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/*!

    \class QDesktopWidget

    \brief The QDesktopWidget class provides access to screen information on multi-head systems.

    \ingroup advanced

    \ingroup desktop

    Systems with more than one graphics card and monitor can manage the

    physical screen space available either as multiple desktops, or as a

    large virtual desktop.

    This class provides information about the user's desktop, such as its

    total size, number of screens, the geometry of each screen, and whether

    they are configured as separate desktops or a single virtual desktop.

    Widgets provided by Qt use this class to place tooltips, menus and

    dialog boxes on the correct screen for their parent or application

    widgets. Applications can use this class to obtain information that

    can be used to save window positions, or to place child widgets and

    dialogs on one particular screen.

    \section1 Obtaining a Desktop Widget

    The QApplication::desktop() function is used to get an instance of

    QDesktopWidget.

    The widget's screenGeometry() function provides information about the

    geometry of the available screens with. The number of screens

    available is returned by screenCount, and the screenCountChanged()

    signal is emitted when screens are added or removed.

    The screen number that a particular point or widget is located in

    is returned by screenNumber().

    \section1 Screen Geometry

    To obtain the dimensions of a particular screen, call the screenGeometry()

    function. On some desktop environments, not all of the screen is

    available for applications to use; for example, an application dock or

    menu bar may take up some space. Use the availableGeometry() function

    to obtain the available area for applications.

    QDesktopWidget also inherits the QWidget properties, width() and

    height(), which specify the size of the desktop. However, for

    desktops with multiple screens, the size of the desktop is the union

    of all the screen sizes, so width() and height() should \e not be

    used for computing the size of a widget to be placed on one of the

    screens.

    On systems that are configured to use the available screens as a

    single, large virtual desktop, the virtualDesktop property will be

    set to true. In this case, the widget's size is usually the size of

    the bounding rectangle of all the screens.

    \section1 Use of the Primary Screen

    For an application, the screen where the main widget resides is the

    primary screen. This is stored in the primaryScreen property.

    All windows opened in the context of the application should be

    constrained to the boundaries of the primary screen; for example,

    it would be inconvenient if a dialog box popped up on a different

    screen, or split over two screens.

    \image qdesktopwidget.png Managing Multiple Screens

    In the illustration above, Application One's primary screen is

    screen 0, and App Two's primary screen is screen 1.

    \sa QApplication, QApplication::desktop(), QX11Info::appRootWindow()

*/

/*!

    \fn QDesktopWidget::QDesktopWidget()

    \internal

    Creates the desktop widget.

    If the system supports a virtual desktop, this widget will have

    the size of the virtual desktop; otherwise this widget will have

    the size of the primary screen.

    Instead of using QDesktopWidget directly, use QApplication::desktop().

*/

/*!

    \fn QDesktopWidget::~QDesktopWidget()

    \internal

    Destroys the desktop widget and frees any allocated resources.

*/

/*!

    \fn int QDesktopWidget::numScreens() const

    Returns the number of available screens.

    \obsolete

    This function is deprecated. Use screenCount instead.

    \sa primaryScreen

*/

/*!

    \fn QWidget *QDesktopWidget::screen(int screen)

    Returns a widget that represents the screen with index \a screen

    (a value of -1 means the default screen).

    If the system uses a virtual desktop, the returned widget will

    have the geometry of the entire virtual desktop; i.e., bounding

    every \a screen.

    \sa primaryScreen, screenCount, virtualDesktop

*/

/*!

    \fn const QRect QDesktopWidget::availableGeometry(int screen) const

     Returns the available geometry of the screen with index \a screen. What

     is available will be subrect of screenGeometry() based on what the

     platform decides is available (for example excludes the dock and menu bar

     on Mac OS X, or the task bar on Windows). The default screen is used if

     \a screen is -1.

     \sa screenNumber(), screenGeometry()

*/

/*!

    \fn const QRect QDesktopWidget::availableGeometry(const QWidget *widget) const

    \overload

    Returns the available geometry of the screen which contains \a widget.

    \sa screenGeometry()

*/

/*!

    \fn const QRect QDesktopWidget::availableGeometry(const QPoint &p) const

    \overload

    Returns the available geometry of the screen which contains \a p.

    \sa screenGeometry()

*/

/*!

    \fn const QRect QDesktopWidget::screenGeometry(int screen) const

    Returns the geometry of the screen with index \a screen. The default

    screen is used if \a screen is -1.

    \sa screenNumber()

*/

/*!

    \fn const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const

    \overload

    Returns the geometry of the screen which contains \a widget.

*/

/*!

    \fn const QRect QDesktopWidget::screenGeometry(const QPoint &p) const

    \overload

    Returns the geometry of the screen which contains \a p.

*/

/*!

    \fn int QDesktopWidget::screenNumber(const QWidget *widget) const

    Returns the index of the screen that contains the largest

    part of \a widget, or -1 if the widget not on a screen.

    \sa primaryScreen

*/

/*!

    \fn int QDesktopWidget::screenNumber(const QPoint &point) const

    \overload

    Returns the index of the screen that contains the \a point, or the

    screen which is the shortest distance from the \a point.

    \sa primaryScreen

*/

/*!

    \fn void QDesktopWidget::resizeEvent(QResizeEvent *event)

    \reimp

*/

/*!

    \fn void QDesktopWidget::resized(int screen)

    This signal is emitted when the size of \a screen changes.

*/

/*!

    \fn void QDesktopWidget::workAreaResized(int screen)

    This signal is emitted when the work area available on \a screen changes.

*/

/*!

    \property QDesktopWidget::screenCount

    \brief the number of screens currently available on the system.

    \since 4.6

    \sa screenCountChanged()

*/

/*!

    \property QDesktopWidget::primaryScreen

    \brief the index of the screen that is configured to be the primary screen

    on the system.

*/

/*!

    \property QDesktopWidget::virtualDesktop

    \brief if the system manages the available screens in a virtual desktop.

    For virtual desktops, screen() will always return the same widget.

    The size of the virtual desktop is the size of this desktop

    widget.

*/

/*!

    \fn void QDesktopWidget::screenCountChanged(int newCount)

    \since 4.6

    This signal is emitted when the number of screens changes to \a newCount.

    \sa screenCount

*/