The QGraphicsEffect class is the base class for all graphics effects. More...

#include <qgraphicseffect.h>

Inheritance diagram for QGraphicsEffect:

Collaboration diagram for QGraphicsEffect:

Public Types
enum	ChangeFlag { SourceAttached = 0x1 , SourceDetached = 0x2 , SourceBoundingRectChanged = 0x4 , SourceInvalidated = 0x8 }

enum	PixmapPadMode { NoPad , PadToTransparentBorder , PadToEffectiveBoundingRect }

Public Slots
void	setEnabled (bool enable)

void	update ()

Public Slots inherited from QObject
void	deleteLater ()

Signals
void	enabledChanged (bool enabled)

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

void	objectNameChanged (const QString &objectName, QPrivateSignal)

Public Member Functions
	QGraphicsEffect (QObject *parent=nullptr)

virtual	~QGraphicsEffect ()

virtual QRectF	boundingRectFor (const QRectF &sourceRect) const

QRectF	boundingRect () const

bool	isEnabled () const

QGraphicsEffectSource *	source () 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

Protected Member Functions
	QGraphicsEffect (QGraphicsEffectPrivate &d, QObject *parent=nullptr)

virtual void	draw (QPainter *painter)=0

virtual void	sourceChanged (ChangeFlags flags)

void	updateBoundingRect ()

bool	sourceIsPixmap () const

QRectF	sourceBoundingRect (Qt::CoordinateSystem system=Qt::LogicalCoordinates) const

void	drawSource (QPainter *painter)

QPixmap	sourcePixmap (Qt::CoordinateSystem system=Qt::LogicalCoordinates, QPoint *offset=nullptr, PixmapPadMode mode=PadToEffectiveBoundingRect) const

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
bool	enabled
	whether the effect is enabled or not. More...

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

Friends
class	QGraphicsItem

class	QGraphicsItemPrivate

class	QGraphicsScenePrivate

class	QWidget

class	QWidgetPrivate

Additional Inherited Members
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 Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

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 QGraphicsEffect class is the base class for all graphics effects.

Since: 4.6

\inmodule QtWidgets

Effects alter the appearance of elements by hooking into the rendering pipeline and operating between the source (e.g., a QGraphicsPixmapItem) and the destination device (e.g., QGraphicsView's viewport). Effects can be disabled by calling setEnabled(false). If effects are disabled, the source is rendered directly.

To add a visual effect to a QGraphicsItem, for example, you can use one of the standard effects, or alternately, create your own effect by creating a subclass of QGraphicsEffect. The effect can then be installed on the item using QGraphicsItem::setGraphicsEffect().

Qt provides the following standard effects:

\list

QGraphicsBlurEffect - blurs the item by a given radius
QGraphicsDropShadowEffect - renders a dropshadow behind the item
QGraphicsColorizeEffect - renders the item in shades of any given color
QGraphicsOpacityEffect - renders the item with an opacity \endlist

\table \row

{2,1} \row
\row
\endtable

For more information on how to use each effect, refer to the specific effect's documentation.

To create your own custom effect, create a subclass of QGraphicsEffect (or any other existing effects) and reimplement the virtual function draw(). This function is called whenever the effect needs to redraw. The draw() function takes the painter with which to draw as an argument. For more information, refer to the documentation for draw(). In the draw() function you can call sourcePixmap() to get a pixmap of the graphics effect source which you can then process.

If your effect changes, use update() to request for a redraw. If your custom effect changes the bounding rectangle of the source, e.g., a radial glow effect may need to apply an extra margin, you can reimplement the virtual boundingRectFor() function, and call updateBoundingRect() to notify the framework whenever this rectangle changes. The virtual sourceChanged() function is called to notify the effects that the source has changed in some way - e.g., if the source is a QGraphicsRectItem and its rectangle parameters have changed.

See also: QGraphicsItem::setGraphicsEffect(), QWidget::setGraphicsEffect()

Definition at line 62 of file qgraphicseffect.h.

Member Enumeration Documentation

◆ ChangeFlag

enum QGraphicsEffect::ChangeFlag

This enum describes what has changed in QGraphicsEffectSource.

\value SourceAttached The effect is installed on a source. \value SourceDetached The effect is uninstalled on a source. \value SourceBoundingRectChanged The bounding rect of the source has changed. \value SourceInvalidated The visual appearance of the source has changed.

Enumerator
SourceAttached
SourceDetached
SourceBoundingRectChanged
SourceInvalidated

Definition at line 67 of file qgraphicseffect.h.

