Touch Event

A touch event is triggered when a finger is pressed, slides, or is lifted from a component.

NOTE

This event is supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version.

Events

Name	Bubbling Supported	Description
onTouch(event: (event?: TouchEvent) => void)	Yes	Invoked when a touch event is triggered. For details about event, see TouchEvent.

TouchEvent

Name	Type	Description
type	TouchType	Type of the touch event.
touches	Array<TouchObject>	All finger information.
changedTouches	Array<TouchObject>	Finger information changed.
stopPropagation	() => void	Stops the event from bubbling upwards or downwards.
timestamp⁸⁺	number	Timestamp of the event. It is interval between the time when the event is triggered and the time when the system starts, in nanoseconds.
target⁸⁺	EventTarget	Display area of the element that triggers the gesture event.
source⁸⁺	SourceType	Event input device.

TouchObject

Name	Type	Description
type	TouchType	Type of the touch event.
id	number	Unique identifier of a finger.
screenX	number	X coordinate of the touch point relative to the upper left corner of the application window.
screenY	number	Y coordinate of the touch point relative to the upper left corner of the application window.
x	number	X coordinate of the touch point relative to the upper left corner of the component being touched.
y	number	Y coordinate of the touch point relative to the upper left corner of the component being touched.

Example

// xxx.ets
@Entry
@Component
struct TouchExample {
  @State text: string = ''
  @State eventType: string = ''

  build() {
    Column() {
      Button('Touch').height(40).width(100)
        .onTouch((event: TouchEvent) => {
          if (event.type === TouchType.Down) {
            this.eventType = 'Down'
          }
          if (event.type === TouchType.Up) {
            this.eventType = 'Up'
          }
          if (event.type === TouchType.Move) {
            this.eventType = 'Move'
          }
          this.text = 'TouchType:' + this.eventType + '\nDistance between touch point and touch element:\nx: '
          + event.touches[0].x + '\n' + 'y: ' + event.touches[0].y + '\nComponent globalPos:('
          + event.target.area.globalPosition.x + ',' + event.target.area.globalPosition.y + ')\nwidth:'
          + event.target.area.width + '\nheight:' + event.target.area.height
        })
      Button('Touch').height(50).width(200).margin(20)
        .onTouch((event: TouchEvent) => {
          if (event.type === TouchType.Down) {
            this.eventType = 'Down'
          }
          if (event.type === TouchType.Up) {
            this.eventType = 'Up'
          }
          if (event.type === TouchType.Move) {
            this.eventType = 'Move'
          }
          this.text = 'TouchType:' + this.eventType + '\nDistance between touch point and touch element:\nx: '
          + event.touches[0].x + '\n' + 'y: ' + event.touches[0].y + '\nComponent globalPos:('
          + event.target.area.globalPosition.x + ',' + event.target.area.globalPosition.y + ')\nwidth:'
          + event.target.area.width + '\nheight:' + event.target.area.height
        })
      Text(this.text)
    }.width('100%').padding(30)
  }
}

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