camera</Text>
<Button onPress={requestPermission} title="grant permission" />
</View>
);
}
function toggleCameraFacing() {
setFacing(current => (current === 'back' ? 'front' : 'back'));
}
return (
<View style={styles.container}>
<CameraView style={styles.camera} facing={facing}>
<View style={styles.buttonContainer}>
<TouchableOpacity style={styles.button} onPress={toggleCameraFacing}>
<Text style={styles.text}>Flip Camera</Text>
</TouchableOpacity>
</View>
</CameraView>
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: 'center',
},
message: {
textAlign: 'center',
paddingBottom: 10,
},
camera: {
flex: 1,
},
buttonContainer: {
flex: 1,
flexDirection: 'row',
backgroundColor: 'transparent',
margin: 64,
},
button: {
flex: 1,
alignSelf: 'flex-end',
alignItems: 'center',
},
text: {
fontSize: 24,
fontWeight: 'bold',
color: 'white',
},
});
Web support
Most browsers support a version of web camera functionality, you can check out the web camera browser support here. Image URIs are always returned as base64 strings because local file system paths are unavailable in the browser.
Chrome iframe usage
When using Chrome versions 64+, if you try to use a web camera in a cross-origin iframe nothing will render. To add support for cameras in your iframe simply add the attribute allow="microphone; camera;" to the iframe element:
<iframe src="..." allow="microphone; camera;">
<!-- <CameraView /> -->
</iframe>
API
import { CameraView } from 'expo-camera';
Component
Type: React.Component<CameraViewProps>
boolean • Default: trueA boolean that determines whether the camera should be active. Useful in situations where the camera may not have unmounted but you still want to stop the camera session.
boolean • Default: trueA boolean that determines whether the camera shutter animation should be enabled.
BarcodeSettingsExample
<CameraView
barcodeScannerSettings={{
barcodeTypes: ["qr"],
}}
/>
boolean • Default: falseA boolean to enable or disable the torch.
CameraType • Default: 'back'Camera facing. Use one of CameraType. When front, use the front-facing camera.
When back, use the back-facing camera.
FlashMode • Default: 'off'Camera flash mode. Use one of FlashMode values. When on, the flash on your device will
turn on when taking a picture. When off, it won't. Setting it to auto will fire flash if required.
boolean • Default: falseA boolean that determines whether the camera should mirror the image when using the front camera.
CameraMode • Default: 'picture'Used to select image or video output.
boolean • Default: falseIf present, video will be recorded with no sound.
(scanningResult: BarcodeScanningResult) => voidCallback that is invoked when a barcode has been successfully scanned. The callback is provided with
an object of the BarcodeScanningResult shape, where the type
refers to the barcode type that was scanned, and the data is the information encoded in the barcode
(in this case of QR codes, this is often a URL). See BarcodeType for supported values.
() => voidCallback invoked when camera preview has been set.
(event: CameraMountError) => voidCallback invoked when camera preview could not start.
(event: ResponsiveOrientationChanged) => voidCallback invoked when responsive orientation changes. Only applicable if responsiveOrientationWhenOrientationLocked is true.
stringA string representing the size of pictures takePictureAsync will take.
Available sizes can be fetched with getAvailablePictureSizesAsync.
Setting this prop will cause the ratio prop to be ignored as the aspect ratio is determined by the selected size.
CameraRatioA string representing the aspect ratio of the preview. For example, 4:3 and 16:9.
Note: Setting the aspect ratio here will change the scaleType of the camera preview from FILL to FIT.
Also, when using 1:1, devices only support certain sizes. If you specify an unsupported size, the closest supported ratio will be used.
booleanWhether to allow responsive orientation of the camera when the screen orientation is locked (that is, when set to true,
landscape photos will be taken if the device is turned that way, even if the app or device orientation is locked to portrait).
numberThe bitrate of the video recording in bits per second.
Note: On iOS, you must specify the video codec when calling recordAsync to use this option.
Example
10_000_000
VideoQualitySpecify the quality of the recorded video. Use one of VideoQuality possible values:
for 16:9 resolution 2160p, 1080p, 720p, 480p : Android only and for 4:3 4:3 (the size is 640x480).
If the chosen quality is not available for a device, the highest available is chosen.
VideoStabilizationThe video stabilization mode used for a video recording. Use one of VideoStabilization.<value>.
You can read more about each stabilization type in Apple Documentation.
number • Default: 0A value between 0 and 1 being a percentage of device's max zoom, where 0 means not zoomed and 1 means maximum zoom.
Inherited Props
Static Methods
Queries the device for the available video codecs that can be used in video recording.
