ArkUI Component Development (ArkTS)

Can custom dialog boxes be defined and used in .ts files?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Unfortunately not. Custom dialog boxes require ArkTS syntax for definition and initialization. Therefore, they can be defined and used only in .ets files.

Reference

Custom Dialog Box

How do I transfer variables in a custom dialog box to a page?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

The variable defined in a custom dialog box needs to be transferred to the page when the dialog box is closed or the variable changes.

Solution

• Method 1: Define the variable as a state variable of the custom dialog box.
• Method 2: During initialization of the custom dialog box, pass to it a method, which is triggered in the custom dialog box and accepts the variable in the custom dialog box as a parameter.
• Method 3: Use AppStorage or LocalStorage to manage page state and implement state sharing between the custom dialog box and page.

Example

• Method 1:

  @CustomDialog
  struct CustomDialog01 {
    @Link inputValue: string
    controller: CustomDialogController
    build() {
      Column() {
        Text('Change text').fontSize(20).margin({ top: 10, bottom: 10 })
        TextInput({ placeholder: '', text: this.inputValue }).height(60).width('90%')
          .onChange((value: string) => {
            this.inputValue = value
          })
      }
    }
  }
  
  
  @Entry
  @Component
  struct DialogDemo01 {
    @State inputValue: string = 'click me'
    dialogController: CustomDialogController = new CustomDialogController({
      builder: CustomDialog01({
        inputValue: $inputValue
      })
    })
  
  
    build() {
      Column() {
        Button(this.inputValue)
          .onClick(() => {
            this.dialogController.open()
          }).backgroundColor(0x317aff)
      }.width('100%').margin({ top: 5 })
    }
  }
  
  
  

• Method 2:

  @CustomDialog
  struct CustomDialog02 {
    private inputValue: string
    changeInputValue: (val: string) => void
    controller: CustomDialogController
    build() {
      Column() {
        Text('Change text').fontSize(20).margin({ top: 10, bottom: 10 })
        TextInput({ placeholder: '', text: this.inputValue }).height(60).width('90%')
          .onChange((value: string) => {
            this.changeInputValue(value)
          })
      }
    }
  }
  
  
  @Entry
  @Component
  struct DialogDemo02 {
    @State inputValue: string = 'click me'
    dialogController: CustomDialogController = new CustomDialogController({
      builder: CustomDialog02({
        inputValue: this.inputValue,
        changeInputValue: (val: string) => {
          this.inputValue = val
        }
      })
    })
  
  
    build() {
      Column() {
        Button(this.inputValue)
          .onClick(() => {
            this.dialogController.open()
          }).backgroundColor(0x317aff)
      }.width('100%').margin({ top: 5 })
    }
  }
  
  
  

• Method 3:

  let storage = LocalStorage.GetShared()
  @CustomDialog
  struct CustomDialog03 {
    @LocalStorageLink('inputVal')  inputValue: string = ''
    controller: CustomDialogController
    build() {
      Column() {
        Text('Change text').fontSize(20).margin({ top: 10, bottom: 10 })
        TextInput({ placeholder: '', text: this.inputValue }).height(60).width('90%')
          .onChange((value: string) => {
            this.inputValue = value;
          })
      }
    }
  }
  
  
  @Entry(storage)
  @Component
  struct DialogDemo03 {
    @LocalStorageLink('inputVal') inputValue: string = ''
    dialogController: CustomDialogController = new CustomDialogController({
      builder: CustomDialog03()
    })
  
  
    build() {
      Column() {
        Button(this.inputValue)
          .onClick(() => {
            this.dialogController.open()
          }).backgroundColor(0x317aff)
      }.width('100%').margin({ top: 5 })
    }
  }
  
  
  

How do I obtain the width and height of a component?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

The width and height of a component need to be obtained to calculate the size and offset of the layout area.

Solution

• Method 1: Use the onAreaChange event of the component, which is triggered when the component is initialized or the component size changes.
• Manner 2: Use the callback in the click or touch event, which provides the area information of the target element.

Reference

Component Area Change Event, Click Event, Touch Event

How do I clear the content of the <TextInput> and <TextArea> components by one click?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

A click-to-clear feature is required to remove all characters in the <TextInput> and <TextArea> component at once.

Solution

Convert the text attribute of the <TextInput> and <TextArea> component to a state variable. Assign an empty string to the state variable when the click-to-clear event is performed.

