Expo 相机

一个 React 组件，用于渲染设备前置或后置摄像头的预览。

Android (device only)

iOS (device only)

Web

Bundled version:

~16.1.11

expo-camera 提供了一个 React 组件，可以渲染设备前置或后置摄像头的预览。相机的变焦、手电筒和闪光模式等参数均可调节。使用 CameraView，你可以拍摄照片和录制视频并保存到应用的缓存中。该组件还能够检测预览中出现的条形码。在你的设备上运行 example 以查看所有这些功能的协同工作。

¥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.

安装

¥Installation

Terminal

- npx expo install expo-camera

If you are installing this in an existing React Native app, make sure to install expo in your project.

应用配置中的配置

¥Configuration in app config

如果你在项目中使用配置插件（EAS 构建或 npx expo run:[android|ios]），则可以使用其内置的配置插件配置 expo-camera。该插件允许你配置无法在运行时设置的各种属性，并且需要构建新的应用二进制文件才能生效。

¥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

app.json

{
"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 `NSCameraUsageDescription` permission message.
`microphonePermission`	`"Allow $(PRODUCT_NAME) to access your microphone"`	Only for: iOS A string to set the `NSMicrophoneUsageDescription` permission message.
`recordAudioAndroid`	`true`	Only for: Android A boolean that determines whether to enable the `RECORD_AUDIO` permission on Android.

Are you using this library in an existing React Native app?

如果你未使用持续原生生成 (CNG)（你正在手动使用原生 Android 和 iOS 项目），则需要在原生项目中配置以下权限：

¥If you're not using Continuous Native Generation (CNG) (you're using native android and ios projects manually), then you need to configure following permissions in your native projects:

安卓

¥Android

expo-camera 会自动将 android.permission.CAMERA 权限添加到项目的 android/app/src/main/AndroidManifest.xml 中。如果你希望录制带音频的视频，请包含 RECORD_AUDIO 权限：

¥expo-camera automatically adds android.permission.CAMERA permission to your project's android/app/src/main/AndroidManifest.xml. If you want to record videos with audio, include RECORD_AUDIO permission:

<!-- Added permission -->
<uses-permission android:name="android.permission.CAMERA" />

<!-- Only add when recording videos with audio -->
<uses-permission android:name="android.permission.RECORD_AUDIO" />

然后，调整 android/build.gradle 文件，在所有其他存储库之后添加新的 maven 块，如下所示：

¥Then, adjust the android/build.gradle file to add new maven block after all other repositories as show below:

allprojects {
  repositories {
      // * Your other repositories here *
      // * Add a new maven block after other repositories / blocks *
      maven {
          // expo-camera bundles a custom com.google.android:cameraview
          url "$rootDir/../node_modules/expo-camera/android/maven"
      }
  }
}

iOS 系统

¥iOS

将 NSCameraUsageDescription 和 NSMicrophoneUsageDescription 键添加到项目的 ios/[app]/Info.plist 中：

¥Add NSCameraUsageDescription and NSMicrophoneUsageDescription keys to your project's ios/[app]/Info.plist:

<key>NSCameraUsageDescription</key>
<string>Allow $(PRODUCT_NAME) to access your camera</string>
<key>NSMicrophoneUsageDescription</key>
<string>Allow $(PRODUCT_NAME) to access your microphone</string>

用法

¥Usage

在任何给定时间只能激活一个相机预览。如果你的应用中有多个屏幕，则只要屏幕未聚焦，你就应该卸载 Camera 组件。

Basic Camera Usage

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',
},
});

高级用法

¥Advanced usage

相机应用示例

一个完整的示例，展示如何拍摄照片并显示它。用 TypeScript 编写。

Web 支持

¥Web support

大多数浏览器都支持网络摄像头功能的版本，你可以查看网络摄像头浏览器支持在这里。图片 URI 始终以 base64 字符串形式返回，因为本地文件系统路径在浏览器中不可用。

¥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` 使用情况

¥Chrome iframe usage

使用 Chrome 版本 64+ 时，如果你尝试在跨源 iframe 中使用网络摄像头，则不会渲染任何内容。要在 iframe 中添加对摄像头的支持，只需将属性 allow="microphone; camera;" 添加到 iframe 元素即可：

¥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

`CameraView`

Type: React.Component<CameraViewProps>

CameraViewProps

`active`

Only for:

iOS

Optional • Type: boolean • Default: true

A 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.