A promise that resolves to a list of strings that represents available codecs.
Check whether the current device has a camera. This is useful for web and simulators cases. This isn't influenced by the Permissions API (all platforms), or HTTP usage (in the browser). You will still need to check if the native permission has been accepted.
Promise<boolean>
| Parameter | Type |
|---|---|
| options (optional) | ScanningOptions |
Presents a modal view controller that uses the DataScannerViewController available on iOS 16+.
Promise<void>
| Parameter | Type | Description |
|---|---|---|
| listener | (event: ScanningResult) => void | Invoked with the ScanningResult when a bar code has been successfully scanned. |
Invokes the listener function when a bar code has been successfully scanned. The callback is provided with
an object of the ScanningResult shape, where the type refers to the bar code type that was scanned and the data is the information encoded in the bar code
(in this case of QR codes, this is often a URL). See BarcodeType for supported values.
EventSubscription
Component Methods
Get picture sizes that are supported by the device.
Promise<string[]>
Returns a Promise that resolves to an array of strings representing picture sizes that can be passed to pictureSize prop.
The list varies across Android devices but is the same for every iOS.
Pauses the camera preview. It is not recommended to use takePictureAsync when preview is paused.
Promise<void>
| Parameter | Type | Description |
|---|---|---|
| options (optional) | CameraRecordingOptions | A map of |
Starts recording a video that will be saved to cache directory. Videos are rotated to match device's orientation. Flipping camera during a recording results in stopping it.
Promise<undefined | {
uri: string
}>
Returns a Promise that resolves to an object containing video file uri property and a codec property on iOS.
The Promise is returned if stopRecording was invoked, one of maxDuration and maxFileSize is reached or camera preview is stopped.
| Parameter | Type | Description |
|---|---|---|
| options (optional) | CameraPictureOptions | An object in form of |
Takes a picture and saves it to app's cache directory. Photos are rotated to match device's orientation
(if options.skipProcessing flag is not enabled) and scaled to match the preview.
Note: Make sure to wait for the
onCameraReadycallback before calling this method.
Promise<undefined | CameraCapturedPicture>
Returns a Promise that resolves to CameraCapturedPicture object, where uri is a URI to the local image file on Android,
iOS, and a base64 string on web (usable as the source for an Image element). The width and height properties specify
the dimensions of the image.
base64 is included if the base64 option was truthy, and is a string containing the JPEG data
of the image in Base64. Prepend it with 'data:image/jpg;base64,' to get a data URI, which you can use as the source
for an Image element for example.
exif is included if the exif option was truthy, and is an object containing EXIF
data for the image. The names of its properties are EXIF tags and their values are the values for those tags.
On native platforms, the local image URI is temporary. Use
FileSystem.copyAsyncto make a permanent copy of the image.
Note: Avoid calling this method while the preview is paused. On Android, this will throw an error. On iOS, this will take a picture of the last frame that is currently on screen.
Hooks
| Parameter | Type |
|---|---|
| options (optional) | PermissionHookOptions<object> |
[null | PermissionResponse, RequestPermissionMethod<PermissionResponse>, GetPermissionMethod<PermissionResponse>]
| Parameter | Type |
|---|---|
| options (optional) | PermissionHookOptions<object> |
[null | PermissionResponse, RequestPermissionMethod<PermissionResponse>, GetPermissionMethod<PermissionResponse>]
Methods
| Parameter | Type | Description |
|---|---|---|
| url | string | URL to get the image from. |
| barcodeTypes (optional) | BarcodeType[] | An array of bar code types. Defaults to all supported bar code types on the platform.
|
Scan bar codes from the image at the given URL.
A possibly empty array of objects of the BarcodeScanningResult shape, where the type
refers to the barcode type that was scanned and the data is the information encoded in the barcode.
Interfaces
An object obtained by permissions get and request functions.
PermissionResponse Properties
| Name | Type | Description |
|---|---|---|
| canAskAgain | boolean | Indicates if user can be asked again for specific permission. If not, one should be directed to the Settings app in order to enable/disable the permission. |
| expires | PermissionExpiration | Determines time when the permission expires. |
| granted | boolean | A convenience boolean that indicates if the permission is granted. |
| status | PermissionStatus | Determines the status of the permission. |
Types
| Name | Type | Description |
|---|---|---|
| origin | BarcodePoint | The origin point of the bounding box. |
| size | BarcodeSize | The size of the bounding box. |
Type: Point
These coordinates are represented in the coordinate space of the camera source (e.g. when you are using the camera view, these values are adjusted to the dimensions of the view).
| Name | Type | Description |
|---|---|---|
| bounds | BarcodeBounds | The |
| cornerPoints | BarcodePoint[] | Corner points of the bounding box.
|
| data | string | The parsed information encoded in the barcode. |
| type | string | The barcode type. |
| Name | Type | Description |
|---|---|---|
| barcodeTypes | BarcodeType[] | - |
Literal Type: string
The available barcode types that can be scanned.
