The QWheelEvent class contains parameters that describe a wheel event. More...

Inheritance diagram for QWheelEvent:

Public Methods
	QWheelEvent (const QPointF &pos, const QPointF &globalPosition, int delta, Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers, Qt::Orientation orientation=Qt::Vertical)

	QWheelEvent (const QPointF &pos, const QPointF &globalPosition, QPoint pixelDelta, QPoint angleDelta, Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers, Qt::ScrollPhase phase, Qt::MouseEventSource source=Qt::MouseEventNotSynthesized)

	QWheelEvent (const QPointF &pos, int delta, Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers, Qt::Orientation orientation=Qt::Vertical)

QPoint	angleDelta () const

Qt::MouseButtons	buttons () const

int	delta () const

QPoint	globalPos () const

const QPointF &	globalPosF () const

int	globalX () const

int	globalY () const

Qt::Orientation	orientation () const

Qt::ScrollPhase	phase () const

QPoint	pixelDelta () const

QPoint	pos () const

const QPointF &	posF () const

Qt::MouseEventSource	source () const

int	x () const

int	y () const

Public Methods inherited from QInputEvent
Qt::KeyboardModifiers	modifiers () const

void	setModifiers (Qt::KeyboardModifiers modifiers)

void	setTimestamp (ulong timestamp)

ulong	timestamp () const

Public Methods inherited from QEvent
	QEvent (const QEvent &other)

	QEvent (Type type)

virtual	~QEvent ()

void	accept ()

void	ignore ()

bool	isAccepted () const

QEvent &	operator= (const QEvent &other)

void	setAccepted (bool accepted)

bool	spontaneous () const

Type	type () const

Friends
class	QApplication

Additional Inherited Members
Public Types inherited from QEvent
enum	Type

Static Public Methods inherited from QEvent
static int	registerEventType (int hint=-1)

Detailed Description

The QWheelEvent class contains parameters that describe a wheel event. Wheel events are sent to the widget under the mouse cursor, but if that widget does not handle the event they are sent to the focus widget. The rotation distance is provided by delta(). The methods pos() and globalPos() return the mouse cursor's location at the time of the event.

A wheel event contains a special accept flag that indicates whether the receiver wants the event. You should call ignore() if you do not handle the wheel event; this ensures that it will be sent to the parent widget.

The QWidget::setEnabled() method can be used to enable or disable mouse and keyboard events for a widget. The event handler QWidget::wheelEvent() receives wheel events.

See also: QMouseEvent, QWidget::grabMouse()

Constructor & Destructor Documentation

QWheelEvent::QWheelEvent	(	const QPointF &	pos,
		int	delta,
		Qt::MouseButtons	buttons,
		Qt::KeyboardModifiers	modifiers,
		Qt::Orientation	orientation = `Qt::Vertical`
	)

Constructs a wheel event object.

The position pos is the location of the mouse cursor within the widget. This constructor does not provide a way to set the global position, it is initialized to the result of QCursor::pos(). Use one of the other constructors if you need to specify the global position explicitly.

The buttons describe the state of the mouse buttons at the time of the event. The value for the delta contains the rotation distance, modifiers holds the keyboard modifier flags at the time of the event, and orientation holds the wheel's orientation.

See also: buttons(), delta(), pos()

QWheelEvent::QWheelEvent	(	const QPointF &	pos,
		const QPointF &	globalPosition,
		int	delta,
		Qt::MouseButtons	buttons,
		Qt::KeyboardModifiers	modifiers,
		Qt::Orientation	orientation = `Qt::Vertical`
	)

Constructs a wheel event object.

The position pos provides the location of the mouse cursor within the widget. The position in global coordinates is specified by globalPosition. The value for delta contains the rotation distance, modifiers holds the keyboard modifier flags at the time of the event, and orientation holds the wheel's orientation.

See also: buttons(), delta(), globalPos(), pos()

QWheelEvent::QWheelEvent	(	const QPointF &	pos,
		const QPointF &	globalPosition,
		QPoint	pixelDelta,
		QPoint	angleDelta,
		Qt::MouseButtons	buttons,
		Qt::KeyboardModifiers	modifiers,
		Qt::ScrollPhase	phase,
		Qt::MouseEventSource	source = `Qt::MouseEventNotSynthesized`
	)

Constructs a wheel event object.

The position pos provides the location of the mouse cursor within the window. The position in global coordinates is specified by globalPosition. The value for pixelDelta contains the scrolling distance in pixels on screen while angleDelta contains the wheel rotation distance. The value of pixelDelta can be null. The mouse and keyboard states at the time of the event are specified by buttons and modifiers. The scrolling phase of the event is specified by phase.

If the wheel event comes from a physical mouse wheel, source is set to Qt::MouseEventNotSynthesized. If it comes from a gesture detected by the operating system, or from a non-mouse hardware device, such that pixelDelta is directly related to finger movement, source is set to Qt::MouseEventSynthesizedBySystem. If it comes from CopperSpice the source will be set to Qt::MouseEventSynthesizedByCS.

See also: posF(), globalPosF(), angleDelta(), pixelDelta(), phase()

Method Documentation

QPoint QWheelEvent::angleDelta ( ) const

inline

Returns the distance that the wheel is rotated, in eighths of a degree. A positive value indicates that the wheel was rotated forwards away from the user, a negative value indicates that the wheel was rotated backwards toward the user.

Most mouse types work in steps of 15 degrees, in which case the delta value is a multiple of 120 since 120 units * 1/8 = 15 degrees.

