\inmodule QtGui More...

#include <qoffscreensurface.h>

Inheritance diagram for QOffscreenSurface:

Collaboration diagram for QOffscreenSurface:

Signals
void	screenChanged (QScreen *screen)
	This signal is emitted when an offscreen surface's screen changes, either by being set explicitly with setScreen(), or automatically when the window's screen is removed.

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	QOffscreenSurface (QScreen screen=nullptr, QObject parent=nullptr)

	~QOffscreenSurface ()
	Destroys the offscreen surface.

SurfaceType	surfaceType () const override
	Returns the surface type of the offscreen surface.

void	create ()
	Allocates the platform resources associated with the offscreen surface.

void	destroy ()
	Releases the native platform resources associated with this offscreen surface.

bool	isValid () const
	Returns `true` if this offscreen surface is valid; otherwise returns `false`.

void	setFormat (const QSurfaceFormat &format)
	Sets the offscreen surface format.

QSurfaceFormat	format () const override
	Returns the actual format of this offscreen surface.

QSurfaceFormat	requestedFormat () const
	Returns the requested surfaceformat of this offscreen surface.

QSize	size () const override
	Returns the size of the offscreen surface.

QScreen *	screen () const
	Returns the screen to which the offscreen surface is connected.

void	setScreen (QScreen *screen)
	Sets the screen to which the offscreen surface is connected.

QPlatformOffscreenSurface *	handle () const
	Returns the platform offscreen surface corresponding to the offscreen surface.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

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
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

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

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Public Member Functions inherited from QSurface
virtual	~QSurface ()
	Destroys the surface.

SurfaceClass	surfaceClass () const
	Returns the surface class of this surface.

virtual QSurfaceFormat	format () const =0
	Returns the format of the surface.

virtual QPlatformSurface *	surfaceHandle () const =0
	Returns a handle to the platform-specific implementation of the surface.

virtual SurfaceType	surfaceType () const =0
	Returns the type of the surface.

bool	supportsOpenGL () const
	Returns true if the surface is OpenGL compatible and can be used in conjunction with QOpenGLContext; otherwise returns false.

virtual QSize	size () const =0
	Returns the size of the surface in pixels.

Private Member Functions
QPlatformSurface *	surfaceHandle () const override
	Returns the platform surface corresponding to the offscreen surface.

Additional Inherited Members
Public Types inherited from QSurface
enum	SurfaceClass { Window , Offscreen }
	The SurfaceClass enum describes the actual subclass of the surface. More...

enum	SurfaceType { RasterSurface , OpenGLSurface , RasterGLSurface , OpenVGSurface , VulkanSurface , MetalSurface , Direct3DSurface }
	The SurfaceType enum describes what type of surface this is. More...

Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

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)
	\threadsafe

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::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

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

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

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

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a 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 inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

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

Protected Member Functions inherited from QSurface
	QSurface (SurfaceClass type)
	Creates a surface with the given type.

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Protected Attributes inherited from QSurface
SurfaceClass	m_type

QSurfacePrivate *	m_reserved

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

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

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

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

\inmodule QtGui

Since: 5.1

The QOffscreenSurface class represents an offscreen surface in the underlying platform.

QOffscreenSurface is intended to be used with QOpenGLContext to allow rendering with OpenGL in an arbitrary thread without the need to create a QWindow.

Even though the surface is typically renderable, the surface's pixels are not accessible. QOffscreenSurface should only be used to create OpenGL resources such as textures or framebuffer objects.

An application will typically use QOffscreenSurface to perform some time-consuming tasks in a separate thread in order to avoid stalling the main rendering thread. Resources created in the QOffscreenSurface's context can be shared with the main OpenGL context. Some common use cases are asynchronous texture uploads or rendering into a QOpenGLFramebufferObject.

How the offscreen surface is implemented depends on the underlying platform, but it will typically use a pixel buffer (pbuffer). If the platform doesn't implement or support offscreen surfaces, QOffscreenSurface will use an invisible QWindow internally.