Example

struct Index {
@State text: string = 'Hello World'
controller: TextInputController = new TextInputController()
  build() {
    Row() {
      Column() {
        TextInput({ placeholder: 'Please input your words.', text: this.text,
          controller:this.controller}).onChange((value) => {
            this.text = value
          })
        Button("Clear TextInput").onClick(() => {
          this.text = "";
        })
      }
      .width('100%')
    }
    .height('100%')
  }
}

How do I set the position of a custom dialog box?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

By default, a custom dialog box is displayed in the center of the window. In some cases, it needs to be aligned with the window border.

Solution

During initialization of the custom dialog box, set the alignment and offset parameters.

Reference

Custom Dialog Box

How do I hide the overflow content of a container component?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

When content overflows in a container component, that is, the child component does not fit in the container component, the overflow content needs to be processed.

Solution

To clip and hide overflow content, set the clip universal attribute to true. By default, this attribute is set to false.

Reference

Shape Clipping

How do I set a custom dialog box to automatically adapt its size to content?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

When a custom dialog box contains a child component whose area size can be changed, it needs to automatically adjust its size.

Solution

• Method 1: Set the custom dialog box to the default style. In this style, the dialog box automatically adapts its width to the grid system and its height to the child components; the maximum height is 90% of the container height.
• Method 2: Set the custom dialog box to a custom style. In this style, the dialog box automatically adapts its width and height to the child components.

Reference

Custom Dialog Box

What is the function of the gridCount parameter in the custom dialog box?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

The gridCount parameter indicates the number of grid columns occupied by the dialog box. The system divides the window width into equal regions. The number of equal regions is the number of grid columns, which varies by device. For example, if the screen density of a device is 320 vp <= horizontal width < 600 vp, the number of grid columns is 4, and the valid value of gridCount is [1, 4].

Note: This parameter is valid only when the custom dialog box is in the default style.

Reference

Custom Dialog Box

How do I remove the white background of a custom dialog box?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

When in the default style a custom dialog box comes with a white background.

Solution

To remove the white background, set the custom dialog box to a custom style.

1. During initialization of the custom dialog box, set customStyle to true.
2. During initialization of the custom dialog box, set backgroundColor to the color you prefer.

Reference

Custom Dialog Box

How do I customize the eye icon for the password input mode of the <TextInput> component?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

The eye icon for the password input mode (with the type attribute of the <TextInput> component set to InputType.Password) cannot be customized.

Solution

The eye icon itself cannot be customized. You can use set the showPasswordIcon attribute of the <TextInput> component to false to hide the icon, and use the <Image> component to control the type of the <TextInput> component.

Reference

TextInput

How do I use the onSubmit event of the <TextInput> component?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Solution

The onSubmit event is triggered when a user presses Enter on the (physical or soft) keyboard. The callback parameter in the event is the current Enter key type. The Enter key type can be set through the enterKeyType attribute of the <TextInput> component. Setting the key style of the soft keyboard requires support by the input method.

Reference

TextInput

How do I set the caret position to the start point for when the <TextInput> component obtains focus?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

When the <TextInput> component obtains focus, the caret automatically moves to the position of the touch point, instead of the start position.

Solution

1. Bind the <TextInput> component to the onEditChange event, which is triggered when the component enters the input state.
2. Call the setTimeout API for asynchronous processing. Then call the TextInputController.caretPosition API in the event callback to set the caret position.

Example

@Entry
@Component
struct TextInputDemo {
  controller: TextInputController = new TextInputController()

  build() {
    Column() {
      TextInput({ controller: this.controller })
        .onEditChange((isEditing: boolean) => {
          if (isEditing) {
            setTimeout(() => {
              this.controller.caretPosition(0)
            }, 100)
          }
        })
    }
  }
}

Reference

TextInput

How do I obtain the current scrolling offset of a scrollable component?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Solution

1. During initialization of the scrollable component, such as <List>, <Grid>, and <Scroll>, set the scroller parameter to bind the component to a scroll controller.
2. Call the currentOffset API of the controller to obtain the horizontal and vertical scrolling offsets.

Reference

Scroll

How do I align text vertically?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Symptom

Text cannot be aligned vertically in the <Text> component.

Solution

Text is aligned horizontally in the <Text> component. To enable text to align vertically, you can split the file, include it in a <Flex> container, and set the container’s main axis direction to vertical.

