harmony 鸿蒙@ohos.mediaquery (Media Query)
@ohos.mediaquery (Media Query)
The mediaquery module provides different styles for different media types.
NOTE
The APIs of this module are supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version.
This module cannot be used in the file declaration of the UIAbility. In other words, the APIs of this module can be used only after a component instance is created; they cannot be called in the lifecycle of the UIAbility.
The functionality of this module depends on UI context. This means that the APIs of this module cannot be used where the UI context is unclear. For details, see UIContext.
Modules to Import
import { mediaquery } from '@kit.ArkUI';
mediaquery.matchMediaSync(deprecated)
matchMediaSync(condition: string): MediaQueryListener
Sets the media query condition. This API returns the corresponding media query listener.
NOTE
This API is deprecated since API version 18. You are advised to use matchMediaSync instead on the obtained MediaQuery object.
Since API version 10, you can use the getMediaQuery API in UIContext to obtain the MediaQuery object associated with the current UI context.
Widget capability: This API can be used in ArkTS widgets since API version 12.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
condition | string | Yes | Media query condition. For details, see Syntax. |
Return value
Type | Description |
---|---|
MediaQueryListener | Media query listener, which is used to register or deregister the listening callback. |
Example
import { mediaquery } from '@kit.ArkUI';
let listener: mediaquery.MediaQueryListener = mediaquery.matchMediaSync('(orientation: landscape)'); // Listen for landscape events.
MediaQueryListener
Implements the media query listener, including the first query result when the listener is applied for. The specified media query condition, for example, ’(width <= 600vp)’, is compared system information. If related information is not initialized during the first query, matches returns false.
Inherits from MediaQueryResult.
Widget capability: This API can be used in ArkTS widgets since API version 12.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.ArkUI.ArkUI.Full
on(‘change’)
on(type: ‘change’, callback: Callback<MediaQueryResult>): void
Registers a media query listener. The callback is triggered when the media attributes change.
NOTE
The on or off function cannot be called in the registered callback.
Widget capability: This API can be used in ArkTS widgets since API version 12.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
type | string | Yes | Listener type. The value is fixed at ‘change’. |
callback | Callback<MediaQueryResult> | Yes | Callback registered with media query. |
Example
See the example of off.
off(‘change’)
off(type: ‘change’, callback?: Callback<MediaQueryResult>): void
Deregisters a media query listener, so that no callback is triggered when the media attributes change.
Widget capability: This API can be used in ArkTS widgets since API version 12.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
type | string | Yes | Listener type. The value is fixed at ‘change’. |
callback | Callback<MediaQueryResult> | No | Callback to be deregistered. If the default value is used, all callbacks of the handle are deregistered. |
Example
import { mediaquery } from '@kit.ArkUI';
let listener = mediaquery.matchMediaSync('(orientation: landscape)'); // Listen for landscape events.
function onPortrait(mediaQueryResult:mediaquery.MediaQueryResult) {
if (mediaQueryResult.matches) {
// do something here
} else {
// do something here
}
}
listener.on('change', onPortrait) // Register the media query listener.
listener.off('change', onPortrait) // Deregister the listener.
MediaQueryResult
Provides the media query result.
Widget capability: This API can be used in ArkTS widgets since API version 12.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.ArkUI.ArkUI.Full
Properties
Name | Type | Readable | Writable | Description |
---|---|---|---|---|
matches | boolean | Yes | No | Whether the media query condition is met. The value true means that the query conditions are met, and false means the opposite. |
media | string | Yes | No | Media query condition. |
Example
NOTE
You are advised to use the getMediaQuery API in UIContext to obtain the MediaQuery object associated with the current UI context.
import { mediaquery } from '@kit.ArkUI';
@Entry
@Component
struct MediaQueryExample {
@State color: string = '#DB7093'
@State text: string = 'Portrait'
listener = mediaquery.matchMediaSync('(orientation: landscape)') // You are advised to use this.getUIContext().getMediaQuery().matchMediaSync().
onPortrait(mediaQueryResult:mediaquery.MediaQueryResult) {
if (mediaQueryResult.matches) {
this.color = '#FFD700'
this.text = 'Landscape'
} else {
this.color = '#DB7093'
this.text = 'Portrait'
}
}
aboutToAppear() {
let portraitFunc = (mediaQueryResult: mediaquery.MediaQueryResult): void => this.onPortrait(mediaQueryResult)
// Register the callback.
this.listener.on('change', portraitFunc);
}
aboutToDisappear() {
// Unregister the callback.
this.listener.off('change');
}
build() {
Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
Text(this.text).fontSize(24).fontColor(this.color)
}
.width('100%').height('100%')
}
}
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