Scroll

The <Scroll> component scrolls the content when the layout size of a component exceeds the size of its parent component.

NOTE

• This component is supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version.
• When nesting a <List> within this component, specify the width and height for the <List> under scenarios where consistently high performance is required. If the width and height are not specified, this component will load all content of the <List>.
• This component can scroll only when the size on the main axis is less than the content size.
• This component can produce a bounce effect only when there is more than one screen of content.

Child Components

This component supports only one child component.

APIs

Scroll(scroller?: Scroller)

Attributes

In addition to the universal attributes, the following attributes are supported.

ScrollDirection

Events

NOTE

If the onScrollBegin event and scrollBy API are used to implement nested scrolling, you must set edgeEffect of the scrolling child node to None. For example, if a <List> is nested in the <Scroll> component, the edgeEffect attribute of the <List> must be set to EdgeEffect.None.

Scroller

Implements a controller for a scrollable container component. You can bind this component to a container component and use it to control the scrolling of that component. Currently, this controller can be bound to the <List>, <Scroll> and <ScrollBar> components. One controller can control only one container component.

Objects to Import

scroller: Scroller = new Scroller()

scrollTo

scrollTo(value: { xOffset: number | string, yOffset: number | string, animation?: { duration: number, curve: Curve } }): void

Scrolls to the specified position.

Parameters

scrollEdge

scrollEdge(value: Edge): void

Scrolls to the edge of the container.

Parameters

scrollPage

scrollPage(value: { next: boolean, direction?: Axis }): void

Scrolls to the next or previous page.

Parameters

currentOffset

currentOffset()

Obtains the scrolling offset.

Return value

scrollToIndex

scrollToIndex(value: number): void

Scrolls to the item with the specified index.

NOTE

Only the <List> component is supported.

Parameters

scrollBy⁹⁺

scrollBy(dx: Length, dy: Length): void

Scrolls by the specified amount.

NOTE

Only the <Scroll> component is supported.

Parameters

Example

Example 1

// xxx.ets
@Entry
@Component
struct ScrollExample {
  scroller: Scroller = new Scroller();
  private arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

  build() {
    Stack({ alignContent: Alignment.TopStart }) {
      Scroll(this.scroller) {
        Column() {
          ForEach(this.arr, (item) => {
            Text(item.toString())
              .width('90%')
              .height(150)
              .backgroundColor(0xFFFFFF)
              .borderRadius(15)
              .fontSize(16)
              .textAlign(TextAlign.Center)
              .margin({ top: 10 })
          }, item => item)
        }.width('100%')
      }
      .scrollable(ScrollDirection.Vertical)  // The scrollbar scrolls in the vertical direction.
      .scrollBar(BarState.On)  // The scrollbar is always displayed.
      .scrollBarColor(Color.Gray)  // Color of the scrollbar.
      .scrollBarWidth(30) // Width of the scrollbar.
      .edgeEffect(EdgeEffect.None)
      .onScroll((xOffset: number, yOffset: number) => {
        console.info(xOffset + ' ' + yOffset);
      })
      .onScrollEdge((side: Edge) => {
        console.info('To the edge');
      })
      .onScrollEnd(() => {
        console.info('Scroll Stop');
      })

      Button('scroll 150')
        .onClick(() => { // Click to scroll down to 150.0 vp.
          this.scroller.scrollBy(0,150);
        })
        .margin({ top: 10, left: 20 })
      Button('scroll 100')
        .onClick(() => { // Click to scroll down by 100.0 vp.
          this.scroller.scrollTo({ xOffset: 0, yOffset: this.scroller.currentOffset().yOffset + 100 });
        })
        .margin({ top: 60, left: 20 })
      Button('back top')
        .onClick(() => { // Click to go back to the top.
          this.scroller.scrollEdge(Edge.Top);
        })
        .margin({ top: 110, left: 20 })
      Button('next page')
        .onClick(() => { // Click to go to the next page.
          this.scroller.scrollPage({ next: true });
        })
        .margin({ top: 170, left: 20 })
    }.width('100%').height('100%').backgroundColor(0xDCDCDC)
  }
}

Example 2

@Entry
@Component
struct NestedScroll {
  @State listPosition: number = 0; // 0 indicates scrolling to the top of the list, 1 indicates scrolling to the middle of the list, and 2 indicates scrolling to the bottom of the list.
  private arr: number[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
  private scroller: Scroller = new Scroller();

  build() {
    Flex() {
      Scroll(this.scroller) {
        Column() {
          Text("Scroll Area")
            .width("100%").height("40%").backgroundColor(0X330000FF)
            .fontSize(16).textAlign(TextAlign.Center)

          List({ space: 20 }) {
            ForEach(this.arr, (item) => {
              ListItem() {
                Text("ListItem" + item)
                  .width("100%").height("100%").borderRadius(15)
                  .fontSize(16).textAlign(TextAlign.Center).backgroundColor(Color.White)
              }.width("100%").height(100)
            }, item => item)
          }
          .width("100%").height("50%").edgeEffect(EdgeEffect.None)
          .onReachStart(() => {
            this.listPosition = 0;
          })
          .onReachEnd(() => {
            this.listPosition = 2;
          })
          .onScrollBegin((dx: number, dy: number) => {
            if ((this.listPosition == 0 && dy >= 0) || (this.listPosition == 2 && dy <= 0)) {
              this.scroller.scrollBy(0, -dy);
              return { dxRemain: dx, dyRemain: 0 };
            }
            this.listPosition = 1;
            return { dxRemain: dx, dyRemain: dy };
          })

          Text("Scroll Area")
            .width("100%").height("40%").backgroundColor(0X330000FF)
            .fontSize(16).textAlign(TextAlign.Center)
        }
      }
      .width("100%").height("100%")
    }.width('100%').height('100%').backgroundColor(0xDCDCDC).padding(20)
  }
}