The QGraphicsOpacityEffect class provides an opacity effect. More...

#include <qgraphicseffect.h>

Inheritance diagram for QGraphicsOpacityEffect:

Collaboration diagram for QGraphicsOpacityEffect:

Public Slots
void	setOpacity (qreal opacity)

void	setOpacityMask (const QBrush &mask)

Public Slots inherited from QGraphicsEffect
void	setEnabled (bool enable)

void	update ()
	Schedules a redraw of the effect.

Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Signals
void	opacityChanged (qreal opacity)
	This signal is emitted whenever the effect's opacity changes.

void	opacityMaskChanged (const QBrush &mask)
	This signal is emitted whenever the effect's opacity mask changes.

Signals inherited from QGraphicsEffect
void	enabledChanged (bool enabled)
	This signal is emitted whenever the effect is enabled or disabled.

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
	QGraphicsOpacityEffect (QObject *parent=nullptr)
	Constructs a new QGraphicsOpacityEffect instance.

	~QGraphicsOpacityEffect ()
	Destroys the effect.

qreal	opacity () const

QBrush	opacityMask () const

Public Member Functions inherited from QGraphicsEffect
	QGraphicsEffect (QObject *parent=nullptr)
	Constructs a new QGraphicsEffect instance having the specified parent.

virtual	~QGraphicsEffect ()
	Removes the effect from the source, and destroys the graphics effect.

virtual QRectF	boundingRectFor (const QRectF &sourceRect) const
	Returns the effective bounding rectangle for this effect, given the provided rect in the device coordinates.

QRectF	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.

bool	isEnabled () const

QGraphicsEffectSource *	source () const

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.

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

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::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

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

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, 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 (QAnyStringView 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 >
T	findChild (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.

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`.

Protected Member Functions
void	draw (QPainter *painter) override
	\reimp

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

virtual void	sourceChanged (ChangeFlags flags)
	This virtual function is called by QGraphicsEffect to notify the effect that the source has changed.

void	updateBoundingRect ()
	This function notifies the effect framework when the effect's bounding rectangle has changed.

bool	sourceIsPixmap () const
	Returns `true` if the source effectively is a pixmap, e.g., a QGraphicsPixmapItem.

QRectF	sourceBoundingRect (Qt::CoordinateSystem system=Qt::LogicalCoordinates) const
	Returns the bounding rectangle of the source mapped to the given system.

void	drawSource (QPainter *painter)
	Draws the source directly using the given painter.

QPixmap	sourcePixmap (Qt::CoordinateSystem system=Qt::LogicalCoordinates, QPoint *offset=nullptr, PixmapPadMode mode=PadToEffectiveBoundingRect) const
	Returns a pixmap with the source painted into it.

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)

Properties
qreal	opacity
	the opacity of the effect.

QBrush	opacityMask
	the opacity mask of the effect.

Properties inherited from QGraphicsEffect
bool	enabled
	whether the effect is enabled or not.

Properties inherited from QObject
QString	objectName
	the name of this object

Additional Inherited Members
Public Types inherited from QGraphicsEffect
enum	ChangeFlag { SourceAttached = 0x1 , SourceDetached = 0x2 , SourceBoundingRectChanged = 0x4 , SourceInvalidated = 0x8 }
	This enum describes what has changed in QGraphicsEffectSource. More...

enum	PixmapPadMode { NoPad , PadToTransparentBorder , PadToEffectiveBoundingRect }
	This enum describes how the pixmap returned from sourcePixmap should be padded. More...

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 Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

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

The QGraphicsOpacityEffect class provides an opacity effect.

Since: 4.6 \inmodule QtWidgets

An opacity effect renders the source with an opacity. This effect is useful for making the source semi-transparent, similar to a fade-in/fade-out sequence. The opacity can be modified using the setOpacity() function.

By default, the opacity is 0.7.

See also: QGraphicsDropShadowEffect, QGraphicsBlurEffect, QGraphicsColorizeEffect

Definition at line 216 of file qgraphicseffect.h.

Constructor & Destructor Documentation

◆ QGraphicsOpacityEffect()

QGraphicsOpacityEffect::QGraphicsOpacityEffect ( QObject * parent = nullptr )

Constructs a new QGraphicsOpacityEffect instance.

The parent parameter is passed to QGraphicsEffect's constructor.

