ts-universal-events-drag-drop.md

# Drag/Drop Event


> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> This component is supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.


| Name | Bubble Supported | Description |
| -------- | -------- | -------- |
| onDragStart(callback: (event: [DragEvent](#DragEvent), extraParams?: string) =&gt;\|[Custom Builder](../../ui/ts-types.md)) | No | Triggered when the component bound to the event is dragged for the first time.<br/>-**event**: information about the drag event, including the coordinates of the item that is being dragged.<br/>-**extraParams**: additional information about the drag event. For details, see extraParam.<br/>Return value: object being dragged, which is used for prompts displayed when the object is dragged.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> - A drag event can be triggered by a 150 ms long press.<br/>> <br/>> - If the duration of a long-press gesture is set to less than or equal to 150 ms, the callback for the long-press gesture takes precedence. Otherwise, the callback for the drag event takes precedence. |
| onDragEnter(callback: (event: [DragEvent](#DragEvent), extraParams?: string) =&gt; void) | No | Triggered when the dragged item enters a valid drop target.<br/>-**event**: information about the drag event, including the coordinates of the item that is being dragged.<br/>-**extraParams**: additional information about the drag event. For details, see extraParam.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> This event is valid only when the **onDrop** event is listened to. |
| onDragMove(callback: (event: [DragEvent](#DragEvent), extraParams?: string) =&gt; void) | No | Triggered when the dragged item moves in a valid drop target.<br/>-**event**: information about the drag event, including the coordinates of the item that is being dragged.<br/>-**extraParams**: additional information about the drag event. For details, see extraParam.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> This event is valid only when the **onDrop** event is listened to. |
| onDragLeave(callback: (event: [DragEvent](#DragEvent), extraParams?: string) =&gt; void) | No | Triggered when the dragged item leaves a valid drop target.<br/>-**event**: information about the drag event, including the coordinates of the item that is being dragged.<br/>-**extraParams**: additional information about the drag event. For details, see extraParam.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> This event is valid only when the **onDrop** event is listened to. |
| onDrop(callback: (event:[DragEvent](#DragEvent), extraParams?: string) =&gt; void) | No | Triggered when the dragged item is dropped on a valid drop target.<br/>-**event**: information about the drag event, including the coordinates of the item that is being dragged.<br/>-**extraParams**: additional information about the drag event. For details, see extraParam. |


- extraParam
  Returns additional information required for dragging an item.

    **extraParam** is a string converted from a JSON object. You can obtain the following attributes using the JSON object converted from **Json.parse**.
    | Name | Type | Description | 
  | -------- | -------- | -------- |
  | selectedIndex | number | Index of the dragged item in the parent container. The value of **selectedindex** starts from **0**.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> This attribute is valid only in the **ListItem** component. | 
  | insertIndex | number | Index of the element into which the dragged item is dropped in the **List** component. The value of **insertIndex** starts from **0**.<br/>> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>> This attribute is valid only in the drag event of the **List** component. | 


### DragEvent

- APIs
    | Name | Return Value Type | Description | 
  | -------- | -------- | -------- |
  | getX() | number | X-coordinate of the item that is being dragged, in vp. | 
  | getY() | number | Y-coordinate of the item that is being dragged, in vp. | 


## Example


```
@Entry
@Component
struct DragExample {
  @State numbers: string[] = ['one', 'two', 'three', 'four', 'five', 'six']
  @State text: string = ''
  @State bool: boolean = false
  @State bool1: boolean = false
  @State size: string = ''
  @State appleVisible: Visibility = Visibility.Visible
  @State orangeVisible: Visibility = Visibility.Visible
  @State bananaVisible: Visibility = Visibility.Visible
  @State select: number = 0
  @State currentIndex: number = 0

  @Builder pixelMapBuilder() {
    Column() {
      Text(this.text)
        .width('50%').height(60).fontSize(16).borderRadius(10)
        .textAlign(TextAlign.Center).backgroundColor(Color.Yellow)
    }
  }

  build() {
    Column() {
      Text('There are three Text elements here')
        .fontSize(12).fontColor(0xCCCCCC).width('90%')
        .textAlign(TextAlign.Start).margin(5)
      Flex({ direction: FlexDirection.Row, alignItems: ItemAlign.Center, justifyContent: FlexAlign.SpaceAround }) {
        Text('apple').width('25%').height(35).fontSize(16)
          .textAlign(TextAlign.Center).backgroundColor(0xAFEEEE)
          .visibility(this.appleVisible)
          .onDragStart(() => {
            this.bool = true
            this.text = 'apple'
            this.appleVisible = Visibility.Hidden
            return this.pixelMapBuilder
          })
        Text('orange').width('25%').height(35).fontSize(16)
          .textAlign(TextAlign.Center).backgroundColor(0xAFEEEE)
          .visibility(this.orangeVisible)
          .onDragStart(() => {
            this.bool = true
            this.text = 'orange'
            this.orangeVisible = Visibility.Hidden
            return this.pixelMapBuilder
          })
        Text('banana').width('25%').height(35).fontSize(16)
          .textAlign(TextAlign.Center).backgroundColor(0xAFEEEE)
          .visibility(this.bananaVisible)
          .onDragStart((event: DragEvent, extraParams: string) => {
            console.log('Text onDragStarts, ' + extraParams)
            this.bool = true
            this.text = 'banana'
            this.bananaVisible = Visibility.Hidden
            return this.pixelMapBuilder
          })
      }.border({ width: 1 }).width('90%').padding({ top: 10, bottom: 10 }).margin(10)

      Text('This is a List element').fontSize(12)
        .fontColor(0xCCCCCC).width('90%')
        .textAlign(TextAlign.Start).margin(15)
      List({ space: 20, initialIndex: 0 }) {
        ForEach(this.numbers, (item) => {
          ListItem() {
            Text('' + item)
              .width('100%').height(80).fontSize(16).borderRadius(10)
              .textAlign(TextAlign.Center).backgroundColor(0xAFEEEE)
          }
          .onDragStart((event: DragEvent, extraParams: string) => {
            console.log('ListItem onDragStarts, ' + extraParams)
            var jsonString = JSON.parse(extraParams)
            this.bool1 = true
            this.text = this.numbers[jsonString.selectedIndex]
            this.select = jsonString.selectedIndex
            return this.pixelMapBuilder
          })
        }, item => item)
      }
      .editMode(true)
      .height('50%').width('90%').border({ width: 1 })
      .divider({ strokeWidth: 2, color: 0xFFFFFF, startMargin: 20, endMargin: 20 })
      .onDragEnter((event: DragEvent, extraParams: string) => {
        console.log('List onDragEnter, ' + extraParams)
      })
      .onDragMove((event: DragEvent, extraParams: string) => {
        console.log('List onDragMove, ' + extraParams)
      })
      .onDragLeave((event: DragEvent, extraParams: string) => {
        console.log('List onDragLeave, ' + extraParams)
      })
      .onDrop((event: DragEvent, extraParams: string) => {
        var jsonString = JSON.parse(extraParams)
        if (this.bool) {
          this.numbers.splice(jsonString.insertIndex, 0, this.text)
          this.bool = false
        } else if (this.bool1) {
          this.numbers.splice(jsonString.selectedIndex, 1)
          this.numbers.splice(jsonString.insertIndex, 0, this.text)
          this.bool = false
          this.bool1 = false
        }
      })
    }.width('100%').height('100%').padding({ top: 20 }).margin({ top: 20 })
  }
}
```

![en-us_image_0000001212218450](figures/en-us_image_0000001212218450.gif)