The QQmlProperty class abstracts accessing properties on objects created from QML. More...

#include <qqmlproperty.h>

Collaboration diagram for QQmlProperty:

Public Types
enum	PropertyTypeCategory { InvalidCategory , List , Object , Normal }
	This enum specifies a category of QML property. More...
enum	Type { Invalid , Property , SignalProperty }
	This enum specifies a type of QML property. More...

Public Member Functions
	QQmlProperty ()
	Create an invalid QQmlProperty.
	~QQmlProperty ()
	QQmlProperty (QObject *)
	Creates a QQmlProperty for the default property of obj.
	QQmlProperty (QObject , QQmlContext )
	Creates a QQmlProperty for the default property of obj using the \l{QQmlContext} {context} ctxt.
	QQmlProperty (QObject , QQmlEngine )
	Creates a QQmlProperty for the default property of obj using the environment for instantiating QML components that is provided by engine.
	QQmlProperty (QObject *, const QString &)
	Creates a QQmlProperty for the property name of obj.
	QQmlProperty (QObject , const QString &, QQmlContext )
	Creates a QQmlProperty for the property name of obj using the \l{QQmlContext} {context} ctxt.
	QQmlProperty (QObject , const QString &, QQmlEngine )
	Creates a QQmlProperty for the property name of obj using the environment for instantiating QML components that is provided by engine.
	QQmlProperty (const QQmlProperty &)
	Create a copy of other.
QQmlProperty &	operator= (const QQmlProperty &)
	Assign other to this QQmlProperty.
	QQmlProperty (QQmlProperty &&other) noexcept
void	swap (QQmlProperty &other) noexcept
bool	operator== (const QQmlProperty &) const
	Returns true if other and this QQmlProperty represent the same property.
Type	type () const
	Returns the type of the property.
bool	isValid () const
	Returns true if the QQmlProperty refers to a valid property, otherwise false.
bool	isProperty () const
	Returns true if this QQmlProperty represents a regular Qt property.
bool	isSignalProperty () const
	Returns true if this QQmlProperty represents a QML signal property.
int	propertyType () const
	Returns the metatype id of the property, or QMetaType::UnknownType if the property has no metatype.
QMetaType	propertyMetaType () const
	Returns the metatype of the property.
PropertyTypeCategory	propertyTypeCategory () const
	Returns the property category.
const char *	propertyTypeName () const
	Returns the type name of the property, or 0 if the property has no type name.
QString	name () const
	Return the name of this QML property.
QVariant	read () const
	Returns the property value.
bool	write (const QVariant &) const
	Sets the property value to value.
bool	reset () const
	Resets the property and returns true if the property is resettable.
bool	hasNotifySignal () const
	Returns true if the property has a change notifier signal, otherwise false.
bool	needsNotifySignal () const
	Returns true if the property needs a change notifier signal for bindings to remain upto date, false otherwise.
bool	connectNotifySignal (QObject dest, const char slot) const
	Connects the property's change notifier signal to the specified slot of the dest object and returns true.
bool	connectNotifySignal (QObject *dest, int method) const
	Connects the property's change notifier signal to the specified method of the dest object and returns true.
bool	isWritable () const
	Returns true if the property is writable, otherwise false.
bool	isBindable () const
bool	isDesignable () const
	Returns true if the property is designable, otherwise false.
bool	isResettable () const
	Returns true if the property is resettable, otherwise false.
QObject *	object () const
	Returns the QQmlProperty's QObject.
int	index () const
	Return the Qt metaobject index of the property.
QMetaProperty	property () const
	Returns the \l{QMetaProperty} {Qt property} associated with this QML property.
QMetaMethod	method () const
	Return the QMetaMethod for this property if it is a SignalProperty, otherwise returns an invalid QMetaMethod.