◆ PixmapPadMode

enum QGraphicsEffect::PixmapPadMode

This enum describes how the pixmap returned from sourcePixmap should be padded.

\value NoPad The pixmap should not receive any additional padding. \value PadToTransparentBorder The pixmap should be padded to ensure it has a completely transparent border. \value PadToEffectiveBoundingRect The pixmap should be padded to match the effective bounding rectangle of the effect.

Enumerator
NoPad
PadToTransparentBorder
PadToEffectiveBoundingRect

Definition at line 76 of file qgraphicseffect.h.

Constructor & Destructor Documentation

◆ QGraphicsEffect() [1/2]

QGraphicsEffect::QGraphicsEffect ( QObject * parent = nullptr )

Constructs a new QGraphicsEffect instance having the specified parent.

Definition at line 399 of file qgraphicseffect.cpp.

◆ ~QGraphicsEffect()

QGraphicsEffect::~QGraphicsEffect ( )

virtual

Removes the effect from the source, and destroys the graphics effect.

Definition at line 415 of file qgraphicseffect.cpp.

◆ QGraphicsEffect() [2/2]

QGraphicsEffect::QGraphicsEffect	(	QGraphicsEffectPrivate &	d,
		QObject *	parent = `nullptr`
	)

protected

Definition at line 407 of file qgraphicseffect.cpp.

Member Function Documentation

◆ boundingRect()

QRectF QGraphicsEffect::boundingRect ( ) const

Returns the effective bounding rectangle for this effect, i.e., the bounding rectangle of the source in device coordinates, adjusted by any margins applied by the effect itself.

See also: boundingRectFor(), updateBoundingRect()

Definition at line 428 of file qgraphicseffect.cpp.

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◆ boundingRectFor()

QRectF QGraphicsEffect::boundingRectFor ( const QRectF & rect ) const

virtual

Returns the effective bounding rectangle for this effect, given the provided rect in the device coordinates. When writing you own custom effect, you must call updateBoundingRect() whenever any parameters are changed that may cause this this function to return a different value.

See also: sourceBoundingRect()

Reimplemented in PaddingEffect, TestGraphicsEffect, CustomEffect, DeviceEffect, PixmapItemEffect, CustomEffect, QGraphicsDropShadowEffect, and QGraphicsBlurEffect.

Definition at line 445 of file qgraphicseffect.cpp.

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◆ draw()

void QGraphicsEffect::draw ( QPainter * painter )

protectedpure virtual

This pure virtual function draws the effect and is called whenever the source needs to be drawn.

Reimplement this function in a QGraphicsEffect subclass to provide the effect's drawing implementation, using painter.

For example:

This function should not be called explicitly by the user, since it is meant for reimplementation purposes only.

Implemented in TestGraphicsEffect, CustomEffect, DeviceEffect, PixmapItemEffect, CustomEffect, QGraphicsOpacityEffect, QGraphicsDropShadowEffect, QGraphicsBlurEffect, QGraphicsColorizeEffect, BlurEffect, ListItemCache, and PaddingEffect.

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◆ drawSource()

void QGraphicsEffect::drawSource ( QPainter * painter )

protected

Draws the source directly using the given painter.

This function should only be called from QGraphicsEffect::draw().

For example:

See also: QGraphicsEffect::draw()

Definition at line 251 of file qgraphicseffect.cpp.

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◆ enabledChanged

void QGraphicsEffect::enabledChanged ( bool enabled )

signal

This signal is emitted whenever the effect is enabled or disabled. The enabled parameter holds the effects's new enabled state.

See also: isEnabled()

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◆ isEnabled()

bool QGraphicsEffect::isEnabled ( ) const

Definition at line 463 of file qgraphicseffect.cpp.

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◆ setEnabled

void QGraphicsEffect::setEnabled ( bool enable )

slot

Definition at line 469 of file qgraphicseffect.cpp.

◆ source()

QGraphicsEffectSource * QGraphicsEffect::source ( ) const

Definition at line 513 of file qgraphicseffect.cpp.

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◆ sourceBoundingRect()

QRectF QGraphicsEffect::sourceBoundingRect ( Qt::CoordinateSystem system = Qt::LogicalCoordinates ) const

protected

Returns the bounding rectangle of the source mapped to the given system.

Calling this function with Qt::DeviceCoordinates outside of QGraphicsEffect::draw() will give undefined results, as there is no device context available.

See also: draw()

Definition at line 171 of file qgraphicseffect.cpp.

