QNativeGestureEvent Class

The QNativeGestureEvent class contains parameters that describe a gesture event. More...

Header: #include <QNativeGestureEvent>
CMake: find_package(Qt6 REQUIRED COMPONENTS Gui)
target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake: QT += gui
Inherits: QSinglePointEvent

Public Functions

QNativeGestureEvent(Qt::NativeGestureType type, const QPointingDevice *device, int fingerCount, const QPointF &localPos, const QPointF &scenePos, const QPointF &globalPos, qreal value, const QPointF &delta, quint64 sequenceId = UINT64_MAX)
QPointF delta() const
int fingerCount() const
Qt::NativeGestureType gestureType() const
qreal value() const

Detailed Description

Native gesture events are generated by the operating system, typically by interpreting trackpad touch events. Gesture events are high-level events such as zoom, rotate or pan. Several types hold incremental values: that is, value() and delta() provide the difference from the previous event to the current event.

Event TypeDescriptionTouch sequence
Qt::ZoomNativeGestureMagnification delta in percent.macOS and Wayland: Two-finger pinch.
Qt::SmartZoomNativeGestureBoolean magnification state.macOS: Two-finger douple tap (trackpad) / One-finger douple tap (magic mouse).
Qt::RotateNativeGestureRotation delta in degrees.macOS and Wayland: Two-finger rotate.
Qt::SwipeNativeGestureSwipe angle in degrees.macOS: Configurable in trackpad settings.
Qt::PanNativeGestureDisplacement delta in pixels.Wayland: Three or more fingers moving as a group, in any direction.

In addition, BeginNativeGesture and EndNativeGesture are sent before and after gesture event streams:

BeginNativeGesture ZoomNativeGesture ZoomNativeGesture ZoomNativeGesture EndNativeGesture

The event stream may include interleaved gestures of different types: for example the two-finger pinch gesture generates a stream of Zoom and Rotate events, and PanNativeGesture may sometimes be interleaved with those, depending on the platform.

Other types are standalone events: SmartZoomNativeGesture and SwipeNativeGesture occur only once each time the gesture is detected.

Note: On a touchpad, moving two fingers as a group (the two-finger flick gesture) is usually reserved for scrolling; in that case, Qt generates QWheelEvents. This is the reason that three or more fingers are needed to generate a PanNativeGesture.

See also Qt::NativeGestureType, QGestureEvent, and QWheelEvent.

Member Function Documentation

[since 6.2] QNativeGestureEvent::QNativeGestureEvent(Qt::NativeGestureType type, const QPointingDevice *device, int fingerCount, const QPointF &localPos, const QPointF &scenePos, const QPointF &globalPos, qreal value, const QPointF &delta, quint64 sequenceId = UINT64_MAX)

Constructs a native gesture event of type type originating from device describing a gesture at scenePos in which fingerCount fingers are involved.

The points localPos, scenePos and globalPos specify the gesture position relative to the receiving widget or item, window, and screen or desktop, respectively.

value has a gesture-dependent interpretation: for RotateNativeGesture or SwipeNativeGesture, it's an angle in degrees. For ZoomNativeGesture, value is an incremental scaling factor, usually much less than 1, indicating that the target item should have its scale adjusted like this: item.scale = item.scale * (1 + event.value)

For PanNativeGesture, delta gives the distance in pixels that the viewport, widget or item should be moved or panned.

Note: The delta is stored in single precision (QVector2D), so delta() may return slightly different values in some cases. This is subject to change in future versions of Qt.

This function was introduced in Qt 6.2.

[since 6.2] QPointF QNativeGestureEvent::delta() const

Returns the distance moved since the previous event, in pixels. A Pan gesture provides the distance in pixels by which the target widget, item or viewport contents should be moved.

This function was introduced in Qt 6.2.

See also QPanGesture::delta().

[since 6.2] int QNativeGestureEvent::fingerCount() const

Returns the number of fingers participating in the gesture, if known. When gestureType() is Qt::BeginNativeGesture or Qt::EndNativeGesture, often this information is unknown, and fingerCount() returns 0.

This function was introduced in Qt 6.2.

Qt::NativeGestureType QNativeGestureEvent::gestureType() const

Returns the gesture type.

qreal QNativeGestureEvent::value() const

Returns the gesture value. The value should be interpreted based on the gesture type. For example, a Zoom gesture provides a scale factor delta while a Rotate gesture provides a rotation delta.

See also QNativeGestureEvent and gestureType().

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