Static Public Member Functions
static QVariant	read (const QObject *, const QString &)
	Return the name property value of object.
static QVariant	read (const QObject , const QString &, QQmlContext )
	Return the name property value of object using the \l{QQmlContext} {context} ctxt.
static QVariant	read (const QObject , const QString &, QQmlEngine )
	Return the name property value of object using the environment for instantiating QML components that is provided by engine.
static bool	write (QObject *, const QString &, const QVariant &)
	Writes value to the name property of object.
static bool	write (QObject , const QString &, const QVariant &, QQmlContext )
	Writes value to the name property of object using the \l{QQmlContext} {context} ctxt.
static bool	write (QObject , const QString &, const QVariant &, QQmlEngine )
	Writes value to the name property of object using the environment for instantiating QML components that is provided by engine.

Properties
QML_ANONYMOUSQObject *	object
	the QObject represented by the QML property.
QString	name
	the name of the QML property.

Friends
class	QQmlPropertyPrivate

Detailed Description

The QQmlProperty class abstracts accessing properties on objects created from QML.

Since: 5.0 \inmodule QtQml

As QML uses Qt's meta-type system all of the existing QMetaObject classes can be used to introspect and interact with objects created by QML. However, some of the new features provided by QML - such as type safety and attached properties - are most easily used through the QQmlProperty class that simplifies some of their natural complexity.

Unlike QMetaProperty which represents a property on a class type, QQmlProperty encapsulates a property on a specific object instance. To read a property's value, programmers create a QQmlProperty instance and call the read() method. Likewise to write a property value the write() method is used.

For example, for the following QML code:

\qml MyItem.qml import QtQuick 2.0

Text { text: "A bit of text" } \endqml

The \l Text object's properties could be accessed using QQmlProperty, like this:

#include <QQmlProperty>
#include <QGraphicsObject>
 
...
 
QQuickView view(QUrl::fromLocalFile("MyItem.qml"));
QQmlProperty property(view.rootObject(), "font.pixelSize");
qWarning() << "Current pixel size:" << property.read().toInt();
property.write(24);
qWarning() << "Pixel size should now be 24:" << property.read().toInt();

Definition at line 22 of file qqmlproperty.h.

Member Enumeration Documentation

◆ PropertyTypeCategory

enum QQmlProperty::PropertyTypeCategory

This enum specifies a category of QML property.

\value InvalidCategory The property is invalid, or is a signal property. \value List The property is a QQmlListProperty list property \value Object The property is a QObject derived type pointer \value Normal The property is a normal value property.

Enumerator
InvalidCategory
List
Object
Normal

Definition at line 30 of file qqmlproperty.h.

◆ Type

enum QQmlProperty::Type

This enum specifies a type of QML property.

\value Invalid The property is invalid. \value Property The property is a regular Qt property. \value SignalProperty The property is a signal property.

Enumerator
Invalid
Property
SignalProperty

Definition at line 37 of file qqmlproperty.h.

Constructor & Destructor Documentation

◆ QQmlProperty() [1/9]

QQmlProperty::QQmlProperty ( )

default

Create an invalid QQmlProperty.

◆ ~QQmlProperty()

QQmlProperty::~QQmlProperty ( )

Definition at line 94 of file qqmlproperty.cpp.

◆ QQmlProperty() [2/9]

QQmlProperty::QQmlProperty ( QObject * obj )

Creates a QQmlProperty for the default property of obj.

If there is no default property, an invalid QQmlProperty will be created.

Definition at line 105 of file qqmlproperty.cpp.

◆ QQmlProperty() [3/9]

QQmlProperty::QQmlProperty	(	QObject *	obj,
		QQmlContext *	ctxt )

Creates a QQmlProperty for the default property of obj using the \l{QQmlContext} {context} ctxt.

If there is no default property, an invalid QQmlProperty will be created.

Definition at line 117 of file qqmlproperty.cpp.

◆ QQmlProperty() [4/9]

QQmlProperty::QQmlProperty	(	QObject *	obj,
		QQmlEngine *	engine )

Creates a QQmlProperty for the default property of obj using the environment for instantiating QML components that is provided by engine.

If there is no default property, an invalid QQmlProperty will be created.

Definition at line 133 of file qqmlproperty.cpp.

◆ QQmlProperty() [5/9]

QQmlProperty::QQmlProperty	(	QObject *	obj,
		const QString &	name )

Creates a QQmlProperty for the property name of obj.