`animateShutter`

Optional • Type: boolean • Default: true

A boolean that determines whether the camera shutter animation should be enabled.

`autofocus`

Only for:

iOS

Optional • Type: FocusMode • Default: off

Indicates the focus mode to use.

`barcodeScannerSettings`

Optional • Type: BarcodeSettings

Example

<CameraView
  barcodeScannerSettings={{
    barcodeTypes: ["qr"],
  }}
/>

`enableTorch`

Optional • Type: boolean • Default: false

A boolean to enable or disable the torch.

`facing`

Optional • Type: CameraType • Default: 'back'

Camera facing. Use one of CameraType. When front, use the front-facing camera. When back, use the back-facing camera.

`flash`

Optional • Type: 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.

`mirror`

Optional • Type: boolean • Default: false

A boolean that determines whether the camera should mirror the image when using the front camera.

`mode`

Optional • Type: CameraMode • Default: 'picture'

Used to select image or video output.

`mute`

Optional • Type: boolean • Default: false

If present, video will be recorded with no sound.

`onAvailableLensesChanged`

Only for:

iOS

Optional • Type: (event: AvailableLenses) => void

Callback invoked when the cameras available lenses change.

event: AvailableLenses

result object that contains a lenses property containing an array of available lenses.

`onBarcodeScanned`

Optional • Type: (scanningResult: BarcodeScanningResult) => void

Callback 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.

`onCameraReady`

Optional • Type: () => void

Callback invoked when camera preview has been set.

`onMountError`

Optional • Type: (event: CameraMountError) => void

Callback invoked when camera preview could not start.

event: CameraMountError

Error object that contains a message.

`onResponsiveOrientationChanged`

Only for:

iOS

Optional • Type: (event: ResponsiveOrientationChanged) => void

Callback invoked when responsive orientation changes. Only applicable if responsiveOrientationWhenOrientationLocked is true.

event: ResponsiveOrientationChanged

result object that contains updated orientation of camera

`pictureSize`

Optional • Type: string

A 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.

`poster`

Only for:

Web

Optional • Type: string

A URL for an image to be shown while the camera is loading.

`ratio`

Only for:

Android

Optional • Type: CameraRatio

A 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.

`responsiveOrientationWhenOrientationLocked`

Only for:

iOS

Optional • Type: boolean

Whether 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).

`selectedLens`

Only for:

iOS

Optional • Type: string • Default: 'builtInWideAngleCamera'

Available lenses are emitted to the onAvailableLensesChanged callback whenever the currently selected camera changes or by calling getAvailableLensesAsync. You can read more about the available lenses in the Apple documentation.

`videoBitrate`

Optional • Type: number

The 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

`videoQuality`

Optional • Type: VideoQuality

Specify 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.

`videoStabilizationMode`

Only for:

iOS

Optional • Type: VideoStabilization

The video stabilization mode used for a video recording. Use one of VideoStabilization.<value>. You can read more about each stabilization type in Apple Documentation.

`zoom`

Optional • Type: number • Default: 0

A 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

ViewProps

Static Methods

`dismissScanner()`

Only for:

iOS

Dismiss the scanner presented by launchScanner.

On Android, the scanner is dismissed automatically when a barcode is scanned.

Returns:

Promise<void>

`getAvailableVideoCodecsAsync()`

Only for:

iOS

Queries the device for the available video codecs that can be used in video recording.

Returns:

Promise<VideoCodec[]>

A promise that resolves to a list of strings that represents available codecs.

`isAvailableAsync()`

Only for:

Web

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.

Returns:

Promise<boolean>

`launchScanner(options)`

Only for:

Android

iOS

Parameter	Type
options(optional)	`ScanningOptions`

On Android, we will use the Google code scanner. On iOS, presents a modal view controller that uses the DataScannerViewController available on iOS 16+.

Returns:

Promise<void>

`onModernBarcodeScanned(listener)`

Only for:

Android

iOS

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.

Returns:

EventSubscription

Component Methods

`getAvailableLensesAsync()`

Only for:

iOS

Returns the available lenses for the currently selected camera.

