The QGuiApplication class manages the GUI application's control flow and main settings. More...

#include <qguiapplication.h>

Inheritance diagram for QGuiApplication:

Collaboration diagram for QGuiApplication:

Signals
void	fontDatabaseChanged ()

void	screenAdded (QScreen *screen)

void	screenRemoved (QScreen *screen)

void	primaryScreenChanged (QScreen *screen)

void	lastWindowClosed ()

void	focusObjectChanged (QObject *focusObject)

void	focusWindowChanged (QWindow *focusWindow)

void	applicationStateChanged (Qt::ApplicationState state)

void	layoutDirectionChanged (Qt::LayoutDirection direction)

void	commitDataRequest (QSessionManager &sessionManager)

void	saveStateRequest (QSessionManager &sessionManager)

void	applicationDisplayNameChanged ()

Signals inherited from QCoreApplication
void	aboutToQuit (QPrivateSignal)

void	organizationNameChanged ()

void	organizationDomainChanged ()

void	applicationNameChanged ()

void	applicationVersionChanged ()

Signals inherited from QObject
void	destroyed (QObject *=nullptr)

void	objectNameChanged (const QString &objectName, QPrivateSignal)

Public Member Functions
	QGuiApplication (int &argc, char **argv, int=ApplicationFlags)

	~QGuiApplication ()

qreal	devicePixelRatio () const

bool	notify (QObject , QEvent ) override

bool	isSessionRestored () const

QString	sessionId () const

QString	sessionKey () const

bool	isSavingSession () const

Public Member Functions inherited from QCoreApplication
	QCoreApplication (int &argc, char **argv, int=ApplicationFlags)

	~QCoreApplication ()

void	installNativeEventFilter (QAbstractNativeEventFilter *filterObj)

void	removeNativeEventFilter (QAbstractNativeEventFilter *filterObj)

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)

virtual	~QObject ()

virtual bool	eventFilter (QObject watched, QEvent event)

QString	objectName () const

void	setObjectName (const QString &name)

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const

bool	isWindowType () const

bool	signalsBlocked () const noexcept

bool	blockSignals (bool b) noexcept

QThread *	thread () const

void	moveToThread (QThread *thread)

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)

template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

const QObjectList &	children () const

void	setParent (QObject *parent)

void	installEventFilter (QObject *filterObj)

void	removeEventFilter (QObject *obj)

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const

void	dumpObjectInfo () const

bool	setProperty (const char *name, const QVariant &value)

QVariant	property (const char *name) const

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const

bool	inherits (const char *classname) const

Static Public Member Functions
static void	setApplicationDisplayName (const QString &name)

static QString	applicationDisplayName ()

static void	setDesktopFileName (const QString &name)

static QString	desktopFileName ()

static QWindowList	allWindows ()

static QWindowList	topLevelWindows ()

static QWindow *	topLevelAt (const QPoint &pos)

static void	setWindowIcon (const QIcon &icon)

static QIcon	windowIcon ()

static QString	platformName ()

static QWindow *	modalWindow ()

static QWindow *	focusWindow ()

static QObject *	focusObject ()

static QScreen *	primaryScreen ()

static QList< QScreen * >	screens ()

static QScreen *	screenAt (const QPoint &point)

static QCursor *	overrideCursor ()

static void	setOverrideCursor (const QCursor &)

static void	changeOverrideCursor (const QCursor &)

static void	restoreOverrideCursor ()

static QFont	font ()

static void	setFont (const QFont &)

static QClipboard *	clipboard ()

static QPalette	palette ()

static void	setPalette (const QPalette &pal)

static Qt::KeyboardModifiers	keyboardModifiers ()

static Qt::KeyboardModifiers	queryKeyboardModifiers ()

static Qt::MouseButtons	mouseButtons ()

static void	setLayoutDirection (Qt::LayoutDirection direction)

static Qt::LayoutDirection	layoutDirection ()

static bool	isRightToLeft ()

static bool	isLeftToRight ()

static QStyleHints *	styleHints ()

static void	setDesktopSettingsAware (bool on)

static bool	desktopSettingsAware ()

static QInputMethod *	inputMethod ()

static QPlatformNativeInterface *	platformNativeInterface ()

static QFunctionPointer	platformFunction (const QByteArray &function)

static void	setQuitOnLastWindowClosed (bool quit)

static bool	quitOnLastWindowClosed ()

static Qt::ApplicationState	applicationState ()

static void	setHighDpiScaleFactorRoundingPolicy (Qt::HighDpiScaleFactorRoundingPolicy policy)

static Qt::HighDpiScaleFactorRoundingPolicy	highDpiScaleFactorRoundingPolicy ()

static int	exec ()

static void	sync ()

Static Public Member Functions inherited from QCoreApplication
static QStringList	arguments ()

static void	setAttribute (Qt::ApplicationAttribute attribute, bool on=true)
	[95] More...

static bool	testAttribute (Qt::ApplicationAttribute attribute)

static void	setOrganizationDomain (const QString &orgDomain)

static QString	organizationDomain ()

static void	setOrganizationName (const QString &orgName)
	[11] More...

