\inmodule QtOpenGL More...

#include <qopenglwindow.h>

Inheritance diagram for QOpenGLWindow:

Collaboration diagram for QOpenGLWindow:

Public Types
enum	UpdateBehavior { NoPartialUpdate , PartialUpdateBlit , PartialUpdateBlend }
	This enum describes the update strategy of the QOpenGLWindow. More...

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 Types inherited from QPaintDevice
enum	PaintDeviceMetric { PdmWidth = 1 , PdmHeight , PdmWidthMM , PdmHeightMM , PdmNumColors , PdmDepth , PdmDpiX , PdmDpiY , PdmPhysicalDpiX , PdmPhysicalDpiY , PdmDevicePixelRatio , PdmDevicePixelRatioScaled }

Signals
void	frameSwapped ()
	This signal is emitted after the potentially blocking \l{QOpenGLContext::swapBuffers()}{buffer swap} has been done.

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

void	modalityChanged (Qt::WindowModality modality)
	This signal is emitted when the Qwindow::modality property changes to modality.

void	windowStateChanged (Qt::WindowState windowState)
	This signal is emitted when the windowState changes, either by being set explicitly with setWindowStates(), or automatically when the user clicks one of the titlebar buttons or by other means.

	Q_REVISION (2, 2) void windowTitleChanged(const QString &title)

void	xChanged (int arg)

void	yChanged (int arg)

void	widthChanged (int arg)

void	heightChanged (int arg)

void	minimumWidthChanged (int arg)

void	minimumHeightChanged (int arg)

void	maximumWidthChanged (int arg)

void	maximumHeightChanged (int arg)

void	visibleChanged (bool arg)

Q_REVISION(2, 1) void visibilityChanged(QWindow	Q_REVISION (2, 1) void activeChanged()

void	contentOrientationChanged (Qt::ScreenOrientation orientation)

void	focusObjectChanged (QObject *object)
	This signal is emitted when the final receiver of events tied to focus is changed to object.

	Q_REVISION (2, 1) void opacityChanged(qreal opacity)

	Q_REVISION (2, 13) void transientParentChanged(QWindow *transientParent)

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
	QOpenGLWindow (UpdateBehavior updateBehavior=NoPartialUpdate, QWindow *parent=nullptr)
	Constructs a new QOpenGLWindow with the given parent and updateBehavior.

	QOpenGLWindow (QOpenGLContext shareContext, UpdateBehavior updateBehavior=NoPartialUpdate, QWindow parent=nullptr)
	Constructs a new QOpenGLWindow with the given parent and updateBehavior.

	~QOpenGLWindow ()
	Destroys the QOpenGLWindow instance, freeing its resources.

UpdateBehavior	updateBehavior () const

bool	isValid () const

void	makeCurrent ()
	Prepares for rendering OpenGL content for this window by making the corresponding context current and binding the framebuffer object, if there is one, in that context.

void	doneCurrent ()
	Releases the context.

QOpenGLContext *	context () const

QOpenGLContext *	shareContext () const

GLuint	defaultFramebufferObject () const
	The framebuffer object handle used by this window.

QImage	grabFramebuffer ()
	Returns a copy of the framebuffer.

Public Member Functions inherited from QPaintDeviceWindow
void	update (const QRect &rect)
	Marks the rect of the window as dirty and schedules a repaint.

void	update (const QRegion &region)
	Marks the region of the window as dirty and schedules a repaint.

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.

Public Member Functions inherited from QPaintDevice
virtual	~QPaintDevice ()

virtual int	devType () const

bool	paintingActive () const

virtual QPaintEngine *	paintEngine () const =0

int	width () const

int	height () const

int	widthMM () const

int	heightMM () const

int	logicalDpiX () const

int	logicalDpiY () const

int	physicalDpiX () const

int	physicalDpiY () const

qreal	devicePixelRatio () const

qreal	devicePixelRatioF () const

int	colorCount () const

int	depth () const

Protected Member Functions
virtual void	initializeGL ()
	This virtual function is called once before the first call to paintGL() or resizeGL().

virtual void	resizeGL (int w, int h)
	This virtual function is called whenever the widget has been resized.

virtual void	paintGL ()
	This virtual function is called whenever the window contents needs to be painted.

virtual void	paintUnderGL ()
	The virtual function is called before each invocation of paintGL().

virtual void	paintOverGL ()
	This virtual function is called after each invocation of paintGL().

void	paintEvent (QPaintEvent *event) override
	Paint event handler.