Acceptable values are: 'aztec' | 'ean13' | 'ean8' | 'qr' | 'pdf417' | 'upc_e' | 'datamatrix' | 'code39' | 'code93' | 'itf14' | 'codabar' | 'code128' | 'upc_a'
| Name | Type | Description |
|---|---|---|
| base64 (optional) | string | A Base64 representation of the image. |
| exif (optional) | Partial<MediaTrackSettings> | any | On Android and iOS this object may include various fields based on the device and operating system.
On web, it is a partial representation of the |
| height | number | Captured image height. |
| uri | string | On web, the value of |
| width | number | Captured image width. |
Literal Type: string
Acceptable values are: 'portrait' | 'portraitUpsideDown' | 'landscapeLeft' | 'landscapeRight'
| Name | Type | Description |
|---|---|---|
| additionalExif (optional) | Record<string, any> | Only for: Android iOS Additional EXIF data to be included for the image. Only useful when |
| base64 (optional) | boolean | Whether to also include the image data in Base64 format. |
| exif (optional) | boolean | Whether to also include the EXIF data for the image. |
| imageType (optional) | ImageType | - |
| isImageMirror (optional) | boolean | - |
| mirror (optional) | boolean |
Android iOS When set to Default: false |
| onPictureSaved (optional) | (picture: CameraCapturedPicture) => void | A callback invoked when picture is saved. If set, the promise of this method will resolve immediately with no data after picture is captured. The data that it should contain will be passed to this callback. If displaying or processing a captured photo right after taking it is not your case, this callback lets you skip waiting for it to be saved. |
| quality (optional) | number | Specify the compression quality from |
| scale (optional) | number | - |
| shutterSound (optional) | boolean | To programmatically disable the camera shutter sound Default: true |
| skipProcessing (optional) | boolean | If set to
|
| Name | Type | Description |
|---|---|---|
| codec (optional) | VideoCodec | Only for: iOS This option specifies what codec to use when recording the video. See |
| maxDuration (optional) | number | Maximum video duration in seconds. |
| maxFileSize (optional) | number | Maximum video file size in bytes. |
| mirror (optional) | boolean |
If |
Literal Type: string
This option specifies the mode of focus on the device.
on- Indicates that the device should autofocus once and then lock the focus.off- Indicates that the device should automatically focus when needed.
Acceptable values are: 'on' | 'off'
Literal Type: multiple types
Permission expiration time. Currently, all permissions are granted permanently.
Acceptable values are: 'never' | number
Literal Type: multiple types
Acceptable values are: PermissionHookBehavior | Options
| Name | Type | Description |
|---|---|---|
| orientation | CameraOrientation | - |
| Name | Type | Description |
|---|---|---|
| barcodeTypes | BarcodeType[] | The type of codes to scan for. |
| isGuidanceEnabled (optional) | boolean | Guidance text, such as “Slow Down,” appears over the live video. Default: true |
| isHighlightingEnabled (optional) | boolean | Indicates whether the scanner displays highlights around recognized items. Default: false |
| isPinchToZoomEnabled (optional) | boolean | Indicates whether people can use a two-finger pinch-to-zoom gesture. Default: true |
Type: Omit<BarcodeScanningResult, 'bounds'>
A subscription object that allows to conveniently remove an event listener from the emitter.
| Name | Type | Description |
|---|---|---|
| remove | () => void | Removes an event listener for which the subscription has been created. After calling this function, the listener will no longer receive any events from the emitter. |
Literal Type: string
This option specifies what codec to use when recording a video.
Acceptable values are: 'avc1' | 'hvc1' | 'jpeg' | 'apcn' | 'ap4h'
Literal Type: string
Acceptable values are: '2160p' | '1080p' | '720p' | '480p' | '4:3'
Literal Type: string
This option specifies the stabilization mode to use when recording a video.
Acceptable values are: 'off' | 'standard' | 'cinematic' | 'auto'
Enums
Permissions
Android
This package automatically adds the CAMERA permission to your app. If you want to record videos with audio, you have to include the RECORD_AUDIO in your app.json inside the expo.android.permissions array.
| Android Permission | Description |
|---|---|
Required to be able to access the camera device. | |
Allows an application to record audio. |
iOS
The following usage description keys are used by this library: