Expo 亮度

提供对 API 的访问以获取和设置屏幕亮度的库。

Android

iOS

Included in Expo Go

Bundled version:

~14.0.8

用于获取和设置屏幕亮度的 API。

🌐 An API to get and set screen brightness.

在安卓系统上，有一个全局系统亮度设置，每个应用都有自己的亮度设置，可选择性地覆盖全局设置。可以使用此 API 设置其中的任意一个值。在 iOS 上，系统亮度设置无法通过编程方式更改；相反，对屏幕亮度的任何更改都会持续有效，直到设备被锁定或关闭电源。

🌐 On Android, there is a global system-wide brightness setting, and each app has its own brightness setting that can optionally override the global setting. It is possible to set either of these values with this API. On iOS, the system brightness setting cannot be changed programmatically; instead, any changes to the screen brightness will persist until the device is locked or powered off.

安装

🌐 Installation

Terminal

- npx expo install expo-brightness

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

配置

🌐 Configuration

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

如果你没有使用连续本地生成（CNG），或者你是在手动使用本地 android 项目，那么你需要在 AndroidManifest.xml 文件中添加 android.permission.WRITE_SETTINGS 权限：

🌐 If you're not using Continuous Native Generation (CNG) or you're using a native android project manually, then you need to add the android.permission.WRITE_SETTINGS permission to the AndroidManifest.xml file:

android/app/src/main/AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_SETTINGS" />

用法

🌐 Usage

Basic Brightness Usage

import { useEffect } from 'react';
import { StyleSheet, View, Text } from 'react-native';
import * as Brightness from 'expo-brightness';

export default function App() {
  useEffect(() => {
    (async () => {
      const { status } = await Brightness.requestPermissionsAsync();
      if (status === 'granted') {
        Brightness.setSystemBrightnessAsync(1);
      }
    })();
  }, []);

  return (
    <View style={styles.container}>
      <Text>Brightness Module Example</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

应用接口

🌐 API

import * as Brightness from 'expo-brightness';

Hooks

`usePermissions(options)`

Android

iOS

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

Check or request permissions to modify the system brightness. This uses both requestPermissionAsync and getPermissionsAsync to interact with the permissions.

Returns:

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

Example

const [permissionResponse, requestPermission] = Brightness.usePermissions();

Deprecated: Use restoreSystemBrightnessAsync method instead.

`useSystemBrightnessAsync()`

Android

Returns:

Promise<void>

Methods

`Brightness.getBrightnessAsync()`

Android

iOS

Gets the current brightness level of the device's main screen.

Returns:

Promise<number>

A Promise that fulfils with a number between 0 and 1, inclusive, representing the current screen brightness.

`Brightness.getPermissionsAsync()`

Android

iOS

Checks user's permissions for accessing system brightness.

Returns:

Promise<PermissionResponse>

A promise that fulfils with an object of type PermissionResponse.

`Brightness.getSystemBrightnessAsync()`

Android

Gets the global system screen brightness.

Returns:

Promise<number>

A Promise that is resolved with a number between 0 and 1, inclusive, representing the current system screen brightness.

`Brightness.getSystemBrightnessModeAsync()`

Android

Gets the system brightness mode (e.g. whether or not the OS will automatically adjust the screen brightness depending on ambient light).

Returns:

Promise<BrightnessMode>

A Promise that fulfils with a BrightnessMode. Requires SYSTEM_BRIGHTNESS permissions.

`Brightness.isAvailableAsync()`

Android

iOS

Returns whether the Brightness API is enabled on the current device. This does not check the app permissions.

Returns:

Promise<boolean>

Async boolean, indicating whether the Brightness API is available on the current device. Currently this resolves true on iOS and Android only.

`Brightness.isUsingSystemBrightnessAsync()`

Android

Returns a boolean specifying whether or not the current activity is using the system-wide brightness value.

Returns:

Promise<boolean>

A Promise that fulfils with true when the current activity is using the system-wide brightness value, and false otherwise.

`Brightness.requestPermissionsAsync()`

Android

iOS

Asks the user to grant permissions for accessing system brightness.

Returns:

Promise<PermissionResponse>

A promise that fulfils with an object of type PermissionResponse.

`Brightness.restoreSystemBrightnessAsync()`

Android

Resets the brightness setting of the current activity to use the system-wide brightness value rather than overriding it.

Returns:

Promise<void>

A Promise that fulfils when the setting has been successfully changed.

