harmony(鸿蒙)Button

2022-08-09
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Button

The <Button> component is usually activated by user clicks to perform a specific action, for example, submitting a form. Buttons are classified as capsule, circle, or normal buttons. For details, see Button.

Creating a Button

You can create a button that contains or does not contain child components.

Create a button that contains child components.

Button(options?: {type?: ButtonType, stateEffect?: boolean}), where type indicates the button type, and stateEffect indicates whether to enable the click effect for the button.

  Button({ type: ButtonType.Normal, stateEffect: true }) {
    Row() {
      Image($r('app.media.loading')).width(20).height(20).margin({ left: 12 })
      Text('loading').fontSize(12).fontColor(0xffffff).margin({ left: 5, right: 12 })
    }.alignItems(VerticalAlign.Center)
  }.borderRadius(8).backgroundColor(0x317aff).width(90)

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Create a button that does not contain child components.

Button(label?: string, options?: { type?: ButtonType, stateEffect?: boolean }), where label indicates whether the button contains child components.

  Button('Ok', { type: ButtonType.Normal, stateEffect: true })
    .borderRadius(8)
    .backgroundColor(0x317aff)
    .width(90)

en-us_image_0000001215796030

Setting the Button Type

Use the type parameter to set the button type to Capsule, Circle, or Normal.

Capsule button (default type)

  Button('Disable', { type: ButtonType.Capsule, stateEffect: false })
    .backgroundColor(0x317aff)
    .width(90)

en-us_image_0000001215645452

Circle button

  Button('Circle', { type: ButtonType.Circle, stateEffect: false })
    .backgroundColor(0x317aff)
    .width(90)
    .height(90)

en-us_image_0000001215965420

Setting Styles

Set the border radius: In general cases, you can use universal attributes to define the button styles. For example, you can use the borderRadius attribute to set the border radius.

  Button('circle border', { type: ButtonType.Normal })
    .borderRadius(20)

en-us_image_0000001190463780

Set the text style:

Add a font style for text displayed on the button.

  Button('font style', { type: ButtonType.Normal })
    .fontSize(20)
    .fontColor(Color.Red)
    .fontWeight(800)

en-us_image_0000001189744672

Set the background color:

You can do so by adding the backgroundColor attribute.

  Button('background color').backgroundColor(0xF55A42)

en-us_image_0000001235146483

Assign a function to the button:

In this example, we are creating a button with the delete function.

  Button({ type: ButtonType.Circle, stateEffect: true }) {
    Image($r('app.media.ic_public_delete_filled')).width(30).height(30)
  }.width(55).height(55).margin({ left: 20 }).backgroundColor(0xF55A42)

en-us_image_0000001260373911

Adding Events

The <Button> component is usually used to trigger actions. You can bind the onClick event to the button to have it respond with custom behavior after being clicked.

Button('Ok', { type: ButtonType.Normal, stateEffect: true })
  .onClick(()=>{
    console.info('Button onClick')
  })

Example Scenarios

Using the Button for Startup

You can use the button for any UI element that involves the startup operation. The button triggers the predefined event based on the user’s operation. For example, you can use a button in the <List> container to redirect the user to another page.

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

  @Entry
  @Component
  struct ButtonCase1 {
    build() {
      List({ space: 4 }) {
        ListItem() {
          Button("First").onClick(() => {
            router.push({ url: 'xxx' })
          })
        }

        ListItem() {
          Button("Second").onClick(() => {
            router.push({ url: 'yyy' })
          })
        }

        ListItem() {
          Button("Third").onClick(() => {
            router.push({ url: 'zzz' })
          })
        }
      }
      .listDirection(Axis.Vertical)
      .backgroundColor(0xDCDCDC).padding(20)
    }
  }

en-us_image_0000001235626467

Using the Button for Submitting Forms

On the user login/registration page, you can use a button to submit a login or registration request.

  // xxx.ets  
  @Entry
    @Component
    struct ButtonCase2 {
      build() {
        Column() {
          TextInput({ placeholder: 'input your username' }).margin({ top: 20 })
          TextInput({ placeholder: 'input your password' }).type(InputType.Password).margin({ top: 20 })
          Button('Register').width(300).margin({ top: 20 })
        }.padding(20)
      }
    }

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