Media Query

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.

Modules to Import

import mediaquery from '@ohos.mediaquery'

Required Permissions

None.

mediaquery.matchMediaSync

matchMediaSync(condition: string): MediaQueryListener

Sets the media query criteria and returns the corresponding listening handle.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
condition	string	Yes	Matching condition of a media event. For details, see Syntax of Media Query Conditions.

Return value

Type	Description
MediaQueryListener	Listening handle to a media event, which is used to register or deregister the listening callback.

Example

listener = mediaquery.matchMediaSync('(orientation: landscape)'); // Listen for landscape events.

MediaQueryListener

Media query handle, including the first query result when the handle is applied for.

System capability: SystemCapability.ArkUI.ArkUI.Full

Attributes

Name	Type	Readable	Writable	Description
matches	boolean	Yes	No	Whether the match condition is met.
media	string	Yes	No	Matching condition of a media event.

on

on(type: 'change', callback: Callback<MediaQueryResult>): void

Registers a callback with the corresponding query condition by using the handle. This callback is triggered when the media attributes change.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Must enter the string 'change'.
callback	Callback<MediaQueryResult>	Yes	Callback registered with media query.

Example For details, see off Example.

off

off(type: 'change', callback?: Callback<MediaQueryResult>): void

Deregisters a callback with the corresponding query condition by using the handle, so that no callback is triggered when the media attributes change.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
type	boolean	Yes	Must enter the string 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 '@ohos.mediaquery'
  
  let listener = mediaquery.matchMediaSync('(orientation: landscape)'); // Listen for landscape events.
  function onPortrait(mediaQueryResult) {
      if (mediaQueryResult.matches) {
          // do something here
      } else {
          // do something here
      }
  }
  listener.on('change', onPortrait) // Register a callback.
  listener.off('change', onPortrait) // Deregister a callback.

MediaQueryResult

Attributes

Name	Type	Readable	Writable	Description
matches	boolean	Yes	No	Whether the match condition is met.
media	string	Yes	No	Matching condition of a media event.

Example

import mediaquery from '@ohos.mediaquery'

let portraitFunc = null

@Entry
@Component
struct MediaQueryExample {
  @State color: string = '#DB7093'
  @State text: string = 'Portrait'
  listener = mediaquery.matchMediaSync('(orientation: landscape)')

  onPortrait(mediaQueryResult) {
    if (mediaQueryResult.matches) {
      this.color = '#FFD700'
      this.text = 'Landscape'
    } else {
      this.color = '#DB7093'
      this.text = 'Portrait'
    }
  }

  aboutToAppear() {
    portraitFunc = this.onPortrait.bind(this) //bind current js instance
    this.listener.on('change', portraitFunc)
  }

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Text(this.text).fontSize(24).fontColor(this.color)
    }
    .width('100%').height('100%')
  }
}