1# Touch Event 2 3A touch event is triggered when a finger is pressed against, swipes on, or is lifted from a component. 4 5> **NOTE** 6> 7> This event is supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version. 8 9## onTouch 10 11onTouch(event: (event: TouchEvent) => void) 12 13Invoked when a touch event is triggered. 14 15**Widget capability**: Since API version 9, this feature is supported in ArkTS widgets. 16 17**System capability**: SystemCapability.ArkUI.ArkUI.Full 18 19**Parameters** 20 21| Name| Type | Mandatory| Description | 22| ------ | --------------------------------- | ---- | -------------------- | 23| event | [TouchEvent](#touchevent) | Yes | **TouchEvent** object.| 24 25## TouchEvent 26 27| Name | Type | Description | 28| ------------------- | ---------------------------------------- | ------------ | 29| type | [TouchType](ts-appendix-enums.md#touchtype) | Type of the touch event. | 30| touches | Array<[TouchObject](#touchobject)> | All finger information. | 31| changedTouches | Array<[TouchObject](#touchobject)> | Finger information changed.| 32| stopPropagation | () => void | Stops the event from bubbling upwards or downwards.| 33| timestamp<sup>8+</sup> | number | Timestamp of the event. It is the interval between the time when the event is triggered and the time when the system starts.<br>For example, if the system starts at 2023/10/12 11:33 and the touch event is triggered at 2023/10/12 11:34, then the returned timestamp value is 60,000,000,000 ns.<br>Unit: ns| 34| target<sup>8+</sup> | [EventTarget](ts-universal-events-click.md#eventtarget8) | Display area of the element that triggers the gesture event.| 35| source<sup>8+</sup> | [SourceType](ts-gesture-settings.md#sourcetype)| Event input device.| 36 37 38### getHistoricalPoints<sup>10+</sup> 39 40getHistoricalPoints(): Array<HistoricalPoint> 41 42Obtains all historical points of the current frame. The touch event frequency of a frame varies by device, and all touch events of the current frame are referred to as its historical points. This API can be called only in [TouchEvent](#touchevent). You can use this API to obtain the historical points of the current frame when [onTouch](#ontouch) is invoked. [onTouch](#ontouch) is invoked only once for a frame. If the value of [TouchEvent](#touchevent) received by the current frame is greater than 1, the last point of the frame is returned through [onTouch](#ontouch). The remaining points are regarded as historical points. 43 44**Return value** 45 46| Type | Description | 47| ------ | ----------------------- | 48| Array<[HistoricalPoint](#historicalpoint10)>| Array of historical points.| 49 50 51## TouchObject 52 53| Name | Type | Description | 54| ------- | ------------------------------------------- | ------------------------------------- | 55| type | [TouchType](ts-appendix-enums.md#touchtype) | Type of the touch event. | 56| id | number | Unique identifier of a finger. | 57| x | number | X coordinate of the touch point relative to the upper left corner of the original area of the touched element.| 58| y | number | Y coordinate of the touch point relative to the upper left corner of the original area of the touched element.| 59| windowX<sup>10+</sup> | number | X coordinate of the touch point relative to the upper left corner of the application window. | 60| windowY<sup>10+</sup> | number | Y coordinate of the touch point relative to the upper left corner of the application window. | 61| displayX<sup>10+</sup> | number | X coordinate of the touch point relative to the upper left corner of the application screen. | 62| displayY<sup>10+</sup> | number | Y coordinate of the touch point relative to the upper left corner of the application screen. | 63| screenX<sup>(deprecated)</sup> | number | X coordinate of the touch point relative to the upper left corner of the application window.<br>This API is deprecated since API version 10. You are advised to use **windowX** instead. | 64| screenY<sup>(deprecated)</sup> | number | Y coordinate of the touch point relative to the upper left corner of the application window.<br>This API is deprecated since API version 10. You are advised to use **windowX** instead. | 65 66## HistoricalPoint<sup>10+</sup> 67 68| Name | Type | Description | 69| ----------- | ----------------------------------- | ----------------------------------------------------------------------------- | 70| touchObject | [TouchObject](#touchobject) | Basic information of the historical point. | 71| size | number | Size of the contact area between the finger and screen for the historical point.<br>Default value: **0** | 72| force | number | Touch force of the historical point.<br>Default value: **0**<br>Value range: [0,1]. A larger value indicates a greater touch force.<br>The support for this API varies by device. Currently, it is only available on tablets.| 73| timestamp | number | Timestamp of the historical point. It is the interval between the time when the event is triggered and the time when the system starts.<br>Unit: ns | 74## Example 75 76```ts 77// xxx.ets 78@Entry 79@Component 80struct TouchExample { 81 @State text: string = '' 82 @State eventType: string = '' 83 84 build() { 85 Column() { 86 Button('Touch').height(40).width(100) 87 .onTouch((event?: TouchEvent) => { 88 if(event){ 89 if (event.type === TouchType.Down) { 90 this.eventType = 'Down' 91 } 92 if (event.type === TouchType.Up) { 93 this.eventType = 'Up' 94 } 95 if (event.type === TouchType.Move) { 96 this.eventType = 'Move' 97 } 98 this.text = 'TouchType:' + this.eventType + '\nDistance between touch point and touch element:\nx: ' 99 + event.touches[0].x + '\n' + 'y: ' + event.touches[0].y + '\nComponent globalPos:(' 100 + event.target.area.globalPosition.x + ',' + event.target.area.globalPosition.y + ')\nwidth:' 101 + event.target.area.width + '\nheight:' + event.target.area.height 102 } 103 }) 104 Button('Touch').height(50).width(200).margin(20) 105 .onTouch((event?: TouchEvent) => { 106 if(event){ 107 if (event.type === TouchType.Down) { 108 this.eventType = 'Down' 109 } 110 if (event.type === TouchType.Up) { 111 this.eventType = 'Up' 112 } 113 if (event.type === TouchType.Move) { 114 this.eventType = 'Move' 115 } 116 this.text = 'TouchType:' + this.eventType + '\nDistance between touch point and touch element:\nx: ' 117 + event.touches[0].x + '\n' + 'y: ' + event.touches[0].y + '\nComponent globalPos:(' 118 + event.target.area.globalPosition.x + ',' + event.target.area.globalPosition.y + ')\nwidth:' 119 + event.target.area.width + '\nheight:' + event.target.area.height 120 } 121 }) 122 Text(this.text) 123 }.width('100%').padding(30) 124 } 125} 126``` 127 128 129
