HarmonyOS 组件的拖拽如何实现

需要配合CopyOptions一起使用，设置copyOptions为CopyOptions.InApp或者CopyOptions.LocalDevice，并且draggable设置为true时，支持对选中文本的拖拽以及选中内容复制到输入框，参考文档：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-basic-components-text-V5#ZH-CN_TOPIC_0000001893209429__draggable9

参考示例如下：

// xxx.ets
import UDC from '@ohos.data.unifiedDataChannel';
import UTD from '@ohos.data.uniformTypeDescriptor';
import promptAction from '@ohos.promptAction';
import { BusinessError } from '@ohos.base';

@Entry
@Component
struct Index {
  @State targetImage: string = '';
  @State targetText: string = 'Drag Text';
  @State imageWidth: number = 100;
  @State imageHeight: number = 100;
  @State imgState: Visibility = Visibility.Visible;
  @State videoSrc: string = 'resource://RAWFILE/02.mp4';
  @State abstractContent: string = "abstract";
  @State textContent: string = "";
  @State backGroundColor: Color = Color.Transparent;

  @Builder
  pixelMapBuilder() {
    Column() {
      Image($r('app.media.icon'))
        .width(120)
        .height(120)
        .backgroundColor(Color.Yellow)
    }
  }

  getDataFromUdmfRetry(event: DragEvent, callback: (data: DragEvent) => void) {
    try {
      let data: UnifiedData = event.getData();
      if (!data) {
        return false;
      }
      let records: Array<UDC.UnifiedRecord> = data.getRecords();
      if (!records || records.length <= 0) {
        return false;
      }
      callback(event);
      return true;
    } catch (e) {
      console.log("getData failed, code = " + (e as BusinessError).code + ", message = " +
      (e as BusinessError).message);
      return false;
    }
  }

  getDataFromUdmf(event: DragEvent, callback: (data: DragEvent) => void) {
    if (this.getDataFromUdmfRetry(event, callback)) {
      return;
    }
    setTimeout(() => {
      this.getDataFromUdmfRetry(event, callback);
    }, 1500);
  }

  private PreDragChange(preDragStatus: PreDragStatus): void {
    if (preDragStatus == PreDragStatus.READY_TO_TRIGGER_DRAG_ACTION) {
      this.backGroundColor = Color.Red;
    } else if (preDragStatus == PreDragStatus.ACTION_CANCELED_BEFORE_DRAG
      || preDragStatus == PreDragStatus.PREVIEW_LANDING_FINISHED) {
      this.backGroundColor = Color.Blue;
    }
  }

  build() {
    Row() {
      Column() {
        Text('start Drag')
          .fontSize(18)
          .width('100%')
          .height(40)
          .margin(10)
          .backgroundColor('#008888')
        Image($r('app.media.icon'))
          .width(100)
          .height(100)
          .draggable(true)
          .margin({ left: 15 })
          .visibility(this.imgState)
          .onDragEnd((event) => {
            // onDragEnd里取到的result值在接收方onDrop设置
            if (event.getResult() === DragResult.DRAG_SUCCESSFUL) {
              promptAction.showToast({ duration: 100, message: 'Drag Success' });
            } else if (event.getResult() === DragResult.DRAG_FAILED) {
              promptAction.showToast({ duration: 100, message: 'Drag failed' });
            }
          })
        Text('test drag event')
          .width('100%')
          .height(100)
          .draggable(true)
          .margin({ left: 15 })
          .copyOption(CopyOptions.InApp)
        TextArea({ placeholder: 'please input words' })
          .copyOption(CopyOptions.InApp)
          .width('100%')
          .height(50)
          .draggable(true)
        Search({ placeholder: 'please input you word' })
          .searchButton('Search')
          .width('100%')
          .height(80)
          .textFont({ size: 20 })
        Column() {
          Text('change video source')
        }.draggable(true)
        .onDragStart((event) => {
          let video: UDC.Video = new UDC.Video();
          video.videoUri = '/resources/rawfile/01.mp4';
          let data: UDC.UnifiedData = new UDC.UnifiedData(video);
          (event as DragEvent).setData(data);
          return {
            builder: () => {
              this.pixelMapBuilder()
            }, extraInfo: 'extra info'
          };
        })