Definition at line 157 of file qqmlproperty.cpp.

◆ QQmlProperty() [6/9]

QQmlProperty::QQmlProperty	(	QObject *	obj,
		const QString &	name,
		QQmlContext *	ctxt )

Creates a QQmlProperty for the property name of obj using the \l{QQmlContext} {context} ctxt.

Creating a QQmlProperty without a context will render some properties - like attached properties - inaccessible.

Definition at line 171 of file qqmlproperty.cpp.

◆ QQmlProperty() [7/9]

QQmlProperty::QQmlProperty	(	QObject *	obj,
		const QString &	name,
		QQmlEngine *	engine )

Creates a QQmlProperty for the property name of obj using the environment for instantiating QML components that is provided by engine.

Definition at line 192 of file qqmlproperty.cpp.

◆ QQmlProperty() [8/9]

QQmlProperty::QQmlProperty ( const QQmlProperty & other )

Create a copy of other.

Definition at line 490 of file qqmlproperty.cpp.

◆ QQmlProperty() [9/9]

QQmlProperty::QQmlProperty ( QQmlProperty && other )

inlinenoexcept

Definition at line 57 of file qqmlproperty.h.

Member Function Documentation

◆ connectNotifySignal() [1/2]

bool QQmlProperty::connectNotifySignal	(	QObject *	dest,
		const char *	slot ) const

Connects the property's change notifier signal to the specified slot of the dest object and returns true.

Returns false if this metaproperty does not represent a regular Qt property or if it has no change notifier signal, or if the dest object does not have the specified slot.

Note: slot should be passed using the SLOT() macro so it is correctly identified.

Definition at line 2188 of file qqmlproperty.cpp.

◆ connectNotifySignal() [2/2]

bool QQmlProperty::connectNotifySignal	(	QObject *	dest,
		int	method ) const

Connects the property's change notifier signal to the specified method of the dest object and returns true.

Returns false if this metaproperty does not represent a regular Qt property or if it has no change notifier signal, or if the dest object does not have the specified method.

Definition at line 2164 of file qqmlproperty.cpp.

◆ hasNotifySignal()

bool QQmlProperty::hasNotifySignal ( ) const

Returns true if the property has a change notifier signal, otherwise false.

Definition at line 2136 of file qqmlproperty.cpp.

◆ index()

int QQmlProperty::index ( ) const

Return the Qt metaobject index of the property.

Definition at line 2205 of file qqmlproperty.cpp.

◆ isBindable()

bool QQmlProperty::isBindable ( ) const

Returns true if the property is bindable, otherwise false.

Definition at line 703 of file qqmlproperty.cpp.

◆ isDesignable()

bool QQmlProperty::isDesignable ( ) const

Returns true if the property is designable, otherwise false.

Definition at line 717 of file qqmlproperty.cpp.

◆ isProperty()

bool QQmlProperty::isProperty ( ) const

Returns true if this QQmlProperty represents a regular Qt property.

Definition at line 643 of file qqmlproperty.cpp.

◆ isResettable()

bool QQmlProperty::isResettable ( ) const

Returns true if the property is resettable, otherwise false.

Definition at line 730 of file qqmlproperty.cpp.

◆ isSignalProperty()

bool QQmlProperty::isSignalProperty ( ) const

Returns true if this QQmlProperty represents a QML signal property.

Definition at line 651 of file qqmlproperty.cpp.

◆ isValid()

bool QQmlProperty::isValid ( ) const

Returns true if the QQmlProperty refers to a valid property, otherwise false.

Definition at line 744 of file qqmlproperty.cpp.

◆ isWritable()

bool QQmlProperty::isWritable ( ) const

Returns true if the property is writable, otherwise false.

Definition at line 683 of file qqmlproperty.cpp.

◆ method()

QMetaMethod QQmlProperty::method ( ) const

Return the QMetaMethod for this property if it is a SignalProperty, otherwise returns an invalid QMetaMethod.

Definition at line 801 of file qqmlproperty.cpp.

◆ name()

QString QQmlProperty::name ( ) const

Return the name of this QML property.

