Gesture Binding

Bind different types of gesture events to components and set response methods for them.

NOTE

The APIs of this module are supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version.

Binding Gesture Recognition

Use the following attributes to bind gesture recognition to a component. When a gesture is recognized, the event callback is invoked to notify the component.

Name Type Default Value Description
gesture gesture: GestureType,
mask?: GestureMask
gesture: -,
mask: GestureMask.Normal
Gesture to bind.
- gesture: type of the gesture to bind.
- mask: event response setting.
priorityGesture gesture: GestureType,
mask?: GestureMask
gesture: -,
mask: GestureMask.Normal
Gesture to preferentially recognize.
- gesture: type of the gesture to bind.
- mask: event response setting.
By default, a component recognizes gestures bound through gesture. When priorityGesture is configured for its parent component, the component preferentially recognizes gestures bound through priorityGesture.
parallelGesture gesture: GestureType,
mask?: GestureMask
gesture: -,
mask: GestureMask.Normal
Gesture that can be triggered together with the child component gesture.
- gesture: type of the gesture to bind.
- mask: event response setting.
The gesture event is not a bubbling event. When parallelGesture is set for the parent component, gesture events that are the same for the parent and child components can be triggered, thereby implementing a bubbling effect. If both the single-tap gesture event and the double-tap gesture event are bound to the parent and child components, only the single-tap gesture event is responded.

GestureType

Name Description
TapGesture Tap gesture, which can be a single-tap or multi-tap gesture.
LongPressGesture Long press gesture.
PanGesture Pan gesture, which requires a minimum 5 vp movement distance of a finger on the screen.
PinchGesture Pinch gesture.
RotationGesture Rotation gesture.
SwipeGesture Swipe gesture, which can be recognized when the swipe speed is 100 vp/s or higher.
GestureGroup A group of gestures. Continuous recognition, parallel recognition, and exclusive recognition are supported.

GestureMask

Name Description
Normal The gestures of child components are not ignored and are recognized based on the default gesture recognition sequence.
IgnoreInternal The gestures of child components are ignored, including the built-in gestures. For example, if the child component is <List>, its built-in swipe gesture is also ignored.

Gesture Response Event

The component binds gesture objects of different GestureTypes through gesture events. Each gesture object provides gesture-related information in the gesture response event. In the following example, the TapGesture object provides gesture-related information in the onAction event. For details about the event definitions of other gestures, see the corresponding gesture sections. To bind multiple gestures, use combined gestures.

TapGesture

Name Description
onAction((event?:GestureEvent) => void) Callback invoked when a tap gesture is recognized.

GestureEvent

Name Type Description
repeat boolean Whether the event is triggered repeatedly. This attribute is used for the LongPressGesture event.
offsetX number Offset of the gesture event on the x-axis, in vp. This attribute is used for the PanGesture event. A positive value means to pan from left to right, and a negative value means the opposite.
offsetY number Offset of the gesture event on the y-axis, in vp. This attribute is used for the PanGesture event. A positive value means to pan from top to bottom, and a negative value means the opposite.
angle number Rotation angle for the RotationGesture event;
angle of the swipe gesture for the SwipeGesture event, that is, the change in the included angle between the line segment created by the two fingers and the horizontal direction.
NOTE
Angle calculation method: After a swipe gesture is recognized, a line connecting the two fingers is identified as the initial line. As the fingers swipe, the line between the fingers rotates. Based on the coordinates of the initial line's and current line's end points, an arc tangent function is used to calculate the respective included angle of the points relative to the horizontal direction by using the following formula: Rotation angle = arctan2(cy2-cy1,cx2-cx1) – arctan2(y2-y1,x2-x1) The initial line is used as the coordinate system. The clockwise rotation is 0 to 180 degrees, and the counter-clockwise rotation is –180 to 0 degrees.
scale number Scale ratio. This attribute is used for the PinchGesture event.
pinchCenterX number X-coordinate of the center of the pinch gesture, in px relative to the upper left corner of the current component. This attribute is used for the PinchGesture event.
pinchCenterY number Y-coordinate of the center of the pinch gesture, in px relative to the upper left corner of the current component. This attribute is used for the PinchGesture event.
speed8+ number Swipe gesture speed, that is, the average swipe speed of all fingers. The unit is vp/s. This attribute is used for the SwipeGesture event.
fingerList8+ FingerInfo[] Information about all fingers that trigger the event, which is used for the LongPressGesture and TapGesture events.
timestamp8+ number Timestamp of the event.
target8+ EventTarget Display area of the element that triggers the gesture event.
source8+ SourceType Event input device.
pressure9+ number Press pressure.
tiltX9+ number Angle between the projection of the stylus on the device plane and the x-axis.
tiltY9+ number Angle between the projection of the stylus on the device plane and the y-axis.
sourceTool9+ SourceTool Event input source.

SourceType

Name Description
Unknown Unknown device type.
Mouse Mouse.
TouchScreen Touchscreen.

FingerInfo

Name Type Description
id number Index of a finger.
globalX number X-coordinate relative to the upper left corner of the application window.
globalY number Y-coordinate relative to the upper left corner of the application window.
localX number X-coordinate relative to the upper left corner of the current component.
localY number Y-coordinate relative to the upper left corner of the current component.

SourceTool

Name Description
Unknown Unknown input source.
Finger Finger input.
Pen Stylus input.

Example

// xxx.ets
@Entry
@Component
struct GestureSettingsExample {
  @State priorityTestValue: string = ''
  @State parallelTestValue: string = ''

  build() {
    Column() {
      Column() {
        Text('TapGesture:' + this.priorityTestValue).fontSize(28)
          .gesture(
          TapGesture()
            .onAction(() => {
              this.priorityTestValue += '\nText'
            }))
      }
      .height(200)
      .width(250)
      .padding(20)
      .margin(20)
      .border({ width: 3 })
      // When priorityGesture is set, the tap gesture on the <Column> component is prioritized over the tap gesture on the child <Text> component.
      .priorityGesture(
      TapGesture()
        .onAction((event: GestureEvent) => {
          this.priorityTestValue += '\nColumn'
        }), GestureMask.IgnoreInternal)

      Column() {
        Text('TapGesture:' + this.parallelTestValue).fontSize(28)
          .gesture(
          TapGesture()
            .onAction(() => {
              this.parallelTestValue += '\nText'
            }))
      }
      .height(200)
      .width(250)
      .padding(20)
      .margin(20)
      .border({ width: 3 })
      // When parallelGesture is set, the tap gestures on the <Column> component and on the child <Text> component are both recognized.
      .parallelGesture(
      TapGesture()
        .onAction((event: GestureEvent) => {
          this.parallelTestValue += '\nColumn'
        }), GestureMask.Normal)
    }
  }
}

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