void	resizeEvent (QResizeEvent *event) override
	Resize event handler.

int	metric (PaintDeviceMetric metric) const override

QPaintDevice *	redirected (QPoint *) const override

Protected Member Functions inherited from QPaintDeviceWindow
void	exposeEvent (QExposeEvent *) override

void	paintEvent (QPaintEvent *event) override
	Handles paint events passed in the event parameter.

int	metric (PaintDeviceMetric metric) const override

bool	event (QEvent *event) override

	QPaintDeviceWindow (QPaintDeviceWindowPrivate &dd, QWindow *parent)

Protected Member Functions inherited from QWindow
virtual void	exposeEvent (QExposeEvent *)
	The expose event (ev) is sent by the window system when a window moves between the un-exposed and exposed states.

virtual void	resizeEvent (QResizeEvent *)
	Override this to handle resize events (ev).

virtual void	paintEvent (QPaintEvent *)
	The paint event (ev) is sent by the window system whenever an area of the window needs a repaint, for example when initially showing the window, or due to parts of the window being uncovered by moving another window.

virtual void	moveEvent (QMoveEvent *)
	Override this to handle window move events (ev).

virtual void	focusInEvent (QFocusEvent *)
	Override this to handle focus in events (ev).

virtual void	focusOutEvent (QFocusEvent *)
	Override this to handle focus out events (ev).

virtual void	showEvent (QShowEvent *)
	Override this to handle show events (ev).

virtual void	hideEvent (QHideEvent *)
	Override this to handle hide events (ev).

virtual void	closeEvent (QCloseEvent *)
	Override this to handle close events (ev).

virtual bool	event (QEvent *) override
	Override this to handle any event (ev) sent to the window.

virtual void	keyPressEvent (QKeyEvent *)
	Override this to handle key press events (ev).

virtual void	keyReleaseEvent (QKeyEvent *)
	Override this to handle key release events (ev).

virtual void	mousePressEvent (QMouseEvent *)
	Override this to handle mouse press events (ev).

virtual void	mouseReleaseEvent (QMouseEvent *)
	Override this to handle mouse release events (ev).

virtual void	mouseDoubleClickEvent (QMouseEvent *)
	Override this to handle mouse double click events (ev).

virtual void	mouseMoveEvent (QMouseEvent *)
	Override this to handle mouse move events (ev).

virtual void	touchEvent (QTouchEvent *)
	Override this to handle touch events (ev).

virtual bool	nativeEvent (const QByteArray &eventType, void message, qintptr result)
	Override this to handle platform dependent events.

	QWindow (QWindowPrivate &dd, QWindow *parent)
	Creates a window as a child of the given parent window with the dd private implementation.

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 Member Functions inherited from QPaintDevice
	QPaintDevice () noexcept

virtual int	metric (PaintDeviceMetric metric) const

virtual void	initPainter (QPainter *painter) const

virtual QPaintDevice *	redirected (QPoint *offset) const

virtual QPainter *	sharedPainter () const

Additional Inherited Members
Public Slots inherited from QPaintDeviceWindow
void	update ()
	Marks the entire window as dirty and schedules a repaint.

Public Slots inherited from QWindow
	Q_REVISION (2, 1) void requestActivate()

void	setVisible (bool visible)

void	show ()
	Shows the window.

void	hide ()
	Hides the window.

void	showMinimized ()
	Shows the window as minimized.

void	showMaximized ()
	Shows the window as maximized.

void	showFullScreen ()
	Shows the window as fullscreen.

void	showNormal ()
	Shows the window as normal, i.e.

bool	close ()
	Close the window.

void	raise ()
	Raise the window in the windowing system.

void	lower ()
	Lower the window in the windowing system.

bool	startSystemResize (Qt::Edges edges)
	Start a system-specific resize operation.

bool	startSystemMove ()
	Start a system-specific move operation.

void	setTitle (const QString &)

void	setX (int arg)

void	setY (int arg)

void	setWidth (int arg)

void	setHeight (int arg)

void	setGeometry (int posx, int posy, int w, int h)
	Sets the geometry of the window, excluding its window frame, to a rectangle constructed from posx, posy, w and h.

void	setGeometry (const QRect &rect)
	Sets the geometry of the window, excluding its window frame, to rect.

void	setMinimumWidth (int w)

void	setMinimumHeight (int h)

void	setMaximumWidth (int w)

void	setMaximumHeight (int h)

