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Internal/Contributor docs for the Qt SDK. <b>Note:</b> These are NOT official API docs; those are found <a href='https://doc.qt.io/'>here</a>.
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QPixmapConvolutionFilter Class Reference

The QPixmapConvolutionFilter class provides convolution filtering for pixmaps. More...

#include <qpixmapfilter_p.h>

+ Inheritance diagram for QPixmapConvolutionFilter:
+ Collaboration diagram for QPixmapConvolutionFilter:

Public Member Functions

 QPixmapConvolutionFilter (QObject *parent=nullptr)
 Constructs a pixmap convolution filter.
 
 ~QPixmapConvolutionFilter ()
 Destructor of pixmap convolution filter.
 
void setConvolutionKernel (const qreal *matrix, int rows, int columns)
 Sets convolution kernel with the given number of rows and columns.
 
QRectF boundingRectFor (const QRectF &rect) const override
 
void draw (QPainter *painter, const QPointF &dest, const QPixmap &src, const QRectF &srcRect=QRectF()) const override
 
- Public Member Functions inherited from QPixmapFilter
virtual ~QPixmapFilter ()=0
 Destroys the pixmap filter.
 
FilterType type () const
 Returns the type of the filter.
 
- 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.
 

Friends

class QVGPixmapConvolutionFilter
 

Additional Inherited Members

- Public Types inherited from QPixmapFilter
enum  FilterType {
  ConvolutionFilter , ColorizeFilter , DropShadowFilter , BlurFilter ,
  UserFilter = 1024
}
 
- Public Slots inherited from QObject
void deleteLater ()
 \threadsafe
 
- 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.
 
- 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 Member Functions inherited from QPixmapFilter
 QPixmapFilter (QPixmapFilterPrivate &d, FilterType type, QObject *parent)
 
 QPixmapFilter (FilterType type, QObject *parent)
 Constructs a default QPixmapFilter with the given type.
 
- 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 Attributes inherited from QObject
QScopedPointer< QObjectData > d_ptr
 
- Properties inherited from QObject
QString objectName
 the name of this object
 
- Related Symbols inherited from QObject
 Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
 
 
 
 \macro Q_CLASSINFO(Name, Value)
 

Detailed Description

The QPixmapConvolutionFilter class provides convolution filtering for pixmaps.

Since
4.5

QPixmapConvolutionFilter implements a convolution pixmap filter, which is applied when \l{QPixmapFilter::}{draw()} is called. A convolution filter lets you distort an image by setting the values of a matrix of qreal values called its \l{setConvolutionKernel()}{kernel}. The matrix's values are usually between -1.0 and 1.0.

\omit In convolution filtering, the pixel value is calculated from the neighboring pixels based on the weighting convolution kernel. This needs explaining to be useful. \endomit

Example:

QPixmapConvolutionFilter *myFilter = new QPixmapConvolutionFilter;
qreal kernel[] = {
0.0,-1.0, 0.0,
-1.0, 5.0,-1.0,
0.0,-1.0, 0.0
};
myFilter->setConvolutionKernel(kernel, 3, 3);
myFilter->draw(painter, QPoint(0, 0), originalPixmap);
See also
{Pixmap Filters Example}, QPixmapColorizeFilter, QPixmapDropShadowFilter

Definition at line 61 of file qpixmapfilter_p.h.

Constructor & Destructor Documentation

◆ QPixmapConvolutionFilter()

QPixmapConvolutionFilter::QPixmapConvolutionFilter ( QObject * parent = nullptr)

Constructs a pixmap convolution filter.

By default there is no convolution kernel.

Definition at line 193 of file qpixmapfilter.cpp.

References d.

◆ ~QPixmapConvolutionFilter()

QPixmapConvolutionFilter::~QPixmapConvolutionFilter ( )

Destructor of pixmap convolution filter.

Definition at line 205 of file qpixmapfilter.cpp.

Member Function Documentation

◆ boundingRectFor()

QRectF QPixmapConvolutionFilter::boundingRectFor ( const QRectF & rect) const
overridevirtual

Reimplemented from QPixmapFilter.

Definition at line 267 of file qpixmapfilter.cpp.

References d, and rect.

Referenced by draw().

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◆ draw()

void QPixmapConvolutionFilter::draw ( QPainter * painter,
const QPointF & p,
const QPixmap & src,
const QRectF & srcRect = QRectF() ) const
overridevirtual

Implements QPixmapFilter.

Definition at line 376 of file qpixmapfilter.cpp.

References boundingRectFor(), QPainter::combinedTransform(), QRasterPaintEngine::ComplexClip, QPainter::CompositionMode_Source, QPainter::CompositionMode_SourceOver, QRectF::contains(), convolute(), d, QPainter::deviceTransform(), QPaintDevice::devType(), QPainter::drawImage(), QImage::Format_ARGB32_Premultiplied, QInternal::Image, QPainter::isActive(), QRect::isNull(), QPaintEngine::paintDevice(), QPainter::paintEngine(), painter, rect, QRectF::toRect(), and QTransform::TxTranslate.

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◆ setConvolutionKernel()

void QPixmapConvolutionFilter::setConvolutionKernel ( const qreal * kernel,
int rows,
int columns )

Sets convolution kernel with the given number of rows and columns.

Values from kernel are copied to internal data structure.

To preserve the intensity of the pixmap, the sum of all the values in the convolution kernel should add up to 1.0. A sum greater than 1.0 produces a lighter result and a sum less than 1.0 produces a darker and transparent result.

Definition at line 220 of file qpixmapfilter.cpp.

References d, and kernel.

Friends And Related Symbol Documentation

◆ QVGPixmapConvolutionFilter

friend class QVGPixmapConvolutionFilter
friend

Definition at line 76 of file qpixmapfilter_p.h.

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