Returns:

Promise<string[]>

Returns a Promise that resolves to an array of strings representing the lens type that can be passed to selectedLens prop.

`getAvailablePictureSizesAsync()`

Get picture sizes that are supported by the device.

Returns:

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.

`getSupportedFeatures()`

Returns an object with the supported features of the camera on the current device.

Returns:

{
  isModernBarcodeScannerAvailable: boolean, 
  toggleRecordingAsyncAvailable: boolean
}

`pausePreview()`

Pauses the camera preview. It is not recommended to use takePictureAsync when preview is paused.

Returns:

Promise<void>

`recordAsync(options)`

Only for:

Android

iOS

Parameter	Type	Description
options(optional)	`CameraRecordingOptions`	A map of `CameraRecordingOptions` type.

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.

Returns:

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.

`resumePreview()`

Resumes the camera preview.

Returns:

Promise<void>

`stopRecording()`

Only for:

Android

iOS

Stops recording if any is in progress.

Returns:

void

`takePictureAsync(options)`

Parameter	Type	Description
options	`CameraPictureOptions & { pictureRef: true }`	An object in form of `CameraPictureOptions` type.

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 onCameraReady callback before calling this method.

Returns:

Promise<PictureRef>

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.copyAsync to 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.

`takePictureAsync(options)`

Parameter	Type	Description
options(optional)	`CameraPictureOptions`	An object in form of `CameraPictureOptions` type.

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 onCameraReady callback before calling this method.

Returns:

Promise<CameraCapturedPicture>

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.copyAsync to 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.

`toggleRecordingAsync()`

Pauses or resumes the video recording. Only has an effect if there is an active recording. On iOS, this method only supported on iOS 18.

Returns:

Promise<undefined | void>

Example

const { toggleRecordingAsyncAvailable } = getSupportedFeatures()

return (
 {toggleRecordingAsyncAvailable && (
   <Button title="Toggle Recording" onPress={toggleRecordingAsync} />
 )}
)

Hooks

`useCameraPermissions(options)`

Parameter	Type
options(optional)	`PermissionHookOptions<object>`

Check or request permissions to access the camera. This uses both requestCameraPermissionsAsync and getCameraPermissionsAsync to interact with the permissions.

Returns:

[null | PermissionResponse, RequestPermissionMethod<PermissionResponse>, GetPermissionMethod<PermissionResponse>]

Example

const [status, requestPermission] = useCameraPermissions();

`useMicrophonePermissions(options)`

Parameter	Type
options(optional)	`PermissionHookOptions<object>`

Check or request permissions to access the microphone. This uses both requestMicrophonePermissionsAsync and getMicrophonePermissionsAsync to interact with the permissions.

Returns:

[null | PermissionResponse, RequestPermissionMethod<PermissionResponse>, GetPermissionMethod<PermissionResponse>]

Example

const [status, requestPermission] = Camera.useMicrophonePermissions();

Classes

`CameraNativeModule`

Type: Class extends _default<CameraEvents>

CameraNativeModule Properties

`dismissScanner`

Read Only • Type: () => Promise<void>

`getAvailableVideoCodecsAsync`

Read Only • Type: () => Promise<VideoCodec[]>

`getCameraPermissionsAsync`

Read Only • Type: () => Promise<PermissionResponse>

`getMicrophonePermissionsAsync`

Read Only • Type: () => Promise<PermissionResponse>

`isAvailableAsync`

Read Only • Type: () => Promise<boolean>

`isModernBarcodeScannerAvailable`

Read Only • Type: boolean

`launchScanner`

Read Only • Type: (options?: ScanningOptions) => Promise<void>

`requestCameraPermissionsAsync`

Read Only • Type: () => Promise<PermissionResponse>

`requestMicrophonePermissionsAsync`

Read Only • Type: () => Promise<PermissionResponse>

`scanFromURLAsync`

Read Only • Type: (url: string, barcodeTypes?: BarcodeType[]) => Promise<BarcodeScanningResult[]>

`toggleRecordingAsyncAvailable`

Read Only • Type: boolean

`PictureRef`

Type: Class extends SharedRef<'image'>

A reference to a native instance of the image.

PictureRef Properties

`height`

Type: number

Height of the image.

`nativeRefType`

Type: string

The type of the native reference.