	Q_REVISION (2, 1) void alert(int msec)

	Q_REVISION (2, 3) void requestUpdate()

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)

Static Public Member Functions inherited from QPaintDevice
static qreal	devicePixelRatioFScale ()

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Protected Attributes inherited from QSurface
SurfaceClass	m_type

QSurfacePrivate *	m_reserved

Protected Attributes inherited from QPaintDevice
ushort	painters

Properties inherited from QPaintDeviceWindow
int	width
	the width of the window's geometry

int	height
	the height of the window's geometry

Properties inherited from QWindow
QString	title
	the window's title in the windowing system

Qt::WindowModality	modality
	the modality of the window

Qt::WindowFlags	flags
	the window flags of the window

int	x
	the x position of the window's geometry

int	y
	the y position of the window's geometry

int	width
	the width of the window's geometry

int	height
	the height of the window's geometry

int	minimumWidth
	the minimum width of the window's geometry

int	minimumHeight
	the minimum height of the window's geometry

int	maximumWidth
	the maximum width of the window's geometry

int	maximumHeight
	the maximum height of the window's geometry

bool	visible
	whether the window is visible or not

bool	active
	the active status of the window

Visibility	visibility
	the screen-occupation state of the window

Qt::ScreenOrientation	contentOrientation
	the orientation of the window's contents

qreal	opacity
	The opacity of the window in the windowing system.

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 QtOpenGL

Since: 5.4

The QOpenGLWindow class is a convenience subclass of QWindow to perform OpenGL painting.

QOpenGLWindow is an enhanced QWindow that allows easily creating windows that perform OpenGL rendering using an API that is compatible with QOpenGLWidget Unlike QOpenGLWidget, QOpenGLWindow has no dependency on the widgets module and offers better performance.

A typical application will subclass QOpenGLWindow and reimplement the following virtual functions:

\list

initializeGL() to perform OpenGL resource initialization

resizeGL() to set up the transformation matrices and other window size dependent resources

paintGL() to issue OpenGL commands or draw using QPainter

\endlist

To schedule a repaint, call the update() function. Note that this will not immediately result in a call to paintGL(). Calling update() multiple times in a row will not change the behavior in any way.

This is a slot so it can be connected to a \l QTimer::timeout() signal to perform animation. Note however that in the modern OpenGL world it is a much better choice to rely on synchronization to the vertical refresh rate of the display. See \l{QSurfaceFormat::setSwapInterval()}{setSwapInterval()} on a description of the swap interval. With a swap interval of 1, which is the case on most systems by default, the \l{QOpenGLContext::swapBuffers()}{swapBuffers()} call, that is executed internally by QOpenGLWindow after each repaint, will block and wait for vsync. This means that whenever the swap is done, an update can be scheduled again by calling update(), without relying on timers.

To request a specific configuration for the context, use setFormat() like for any other QWindow. This allows, among others, requesting a given OpenGL version and profile, or enabling depth and stencil buffers.

Note: It is up to the application to ensure depth and stencil buffers are requested from the underlying windowing system interface. Without requesting a non-zero depth buffer size there is no guarantee that a depth buffer will be available, and as a result depth testing related OpenGL operations may fail to function as expected.

Commonly used depth and stencil buffer size requests are 24 and 8, respectively. For example, a QOpenGLWindow subclass could do this in its constructor:

QSurfaceFormat format;
format.setDepthBufferSize(24);
format.setStencilBufferSize(8);
setFormat(format);

Unlike QWindow, QOpenGLWindow allows opening a painter on itself and perform QPainter-based drawing.

QOpenGLWindow supports multiple update behaviors. The default, NoPartialUpdate is equivalent to a regular, OpenGL-based QWindow. In contrast, PartialUpdateBlit and PartialUpdateBlend are more in line with QOpenGLWidget's way of working, where there is always an extra, dedicated framebuffer object present. These modes allow, by sacrificing some performance, redrawing only a smaller area on each paint and having the rest of the content preserved from of the previous frame. This is useful for applications than render incrementally using QPainter, because this way they do not have to redraw the entire window content on each paintGL() call.

Similarly to QOpenGLWidget, QOpenGLWindow supports the Qt::AA_ShareOpenGLContexts attribute. When enabled, the OpenGL contexts of all QOpenGLWindow instances will share with each other. This allows accessing each other's shareable OpenGL resources.

For more information on graphics in Qt, see \l {Graphics}.

Definition at line 19 of file qopenglwindow.h.

