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

#include <qoffscreensurface.h>

Inheritance diagram for QOffscreenSurface:

Collaboration diagram for QOffscreenSurface:

Signals
void	screenChanged (QScreen *screen)

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

void	objectNameChanged (const QString &objectName, QPrivateSignal)

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

	~QOffscreenSurface ()

SurfaceType	surfaceType () const override

void	create ()

void	destroy ()

bool	isValid () const

void	setFormat (const QSurfaceFormat &format)

QSurfaceFormat	format () const override

QSurfaceFormat	requestedFormat () const

QSize	size () const override

QScreen *	screen () const

void	setScreen (QScreen *screen)

QPlatformOffscreenSurface *	handle () const

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

virtual	~QObject ()

virtual bool	event (QEvent *event)

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

Public Member Functions inherited from QSurface
virtual	~QSurface ()

SurfaceClass	surfaceClass () const

bool	supportsOpenGL () const

Additional Inherited Members
Public Types inherited from QSurface
enum	SurfaceClass { Window , Offscreen }

enum	SurfaceType { RasterSurface , OpenGLSurface , RasterGLSurface , OpenVGSurface , VulkanSurface , MetalSurface , Direct3DSurface }

Public Slots inherited from QObject
void	deleteLater ()

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 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)

Protected Member Functions inherited from QSurface
	QSurface (SurfaceClass 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 More...

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 QOffscreenSurface class represents an offscreen surface in the underlying platform.

\inmodule QtGui

Since: 5.1

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 56 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 104 of file qoffscreensurface.cpp.

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◆ ~QOffscreenSurface()

QOffscreenSurface::~QOffscreenSurface ( )

Destroys the offscreen surface.

Definition at line 123 of file qoffscreensurface.cpp.

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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 151 of file qoffscreensurface.cpp.

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◆ destroy()

void QOffscreenSurface::destroy ( )

Releases the native platform resources associated with this offscreen surface.

See also: create()

Definition at line 187 of file qoffscreensurface.cpp.

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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 256 of file qoffscreensurface.cpp.

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◆ handle()

QPlatformOffscreenSurface * QOffscreenSurface::handle ( ) const

Returns the platform offscreen surface corresponding to the offscreen surface.

Definition at line 339 of file qoffscreensurface.cpp.

◆ 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 210 of file qoffscreensurface.cpp.

◆ 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 241 of file qoffscreensurface.cpp.

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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 280 of file qoffscreensurface.cpp.

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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.

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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 225 of file qoffscreensurface.cpp.

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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 293 of file qoffscreensurface.cpp.

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◆ size()

QSize QOffscreenSurface::size ( ) const

overridevirtual

Returns the size of the offscreen surface.

Implements QSurface.

Definition at line 269 of file qoffscreensurface.cpp.

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◆ 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 133 of file qoffscreensurface.cpp.

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

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

Signals

Public 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()

◆ surfaceType()