Definition at line 1057 of file qgraphicseffect.cpp.

◆ ~QGraphicsOpacityEffect()

QGraphicsOpacityEffect::~QGraphicsOpacityEffect ( )

Destroys the effect.

Definition at line 1065 of file qgraphicseffect.cpp.

Member Function Documentation

◆ draw()

void QGraphicsOpacityEffect::draw ( QPainter * painter )

overrideprotectedvirtual

\reimp

Implements QGraphicsEffect.

Definition at line 1153 of file qgraphicseffect.cpp.

References QPainter::CompositionMode_DestinationIn, d, Qt::DeviceCoordinates, QPainter::drawPixmap(), QGraphicsEffect::drawSource(), QTransform::fromTranslate(), Qt::LogicalCoordinates, QGraphicsEffect::NoPad, painter, pixmap, QPainter::renderHints(), QPainter::restore(), QPainter::save(), QPainter::setOpacity(), QPainter::setWorldTransform(), QGraphicsEffect::sourceBoundingRect(), QGraphicsEffect::sourceIsPixmap(), QGraphicsEffect::sourcePixmap(), and QPainter::worldTransform().

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◆ opacity()

qreal QGraphicsOpacityEffect::opacity ( ) const

Definition at line 1080 of file qgraphicseffect.cpp.

References d.

◆ opacityChanged

void QGraphicsOpacityEffect::opacityChanged ( qreal opacity )

signal

This signal is emitted whenever the effect's opacity changes.

The opacity parameter holds the effect's new opacity.

Referenced by setOpacity().

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◆ opacityMask()

QBrush QGraphicsOpacityEffect::opacityMask ( ) const

Definition at line 1124 of file qgraphicseffect.cpp.

References d.

◆ opacityMaskChanged

void QGraphicsOpacityEffect::opacityMaskChanged ( const QBrush & mask )

signal

This signal is emitted whenever the effect's opacity mask changes.

The mask parameter holds the effect's new opacity mask.

Referenced by setOpacityMask().

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◆ setOpacity

void QGraphicsOpacityEffect::setOpacity ( qreal opacity )

slot

Definition at line 1086 of file qgraphicseffect.cpp.

References d, emit, opacity, opacityChanged(), qBound(), qFuzzyCompare(), qFuzzyIsNull(), and QGraphicsEffect::update().

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◆ setOpacityMask

void QGraphicsOpacityEffect::setOpacityMask ( const QBrush & mask )

slot

Definition at line 1130 of file qgraphicseffect.cpp.

References d, emit, Qt::NoBrush, opacityMaskChanged(), and QGraphicsEffect::update().

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Property Documentation

◆ opacity

QGraphicsOpacityEffect::opacity

readwrite

the opacity of the effect.

The value should be in the range of 0.0 to 1.0, where 0.0 is fully transparent and 1.0 is fully opaque.

By default, the opacity is 0.7.

See also: setOpacityMask()

Definition at line 219 of file qgraphicseffect.h.

Referenced by setOpacity().

◆ opacityMask

QGraphicsOpacityEffect::opacityMask

readwrite

the opacity mask of the effect.

An opacity mask allows you apply opacity to portions of an element.

For example:

...
QLinearGradient alphaGradient(rect.topLeft(), rect.bottomLeft());
alphaGradient.setColorAt(0.0, Qt::transparent);
alphaGradient.setColorAt(0.5, Qt::black);
alphaGradient.setColorAt(1.0, Qt::transparent);
QGraphicsOpacityEffect *effect = new QGraphicsOpacityEffect;
effect->setOpacityMask(alphaGradient);
...

There is no opacity mask by default.

See also: setOpacity()

Definition at line 220 of file qgraphicseffect.h.

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

qtbase/src/widgets/effects/qgraphicseffect.h (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/widgets/effects/qgraphicseffect.cpp (05fc3aef53348fb58be6308076e000825b704e58)

Public Slots

Signals

Public Member Functions

Protected Member Functions

Properties

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QGraphicsOpacityEffect()

◆ ~QGraphicsOpacityEffect()

Member Function Documentation

◆ draw()

◆ opacity()

◆ opacityChanged

◆ opacityMask()

◆ opacityMaskChanged

◆ setOpacity

◆ setOpacityMask

Property Documentation

◆ opacity

◆ opacityMask