Member Enumeration Documentation

◆ UpdateBehavior

enum QOpenGLWindow::UpdateBehavior

This enum describes the update strategy of the QOpenGLWindow.

\value NoPartialUpdate Indicates that the entire window surface will redrawn on each update and so no additional framebuffers are needed. This is the setting used in most cases and is equivalent to how drawing directly via QWindow would function.

\value PartialUpdateBlit Indicates that the drawing performed in paintGL() does not cover the entire window. In this case an extra framebuffer object is created under the hood, and rendering performed in paintGL() will target this framebuffer. This framebuffer is then blitted onto the window surface's default framebuffer after each paint. This allows having QPainter-based drawing code in paintGL() which only repaints a smaller area at a time, because, unlike NoPartialUpdate, the previous content is preserved.

\value PartialUpdateBlend Similar to PartialUpdateBlit, but instead of using framebuffer blits, the contents of the extra framebuffer is rendered by drawing a textured quad with blending enabled. This, unlike PartialUpdateBlit, allows alpha blended content and works even when the glBlitFramebuffer is not available. Performance-wise this setting is likely to be somewhat slower than PartialUpdateBlit.

Enumerator
NoPartialUpdate
PartialUpdateBlit
PartialUpdateBlend

Definition at line 25 of file qopenglwindow.h.

Constructor & Destructor Documentation

◆ QOpenGLWindow() [1/2]

QOpenGLWindow::QOpenGLWindow	(	QOpenGLWindow::UpdateBehavior	updateBehavior = `NoPartialUpdate`,
		QWindow *	parent = `nullptr`
	)

explicit

Constructs a new QOpenGLWindow with the given parent and updateBehavior.

See also: QOpenGLWindow::UpdateBehavior

Definition at line 332 of file qopenglwindow.cpp.

References QSurface::OpenGLSurface.

◆ QOpenGLWindow() [2/2]

QOpenGLWindow::QOpenGLWindow	(	QOpenGLContext *	shareContext,
		UpdateBehavior	updateBehavior = `NoPartialUpdate`,
		QWindow *	parent = `nullptr`
	)

explicit

Constructs a new QOpenGLWindow with the given parent and updateBehavior.

The QOpenGLWindow's context will share with shareContext.

See also: QOpenGLWindow::UpdateBehavior shareContext

Definition at line 343 of file qopenglwindow.cpp.

References QSurface::OpenGLSurface.

◆ ~QOpenGLWindow()

QOpenGLWindow::~QOpenGLWindow ( )

Destroys the QOpenGLWindow instance, freeing its resources.

The OpenGLWindow's context is made current in the destructor, allowing for safe destruction of any child object that may need to release OpenGL resources belonging to the context provided by this window.

Warning: if you have objects wrapping OpenGL resources (such as QOpenGLBuffer, QOpenGLShaderProgram, etc.) as members of a QOpenGLWindow subclass, you may need to add a call to makeCurrent() in that subclass' destructor as well. Due to the rules of C++ object destruction, those objects will be destroyed {before} calling this function (but after that the destructor of the subclass has run), therefore making the OpenGL context current in this function happens too late for their safe disposal.

See also: makeCurrent

Since: 5.5

Definition at line 368 of file qopenglwindow.cpp.

References makeCurrent().

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Member Function Documentation

◆ context()

QOpenGLContext * QOpenGLWindow::context ( ) const

Returns: The QOpenGLContext used by this window or 0 if not yet initialized.

Definition at line 458 of file qopenglwindow.cpp.

References d.

◆ defaultFramebufferObject()

GLuint QOpenGLWindow::defaultFramebufferObject ( ) const

The framebuffer object handle used by this window.

When the update behavior is set to NoPartialUpdate, there is no separate framebuffer object. In this case the returned value is the ID of the default framebuffer.

Otherwise the value of the ID of the framebuffer object or 0 if not yet initialized.

Definition at line 483 of file qopenglwindow.cpp.

References QOpenGLContext::currentContext(), d, and NoPartialUpdate.

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◆ doneCurrent()

void QOpenGLWindow::doneCurrent ( )

Releases the context.

It is not necessary to call this function in most cases, since the widget will make sure the context is bound and released properly when invoking paintGL().

See also: makeCurrent()

Definition at line 445 of file qopenglwindow.cpp.

References d, and isValid().

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◆ frameSwapped

void QOpenGLWindow::frameSwapped ( )

signal

This signal is emitted after the potentially blocking \l{QOpenGLContext::swapBuffers()}{buffer swap} has been done.