static QString	organizationName ()

static void	setApplicationName (const QString &application)

static QString	applicationName ()

static void	setApplicationVersion (const QString &version)

static QString	applicationVersion ()

static void	setSetuidAllowed (bool allow)

static bool	isSetuidAllowed ()

static QCoreApplication *	instance ()

static int	exec ()

static void	processEvents (QEventLoop::ProcessEventsFlags flags=QEventLoop::AllEvents)

static void	processEvents (QEventLoop::ProcessEventsFlags flags, int maxtime)

static bool	sendEvent (QObject receiver, QEvent event)

static void	postEvent (QObject receiver, QEvent event, int priority=Qt::NormalEventPriority)

static void	sendPostedEvents (QObject *receiver=nullptr, int event_type=0)

static void	removePostedEvents (QObject *receiver, int eventType=0)

static QAbstractEventDispatcher *	eventDispatcher ()

static void	setEventDispatcher (QAbstractEventDispatcher *eventDispatcher)

static bool	startingUp ()

static bool	closingDown ()

static QString	applicationDirPath ()

static QString	applicationFilePath ()

static qint64	applicationPid () Q_DECL_CONST_FUNCTION

static bool	installTranslator (QTranslator *messageFile)

static bool	removeTranslator (QTranslator *messageFile)

static QString	translate (const char context, const char key, const char *disambiguation=nullptr, int n=-1)

static bool	isQuitLockEnabled ()

static void	setQuitLockEnabled (bool enabled)

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

static QMetaObject::Connection ::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 slot)

static QMetaObject::Connection ::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject context, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static std::enable_if< QtPrivate::FunctionPointer< Func2 >::ArgumentCount==-1 &&!std::is_convertible_v< Func2, const char * >, QMetaObject::Connection >::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 slot)

template<typename Func1 , typename Func2 >
static std::enable_if< QtPrivate::FunctionPointer< Func2 >::ArgumentCount==-1 &&!std::is_convertible_v< Func2, const char * >, QMetaObject::Connection >::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject context, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Protected Member Functions
bool	event (QEvent *) override

bool	compressEvent (QEvent , QObject receiver, QPostEventList *) override

	QGuiApplication (QGuiApplicationPrivate &p)

Protected Member Functions inherited from QCoreApplication
	QCoreApplication (QCoreApplicationPrivate &p)

Protected Member Functions inherited from QObject
QObject *	sender () const

int	senderSignalIndex () const

int	receivers (const char *signal) const

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)

virtual void	childEvent (QChildEvent *event)

virtual void	customEvent (QEvent *event)

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Properties
QIcon	windowIcon
	the default window icon More...

QString	applicationDisplayName
	the user-visible name of this application More...

QString	desktopFileName
	the base name of the desktop entry for this application More...

Qt::LayoutDirection	layoutDirection
	the default layout direction for this application More...

QString	platformName
	The name of the underlying platform plugin. More...

bool	quitOnLastWindowClosed
	whether the application implicitly quits when the last window is closed. More...

QScreen *	primaryScreen
	the primary (or default) screen of the application. More...

Properties inherited from QCoreApplication
QString	applicationName
	the name of this application More...

QString	applicationVersion
	the version of this application More...

QString	organizationName
	the name of the organization that wrote this application More...

QString	organizationDomain
	the Internet domain of the organization that wrote this application More...

bool	quitLockEnabled
	Whether the use of the QEventLoopLocker feature can cause the application to quit. More...

Properties inherited from QObject
QString	objectName
	the name of this object More...

Friends
class	QFontDatabasePrivate

class	QPlatformIntegration

class	QPlatformSessionManager

Additional Inherited Members
Public Types inherited from QCoreApplication
enum	{ ApplicationFlags = QT_VERSION }

Public Slots inherited from QCoreApplication
static void	quit ()

static void	exit (int retcode=0)

Public Slots inherited from QObject
void	deleteLater ()

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Related Functions inherited from QCoreApplication
void	qAddPostRoutine (QtCleanUpFunction ptr)

void	qRemovePostRoutine (QtCleanUpFunction ptr)

void *	resolveInterface (const char *name, int revision) const

Related Functions inherited from QObject
template< class T > T	qobject_cast (const QObject *object)

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList

Detailed Description

The QGuiApplication class manages the GUI application's control flow and main settings.

\macro qGuiApp

A global pointer referring to the unique application object. Only valid for use when that object is a QGuiApplication.

See also: QCoreApplication::instance(), qApp

\inmodule QtGui

Since: 5.0

QGuiApplication contains the main event loop, where all events from the window system and other sources are processed and dispatched. It also handles the application's initialization and finalization, and provides session management. In addition, QGuiApplication handles most of the system-wide and application-wide settings.

For any GUI application using Qt, there is precisely one QGuiApplication object no matter whether the application has 0, 1, 2 or more windows at any given time. For non-GUI Qt applications, use QCoreApplication instead, as it does not depend on the Qt GUI module. For QWidget based Qt applications, use QApplication instead, as it provides some functionality needed for creating QWidget instances.

