Qt Toolkit - QWheelEvent Class

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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 )
- QWheelEvent ( const QPoint & pos, const QPoint & globalPos, int delta, int state )
- 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
- bool isAccepted () const
- void accept ()
- void ignore ()

## Detailed Description

The QWheelEvent class contains parameters that describe a wheel event.

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 which tells 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() receive wheel events.

See also QMouseEvent and QWidget::grabMouse().

## Member Function Documentation

### QWheelEvent::QWheelEvent ( const QPoint & pos, const QPoint & globalPos, int delta, int state )

Constructs a wheel event object.

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

### QWheelEvent::QWheelEvent ( const QPoint & pos, int delta, int state )

Constructs a wheel event object.

The globalPos() is initialized to QCursor::pos(), which usually is right but not always. Use the other constructor if you need to specify the global position explicitly.

See also pos(), 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 set at 120 currently.A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, 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 like X11: Whenever you move your widgets around in response to mouse evens, 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.

### 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 evens, 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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