\brief The HbPinchGesture class provides multitouch support.

    HbPinchGesture is an extension to Qt standard QPinchGesture. It offers

    convenience functions for handling the pinch gesture properties directly

    in scene coordinates. This removes any need for manual conversions from

    the screen (global) coordinates of the QPinchGesture base class

    properties.

    You can use HbPinchGesture, for example, to let the user change an

    image size in a photo application by dragging the two opposing corners

    of the image at the same time. Another example would be rotating a widget

    with two fingers.

    \section _usecases_hbpinchgesture Using the HbPinchGesture class

    This example shows how to make a custom widget recognize the pinch

    gesture. The custom widget in the example derives from HbWidget.

    <ol>

    <li>

    In order to receive touch events, which are required by the pinch gesture,

    at least one widget in the scene needs to accept the QEvent::TouchBegin event.

    To make sure this is done, you can do this in your widget by reimplementing

    QGraphicsWidget::event().

    \code

    bool MyWidget::event(QEvent *e)

    {

        if (e->type() == QEvent::TouchBegin) {

            return true;

        }

        return HbWidget::event(e);

    }    

    \endcode 

    </li>

    <li>

    Register for pinch gestures by using the base class function

    QGraphicsObject::grabGesture(). QGraphicsObject::grabGesture() can be

    called several times with different arguments, if the widget is

    interested in other gesture types as well.

    \code

    // This widget is interested in pinch and tap gestures.

    grabGesture(Qt::PinchGesture);

    grabGesture(Qt::TapGesture);

    \endcode

    </li>

    <li>

    Reimplement HbWidgetBase::gestureEvent() to handle gestures that are

    meaningful for your custom widget.

    \code

    void MyWidget::gestureEvent(QGestureEvent *event)

    {

        if (HbPinchGesture *pinch = qobject_cast<HbPinchGesture *>

            (event->gesture(Qt::PinchGesture))) {

            switch (pinch->state()) {

            case Qt::GestureStarted:

                // Visualize the active state of the widget.

                // Emit a signal to move the content.

                break;

            case Qt::GestureUpdated:

                // Emit a signal to move the content.

                break;

            case Qt::GestureCanceled:

                // Visualize the non-active state of the widget.

                // Emit a signal to return the content to the starting

                // position.

                break;

            case Qt::GestureFinished:              

                // Visualize the non-active state of the widget.              

                // Emit a signal to move the content.             

                break;

            default:

                break;

            }           

        }

        // Handle other gesture types that have been grabbed. There may be several,

        // since all gestures that are active at the same moment are sent within

        // the same gesture event.

        if (HbTapGesture *tap = qobject_cast<HbTapGesture *>

            (event->gesture(Qt::TapGesture))) {

            // handle the tap gesture

        }

    }   

    \endcode

    </li>

    </ol>

    Constructor.

    Constructor required by the shared d-pointer paradigm.

    Destructor.

    Returns the total angle covered by the gesture in scene coordinates.

    \sa setSceneTotalRotationAngle(), QPinchGesture::totalRotationAngle()

/*!

    Sets the total angle covered by the gesture in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneTotalRotationAngle(), QPinchGesture::setTotalRotationAngle()

*/

    Returns the last reported angle covered by the gesture in scene

    coordinates.

    \sa setSceneLastRotationAngle(), QPinchGesture::lastRotationAngle()

/*!

    Sets the last reported angle covered by the gesture in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneLastRotationAngle(), QPinchGesture::setLastRotationAngle()

*/

    Returns the angle covered by the gesture since last update

    in scene coordinates.

    \sa setSceneRotationAngle(), QPinchGesture::rotationAngle()

/*!

    Sets the angle covered by the gesture since last update

    in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneRotationAngle(), QPinchGesture::setRotationAngle()

*/

    Returns the starting position of the center point in scene coordinates.

    \sa setSceneStartCenterPoint(), QPinchGesture::startCenterPoint()

/*!

    Sets the starting position of the center point in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneStartCenterPoint(), QPinchGesture::setStartCenterPoint()

*/

    Returns the last position of the center point recorded for the gesture

    in scene coordinates.

    \sa setSceneLastCenterPoint(), QPinchGesture::lastCenterPoint()

/*!

    Sets the last position of the center point recorded for the gesture

    in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneLastCenterPoint(), QPinchGesture::setLastCenterPoint()

*/

    Returns the current center point in scene coordinates.

    \sa setSceneCenterPoint(), QPinchGesture::centerPoint()

/*!

    Sets the current center point in scene coordinates.

    This function is used by the framework gesture recognition logic,

    and it should not be used by the widget receiving the gesture.

    \sa sceneCenterPoint(), QPinchGesture::setCenterPoint()

*/