`Brightness.setBrightnessAsync(brightnessValue)`

Android

iOS

Parameter	Type	Description
brightnessValue	`number`	A number between `0` and `1`, inclusive, representing the desired screen brightness.

Sets the current screen brightness. On iOS, this setting will persist until the device is locked, after which the screen brightness will revert to the user's default setting. On Android, this setting only applies to the current activity; it will override the system brightness value whenever your app is in the foreground.

Returns:

Promise<void>

A Promise that fulfils when the brightness has been successfully set.

`Brightness.setSystemBrightnessAsync(brightnessValue)`

Experimental

•

Android

Parameter	Type	Description
brightnessValue	`number`	A number between `0` and `1`, inclusive, representing the desired screen brightness.

Sets the global system screen brightness and changes the brightness mode to MANUAL. Requires SYSTEM_BRIGHTNESS permissions.

Returns:

Promise<void>

A Promise that fulfils when the brightness has been successfully set.

`Brightness.setSystemBrightnessModeAsync(brightnessMode)`

Android

Parameter	Type	Description
brightnessMode	`BrightnessMode`	One of `BrightnessMode.MANUAL` or `BrightnessMode.AUTOMATIC`. The system brightness mode cannot be set to `BrightnessMode.UNKNOWN`.

Sets the system brightness mode.

Returns:

Promise<void>

Event Subscriptions

`Brightness.addBrightnessListener(listener)`

iOS

Parameter	Type	Description
listener	`(event: BrightnessEvent) => void`	A callback that is invoked when brightness (iOS) changes. The callback is provided a single argument that is an object with a `brightness` key.

Subscribe to brightness (iOS) updates. The event fires whenever the power mode is toggled.

On web and android the event never fires.

Returns:

EventSubscription

A Subscription object on which you can call remove() to unsubscribe from the listener.

Types

`BrightnessEvent`

Android

iOS

Property	Type	Description
brightness	`number`	A number between `0` and `1`, inclusive, representing the current screen brightness.

`PermissionExpiration`

Android

iOS

Literal Type: union

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

Acceptable values are: 'never' | number

`PermissionHookOptions`

Android

iOS

Literal Type: union

Acceptable values are: PermissionHookBehavior | Options

`PermissionResponse`

Android

iOS

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.

Enums

`BrightnessMode`

Android

iOS

`UNKNOWN`

BrightnessMode.UNKNOWN ＝ 0

Means that the current brightness mode cannot be determined.

`AUTOMATIC`

BrightnessMode.AUTOMATIC ＝ 1

Mode in which the device OS will automatically adjust the screen brightness depending on the ambient light.

`MANUAL`

BrightnessMode.MANUAL ＝ 2

Mode in which the screen brightness will remain constant and will not be adjusted by the OS.

`PermissionStatus`

Android

iOS

`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.

错误代码

🌐 Error codes

`ERR_BRIGHTNESS`

获取或设置应用亮度时发生错误。

🌐 An error occurred when getting or setting the app brightness.

`ERR_BRIGHTNESS_MODE`

获取或设置系统亮度模式时发生错误。有关详细信息，请参见抛出错误的 nativeError 属性。

🌐 An error occurred when getting or setting the system brightness mode. See the nativeError property of the thrown error for more information.

`ERR_BRIGHTNESS_PERMISSIONS_DENIED`

尝试设置系统亮度，但未获得用户的适当权限。用户未授予 SYSTEM_BRIGHTNESS 权限。

🌐 An attempt to set the system brightness was made without the proper permissions from the user. The user did not grant SYSTEM_BRIGHTNESS permissions.

`ERR_BRIGHTNESS_SYSTEM`

获取或设置系统亮度时发生错误。

🌐 An error occurred when getting or setting the system brightness.

`ERR_INVALID_ARGUMENT`

传递了无效的参数。只允许 BrightnessMode.MANUAL 或 BrightnessMode.AUTOMATIC。

🌐 An invalid argument was passed. Only BrightnessMode.MANUAL or BrightnessMode.AUTOMATIC are allowed.

权限

🌐 Permissions

安卓

🌐 Android

你必须将以下权限添加到你的 app.json 中的 expo.android.permissions 数组里。

🌐 You must add the following permissions to your app.json inside the expo.android.permissions array.

Android Permission	Description
`WRITE_SETTINGS`	Allows an application to read or write the system settings.

iOS

无需权限。

🌐 No permissions required.