`width`

Type: number

Width of the image.

PictureRef Methods

`savePictureAsync(options)`

Parameter	Type	Description
options(optional)	`SavePictureOptions`	A map defining how modified image should be saved.

Saves the image to the file system in the cache directory.

Returns:

Promise<PhotoResult>

Methods

`Camera.scanFromURLAsync(url, barcodeTypes)`

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. Note: Only QR codes are supported on iOS. On android, the barcode should take up the majority of the image for best results.

Scan bar codes from the image at the given URL.

Returns:

Promise<BarcodeScanningResult[]>

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

`Subscription`

A subscription object that allows to conveniently remove an event listener from the emitter.

Subscription Methods

`remove()`

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.

Returns:

void

Types

`AvailableLenses`

Property	Type	Description
lenses	`string[]`	-

`BarcodeBounds`

Property	Type	Description
origin	`BarcodePoint`	The origin point of the bounding box.
size	`BarcodeSize`	The size of the bounding box.

`BarcodePoint`

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).

`BarcodeScanningResult`

Property	Type	Description
bounds	`BarcodeBounds`	The `BarcodeBounds` object. `bounds` in some case will be representing an empty rectangle. Moreover, `bounds` doesn't have to bound the whole barcode. For some types, they will represent the area used by the scanner.
cornerPoints	`BarcodePoint[]`	Corner points of the bounding box. `cornerPoints` is not always available and may be empty. On iOS, for `code39` and `pdf417` you don't get this value.
data	`string`	The parsed information encoded in the barcode.
extra(optional)	`AndroidBarcode`	Only for: Android Extra information returned by the specific type of barcode.
type	`string`	The barcode type.

`BarcodeSettings`

Property	Type	Description
barcodeTypes	`BarcodeType[]`	-

`BarcodeSize`

Property	Type	Description
height	`number`	The height value.
width	`number`	The width value.

`BarcodeType`

Literal Type: string

The available barcode types that can be scanned.

`CameraCapturedPicture`

Property	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 `MediaTrackSettings` dictionary.
format	`'jpg' \| 'png'`	The format of the captured image.
height	`number`	Captured image height.
uri	`string`	On web, the value of `uri` is the same as `base64` because file system URLs are not supported in the browser.
width	`number`	Captured image width.

`CameraEvents`

Property	Type	Description
onModernBarcodeScanned	`(event: ScanningResult) => void`	-

`CameraMode`

Literal Type: string

Acceptable values are: 'picture' | 'video'

`CameraMountError`

Property	Type	Description
message	`string`	-

`CameraOrientation`

Literal Type: string

Acceptable values are: 'portrait' | 'portraitUpsideDown' | 'landscapeLeft' | 'landscapeRight'

`CameraPictureOptions`

Property	Type	Description
additionalExif(optional)	`Record<string, any>`	Only for: Android iOS Additional EXIF data to be included for the image. Only useful when `exif` option is set to `true`.
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`	Only for: Web -
isImageMirror(optional)	`boolean`	Only for: Web -
mirror(optional)	`boolean`	Deprecated Use `mirror` prop on `CameraView` instead. Only for: Android iOS When set to `true`, the output image will be flipped along the vertical axis when using the front camera. 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.
pictureRef(optional)	`boolean`	Whether the camera should return an image ref that can be used directly in the `Image` component.
quality(optional)	`number`	Specify the compression quality from `0` to `1`. `0` means compress for small size, and `1` means compress for maximum quality. Default:`1`
scale(optional)	`number`	Only for: Web -
shutterSound(optional)	`boolean`	To programmatically disable the camera shutter sound Default:`true`
skipProcessing(optional)	`boolean`	If set to `true`, camera skips orientation adjustment and returns an image straight from the device's camera. If enabled, `quality` option is discarded (processing pipeline is skipped as a whole). Although enabling this option reduces image delivery time significantly, it may cause the image to appear in a wrong orientation in the `Image` component (at the time of writing, it does not respect EXIF orientation of the images). Note: Enabling `skipProcessing` would cause orientation uncertainty. `Image` component does not respect EXIF stored orientation information, that means obtained image would be displayed wrongly (rotated by 90°, 180° or 270°). Different devices provide different orientations. For example some Sony Xperia or Samsung devices don't provide correctly oriented images by default. To always obtain correctly oriented image disable `skipProcessing` option.