However, some mice have finer-resolution wheels and send delta values that are less than 120 units (less than 15 degrees). To support this possibility, you can either cumulatively add the delta values from events until the value of 120 is reached, then scroll the widget, or you can partially scroll the widget in response to each wheel event.

void MyWidget::wheelEvent(QWheelEvent *event) {
    QPoint numPixels  = event->pixelDelta();
    QPoint numDegrees = event->angleDelta() / 8;
 
    if (! numPixels.isNull()) {
       scrollWithPixels(numPixels);
 
    } else if (!numDegrees.isNull()) {
       QPoint numSteps = numDegrees / 15;
       scrollWithDegrees(numSteps);
    }
 
    event->accept();
}

On platforms which support scrolling phases the delta may be null when either of these conditions is true.

Scrolling is about to begin but the distance did not yet change (Qt::ScrollBegin)
Scrolling has ended and the distance did not change anymore (Qt::ScrollEnd)

See also: pixelDelta()

Qt::MouseButtons QWheelEvent::buttons ( ) const

inline

Returns the mouse state when the event occurred.

int QWheelEvent::delta ( ) const

inline

Returns the distance that the wheel is rotated in eighths of a degree. A positive value indicates that the wheel was rotated forwards away from the user, a negative value indicates that the wheel was rotated backwards toward the user.

Most mouse types work in steps of 15 degrees, in which case the delta value is a multiple of 120 since 120 units * 1/8 = 15 degrees.

Some mice have finer-resolution wheels and send delta values that are less than 120 units (less than 15 degrees). To support this possibility, you can either cumulatively add the delta values from events until the value of 120 is reached, then scroll the widget, or you can partially scroll the widget in response to each wheel event.

void MyWidget::wheelEvent(QWheelEvent *event) {
  int numDegrees = event->delta() / 8;
  int numSteps   = numDegrees / 15;
 
  if (event->orientation() == Qt::Horizontal) {
     scrollHorizontally(numSteps);
  } else {
     scrollVertically(numSteps);
  }
 
  event->accept();
}

QPoint QWheelEvent::globalPos ( ) const

inline

Returns the global position of the mouse pointer at the time of the event. This is important on asynchronous window systems such as X11. Whenever widgets are moved around in response to mouse events, globalPos() can differ from the current cursor position returned by QCursor::pos().

See also: globalX(), globalY()

const QPointF & QWheelEvent::globalPosF ( ) const

inline

Returns the global position of the mouse pointer at the time of the event. This is important on asynchronous window systems such as X11. Whenever widgets are moved around in response to mouse events, globalPosF() can differ from the current cursor position returned by QCursor::pos().

See also: posF()

int QWheelEvent::globalX ( ) const

inline

Returns the global x position of the mouse cursor at the time of the event.

See also: globalPos(), globalY()

int QWheelEvent::globalY ( ) const

inline

Returns the global y position of the mouse cursor at the time of the event.

See also: globalPos(), globalX()

Qt::Orientation QWheelEvent::orientation ( ) const

inline

Returns the current QWheelEvent orientation which will be either Qt::Vertical or Qt::Horizontal.

Qt::ScrollPhase QWheelEvent::phase ( ) const

inline

Returns the scrolling phase of this wheel event. The Qt::ScrollBegin and Qt::ScrollEnd phases are currently supported only on Mac OS X.

QPoint QWheelEvent::pixelDelta ( ) const

inline

Returns the scrolling distance in pixels on screen. This value is provided on platforms that support high-resolution pixel-based delta values such as Mac OS X. The value should be used directly to scroll content on screen.

void MyWidget::wheelEvent(QWheelEvent *event) {
    QPoint numPixels = event->pixelDelta();
    QPoint numDegrees = event->angleDelta() / 8;
 
    if (! numPixels.isNull()) {
       scrollWithPixels(numPixels);
 
    } else if (!numDegrees.isNull()) {
       QPoint numSteps = numDegrees / 15;
       scrollWithDegrees(numSteps);
    }
 
    event->accept();
}

On platforms which support scrolling phases the delta may be null when either of these conditions is true.

Scrolling is about to begin but the distance did not yet change (Qt::ScrollBegin)
Scrolling has ended and the distance did not change anymore (Qt::ScrollEnd)

On X11 this value is driver specific and unreliable, use angleDelta() instead.

See also: angleDelta()

QPoint QWheelEvent::pos ( ) const

inline

Returns the position of the mouse cursor relative to the widget that received the event. If widgets are moved around in response to mouse events, use globalPos() instead of this method.

See also: globalPos(), x(), y()

const QPointF & QWheelEvent::posF ( ) const

inline

Returns the position of the mouse cursor relative to the widget that received the event. If widgets are moved around in response to mouse events, use globalPosF() instead of this method.

See also: globalPosF()

Qt::MouseEventSource QWheelEvent::source ( ) const

inline

Returns information about the wheel event source. The source can be used to distinguish between events that come from a mouse with a physical wheel and events that are generated by some other means, such as a flick gesture on a touch pad.

Many platforms provide no such information. On such platforms Qt::MouseEventNotSynthesized is returned always.

See also: Qt::MouseEventSource

int QWheelEvent::x ( ) const

inline

Returns the x position of the mouse cursor, relative to the widget that received the event.

See also: pos(), y()

int QWheelEvent::y ( ) const

inline

Returns the y position of the mouse cursor, relative to the widget that received the event.

See also: pos(), x()

Public Methods

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Method Documentation