Definition at line 760 of file qqmlproperty.cpp.

◆ needsNotifySignal()

bool QQmlProperty::needsNotifySignal ( ) const

Returns true if the property needs a change notifier signal for bindings to remain upto date, false otherwise.

Some properties, such as attached properties or those whose value never changes, do not require a change notifier.

Definition at line 2151 of file qqmlproperty.cpp.

◆ object()

QObject * QQmlProperty::object ( ) const

Returns the QQmlProperty's QObject.

Definition at line 665 of file qqmlproperty.cpp.

◆ operator=()

QQmlProperty & QQmlProperty::operator= ( const QQmlProperty & other )

Assign other to this QQmlProperty.

Definition at line 673 of file qqmlproperty.cpp.

◆ operator==()

bool QQmlProperty::operator== ( const QQmlProperty & other ) const

Returns true if other and this QQmlProperty represent the same property.

Definition at line 573 of file qqmlproperty.cpp.

◆ property()

QMetaProperty QQmlProperty::property ( ) const

Returns the \l{QMetaProperty} {Qt property} associated with this QML property.

Definition at line 787 of file qqmlproperty.cpp.

◆ propertyMetaType()

QMetaType QQmlProperty::propertyMetaType ( ) const

Returns the metatype of the property.

See also: propertyType

Definition at line 600 of file qqmlproperty.cpp.

◆ propertyType()

int QQmlProperty::propertyType ( ) const

Returns the metatype id of the property, or QMetaType::UnknownType if the property has no metatype.

See also: propertyMetaType

Definition at line 590 of file qqmlproperty.cpp.

◆ propertyTypeCategory()

QQmlProperty::PropertyTypeCategory QQmlProperty::propertyTypeCategory ( ) const

Returns the property category.

Definition at line 521 of file qqmlproperty.cpp.

◆ propertyTypeName()

const char * QQmlProperty::propertyTypeName ( ) const

Returns the type name of the property, or 0 if the property has no type name.

Definition at line 554 of file qqmlproperty.cpp.

◆ read() [1/4]

QVariant QQmlProperty::read ( ) const

Returns the property value.

Definition at line 1093 of file qqmlproperty.cpp.

◆ read() [2/4]

QVariant QQmlProperty::read	(	const QObject *	object,
		const QString &	name )

static

Return the name property value of object.

This method is equivalent to:

QQmlProperty p(object, name);

p.read();

QQmlProperty::name

QString name

the name of the QML property.

Definition qqmlproperty.h:28

p

GLfloat GLfloat p

Definition qopenglext.h:12698

Definition at line 1119 of file qqmlproperty.cpp.

◆ read() [3/4]

QVariant QQmlProperty::read	(	const QObject *	object,
		const QString &	name,
		QQmlContext *	ctxt )

static

Return the name property value of object using the \l{QQmlContext} {context} ctxt.

This method is equivalent to:

QQmlProperty p(object, name, context);

p.read();

context

static const QString context()

Definition java.cpp:398

Definition at line 1135 of file qqmlproperty.cpp.

◆ read() [4/4]

QVariant QQmlProperty::read	(	const QObject *	object,
		const QString &	name,
		QQmlEngine *	engine )

static

Return the name property value of object using the environment for instantiating QML components that is provided by engine.

This method is equivalent to:

QQmlProperty p(object, name, engine);

p.read();

engine

QJSEngine engine

[0]

Definition src_script_qjsvalue.cpp:14

Definition at line 1152 of file qqmlproperty.cpp.

◆ reset()

bool QQmlProperty::reset ( ) const

Resets the property and returns true if the property is resettable.

If the property is not resettable, nothing happens and false is returned.

Definition at line 2110 of file qqmlproperty.cpp.

◆ swap()

void QQmlProperty::swap ( QQmlProperty & other )

inlinenoexcept

Definition at line 60 of file qqmlproperty.h.

◆ type()

QQmlProperty::Type QQmlProperty::type ( ) const

Returns the type of the property.

Definition at line 635 of file qqmlproperty.cpp.