The QGuiApplication object is accessible through the instance() function, which returns a pointer equivalent to the global \l qApp pointer.

QGuiApplication's main areas of responsibility are: \list

It initializes the application with the user's desktop settings, such as palette(), font() and styleHints(). It keeps track of these properties in case the user changes the desktop globally, for example, through some kind of control panel.

It performs event handling, meaning that it receives events from the underlying window system and dispatches them to the relevant widgets. You can send your own events to windows by using sendEvent() and postEvent().

It parses common command line arguments and sets its internal state accordingly. See the \l{QGuiApplication::QGuiApplication()} {constructor documentation} below for more details.

It provides localization of strings that are visible to the user via translate().

It provides some magical objects like the clipboard().

It knows about the application's windows. You can ask which window is at a certain position using topLevelAt(), get a list of topLevelWindows(), etc.

It manages the application's mouse cursor handling, see setOverrideCursor()

It provides support for sophisticated \l{Session Management} {session management}. This makes it possible for applications to terminate gracefully when the user logs out, to cancel a shutdown process if termination isn't possible and even to preserve the entire application's state for a future session. See isSessionRestored(), sessionId() and commitDataRequest() and saveStateRequest() for details. \endlist

Since the QGuiApplication object does so much initialization, it {must} be created before any other objects related to the user interface are created. QGuiApplication also deals with common command line arguments. Hence, it is usually a good idea to create it before any interpretation or modification of argv is done in the application itself.

\table \header

{2,1} Groups of functions

\row

System settings
desktopSettingsAware(), setDesktopSettingsAware(), styleHints(), palette(), setPalette(), font(), setFont().

\row

Event handling
exec(), processEvents(), exit(), quit(). sendEvent(), postEvent(), sendPostedEvents(), removePostedEvents(), notify().

\row

Windows
allWindows(), topLevelWindows(), focusWindow(), clipboard(), topLevelAt().

\row

Advanced cursor handling
overrideCursor(), setOverrideCursor(), restoreOverrideCursor().

\row

Session management
isSessionRestored(), sessionId(), commitDataRequest(), saveStateRequest().

\row

Miscellaneous
startingUp(), closingDown(). \endtable

See also: QCoreApplication, QAbstractEventDispatcher, QEventLoop

Definition at line 72 of file qguiapplication.h.

Constructor & Destructor Documentation

◆ QGuiApplication() [1/2]

QGuiApplication::QGuiApplication	(	int &	argc,
		char **	argv,
		int	flags = `ApplicationFlags`
	)

Initializes the window system and constructs an application object with argc command line arguments in argv.

Warning: The data referred to by argc and argv must stay valid for the entire lifetime of the QGuiApplication object. In addition, argc must be greater than zero and argv must contain at least one valid character string.

The global qApp pointer refers to this application object. Only one application object should be created.

This application object must be constructed before any \l{QPaintDevice} {paint devices} (including pixmaps, bitmaps etc.).

Note: argc and argv might be changed as Qt removes command line arguments that it recognizes.

Definition at line 654 of file qguiapplication.cpp.

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◆ ~QGuiApplication()

QGuiApplication::~QGuiApplication ( )

Destructs the application.

Definition at line 674 of file qguiapplication.cpp.

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◆ QGuiApplication() [2/2]

QGuiApplication::QGuiApplication ( QGuiApplicationPrivate & p )

protected

Definition at line 666 of file qguiapplication.cpp.

Member Function Documentation

◆ allWindows()

QWindowList QGuiApplication::allWindows ( )

static

Returns a list of all the windows in the application.

The list is empty if there are no windows.

See also: topLevelWindows()

Definition at line 998 of file qguiapplication.cpp.

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◆ applicationDisplayName()

static QString QGuiApplication::applicationDisplayName ( )

static

◆ applicationDisplayNameChanged

void QGuiApplication::applicationDisplayNameChanged ( )

signal

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◆ applicationState()

Qt::ApplicationState QGuiApplication::applicationState ( )

static

Since: 5.2

Returns the current state of the application.

You can react to application state changes to perform actions such as stopping/resuming CPU-intensive tasks, freeing/loading resources or saving/restoring application data.

Definition at line 3659 of file qguiapplication.cpp.

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◆ applicationStateChanged

void QGuiApplication::applicationStateChanged ( Qt::ApplicationState state )

signal

Since: 5.2

This signal is emitted when the state of the application changes.

See also: applicationState()

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◆ changeOverrideCursor()

void QGuiApplication::changeOverrideCursor ( const QCursor & cursor )

static

Changes the currently active application override cursor to cursor.

This function has no effect if setOverrideCursor() was not called.

See also: setOverrideCursor(), overrideCursor(), restoreOverrideCursor(), QWidget::setCursor()

Definition at line 3974 of file qguiapplication.cpp.

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◆ clipboard()

QClipboard * QGuiApplication::clipboard ( )

static

Returns the object for interacting with the clipboard.

Definition at line 3309 of file qguiapplication.cpp.

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◆ commitDataRequest

void QGuiApplication::commitDataRequest ( QSessionManager & manager )

signal

Since: 4.2

This signal deals with \l{Session Management}{session management}. It is emitted when the QSessionManager wants the application to commit all its data.

