harmony 鸿蒙Drag and Drop Control

2023-10-30
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Drag and Drop Control

The drag and drop control attributes set whether a component can respond to drag events.

NOTE

The APIs of this module are supported since API version 10. Updates will be marked with a superscript to indicate their earliest API version.

The ArkUI framework implements the drag and drop capability for the following components, allowing them to serve as the drag source (from which data can be dragged) or drop target (to which data can be dropped). To enable drag and drop for these components, you only need to set their draggable attribute to true.

The following component supports drag actions by default: <Search>, <TextInput>, <TextArea>, <RichEditor>, <Text>, <Image>, <FormComponent>, <Hyperlink>
The following component supports drop actions by default: <Search>, <TextInput>, <TextArea>, <Video>

You can also define drag responses by implementing common drag events.

To enable drag and drop for other components, you need to set the draggable attribute to true and implement data transmission in APIs such as onDragStart.

Attributes

Name	Type	Description
allowDrop	Array<UniformDataType>	Type of data that can be dropped to the component. Default value: empty
draggable	boolean	Whether the component is draggable. Default value: false

Example

// xxx.ets
import UDC from '@ohos.data.unifiedDataChannel';
import UTD from '@ohos.data.uniformTypeDescriptor';

@Entry
@Component
struct ImageExample {
  @State uri: string = ""
  @State AblockArr: string[] = []
  @State BblockArr: string[] = []
  @State AVisible: Visibility = Visibility.Visible
  @State dragSuccess :Boolean = false

  build() {
    Column() {
      Text ('Image drag and drop')
        .fontSize('30dp')
      Flex({ direction: FlexDirection.Row, alignItems: ItemAlign.Center, justifyContent: FlexAlign.SpaceAround }) {
        Image($r('app.media.icon'))
          .width(100)
          .height(100)
          .border({ width: 1 })
          .visibility(this.AVisible)
          .draggable(true)
          .onDragEnd((event: DragEvent) => {
            let ret = event.getResult();
            if(ret == 0) {
              console.log("enter ret == 0")
              this.AVisible = Visibility.Hidden;
            } else {
              console.log("enter ret != 0")
              this.AVisible = Visibility.Visible;
            }
          })
      }
      .margin({ bottom: 20 })
      Row() {
        Column(){
          Text('Invalid drop target')
            .fontSize('15dp')
            .height('10%')
          List(){
            ForEach(this.AblockArr, (item:string, index) => {
              ListItem() {
                Image(item)
                  .width(100)
                  .height(100)
                  .border({width: 1})
              }
              .margin({ left: 30 , top : 30})
            }, (item:string) => item)
          }
          .height('90%')
          .width('100%')
          .allowDrop([UTD.UniformDataType.TEXT])
          .onDrop((event?: DragEvent, extraParams?: string) => {
            this.uri = JSON.parse(extraParams as string).extraInfo;
            this.AblockArr.splice(JSON.parse(extraParams as string).insertIndex, 0, this.uri);
            console.log("ondrop not udmf data");
          })
          .border({width: 1})
        }
        .height("50%")
        .width("45%")
        .border({ width: 1 })
        .margin({ left: 12 })
        Column(){
          Text ('Valid drop target')
            .fontSize('15dp')
            .height('10%')
          List(){
            ForEach(this.BblockArr, (item:string, index) => {
              ListItem() {
                Image(item)
                  .width(100)
                  .height(100)
                  .border({width: 1})
              }
              .margin({ left: 30 , top : 30})
            }, (item:string) => item)
          }
          .border({width: 1})
          .height('90%')
          .width('100%')
          .allowDrop([UTD.UniformDataType.IMAGE])
          .onDrop((event?: DragEvent, extraParams?: string) => {
            console.log("enter onDrop")
            let dragData:UnifiedData = (event as DragEvent).getData() as UnifiedData;
            if(dragData != undefined) {
              let arr:Array<UDC.UnifiedRecord> = dragData.getRecords();
              if(arr.length > 0) {
                let image = arr[0] as UDC.Image;
                this.uri = image.imageUri;
                this.BblockArr.splice(JSON.parse(extraParams as string).insertIndex, 0, this.uri);
              } else {
                console.log(`dragData arr is null`)
              }
            } else {
              console.log(`dragData  is undefined`)
            }
            console.log("ondrop udmf data");
            this.dragSuccess = true
          })
        }
        .height("50%")
        .width("45%")
        .border({ width: 1 })
        .margin({ left: 12 })
      }
    }.width('100%')
  }
}