harmony 鸿蒙Show/Hide Event

2022-08-09
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Show/Hide Event

The show/hide event is triggered when a component is mounted or unmounted from the component tree. A component appears when mounted to the component tree and disappears when unmounted from the component tree.

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.

Events

Name	Bubbling Supported	Description
onAppear(event: () => void)	No	Triggered when the component is displayed. Since API version 9, this API is supported in ArkTS widgets.
onDisAppear(event: () => void)	No	Triggered when the component is hidden. Since API version 9, this API is supported in ArkTS widgets.

Example

// xxx.ets
import promptAction from '@ohos.promptAction'

@Entry
@Component
struct AppearExample {
  @State isShow: boolean = true
  @State changeAppear: string = 'Show/Hide'
  private myText: string = 'Text for onAppear'

  build() {
    Column() {
      Button(this.changeAppear)
        .onClick(() => {
          this.isShow = !this.isShow
        }).margin(15)
      if (this.isShow) {
        Text(this.myText).fontSize(26).fontWeight(FontWeight.Bold)
          .onAppear(() => {
            promptAction.showToast({
              message: 'Text shown.',
              duration: 2000
            })
          })
          .onDisAppear(() => {
            promptAction.showToast({
              message: 'Text hidden.',
              duration: 2000
            })
          })
      }
    }.padding(30).width('100%')
  }
}

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