Usually this means saving all open files, after getting permission from the user. Furthermore you may want to provide a means by which the user can cancel the shutdown.

You should not exit the application within this signal. Instead, the session manager may or may not do this afterwards, depending on the context.

Warning: Within this signal, no user interaction is possible, unless you ask the manager for explicit permission. See QSessionManager::allowsInteraction() and QSessionManager::allowsErrorInteraction() for details and example usage.

Note: You should use Qt::DirectConnection when connecting to this signal.

See also: isSessionRestored(), sessionId(), saveStateRequest(), {Session Management}

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◆ compressEvent()

bool QGuiApplication::compressEvent	(	QEvent *	event,
		QObject *	receiver,
		QPostEventList *	postedEvents
	)

overrideprotectedvirtual

Reimplemented from QCoreApplication.

Reimplemented in QApplication.

Definition at line 1996 of file qguiapplication.cpp.

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◆ desktopFileName()

static QString QGuiApplication::desktopFileName ( )

static

◆ desktopSettingsAware()

bool QGuiApplication::desktopSettingsAware ( )

static

Returns true if Qt is set to use the system's standard colors, fonts, etc.; otherwise returns false. The default is true.

See also: setDesktopSettingsAware()

Definition at line 4145 of file qguiapplication.cpp.

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◆ devicePixelRatio()

qreal QGuiApplication::devicePixelRatio ( ) const

Returns the highest screen device pixel ratio found on the system. This is the ratio between physical pixels and device-independent pixels.

Use this function only when you don't know which window you are targeting. If you do know the target window, use QWindow::devicePixelRatio() instead.

See also: QWindow::devicePixelRatio()

Definition at line 1125 of file qguiapplication.cpp.

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◆ event()

bool QGuiApplication::event ( QEvent * e )

overrideprotectedvirtual

\reimp

Reimplemented from QCoreApplication.

Reimplemented in MyApplication, and QApplication.

Definition at line 1960 of file qguiapplication.cpp.

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◆ exec()

int QGuiApplication::exec ( )

static

Enters the main event loop and waits until exit() is called, and then returns the value that was set to exit() (which is 0 if exit() is called via quit()).

It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets.

Generally, no user interaction can take place before calling exec().

To make your application perform idle processing, e.g., executing a special function whenever there are no pending events, use a QTimer with 0 timeout. More advanced idle processing schemes can be achieved using processEvents().

We recommend that you connect clean-up code to the \l{QCoreApplication::}{aboutToQuit()} signal, instead of putting it in your application's {main()} function. This is because, on some platforms, the QApplication::exec() call may not return.

See also: quitOnLastWindowClosed, quit(), exit(), processEvents(), QCoreApplication::exec()

Definition at line 1882 of file qguiapplication.cpp.

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◆ focusObject()

QObject * QGuiApplication::focusObject ( )

static

Returns the QObject in currently active window that will be final receiver of events tied to focus, such as key events.

Definition at line 982 of file qguiapplication.cpp.

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◆ focusObjectChanged

QGuiApplication::focusObjectChanged ( QObject * focusObject )

signal

This signal is emitted when final receiver of events tied to focus is changed. focusObject is the new receiver.

See also: focusObject()

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◆ focusWindow()

QWindow * QGuiApplication::focusWindow ( )

static

Returns the QWindow that receives events tied to focus, such as key events.

Definition at line 955 of file qguiapplication.cpp.

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◆ focusWindowChanged

QGuiApplication::focusWindowChanged ( QWindow * focusWindow )

signal

This signal is emitted when the focused window changes. focusWindow is the new focused window.

See also: focusWindow()

◆ font()

QFont QGuiApplication::font ( )

static

Returns the default application font.

See also: setFont()

Definition at line 3449 of file qguiapplication.cpp.

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◆ fontDatabaseChanged

void QGuiApplication::fontDatabaseChanged ( )

signal

This signal is emitted when application fonts are loaded or removed.

See also: QFontDatabase::addApplicationFont(), QFontDatabase::addApplicationFontFromData(), QFontDatabase::removeAllApplicationFonts(), QFontDatabase::removeApplicationFont()

◆ highDpiScaleFactorRoundingPolicy()

Qt::HighDpiScaleFactorRoundingPolicy QGuiApplication::highDpiScaleFactorRoundingPolicy ( )

static

Since: 5.14

Returns the high-DPI scale factor rounding policy.

Definition at line 3698 of file qguiapplication.cpp.

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◆ inputMethod()

QInputMethod * QGuiApplication::inputMethod ( )

static

returns the input method.

The input method returns properties about the state and position of the virtual keyboard. It also provides information about the position of the current focused input element.

See also: QInputMethod

Definition at line 4159 of file qguiapplication.cpp.

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◆ isLeftToRight()

bool QGuiApplication::isLeftToRight ( )

inlinestatic

Returns true if the application's layout direction is Qt::LeftToRight; otherwise returns false.

See also: layoutDirection(), isRightToLeft()

Definition at line 145 of file qguiapplication.h.