Applications that wish to continuously repaint synchronized to the vertical refresh, should issue an update() upon this signal. This allows for a much smoother experience compared to the traditional usage of timers.

◆ grabFramebuffer()

QImage QOpenGLWindow::grabFramebuffer ( )

Returns a copy of the framebuffer.

Note: This is a potentially expensive operation because it relies on glReadPixels() to read back the pixels. This may be slow and can stall the GPU pipeline.; When used together with update behavior NoPartialUpdate, the returned image may not contain the desired content when called after the front and back buffers have been swapped (unless preserved swap is enabled in the underlying windowing system interface). In this mode the function reads from the back buffer and the contents of that may not match the content on the screen (the front buffer). In this case the only place where this function can safely be used is paintGL() or paintOverGL().

Definition at line 509 of file qopenglwindow.cpp.

References QPaintDevice::devicePixelRatio(), QWindow::format(), QSurfaceFormat::hasAlpha(), hasAlpha(), isValid(), makeCurrent(), qt_gl_read_framebuffer(), and QWindow::size().

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◆ initializeGL()

void QOpenGLWindow::initializeGL ( )

protectedvirtual

This virtual function is called once before the first call to paintGL() or resizeGL().

Reimplement it in a subclass.

This function should set up any required OpenGL resources and state.

There is no need to call makeCurrent() because this has already been done when this function is called. Note however that the framebuffer, in case partial update mode is used, is not yet available at this stage, so avoid issuing draw calls from here. Defer such calls to paintGL() instead.

See also: paintGL(), resizeGL()

Definition at line 535 of file qopenglwindow.cpp.

◆ isValid()

bool QOpenGLWindow::isValid ( ) const

Returns: true if the window's OpenGL resources, like the context, have been successfully initialized. Note that the return value is always false until the window becomes exposed (shown).

Definition at line 387 of file qopenglwindow.cpp.

References d.

Referenced by doneCurrent(), grabFramebuffer(), and makeCurrent().

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◆ makeCurrent()

void QOpenGLWindow::makeCurrent ( )

Prepares for rendering OpenGL content for this window by making the corresponding context current and binding the framebuffer object, if there is one, in that context.

It is not necessary to call this function in most cases, because it is called automatically before invoking paintGL(). It is provided nonetheless to support advanced, multi-threaded scenarios where a thread different than the GUI or main thread may want to update the surface or framebuffer contents. See QOpenGLContext for more information on threading related issues.

This function is suitable for calling also when the underlying platform window is already destroyed. This means that it is safe to call this function from a QOpenGLWindow subclass' destructor. If there is no native window anymore, an offscreen surface is used instead. This ensures that OpenGL resource cleanup operations in the destructor will always work, as long as this function is called first.

See also: QOpenGLContext, context(), paintGL(), doneCurrent()

Definition at line 413 of file qopenglwindow.cpp.

References d, isValid(), and screen.

Referenced by ~QOpenGLWindow(), and grabFramebuffer().

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◆ metric()

int QOpenGLWindow::metric ( PaintDeviceMetric metric ) const

overrideprotectedvirtual

Reimplemented from QPaintDevice.

Definition at line 653 of file qopenglwindow.cpp.

References d, QPaintDeviceWindow::metric(), metric(), and QPaintDevice::PdmDepth.

Referenced by metric().

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◆ paintEvent()

void QOpenGLWindow::paintEvent ( QPaintEvent * event )

overrideprotectedvirtual

Paint event handler.

Calls paintGL().

See also: paintGL()

Reimplemented from QWindow.

Definition at line 631 of file qopenglwindow.cpp.

References paintGL(), and Q_UNUSED.

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◆ paintGL()

void QOpenGLWindow::paintGL ( )

protectedvirtual

This virtual function is called whenever the window contents needs to be painted.

Reimplement it in a subclass.

There is no need to call makeCurrent() because this has already been done when this function is called.

Before invoking this function, the context and the framebuffer, if there is one, are bound, and the viewport is set up by a call to glViewport(). No other state is set and no clearing or drawing is performed by the framework.

Note: When using a partial update behavior, like PartialUpdateBlend, the output of the previous paintGL() call is preserved and, after the additional drawing performed in the current invocation of the function, the content is blitted or blended over the content drawn directly to the window in paintUnderGL().

See also: initializeGL(), resizeGL(), paintUnderGL(), paintOverGL(), UpdateBehavior

Definition at line 580 of file qopenglwindow.cpp.

