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QWheelEvent Class Reference

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

#include <qevent.h>

Inherits QEvent.

List of all member functions.

Public Members

• QWheelEvent ( const QPoint & pos, int delta, int state, Orientation orient = Vertical )
• QWheelEvent ( const QPoint & pos, const QPoint & globalPos, int delta, int state, Orientation orient = Vertical )
• int delta () const
• const QPoint & pos () const
• const QPoint & globalPos () const
• int x () const
• int y () const
• int globalX () const
• int globalY () const
• ButtonState state () const
• Orientation orientation () const
• bool isAccepted () const
• void accept ()
• void ignore ()

Detailed Description

Wheel events occur when a mouse wheel is turned while the widget has focus. The rotation distance is provided by delta(). The functions pos() and globalPos() return the mouse pointer 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 QWheelEvent::accept() if you handle the wheel event; otherwise it will be sent to the parent widget.

The QWidget::setEnable() function 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() and Event Classes.

Member Function Documentation

QWheelEvent::QWheelEvent ( const QPoint & pos, int delta, int state, Orientation orient = Vertical )

Constructs a wheel event object.

The globalPos() is initialized to QCursor::pos(), i.e. pos, which is usually (but not always) right. Use the other constructor if you need to specify the global position explicitly. delta contains the rotation distance, state holds the keyboard modifier flags at the time of the event and orient holds the wheel's orientation.

See also pos(), delta() and state().

QWheelEvent::QWheelEvent ( const QPoint & pos, const QPoint & globalPos, int delta, int state, Orientation orient = Vertical )

Constructs a wheel event object. The position when the event occurred is given in pos and globalPos. delta contains the rotation distance, state holds the keyboard modifier flags at the time of the event and orient holds the wheel's orientation.

See also pos(), globalPos(), delta() and state().

void QWheelEvent::accept ()

Sets the accept flag of the wheel event object.

Setting the accept parameter indicates that the receiver of the event wants the wheel event. Unwanted wheel events are sent to the parent widget.

The accept flag is set by default.

See also ignore().

int QWheelEvent::delta () const

Returns the distance that the wheel is rotated expressed in multiples or divisions of WHEEL_DELTA, which is currently set at 120. 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.

The WHEEL_DELTA constant was set to 120 by the wheel mouse vendors to allow building finer-resolution wheels in the future, including perhaps a freely rotating wheel with no notches. The expectation is that such a device would send more messages per rotation but with a smaller value in each message.

const QPoint & QWheelEvent::globalPos () const

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 you move your widgets around in response to mouse events, globalPos() can differ a lot from the current pointer position QCursor::pos().

See also globalX() and globalY().

int QWheelEvent::globalX () const

Returns the global x-position of the mouse pointer at the time of the event.

See also globalY() and globalPos().

int QWheelEvent::globalY () const

Returns the global y-position of the mouse pointer at the time of the event.

See also globalX() and globalPos().

void QWheelEvent::ignore ()

Clears the accept flag parameter of the wheel event object.

Clearing the accept parameter indicates that the event receiver does not want the wheel event. Unwanted wheel events are sent to the parent widget. The accept flag is set by default.

See also accept().

bool QWheelEvent::isAccepted () const

Returns TRUE if the receiver of the event handles the wheel event; otherwise returns FALSE.

Orientation QWheelEvent::orientation () const

Returns the wheel's orientation.

const QPoint & QWheelEvent::pos () const

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

If you move your widgets around in response to mouse events, use globalPos() instead of this function.

See also x(), y() and globalPos().

ButtonState QWheelEvent::state () const

Returns the keyboard modifier flags of the event.

The returned value is ShiftButton, ControlButton, and AltButton OR'ed together.

int QWheelEvent::x () const

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

See also y() and pos().

int QWheelEvent::y () const

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

See also x() and pos().

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