◆ isRightToLeft()

bool QGuiApplication::isRightToLeft ( )

inlinestatic

Returns true if the application's layout direction is Qt::RightToLeft; otherwise returns false.

See also: layoutDirection(), isLeftToRight()

Definition at line 144 of file qguiapplication.h.

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◆ isSavingSession()

bool QGuiApplication::isSavingSession ( ) const

Since: 5.0

Returns true if the application is currently saving the \l{Session Management}{session}; otherwise returns false.

This is true when commitDataRequest() and saveStateRequest() are emitted, but also when the windows are closed afterwards by session management.

See also: sessionId(), commitDataRequest(), saveStateRequest()

Definition at line 3860 of file qguiapplication.cpp.

◆ isSessionRestored()

bool QGuiApplication::isSessionRestored ( ) const

Returns true if the application has been restored from an earlier \l{Session Management}{session}; otherwise returns false.

See also: sessionId(), commitDataRequest(), saveStateRequest()

Definition at line 3842 of file qguiapplication.cpp.

◆ keyboardModifiers()

Qt::KeyboardModifiers QGuiApplication::keyboardModifiers ( )

static

Returns the current state of the modifier keys on the keyboard. The current state is updated synchronously as the event queue is emptied of events that will spontaneously change the keyboard state (QEvent::KeyPress and QEvent::KeyRelease events).

It should be noted this may not reflect the actual keys held on the input device at the time of calling but rather the modifiers as last reported in one of the above events. If no keys are being held Qt::NoModifier is returned.

See also: mouseButtons(), queryKeyboardModifiers()

Definition at line 1787 of file qguiapplication.cpp.

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◆ lastWindowClosed

void QGuiApplication::lastWindowClosed ( )

signal

This signal is emitted from exec() when the last visible \l{Primary and Secondary Windows}{primary window} (i.e. top level window with no transient parent) is closed.

By default, QGuiApplication quits after this signal is emitted. This feature can be turned off by setting \l quitOnLastWindowClosed to false.

See also: QWindow::close(), QWindow::isTopLevel(), QWindow::transientParent()

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◆ layoutDirection()

static Qt::LayoutDirection QGuiApplication::layoutDirection ( )

static

◆ layoutDirectionChanged

void QGuiApplication::layoutDirectionChanged ( Qt::LayoutDirection direction )

signal

◆ modalWindow()

QWindow * QGuiApplication::modalWindow ( )

static

Returns the most recently shown modal window. If no modal windows are visible, this function returns zero.

A modal window is a window which has its \l{QWindow::modality}{modality} property set to Qt::WindowModal or Qt::ApplicationModal. A modal window must be closed before the user can continue with other parts of the program.

Modal window are organized in a stack. This function returns the modal window at the top of the stack.

See also: Qt::WindowModality, QWindow::setModality()

Definition at line 810 of file qguiapplication.cpp.

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◆ mouseButtons()

Qt::MouseButtons QGuiApplication::mouseButtons ( )

static

Returns the current state of the buttons on the mouse. The current state is updated synchronously as the event queue is emptied of events that will spontaneously change the mouse state (QEvent::MouseButtonPress and QEvent::MouseButtonRelease events).

It should be noted this may not reflect the actual buttons held on the input device at the time of calling but rather the mouse buttons as last reported in one of the above events. If no mouse buttons are being held Qt::NoButton is returned.

See also: keyboardModifiers()

Definition at line 1828 of file qguiapplication.cpp.

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◆ notify()

bool QGuiApplication::notify	(	QObject *	object,
		QEvent *	event
	)

overridevirtual

\reimp

Reimplemented from QCoreApplication.

Reimplemented in QApplication.

Definition at line 1946 of file qguiapplication.cpp.

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◆ overrideCursor()

QCursor * QGuiApplication::overrideCursor ( )

static

Returns the active application override cursor.

This function returns \nullptr if no application cursor has been defined (i.e. the internal cursor stack is empty).

See also: setOverrideCursor(), restoreOverrideCursor()

Definition at line 3960 of file qguiapplication.cpp.

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◆ palette()

QPalette QGuiApplication::palette ( )

static

Returns the current application palette.

Roles that have not been explicitly set will reflect the system's platform theme.

See also: setPalette()

Definition at line 3341 of file qguiapplication.cpp.

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◆ platformFunction()

QFunctionPointer QGuiApplication::platformFunction ( const QByteArray & function )

static

Definition at line 1848 of file qguiapplication.cpp.

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◆ platformName()

static QString QGuiApplication::platformName ( )

static

◆ platformNativeInterface()

QGuiApplication::platformNativeInterface ( )

static

Definition at line 1838 of file qguiapplication.cpp.

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◆ primaryScreen()

static QScreen* QGuiApplication::primaryScreen ( )

static

◆ primaryScreenChanged

void QGuiApplication::primaryScreenChanged ( QScreen * screen )

signal

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◆ queryKeyboardModifiers()

Qt::KeyboardModifiers QGuiApplication::queryKeyboardModifiers ( )

static

Queries and returns the state of the modifier keys on the keyboard. Unlike keyboardModifiers, this method returns the actual keys held on the input device at the time of calling the method.