Example

@Entry
@Component
struct Index15 {
  private message: string = 'This document is intended for novices in developing applications. It introduces you to the application development process and main files in the project director, by walking you through the building of a simple application with the page redirection/return feature.';
  build() {
    Flex({ direction: FlexDirection.Column, wrap: FlexWrap.Wrap }) {
      ForEach(this.message.split(''), (item, index) => {
        Text(item)
          .fontSize(30)
          .flexShrink(0)
      })
    }
  }
}

How do I set the UI of an ability to transparent?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9)

Solution

Set the background color of the top container component to transparent, and then set the opacity attribute of the XComponent to 0.01.

Example

build() {
  Stack() {
    XComponent({
    id: 'componentId',
    type: 'surface',
    })
    .width('100%')
    .height('100%')
    .opacity(0.01)
    // Page content
  }
  .width('100%')
  .height('100%')
  .backgroundColor('rgba(255,255,255, 0)')
}

Why do the constraintSize settings fail to take effect?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)

Symptom

If constraintSize is set for a component and the width of its child component is set to a percentage, for example, width(‘100%’), constraintSize takes effect by multiplying the maximum width by the percentage. As a result, the child component may overflow, in which case it looks like the constraintSize settings fail to take effect.

Solution

You can use the <Scroll> component at the outer layer. In this way, when constraintSize is set and the space occupied by a child component exceeds the specified constraint value, a scrollbar will be displayed.

How do I set the background color to transparent?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Solution

Set backgroundColor to ‘#00000000’.

What should I do if the <Scroll> component cannot scroll to the bottom?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)

Symptom

Unless otherwise specified, the height of the <Scroll> component is equal to the window height. In this case, the component’s bottom area will be blocked by components (if any) outside of it.

Solution

Set the height of the <Scroll> component or use the flex layout to limit this height.

How do I customize the control bar style of the <Video> component?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)

Solution

1. Set controls to false to disable the default control bar.

2. Sets controller for the <Video> component.

3. Implement a custom control bar in ArkTS and use VideoController to control video playback.

Example

// xxx.ets
@Entry@Componentstruct VideoCreateComponent {
  @State videoSrc: Resource = $rawfile('video1.mp4')
  @State previewUri: Resource = $r('app.media.poster1')
  @State curRate: PlaybackSpeed = PlaybackSpeed.Speed_Forward_1_00_X
  @State isAutoPlay: boolean = false
  @State showControls: boolean = true
  controller: VideoController = new VideoController()
   build() {
    Column() {
      Video({
        src: this.videoSrc,
        previewUri: this.previewUri,
        currentProgressRate: this.curRate,
        controller: this.controller
      }).width('100%').height(600)
        .autoPlay(this.isAutoPlay)
        .controls(this.showControls)
        .onStart(() => {
          console.info('onStart')
        })
        .onPause(() => {
          console.info('onPause')
        })
        .onFinish(() => {
          console.info('onFinish')
        })
        .onError(() => {
          console.info('onError')
        })
        .onPrepared((e) => {
          console.info('onPrepared is ' + e.duration)
        })
        .onSeeking((e) => {
          console.info('onSeeking is ' + e.time)
        })
        .onSeeked((e) => {
          console.info('onSeeked is ' + e.time)
        })
        .onUpdate((e) => {
          console.info('onUpdate is ' + e.time)
        })
             Row() {
        Button('src').onClick(() => {
          this.videoSrc = $rawfile('video2.mp4') // Switch the video source.
        }).margin(5)
        Button('previewUri').onClick(() => {
          this.previewUri = $r('app.media.poster2') // Switch the preview image.
        }).margin(5)

        Button('controls').onClick(() => {
          this.showControls =! this.showControls // Specify whether to show the control bar.
        }).margin(5)
      }
       Row() {
        Button('start').onClick(() => {
          this.controller.start() // Start playback.
        }).margin(5)
        Button('pause').onClick(() => {
          this.controller.pause() // Pause playback.
        }).margin(5)
        Button('stop').onClick(() => {
          this.controller.stop() // Stop playback.
        }).margin(5)
        Button('setTime').onClick(() => {
          this.controller.setCurrentTime(10, SeekMode.Accurate) // Seek to the 10s position of the video.
        }).margin(5)
      }
       Row() {
        Button('rate 0.75').onClick(() => {
          this.curRate = PlaybackSpeed.Speed_Forward_0_75_X // Play the video at the 0.75x speed.
        }).margin(5)
        Button('rate 1').onClick(() => {
          this.curRate = PlaybackSpeed.Speed_Forward_1_00_X // Play the video at the 1x speed.
        }).margin(5)
        Button('rate 2').onClick(() => {
          this.curRate = PlaybackSpeed.Speed_Forward_2_00_X // Play the video at the 2x speed.
        }).margin(5)
      }
    }
  }}

Reference

Video

How do I set state-specific styles for a component?

