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.
Required Permissions
None
Events
Name |
Bubbling Supported |
Description |
onTouch(callback: (event?: TouchEvent) => void) |
Yes |
Invoked when a touch action 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. |
timestamp |
number |
Timestamp of the event. |
target8+ |
EventTarget |
Target of the event. |
Name |
Description |
stopPropagation(): void |
Stops the event from bubbling upwards or downwards. |
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 left edge of the screen. |
screenY |
number |
Y-coordinate of the touch point relative to the upper edge of the device screen. |
x |
number |
X-coordinate of the touch point relative to the left edge of the element being touched. |
y |
number |
Y-coordinate of the touch point relative to the upper edge of the element being touched. |
TouchType Enums
Name |
Description |
Down |
A finger is pressed. |
Up |
A finger is lifted. |
Move |
A finger moves on the screen in pressed state. |
Cancel |
A touch event is canceled. |
Example
@Entry
@Component
struct TouchExample {
@State text: string = ''
@State eventType: string = ''
build() {
Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.SpaceBetween }) {
Button('Touch').backgroundColor(0x2788D9).height(40).width(80)
.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'
}
console.info(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)
}.height(200).width(350).padding({ left: 35, right: 35, top: 35 })
}
}
![en-us_image_0000001212058464](figures/en-us_image_0000001212058464.gif)