It does not rely on the keypress events having been received by this process, which makes it possible to check the modifiers while moving a window, for instance. Note that in most cases, you should use keyboardModifiers(), which is faster and more accurate since it contains the state of the modifiers as they were when the currently processed event was received.

See also: keyboardModifiers()

Definition at line 1808 of file qguiapplication.cpp.

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◆ quitOnLastWindowClosed()

static bool QGuiApplication::quitOnLastWindowClosed ( )

static

◆ restoreOverrideCursor()

void QGuiApplication::restoreOverrideCursor ( )

static

Undoes the last setOverrideCursor().

If setOverrideCursor() has been called twice, calling restoreOverrideCursor() will activate the first cursor set. Calling this function a second time restores the original widgets' cursors.

See also: setOverrideCursor(), overrideCursor()

Definition at line 4086 of file qguiapplication.cpp.

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◆ saveStateRequest

void QGuiApplication::saveStateRequest ( QSessionManager & manager )

signal

Since: 4.2

This signal deals with \l{Session Management}{session management}. It is invoked when the \l{QSessionManager}{session manager} wants the application to preserve its state for a future session.

For example, a text editor would create a temporary file that includes the current contents of its edit buffers, the location of the cursor and other aspects of the current editing session.

You should never exit the application within this signal. Instead, the session manager may or may not do this afterwards, depending on the context. Furthermore, most session managers will very likely request a saved state immediately after the application has been started. This permits the session manager to learn about the application's restart policy.

Warning: Within this signal, no user interaction is possible, unless you ask the manager for explicit permission. See QSessionManager::allowsInteraction() and QSessionManager::allowsErrorInteraction() for details.

Note: You should use Qt::DirectConnection when connecting to this signal.

See also: isSessionRestored(), sessionId(), commitDataRequest(), {Session Management}

◆ screenAdded

void QGuiApplication::screenAdded ( QScreen * screen )

signal

This signal is emitted whenever a new screen screen has been added to the system.

See also: screens(), primaryScreen, screenRemoved()

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◆ screenAt()

QScreen * QGuiApplication::screenAt ( const QPoint & point )

static

Returns the screen at point, or \nullptr if outside of any screen.

The point is in relation to the virtualGeometry() of each set of virtual siblings. If the point maps to more than one set of virtual siblings the first match is returned. If you wish to search only the virtual desktop siblings of a known screen (for example siblings of the screen of your application window QWidget::windowHandle()->screen()), use QScreen::virtualSiblingAt().

Since: 5.10

Definition at line 1063 of file qguiapplication.cpp.

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◆ screenRemoved

void QGuiApplication::screenRemoved ( QScreen * screen )

signal

This signal is emitted whenever a screen is removed from the system. It provides an opportunity to manage the windows on the screen before Qt falls back to moving them to the primary screen.

See also: screens(), screenAdded(), QObject::destroyed(), QWindow::setScreen()

Since: 5.4

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◆ screens()

QList< QScreen * > QGuiApplication::screens ( )

static

Returns a list of all the screens associated with the windowing system the application is connected to.

Definition at line 1047 of file qguiapplication.cpp.

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◆ sessionId()

QString QGuiApplication::sessionId ( ) const

Returns the current \l{Session Management}{session's} identifier.

If the application has been restored from an earlier session, this identifier is the same as it was in that previous session. The session identifier is guaranteed to be unique both for different applications and for different instances of the same application.

See also: isSessionRestored(), sessionKey(), commitDataRequest(), saveStateRequest()

Definition at line 3848 of file qguiapplication.cpp.

◆ sessionKey()

QString QGuiApplication::sessionKey ( ) const

Returns the session key in the current \l{Session Management}{session}.

If the application has been restored from an earlier session, this key is the same as it was when the previous session ended.

The session key changes every time the session is saved. If the shutdown process is cancelled, another session key will be used when shutting down again.

See also: isSessionRestored(), sessionId(), commitDataRequest(), saveStateRequest()

Definition at line 3854 of file qguiapplication.cpp.

◆ setApplicationDisplayName()

void QGuiApplication::setApplicationDisplayName ( const QString & name )

static

Definition at line 745 of file qguiapplication.cpp.

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◆ setDesktopFileName()

void QGuiApplication::setDesktopFileName ( const QString & name )

static

Definition at line 784 of file qguiapplication.cpp.

◆ setDesktopSettingsAware()

void QGuiApplication::setDesktopSettingsAware ( bool on )

static

Sets whether Qt should use the system's standard colors, fonts, etc., to on. By default, this is true.

This function must be called before creating the QGuiApplication object, like this:

See also: desktopSettingsAware()

Definition at line 4134 of file qguiapplication.cpp.

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◆ setFont()

void QGuiApplication::setFont ( const QFont & font )

static

Changes the default application font to font.

See also: font()

Definition at line 3465 of file qguiapplication.cpp.