Referenced by paintEvent().

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◆ paintOverGL()

void QOpenGLWindow::paintOverGL ( )

protectedvirtual

This virtual function is called after each invocation of paintGL().

When the update mode is set to NoPartialUpdate, there is no difference between this function and paintGL(), performing rendering in either of them leads to the same result.

Like paintUnderGL(), rendering in this function targets the default framebuffer of the window, regardless of the update behavior. It gets called after paintGL() has returned and the blit (PartialUpdateBlit) or quad drawing (PartialUpdateBlend) has been done.

See also: paintGL(), paintUnderGL(), UpdateBehavior

Definition at line 622 of file qopenglwindow.cpp.

◆ paintUnderGL()

void QOpenGLWindow::paintUnderGL ( )

protectedvirtual

The virtual function is called before each invocation of paintGL().

When the update mode is set to NoPartialUpdate, there is no difference between this function and paintGL(), performing rendering in either of them leads to the same result.

The difference becomes significant when using PartialUpdateBlend, where an extra framebuffer object is used. There, paintGL() targets this additional framebuffer object, which preserves its contents, while paintUnderGL() and paintOverGL() target the default framebuffer, i.e. directly the window surface, the contents of which is lost after each displayed frame.

Note: Avoid relying on this function when the update behavior is PartialUpdateBlit. This mode involves blitting the extra framebuffer used by paintGL() onto the default framebuffer after each invocation of paintGL(), thus overwriting all drawing generated in this function.

See also: paintGL(), paintOverGL(), UpdateBehavior

Definition at line 604 of file qopenglwindow.cpp.

◆ redirected()

QPaintDevice * QOpenGLWindow::redirected ( QPoint * ) const

overrideprotectedvirtual

Reimplemented from QPaintDevice.

Definition at line 671 of file qopenglwindow.cpp.

References QOpenGLContext::currentContext(), and d.

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◆ resizeEvent()

void QOpenGLWindow::resizeEvent ( QResizeEvent * event )

overrideprotectedvirtual

Resize event handler.

Calls resizeGL().

See also: resizeGL()

Reimplemented from QWindow.

Definition at line 642 of file qopenglwindow.cpp.

References d, QPaintDeviceWindow::height, Q_UNUSED, resizeGL(), and QPaintDeviceWindow::width.

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◆ resizeGL()

void QOpenGLWindow::resizeGL	(	int	w,
		int	h
	)

protectedvirtual

This virtual function is called whenever the widget has been resized.

Reimplement it in a subclass. The new size is passed in w and h.

Note: This is merely a convenience function in order to provide an API that is compatible with QOpenGLWidget. Unlike with QOpenGLWidget, derived classes are free to choose to override resizeEvent() instead of this function.; Avoid issuing OpenGL commands from this function as there may not be a context current when it is invoked. If it cannot be avoided, call makeCurrent().; Scheduling updates from here is not necessary. The windowing systems will send expose events that trigger an update automatically.

See also: initializeGL(), paintGL()

Definition at line 555 of file qopenglwindow.cpp.

References Q_UNUSED.

Referenced by resizeEvent().

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◆ shareContext()

QOpenGLContext * QOpenGLWindow::shareContext ( ) const

Returns: The QOpenGLContext requested to be shared with this window's QOpenGLContext.

Definition at line 467 of file qopenglwindow.cpp.

References d.

◆ updateBehavior()

QOpenGLWindow::UpdateBehavior QOpenGLWindow::updateBehavior ( ) const

Returns: the update behavior for this QOpenGLWindow.

Definition at line 376 of file qopenglwindow.cpp.

References d.

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

qtbase/src/opengl/qopenglwindow.h
qtbase/src/opengl/qopenglwindow.cpp

Public Types

Signals

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ UpdateBehavior

Constructor & Destructor Documentation

◆ QOpenGLWindow() [1/2]

◆ QOpenGLWindow() [2/2]

◆ ~QOpenGLWindow()

Member Function Documentation

◆ context()

◆ defaultFramebufferObject()

◆ doneCurrent()

◆ frameSwapped

◆ grabFramebuffer()

◆ initializeGL()

◆ isValid()

◆ makeCurrent()

◆ metric()

◆ paintEvent()

◆ paintGL()

◆ paintOverGL()

◆ paintUnderGL()

◆ redirected()

◆ resizeEvent()

◆ resizeGL()

◆ shareContext()

◆ updateBehavior()