        Column() {
          Text('this is abstract')
            .fontSize(20)
            .width('100%')
        }
        .margin({ left: 40, top: 20 })
        .width('100%')
        .height(100)
        .onDragStart((event) => {
          this.backGroundColor = Color.Transparent;
          let data: UDC.PlainText = new UDC.PlainText();
          data.abstract = 'this is abstract';
          data.textContent = 'this is content this is content';
          (event as DragEvent).setData(new UDC.UnifiedData(data));
        })
        .onPreDrag((status: PreDragStatus) => {
          this.PreDragChange(status);
        })
        .backgroundColor(this.backGroundColor)
      }.width('45%')
      .height('100%')

      Column() {
        Text('Drag Target Area')
          .fontSize(20)
          .width('100%')
          .height(40)
          .margin(10)
          .backgroundColor('#008888')
        Image(this.targetImage)
          .width(this.imageWidth)
          .height(this.imageHeight)
          .draggable(true)
          .margin({ left: 15 })
          .border({ color: Color.Black, width: 1 })
          .allowDrop([UTD.UniformDataType.IMAGE])
          .onDrop((dragEvent?: DragEvent) => {
            this.getDataFromUdmf((dragEvent as DragEvent), (event: DragEvent) => {
              let records: Array<UDC.UnifiedRecord> = event.getData().getRecords();
              let rect: Rectangle = event.getPreviewRect();
              this.imageWidth = Number(rect.width);
              this.imageHeight = Number(rect.height);
              this.targetImage = (records[0] as UDC.Image).imageUri;
              event.useCustomDropAnimation = false;
              animateTo({ duration: 1000 }, () => {
                this.imageWidth = 100;
                this.imageHeight = 100;
                this.imgState = Visibility.None;
              })
              // 显式设置result为successful，则将该值传递给拖出方的onDragEnd
              event.setResult(DragResult.DRAG_SUCCESSFUL);
            })
          })

        Text(this.targetText)
          .width('100%')
          .height(100)
          .border({ color: Color.Black, width: 1 })
          .margin(15)
          .allowDrop([UTD.UniformDataType.PLAIN_TEXT])
          .onDrop((dragEvent?: DragEvent) => {
            this.getDataFromUdmf((dragEvent as DragEvent), (event: DragEvent) => {
              let records: Array<UDC.UnifiedRecord> = event.getData().getRecords();
              let plainText: UDC.PlainText = records[0] as UDC.PlainText;
              this.targetText = plainText.textContent;
            })
          })

        Video({ src: this.videoSrc, previewUri: $r('app.media.icon') })
          .width('100%')
          .height(200)
          .controls(true)
          .allowDrop([UTD.UniformDataType.VIDEO])

        Column() {
          Text(this.abstractContent).fontSize(20).width('100%')
          Text(this.textContent).fontSize(15).width('100%')
        }
        .width('100%')
        .height(100)
        .margin(20)
        .border({ color: Color.Black, width: 1 })
        .allowDrop([UTD.UniformDataType.PLAIN_TEXT])
        .onDrop((dragEvent?: DragEvent) => {
          this.getDataFromUdmf((dragEvent as DragEvent), (event: DragEvent) => {
            let records: Array<UDC.UnifiedRecord> = event.getData().getRecords();
            let plainText: UDC.PlainText = records[0] as UDC.PlainText;
            this.abstractContent = plainText.abstract as string;
            this.textContent = plainText.textContent;
          })
        })
      }.width('45%')
      .height('100%')
      .margin({ left: '5%' })
    }
    .height('100%')
  }
}