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◆ setHighDpiScaleFactorRoundingPolicy()

void QGuiApplication::setHighDpiScaleFactorRoundingPolicy ( Qt::HighDpiScaleFactorRoundingPolicy policy )

static

Since: 5.14

Sets the high-DPI scale factor rounding policy for the application. The policy decides how non-integer scale factors (such as Windows 150%) are handled.

The two principal options are whether fractional scale factors should be rounded to an integer or not. Keeping the scale factor as-is will make the user interface size match the OS setting exactly, but may cause painting errors, for example with the Windows style.

If rounding is wanted, then which type of rounding should be decided next. Mathematically correct rounding is supported but may not give the best visual results: Consider if you want to render 1.5x as 1x ("small UI") or as 2x ("large UI"). See the Qt::HighDpiScaleFactorRoundingPolicy enum for a complete list of all options.

This function must be called before creating the application object. The QGuiApplication::highDpiScaleFactorRoundingPolicy() accessor will reflect the environment, if set.

The default value is Qt::HighDpiScaleFactorRoundingPolicy::PassThrough.

Definition at line 3688 of file qguiapplication.cpp.

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◆ setLayoutDirection()

void QGuiApplication::setLayoutDirection ( Qt::LayoutDirection direction )

static

Definition at line 3919 of file qguiapplication.cpp.

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◆ setOverrideCursor()

void QGuiApplication::setOverrideCursor ( const QCursor & cursor )

static

Sets the application override cursor to cursor.

Application override cursors are intended for showing the user that the application is in a special state, for example during an operation that might take some time.

This cursor will be displayed in all the application's widgets until restoreOverrideCursor() or another setOverrideCursor() is called.

Application cursors are stored on an internal stack. setOverrideCursor() pushes the cursor onto the stack, and restoreOverrideCursor() pops the active cursor off the stack. changeOverrideCursor() changes the currently active application override cursor.

Every setOverrideCursor() must eventually be followed by a corresponding restoreOverrideCursor(), otherwise the stack will never be emptied.

Example:

See also: overrideCursor(), restoreOverrideCursor(), changeOverrideCursor(), QWidget::setCursor()

Definition at line 4065 of file qguiapplication.cpp.

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◆ setPalette()

void QGuiApplication::setPalette ( const QPalette & pal )

static

Changes the application palette to pal.

The color roles from this palette are combined with the system's platform theme to form the application's final palette.

See also: palette()

Definition at line 3373 of file qguiapplication.cpp.

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◆ setQuitOnLastWindowClosed()

void QGuiApplication::setQuitOnLastWindowClosed ( bool quit )

static

Definition at line 3575 of file qguiapplication.cpp.

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◆ setWindowIcon()

void QGuiApplication::setWindowIcon ( const QIcon & icon )

static

Definition at line 3538 of file qguiapplication.cpp.

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◆ styleHints()

QStyleHints * QGuiApplication::styleHints ( )

static

Returns the application's style hints.

The style hints encapsulate a set of platform dependent properties such as double click intervals, full width selection and others.

The hints can be used to integrate tighter with the underlying platform.

See also: QStyleHints

Definition at line 4116 of file qguiapplication.cpp.

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◆ sync()

void QGuiApplication::sync ( )

static

Since: 5.2

Function that can be used to sync Qt state with the Window Systems state.

This function will first empty Qts events by calling QCoreApplication::processEvents(), then the platform plugin will sync up with the windowsystem, and finally Qts events will be delived by another call to QCoreApplication::processEvents();

This function is timeconsuming and its use is discouraged.

Definition at line 3895 of file qguiapplication.cpp.

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◆ topLevelAt()

QWindow * QGuiApplication::topLevelAt ( const QPoint & pos )

static

Returns the top level window at the given position pos, if any.

Definition at line 1145 of file qguiapplication.cpp.

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◆ topLevelWindows()

QWindowList QGuiApplication::topLevelWindows ( )

static

Returns a list of the top-level windows in the application.

See also: allWindows()

Definition at line 1010 of file qguiapplication.cpp.

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◆ windowIcon()

static QIcon QGuiApplication::windowIcon ( )

static

Friends And Related Function Documentation

◆ QFontDatabasePrivate

friend class QFontDatabasePrivate

friend

Definition at line 213 of file qguiapplication.h.

◆ QPlatformIntegration

friend class QPlatformIntegration

friend

Definition at line 214 of file qguiapplication.h.

◆ QPlatformSessionManager

friend class QPlatformSessionManager

friend

Definition at line 216 of file qguiapplication.h.

Property Documentation

◆ applicationDisplayName

QString QGuiApplication::applicationDisplayName

readwrite

the user-visible name of this application

Since: 5.0

This name is shown to the user, for instance in window titles. It can be translated, if necessary.

If not set, the application display name defaults to the application name.

See also: applicationName

Definition at line 220 of file qguiapplication.h.

◆ desktopFileName

QString QGuiApplication::desktopFileName

readwrite

the base name of the desktop entry for this application

Since: 5.7

This is the file name, without the full path, of the desktop entry that represents this application according to the freedesktop desktop entry specification.

This property gives a precise indication of what desktop entry represents the application and it is needed by the windowing system to retrieve such information without resorting to imprecise heuristics.

