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

#include <qgraphicseffect.h>

Inheritance 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. More...

Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

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

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

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

Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...

Public Functions
qreal	opacity () const

QBrush	opacityMask () const

	QGraphicsOpacityEffect (QObject *parent=0)
	Constructs a new QGraphicsOpacityEffect instance. More...

	~QGraphicsOpacityEffect ()
	Destroys the effect. More...

Public Functions inherited from QGraphicsEffect
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. More...

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

bool	isEnabled () const

	QGraphicsEffect (QObject *parent=0)
	Constructs a new QGraphicsEffect instance having the specified parent. More...

QGraphicsEffectSource *	source () const
	Returns a pointer to the source, which provides extra context information that can be useful for the effect. More...

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

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

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

bool	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=0, const QObject receiver=0, const char *member=0)

bool	disconnect (const QObject receiver, const char member=0)

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

void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...

QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...

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

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

template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...

template<typename T >
QList< T >	findChildren (const QString &aName=QString()) 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. More...

template<typename T >
QList< T >	findChildren (const QRegExp &re) const

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. More...

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

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

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

virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...

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

QString	objectName () const

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

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

Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...

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

void	setObjectName (const QString &name)

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

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

void	setUserData (uint id, QObjectUserData *data)

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

int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...

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

QObjectUserData *	userData (uint id) const

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

Protected Functions
void	draw (QPainter *painter)
	Reimplemented Function More...

Protected Functions inherited from QGraphicsEffect
void	drawSource (QPainter *painter)
	Draws the source directly using the given painter. More...

	QGraphicsEffect (QGraphicsEffectPrivate &d, QObject *parent=0)

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

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

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

QPixmap	sourcePixmap (Qt::CoordinateSystem system=Qt::LogicalCoordinates, QPoint *offset=0, PixmapPadMode mode=PadToEffectiveBoundingRect) const
	Returns a pixmap with the source painted into it. More...

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

Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...

virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...

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

virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...

	QObject (QObjectPrivate &dd, QObject *parent=0)

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

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 0. More...

int	senderSignalIndex () const

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

Properties
qreal	opacity
	the opacity of the effect. More...

QBrush	opacityMask
	the opacity mask of the effect. More...

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 Functions inherited from QObject
static bool	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...

static bool	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	Disconnects signal in object sender from method in object receiver. More...

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

static uint	registerUserData ()

static QString	tr (const char sourceText, const char comment=0, int n=-1)

static QString	trUtf8 (const char sourceText, const char comment=0, int n=-1)

Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...

Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject

Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

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

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()

T *	qobject_cast (QObject *object)

	QObjectList

void *	qt_find_obj_child (QObject parent, const char type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QGraphicsOpacityEffect class provides an opacity effect.

Since: 4.6

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 255 of file qgraphicseffect.h.

Constructors and Destructors

◆ QGraphicsOpacityEffect()

QGraphicsOpacityEffect::QGraphicsOpacityEffect ( QObject * parent = 0 )

Constructs a new QGraphicsOpacityEffect instance.

The parent parameter is passed to QGraphicsEffect's constructor.

Definition at line 1175 of file qgraphicseffect.cpp.

     : QGraphicsEffect(*new QGraphicsOpacityEffectPrivate, parent)
 {
 }

◆ ~QGraphicsOpacityEffect()

QGraphicsOpacityEffect::~QGraphicsOpacityEffect ( )

Destroys the effect.

Definition at line 1183 of file qgraphicseffect.cpp.

1184 {

1185 }

Functions

◆ draw()

void QGraphicsOpacityEffect::draw ( QPainter * painter )

protectedvirtual

Reimplemented Function

Implements QGraphicsEffect.

Definition at line 1283 of file qgraphicseffect.cpp.

 {
     Q_D(QGraphicsOpacityEffect);
 
     // Transparent; nothing to draw.
     if (d->isFullyTransparent)
         return;
 
     // Opaque; draw directly without going through a pixmap.
     if (d->isFullyOpaque && !d->hasOpacityMask) {
         drawSource(painter);
         return;
     }
 
     QPoint offset;
     Qt::CoordinateSystem system = sourceIsPixmap() ? Qt::LogicalCoordinates : Qt::DeviceCoordinates;
     QPixmap pixmap = sourcePixmap(system, &offset, QGraphicsEffect::NoPad);
     if (pixmap.isNull())
         return;
 
     painter->save();
     painter->setOpacity(d->opacity);
 
     if (d->hasOpacityMask) {
         QPainter pixmapPainter(&pixmap);
         pixmapPainter.setRenderHints(painter->renderHints());
         pixmapPainter.setCompositionMode(QPainter::CompositionMode_DestinationIn);
         if (system == Qt::DeviceCoordinates) {
             QTransform worldTransform = painter->worldTransform();
             worldTransform *= QTransform::fromTranslate(-offset.x(), -offset.y());
             pixmapPainter.setWorldTransform(worldTransform);
             pixmapPainter.fillRect(sourceBoundingRect(), d->opacityMask);
         } else {
             pixmapPainter.translate(-offset);
             pixmapPainter.fillRect(pixmap.rect(), d->opacityMask);
         }
     }
 
     if (system == Qt::DeviceCoordinates)
         painter->setWorldTransform(QTransform());
 
     painter->drawPixmap(offset, pixmap);
     painter->restore();
 }

◆ opacity()

qreal QGraphicsOpacityEffect::opacity ( ) const

Referenced by setOpacity(), and ~QGraphicsOpacityEffect().

◆ 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().

◆ opacityMask()

QBrush QGraphicsOpacityEffect::opacityMask ( ) const

Referenced by setOpacity().

◆ 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().

◆ setOpacity

void QGraphicsOpacityEffect::setOpacity ( qreal opacity )

slot

Definition at line 1207 of file qgraphicseffect.cpp.

 {
     Q_D(QGraphicsOpacityEffect);
     opacity = qBound(qreal(0.0), opacity, qreal(1.0));
 
     if (qFuzzyCompare(d->opacity, opacity))
         return;
 
     d->opacity = opacity;
     if ((d->isFullyTransparent = qFuzzyIsNull(d->opacity)))
         d->isFullyOpaque = 0;
     else
         d->isFullyOpaque = qFuzzyIsNull(d->opacity - 1);
     update();
     emit opacityChanged(opacity);
 }

◆ setOpacityMask

void QGraphicsOpacityEffect::setOpacityMask ( const QBrush & mask )

slot

Definition at line 1257 of file qgraphicseffect.cpp.

 {
     Q_D(QGraphicsOpacityEffect);
     if (d->opacityMask == mask)
         return;
 
     d->opacityMask = mask;
     d->hasOpacityMask = (mask.style() != Qt::NoBrush);
     update();
 
     emit opacityMaskChanged(mask);
 }

Properties

◆ opacity

qreal QGraphicsOpacityEffect::opacity

private

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 258 of file qgraphicseffect.h.

◆ opacityMask

QBrush QGraphicsOpacityEffect::opacityMask

private

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 259 of file qgraphicseffect.h.

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

/src/gui/effects/qgraphicseffect.h
/src/gui/effects/qgraphicseffect.cpp

Public Slots

Signals

Public Functions

Protected Functions

Properties

Additional Inherited Members

Detailed Description

Constructors and Destructors

◆ QGraphicsOpacityEffect()

◆ ~QGraphicsOpacityEffect()

Functions

◆ draw()

◆ opacity()

◆ opacityChanged

◆ opacityMask()

◆ opacityMaskChanged

◆ setOpacity

◆ setOpacityMask

Properties

◆ opacity

◆ opacityMask