Note: Due to the fact that QOffscreenSurface is backed by a QWindow on some platforms, cross-platform applications must ensure that create() is only called on the main (GUI) thread. The QOffscreenSurface is then safe to be used with \l{QOpenGLContext::makeCurrent()}{makeCurrent()} on other threads, but the initialization and destruction must always happen on the main (GUI) thread.; In order to create an offscreen surface that is guaranteed to be compatible with a given context and window, make sure to set the format to the context's or the window's actual format, that is, the QSurfaceFormat returned from QOpenGLContext::format() or QWindow::format() {after the context or window has been created}. Passing the format returned from QWindow::requestedFormat() to setFormat() may result in an incompatible offscreen surface since the underlying windowing system interface may offer a different set of configurations for window and pbuffer surfaces.; Some platforms may utilize a surfaceless context extension (for example EGL_KHR_surfaceless_context) when available. In this case there will be no underlying native surface. For the use cases of QOffscreenSurface (rendering to FBOs, texture upload) this is not a problem.

Definition at line 20 of file qoffscreensurface.h.

Constructor & Destructor Documentation

◆ QOffscreenSurface()

QOffscreenSurface::QOffscreenSurface	(	QScreen *	targetScreen = `nullptr`,
		QObject *	parent = `nullptr`
	)

explicit

Since: 5.10

Creates an offscreen surface for the targetScreen with the given parent.

The underlying platform surface is not created until create() is called.

See also: setScreen(), create()

Definition at line 70 of file qoffscreensurface.cpp.

References QObject::connect(), d, QObject::destroyed(), QGuiApplication::primaryScreen, Q_ASSERT, SIGNAL, and SLOT.

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◆ ~QOffscreenSurface()

QOffscreenSurface::~QOffscreenSurface ( )

Destroys the offscreen surface.

Definition at line 89 of file qoffscreensurface.cpp.

References destroy().

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Member Function Documentation

◆ create()

void QOffscreenSurface::create ( )

Allocates the platform resources associated with the offscreen surface.

It is at this point that the surface format set using setFormat() gets resolved into an actual native surface.

Call destroy() to free the platform resources if necessary.

Note: Some platforms require this function to be called on the main (GUI) thread.

See also: destroy()

Definition at line 117 of file qoffscreensurface.cpp.

References QPlatformIntegration::createPlatformOffscreenSurface(), QThread::currentThread(), Qt::CustomizeWindowHint, d, e, Qt::FramelessWindowHint, QSurface::OpenGLSurface, QGuiApplicationPrivate::platformIntegration(), qGuiApp, qt_window_private(), qWarning, QList< T >::removeOne(), QCoreApplication::sendEvent(), QWindowPrivate::setAutomaticPositionAndResizeEnabled(), QPlatformSurfaceEvent::SurfaceCreated, and QGuiApplicationPrivate::window_list.

Referenced by CurrentContext::CurrentContext(), WaylandEglClientBufferIntegrationPrivate::ensureContext(), WaylandEglStreamClientBufferIntegrationPrivate::ensureContext(), QOpenGLWidgetPrivate::initialize(), QGLXContext::queryDummyContext(), and setScreen().

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◆ destroy()

void QOffscreenSurface::destroy ( )

Releases the native platform resources associated with this offscreen surface.

See also: create()

Definition at line 153 of file qoffscreensurface.cpp.

References d, e, QCoreApplication::sendEvent(), and QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed.

Referenced by ~QOffscreenSurface(), and setScreen().

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◆ format()

QSurfaceFormat QOffscreenSurface::format ( ) const

overridevirtual

Returns the actual format of this offscreen surface.

After the offscreen surface has been created, this function will return the actual surface format of the surface. It might differ from the requested format if the requested format could not be fulfilled by the platform.

See also: create(), requestedFormat()

Implements QSurface.

Definition at line 222 of file qoffscreensurface.cpp.

References d.

Referenced by setFormat().

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◆ handle()

QPlatformOffscreenSurface * QOffscreenSurface::handle ( ) const

Returns the platform offscreen surface corresponding to the offscreen surface.

Definition at line 305 of file qoffscreensurface.cpp.

References d.

◆ isValid()

bool QOffscreenSurface::isValid ( ) const

Returns true if this offscreen surface is valid; otherwise returns false.

The offscreen surface is valid if the platform resources have been successfully allocated.

See also: create()

Definition at line 176 of file qoffscreensurface.cpp.