The latest version of the freedesktop desktop entry specification can be obtained \l{http://standards.freedesktop.org/desktop-entry-spec/latest/}{here}.

Definition at line 220 of file qguiapplication.h.

◆ layoutDirection

Qt::LayoutDirection QGuiApplication::layoutDirection

readwrite

the default layout direction for this application

On system start-up, or when the direction is explicitly set to Qt::LayoutDirectionAuto, the default layout direction depends on the application's language.

The notifier signal was introduced in Qt 5.4.

See also: QWidget::layoutDirection, isLeftToRight(), isRightToLeft()

Definition at line 220 of file qguiapplication.h.

◆ platformName

QString QGuiApplication::platformName

read

The name of the underlying platform plugin.

The QPA platform plugins are located in {qtbase\src \plugins\platforms}. At the time of writing, the following platform plugin names are supported:

\list

android
cocoa is a platform plugin for \macos.
directfb
eglfs is a platform plugin for running Qt5 applications on top of EGL and OpenGL ES 2.0 without an actual windowing system (like X11 or Wayland). For more information, see \l{EGLFS}.
ios (also used for tvOS)
linuxfb writes directly to the framebuffer. For more information, see \l{LinuxFB}.
minimal is provided as an examples for developers who want to write their own platform plugins. However, you can use the plugin to run GUI applications in environments without a GUI, such as servers.
minimalegl is an example plugin.
offscreen
qnx
windows
wayland is a platform plugin for modern Linux desktops and some embedded systems.
xcb is the X11 plugin used on regular desktop Linux platforms. \endlist

For more information about the platform plugins for embedded Linux devices, see \l{Qt for Embedded Linux}.

Definition at line 220 of file qguiapplication.h.

◆ primaryScreen

QGuiApplication::primaryScreen

read

the primary (or default) screen of the application.

This will be the screen where QWindows are initially shown, unless otherwise specified.

The primaryScreenChanged signal was introduced in Qt 5.6.

See also: screens()

Definition at line 220 of file qguiapplication.h.

◆ quitOnLastWindowClosed

bool QGuiApplication::quitOnLastWindowClosed

readwrite

whether the application implicitly quits when the last window is closed.

The default is true.

If this property is true, the applications quits when the last visible \l{Primary and Secondary Windows}{primary window} (i.e. top level window with no transient parent) is closed.

See also: quit(), QWindow::close()

Definition at line 220 of file qguiapplication.h.

◆ windowIcon

QIcon QGuiApplication::windowIcon

readwrite

the default window icon

See also: QWindow::setIcon(), {Setting the Application Icon}

Definition at line 220 of file qguiapplication.h.

The documentation for this class was generated from the following files:

src/gui/kernel/qguiapplication.h
src/gui/kernel/qguiapplication.cpp
src/plugins/doc/snippets/code/src_plugins_platforms_qnx_qqnxwindow.cpp

Signals

Public Member Functions

Static Public Member Functions

Protected Member Functions

Properties

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QGuiApplication() [1/2]

◆ ~QGuiApplication()

◆ QGuiApplication() [2/2]

Member Function Documentation

◆ allWindows()

◆ applicationDisplayName()

◆ applicationDisplayNameChanged

◆ applicationState()

◆ applicationStateChanged

◆ changeOverrideCursor()

◆ clipboard()

◆ commitDataRequest

◆ compressEvent()

◆ desktopFileName()

◆ desktopSettingsAware()

◆ devicePixelRatio()

◆ event()

◆ exec()

◆ focusObject()

◆ focusObjectChanged

◆ focusWindow()

◆ focusWindowChanged

◆ font()

◆ fontDatabaseChanged

◆ highDpiScaleFactorRoundingPolicy()

◆ inputMethod()

◆ isLeftToRight()

◆ isRightToLeft()

◆ isSavingSession()

◆ isSessionRestored()

◆ keyboardModifiers()

◆ lastWindowClosed

◆ layoutDirection()

◆ layoutDirectionChanged

◆ modalWindow()

◆ mouseButtons()

◆ notify()

◆ overrideCursor()

◆ palette()

◆ platformFunction()

◆ platformName()

◆ platformNativeInterface()

◆ primaryScreen()

◆ primaryScreenChanged

◆ queryKeyboardModifiers()

◆ quitOnLastWindowClosed()

◆ restoreOverrideCursor()

◆ saveStateRequest

◆ screenAdded

◆ screenAt()

◆ screenRemoved

◆ screens()

◆ sessionId()

◆ sessionKey()

◆ setApplicationDisplayName()

◆ setDesktopFileName()

◆ setDesktopSettingsAware()

◆ setFont()

◆ setHighDpiScaleFactorRoundingPolicy()

◆ setLayoutDirection()

◆ setOverrideCursor()

◆ setPalette()

◆ setQuitOnLastWindowClosed()

◆ setWindowIcon()

◆ styleHints()

◆ sync()

◆ topLevelAt()

◆ topLevelWindows()

◆ windowIcon()

Friends And Related Function Documentation

◆ QFontDatabasePrivate