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◆ sourceChanged()

void QGraphicsEffect::sourceChanged ( ChangeFlags flags )

protectedvirtual

This virtual function is called by QGraphicsEffect to notify the effect that the source has changed. If the effect applies any cache, then this cache must be purged in order to reflect the new appearance of the source.

The flags describes what has changed.

Reimplemented in CustomEffect, and ListItemCache.

Definition at line 588 of file qgraphicseffect.cpp.

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◆ sourceIsPixmap()

bool QGraphicsEffect::sourceIsPixmap ( ) const

protected

Returns true if the source effectively is a pixmap, e.g., a QGraphicsPixmapItem.

This function is useful for optimization purposes. For instance, there's no point in drawing the source in device coordinates to avoid pixmap scaling if this function returns true - the source pixmap will be scaled anyways.

Definition at line 291 of file qgraphicseffect.cpp.

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◆ sourcePixmap()

QPixmap QGraphicsEffect::sourcePixmap	(	Qt::CoordinateSystem	system = `Qt::LogicalCoordinates`,
		QPoint *	offset = `nullptr`,
		QGraphicsEffect::PixmapPadMode	mode = `PadToEffectiveBoundingRect`
	)		const

protected

Returns a pixmap with the source painted into it.

The system specifies which coordinate system to be used for the source. The optional offset parameter returns the offset where the pixmap should be painted at using the current painter. For control on how the pixmap is padded use the mode parameter.

The returned pixmap is clipped to the current painter's device rectangle when system is Qt::DeviceCoordinates.

Calling this function with Qt::DeviceCoordinates outside of QGraphicsEffect::draw() will give undefined results, as there is no device context available.

See also: draw(), boundingRect()

Definition at line 366 of file qgraphicseffect.cpp.

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◆ update

void QGraphicsEffect::update ( )

slot

Schedules a redraw of the effect. Call this function whenever the effect needs to be redrawn. This function does not trigger a redraw of the source.

See also: updateBoundingRect()

Definition at line 498 of file qgraphicseffect.cpp.

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◆ updateBoundingRect()

void QGraphicsEffect::updateBoundingRect ( )

protected

This function notifies the effect framework when the effect's bounding rectangle has changed. As a custom effect author, you must call this function whenever you change any parameters that will cause the virtual boundingRectFor() function to return a different value.

This function will call update() if this is necessary.

See also: boundingRectFor(), boundingRect(), sourceBoundingRect()

Definition at line 529 of file qgraphicseffect.cpp.

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Friends And Related Function Documentation

◆ QGraphicsItem

friend class QGraphicsItem

friend

Definition at line 113 of file qgraphicseffect.h.

◆ QGraphicsItemPrivate

friend class QGraphicsItemPrivate

friend

Definition at line 114 of file qgraphicseffect.h.

◆ QGraphicsScenePrivate

friend class QGraphicsScenePrivate

friend

Definition at line 115 of file qgraphicseffect.h.

◆ QWidget

friend class QWidget

friend

Definition at line 116 of file qgraphicseffect.h.

◆ QWidgetPrivate

friend class QWidgetPrivate

friend

Definition at line 117 of file qgraphicseffect.h.

Property Documentation

◆ enabled

QGraphicsEffect::enabled

readwrite

whether the effect is enabled or not.

If an effect is disabled, the source will be rendered with as normal, with no interference from the effect. If the effect is enabled, the source will be rendered with the effect applied.

This property is enabled by default.

Using this property, you can disable certain effects on slow platforms, in order to ensure that the user interface is responsive.

Definition at line 280 of file qgraphicseffect.h.

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

src/widgets/effects/qgraphicseffect.h
src/widgets/effects/qgraphicseffect.cpp

Public Types

Public Slots

Signals

Public Member Functions

Protected Member Functions

Properties

Friends

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ ChangeFlag

◆ PixmapPadMode

Constructor & Destructor Documentation

◆ QGraphicsEffect() [1/2]

◆ ~QGraphicsEffect()

◆ QGraphicsEffect() [2/2]

Member Function Documentation

◆ boundingRect()

◆ boundingRectFor()

◆ draw()

◆ drawSource()

◆ enabledChanged

◆ isEnabled()

◆ setEnabled

◆ source()

◆ sourceBoundingRect()

◆ sourceChanged()

◆ sourceIsPixmap()

◆ sourcePixmap()

◆ update

◆ updateBoundingRect()

Friends And Related Function Documentation

◆ QGraphicsItem

◆ QGraphicsItemPrivate

◆ QGraphicsScenePrivate

◆ QWidget

◆ QWidgetPrivate

Property Documentation

◆ enabled