References d.

◆ requestedFormat()

QSurfaceFormat QOffscreenSurface::requestedFormat ( ) const

Returns the requested surfaceformat of this offscreen surface.

If the requested format was not supported by the platform implementation, the requestedFormat will differ from the actual offscreen surface format.

This is the value set with setFormat().

See also: setFormat(), format()

Definition at line 207 of file qoffscreensurface.cpp.

References d.

Referenced by QAndroidPlatformIntegration::createPlatformOffscreenSurface(), QEglFSIntegration::createPlatformOffscreenSurface(), QXcbEglIntegration::createPlatformOffscreenSurface(), QCocoaOffscreenSurface::format(), and QIOSOffscreenSurface::format().

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◆ screen()

QScreen * QOffscreenSurface::screen ( ) const

Returns the screen to which the offscreen surface is connected.

See also: setScreen()

Definition at line 246 of file qoffscreensurface.cpp.

References d.

Referenced by QEglFSIntegration::createPlatformOffscreenSurface(), QXcbEglIntegration::createPlatformOffscreenSurface(), QXcbIntegration::createPlatformOffscreenSurface(), and QPlatformOffscreenSurface::screen().

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◆ screenChanged

QOffscreenSurface::screenChanged ( QScreen * screen )

signal

This signal is emitted when an offscreen surface's screen changes, either by being set explicitly with setScreen(), or automatically when the window's screen is removed.

Referenced by setScreen().

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◆ setFormat()

void QOffscreenSurface::setFormat ( const QSurfaceFormat & format )

Sets the offscreen surface format.

The surface format will be resolved in the create() function. Calling this function after create() will not re-resolve the surface format of the native surface.

See also: create(), destroy()

Definition at line 191 of file qoffscreensurface.cpp.

References d, and format().

Referenced by CurrentContext::CurrentContext(), WaylandEglClientBufferIntegrationPrivate::ensureContext(), WaylandEglStreamClientBufferIntegrationPrivate::ensureContext(), and QOpenGLWidgetPrivate::initialize().

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◆ setScreen()

void QOffscreenSurface::setScreen ( QScreen * newScreen )

Sets the screen to which the offscreen surface is connected.

If the offscreen surface has been created, it will be recreated on the newScreen.

See also: screen()

Definition at line 259 of file qoffscreensurface.cpp.

References QObject::connect(), create(), d, destroy(), QObject::destroyed(), disconnect(), emit, QCoreApplication::instance(), QGuiApplication::primaryScreen, screenChanged(), SIGNAL, and SLOT.

Referenced by QOpenGLWidgetPrivate::initialize().

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◆ size()

QSize QOffscreenSurface::size ( ) const

overridevirtual

Returns the size of the offscreen surface.

Implements QSurface.

Definition at line 235 of file qoffscreensurface.cpp.

References d.

Referenced by QEGLPbuffer::QEGLPbuffer(), QGLXPbuffer::QGLXPbuffer(), and QWasmOffscreenSurface::QWasmOffscreenSurface().

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◆ surfaceHandle()

QPlatformSurface * QOffscreenSurface::surfaceHandle ( ) const

overrideprivatevirtual

Returns the platform surface corresponding to the offscreen surface.

Implements QSurface.

Definition at line 329 of file qoffscreensurface.cpp.

References d.

◆ surfaceType()

QOffscreenSurface::SurfaceType QOffscreenSurface::surfaceType ( ) const

overridevirtual

Returns the surface type of the offscreen surface.

The surface type of an offscreen surface is always QSurface::OpenGLSurface.

Implements QSurface.

Definition at line 99 of file qoffscreensurface.cpp.

References d.

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

qtbase/src/gui/kernel/qoffscreensurface.h
qtbase/src/gui/kernel/qoffscreensurface.cpp

Signals

Public Member Functions

Private Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QOffscreenSurface()

◆ ~QOffscreenSurface()

Member Function Documentation

◆ create()

◆ destroy()

◆ format()

◆ handle()

◆ isValid()

◆ requestedFormat()

◆ screen()

◆ screenChanged

◆ setFormat()

◆ setScreen()

◆ size()

◆ surfaceHandle()

◆ surfaceType()