◆ write() [1/4]

bool QQmlProperty::write ( const QVariant & value ) const

Sets the property value to value.

Returns true on success, or false if the property can't be set because the value is the wrong type, for example.

Definition at line 2042 of file qqmlproperty.cpp.

◆ write() [2/4]

bool QQmlProperty::write	(	QObject *	object,
		const QString &	name,
		const QVariant &	value )

static

Writes value to the name property of object.

This method is equivalent to:

QQmlProperty p(object, name);

p.write(value);

value

EGLOutputLayerEXT EGLint EGLAttrib value

[3]

Definition qeglstreamconvenience_p.h:46

Returns true on success, false otherwise.

Definition at line 2058 of file qqmlproperty.cpp.

◆ write() [3/4]

bool QQmlProperty::write	(	QObject *	object,
		const QString &	name,
		const QVariant &	value,
		QQmlContext *	ctxt )

static

Writes value to the name property of object using the \l{QQmlContext} {context} ctxt.

This method is equivalent to:

QQmlProperty p(object, name, ctxt);

p.write(value);

Returns true on success, false otherwise.

Definition at line 2076 of file qqmlproperty.cpp.

◆ write() [4/4]

bool QQmlProperty::write	(	QObject *	object,
		const QString &	name,
		const QVariant &	value,
		QQmlEngine *	engine )

static

Writes value to the name property of object using the environment for instantiating QML components that is provided by engine.

This method is equivalent to:

QQmlProperty p(object, name, engine);

p.write(value);

Returns true on success, false otherwise.

Definition at line 2098 of file qqmlproperty.cpp.

◆ QQmlPropertyPrivate

friend class QQmlPropertyPrivate

friend

Definition at line 103 of file qqmlproperty.h.

Property Documentation

◆ name

QString QQmlProperty::name

read

the name of the QML property.

See also: QQmlProperty::object

Definition at line 28 of file qqmlproperty.h.

Referenced by testing.tools.encode_pdf_filter._PdfStream::RegisterByName().

◆ object

QML_ANONYMOUSQObject * QQmlProperty::object

read

the QObject represented by the QML property.

See also: QQmlProperty::name

Definition at line 27 of file qqmlproperty.h.

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

qtdeclarative/src/qml/qml/qqmlproperty.h (4d5a8b8750916ffdce8ccee8db9747ff09a90ccf)
qtdeclarative/src/qml/qml/qqmlproperty.cpp (738e7b06b5282c3fd615acdfdc456dfc1a05c5ef)

Public Types

Public Member Functions

Static Public Member Functions

Properties

Friends

Detailed Description

Member Enumeration Documentation

◆ PropertyTypeCategory

◆ Type

Constructor & Destructor Documentation

◆ QQmlProperty() [1/9]

◆ ~QQmlProperty()

◆ QQmlProperty() [2/9]

◆ QQmlProperty() [3/9]

◆ QQmlProperty() [4/9]

◆ QQmlProperty() [5/9]

◆ QQmlProperty() [6/9]

◆ QQmlProperty() [7/9]

◆ QQmlProperty() [8/9]

◆ QQmlProperty() [9/9]

Member Function Documentation

◆ connectNotifySignal() [1/2]

◆ connectNotifySignal() [2/2]

◆ hasNotifySignal()

◆ index()

◆ isBindable()

◆ isDesignable()

◆ isProperty()

◆ isResettable()

◆ isSignalProperty()

◆ isValid()

◆ isWritable()

◆ method()

◆ name()

◆ needsNotifySignal()

◆ object()

◆ operator=()

◆ operator==()

◆ property()

◆ propertyMetaType()

◆ propertyType()

◆ propertyTypeCategory()

◆ propertyTypeName()

◆ read() [1/4]

◆ read() [2/4]

◆ read() [3/4]

◆ read() [4/4]

◆ reset()

◆ swap()

◆ type()

◆ write() [1/4]

◆ write() [2/4]

◆ write() [3/4]

◆ write() [4/4]

Friends And Related Symbol Documentation

◆ QQmlPropertyPrivate

Property Documentation

◆ name

◆ object