`CameraRatio`

Literal Type: string

Acceptable values are: '4:3' | '16:9' | '1:1'

`CameraRecordingOptions`

Property	Type	Description
codec(optional)	`VideoCodec`	Only for: iOS This option specifies what codec to use when recording the video. See `VideoCodec` for the possible values.
maxDuration(optional)	`number`	Maximum video duration in seconds.
maxFileSize(optional)	`number`	Maximum video file size in bytes.
mirror(optional)	`boolean`	Deprecated Use `mirror` prop on `CameraView` instead. If `true`, the recorded video will be flipped along the vertical axis. iOS flips videos recorded with the front camera by default, but you can reverse that back by setting this to `true`. On Android, this is handled in the user's device settings.

`CameraType`

Literal Type: string

Acceptable values are: 'front' | 'back'

`FlashMode`

Literal Type: string

Acceptable values are: 'off' | 'on' | 'auto'

`FocusMode`

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'

`ImageType`

Literal Type: string

Acceptable values are: 'png' | 'jpg'

`PermissionExpiration`

Literal Type: union

Permission expiration time. Currently, all permissions are granted permanently.

Acceptable values are: 'never' | number

`PermissionHookOptions`

Literal Type: union

Acceptable values are: PermissionHookBehavior | Options

`PermissionResponse`

An object obtained by permissions get and request functions.

Property	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.

`PhotoResult`

Property	Type	Description
base64(optional)	`string`	A Base64 representation of the image.
height	`number`	Height of the image.
uri	`string`	A URI to the modified image (usable as the source for an `Image` or `Video` element).
width	`number`	Width of the image.

`Point`

Property	Type	Description
x	`number`	-
y	`number`	-

`ResponsiveOrientationChanged`

Property	Type	Description
orientation	`CameraOrientation`	-

`SavePictureOptions`

A map defining how modified image should be saved.

Property	Type	Description
base64(optional)	`boolean`	Whether to also include the image data in Base64 format.
metadata(optional)	`Record<string, any>`	Additional metadata to be included for the image.
quality(optional)	`number`	Specify the compression quality from `0` to `1`. `0` means compress for small size, and `1` means compress for maximum quality.

`ScanningOptions`

Only for:

iOS

Property	Type	Description
barcodeTypes	`BarcodeType[]`	The type of codes to scan for.
isGuidanceEnabled(optional)	`boolean`	Only for: iOS Guidance text, such as “Slow Down,” appears over the live video. Default:`true`
isHighlightingEnabled(optional)	`boolean`	Only for: iOS Indicates whether the scanner displays highlights around recognized items. Default:`false`
isPinchToZoomEnabled(optional)	`boolean`	Only for: iOS Indicates whether people can use a two-finger pinch-to-zoom gesture. Default:`true`

`ScanningResult`

Type: Omit<BarcodeScanningResult, 'bounds' | 'cornerPoints'>

`VideoCodec`

Only for:

iOS

Literal Type: string

This option specifies what codec to use when recording a video.

Acceptable values are: 'avc1' | 'hvc1' | 'jpeg' | 'apcn' | 'ap4h'

`VideoQuality`

Literal Type: string

Acceptable values are: '2160p' | '1080p' | '720p' | '480p' | '4:3'

`VideoStabilization`

Only for:

iOS

Literal Type: string

This option specifies the stabilization mode to use when recording a video.

Acceptable values are: 'off' | 'standard' | 'cinematic' | 'auto'

Enums

`PermissionStatus`

`DENIED`

PermissionStatus.DENIED ＝ "denied"

User has denied the permission.

`GRANTED`

PermissionStatus.GRANTED ＝ "granted"

User has granted the permission.

`UNDETERMINED`

PermissionStatus.UNDETERMINED ＝ "undetermined"

User hasn't granted or denied the permission yet.