Solution

You can use the stateStyles attribute to set styles of a component for different states (stateless, pressed, disabled, focused, or clicked).

Example

//xxx.ts
@Entry
@Component
struct StyleExample {
  @State isEnable: boolean = true;

  @Styles pressedStyles() {
    .backgroundColor("#ED6F21")
    .borderRadius(10)
    .borderStyle(BorderStyle.Dashed)
    .borderWidth(2)
    .borderColor('#33000000')
    .width(120)
    .height(30)
    .opacity(1)
  }
  build() {
    Flex({direction: FlexDirection.Column, alignItems: ItemAlign.Center}) {
      Text("pressed")
        .backgroundColor('#0A59F7')
        .borderRadius(20)
        .borderStyle(BorderStyle.Dotted)
        .borderWidth(2)
        .borderColor(Color.Red)
        .width(100)
        .height(25)
        .opacity(1)
        .fontSize(14)
        .fontColor(Color.White)
        .stateStyles({
          pressed: this.pressedStyles
        })
        .margin({
          bottom: 20
        })
        .textAlign(TextAlign.Center)
    }
    .width(350)
    .height(300)
  }
}

Reference

Polymorphic Style

What should I do if the flex width and height in the <Scroll> component conflicts with the scrolling?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)

Symptom

When a container component with a fixed size is added to the <Scroll> component, a scrolling error occurs.

Solution

Do not set a size for any container component in the <Scroll> component. In this way, the <Scroll> component can adapt its size to the content.

How does a component process click events in its child components?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)

When a child component is initialized in the parent component, the method defined in the parent component is transferred to and invoked in the child component. This process is similar to variable transfer.

Example

class Model {
  value: string
}
@Entry
@Component
struct EntryComponent {
  test() {
    console.log('testTag test in my component');
  }
  build() {
    Column() {
      MyComponent({ title: { value: 'Hello World 2' }, count: 7, onClick: this.test }) // The defined method is transferred during initialization.
    }
  }
}

@Component
struct MyComponent {
  @State title: Model = { value: 'Hello World' }
  @State count: number = 0
  onClick: any;
  private toggle: string = 'Hello World'
  private increaseBy: number = 1

  build() {
    Column() {
      Text(`${this.title.value}`).fontSize(30)
      Button(`Click to increase count=${this.count}`)
        .margin(20)
        .onClick(() => {
          // Change the count value of the internal state variable.
          this.count += this.increaseBy
          this.onClick.call();
        })
    }
  }
}

How do I implement a text input box that automatically brings up the soft keyboard?

Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)

Solution

You can use focusControl.requestFocus to control the focus of the text input box. When the text input box is in focus, it automatically brings up the soft keyboard.

Reference

Focus Control

How do I set the controlButton attribute for the <SideBarContainer> component?

Applicable to: OpenHarmony 3.2 Beta5 (API version 9)

Solution

Refer to the following sample code:

@Entry
@Component
struct SideBarContainerExample {
  normalIcon : Resource = $r("app.media.icon")
  selectedIcon: Resource = $r("app.media.icon")
  @State arr: number[] = [1, 2, 3]
  @State current: number = 1

  build() {
    SideBarContainer(SideBarContainerType.Embed)
    {
      Column() {
        ForEach(this.arr, (item, index) => {
          Column({ space: 5 }) {
            Image(this.current === item ? this.selectedIcon : this.normalIcon).width(64).height(64)
            Text("Index0" + item)
              .fontSize(25)
              .fontColor(this.current === item ? '#0A59F7' : '#999')
              .fontFamily('source-sans-pro,cursive,sans-serif')
          }
          .onClick(() => {
            this.current = item
          })
        }, item => item)
      }.width('100%')
      .justifyContent(FlexAlign.SpaceEvenly)
      .backgroundColor('#19000000')


      Column() {
        Text('SideBarContainer content text1').fontSize(25)
        Text('SideBarContainer content text2').fontSize(25)
      }
      .margin({ top: 50, left: 20, right: 30 })
    }
    .sideBarWidth(150)
    .minSideBarWidth(50)
    .controlButton({left:32,
      top:32,
      width:32,
      height:32, 
      icons:{shown: $r("app.media.icon"),
        hidden: $r("app.media.icon"),
        switching: $r("app.media.icon")}})
    .maxSideBarWidth(300)
    .onChange((value: boolean) => {
      console.info('status:' + value)
    })
  }
}

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