权限

¥Permissions

安卓

¥Android

此包会自动向你的应用添加 CAMERA 权限。如果你想录制带有音频的视频，则必须将 RECORD_AUDIO 包含在 app.json 的 expo.android.permissions 数组内。

¥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
`CAMERA`	Required to be able to access the camera device.
`RECORD_AUDIO`	Allows an application to record audio.

iOS 系统

¥iOS

该库使用以下用法描述键：

¥The following usage description keys are used by this library:

Info.plist Key	Description
`NSCameraUsageDescription`	A message that tells the user why the app is requesting access to the device’s camera.
`NSMicrophoneUsageDescription`	A message that tells the user why the app is requesting access to the device’s microphone.

Expo 相机

安装

应用配置中的配置

Example app.json with config plugin

Configurable properties

用法

高级用法

Web 支持

Chrome iframe 使用情况

API

Component

CameraView

active

animateShutter

autofocus

barcodeScannerSettings

enableTorch

facing

flash

mirror

mode

mute

onAvailableLensesChanged

onBarcodeScanned

onCameraReady

onMountError

onResponsiveOrientationChanged

pictureSize

poster

ratio

responsiveOrientationWhenOrientationLocked

selectedLens

videoBitrate

videoQuality

videoStabilizationMode

zoom

Inherited Props

Static Methods

dismissScanner()

getAvailableVideoCodecsAsync()

isAvailableAsync()

launchScanner(options)

onModernBarcodeScanned(listener)

Component Methods

getAvailableLensesAsync()

getAvailablePictureSizesAsync()

getSupportedFeatures()

pausePreview()

recordAsync(options)

resumePreview()

stopRecording()

takePictureAsync(options)

takePictureAsync(options)

toggleRecordingAsync()

Hooks

useCameraPermissions(options)

useMicrophonePermissions(options)

Classes

CameraNativeModule

dismissScanner

getAvailableVideoCodecsAsync

getCameraPermissionsAsync

getMicrophonePermissionsAsync

isAvailableAsync

isModernBarcodeScannerAvailable

launchScanner

requestCameraPermissionsAsync

requestMicrophonePermissionsAsync

scanFromURLAsync

toggleRecordingAsyncAvailable

PictureRef

height

nativeRefType

width

savePictureAsync(options)

Methods

Camera.scanFromURLAsync(url, barcodeTypes)

Interfaces

Subscription

remove()

Chrome `iframe` 使用情况

`CameraView`

`active`

`animateShutter`

`autofocus`

`barcodeScannerSettings`

`enableTorch`

`facing`

`flash`

`mirror`

`mode`

`mute`

`onAvailableLensesChanged`

`onBarcodeScanned`

`onCameraReady`

`onMountError`

`onResponsiveOrientationChanged`

`pictureSize`

`poster`

`ratio`

`responsiveOrientationWhenOrientationLocked`

`selectedLens`

`videoBitrate`

`videoQuality`

`videoStabilizationMode`

`zoom`

`dismissScanner()`

`getAvailableVideoCodecsAsync()`

`isAvailableAsync()`

`launchScanner(options)`

`onModernBarcodeScanned(listener)`

`getAvailableLensesAsync()`

`getAvailablePictureSizesAsync()`

`getSupportedFeatures()`

`pausePreview()`

`recordAsync(options)`

`resumePreview()`

`stopRecording()`

`takePictureAsync(options)`

`takePictureAsync(options)`

`toggleRecordingAsync()`

`useCameraPermissions(options)`

`useMicrophonePermissions(options)`

`CameraNativeModule`

`dismissScanner`

`getAvailableVideoCodecsAsync`

`getCameraPermissionsAsync`

`getMicrophonePermissionsAsync`

`isAvailableAsync`

`isModernBarcodeScannerAvailable`

`launchScanner`

`requestCameraPermissionsAsync`

`requestMicrophonePermissionsAsync`

`scanFromURLAsync`

`toggleRecordingAsyncAvailable`

`PictureRef`

`height`

`nativeRefType`

`width`

`savePictureAsync(options)`

`Camera.scanFromURLAsync(url, barcodeTypes)`

`Subscription`

`remove()`

`AvailableLenses`

`BarcodeBounds`

`BarcodePoint`

`BarcodeScanningResult`

`BarcodeSettings`

`BarcodeSize`

`BarcodeType`

`CameraCapturedPicture`

`CameraEvents`

`CameraMode`

`CameraMountError`

`CameraOrientation`

`CameraPictureOptions`

`CameraRatio`

`CameraRecordingOptions`

`CameraType`

`FlashMode`