The QQmlContext class defines a context within a QML engine. More...

#include <qqmlcontext.h>

Inheritance diagram for QQmlContext:

Collaboration diagram for QQmlContext:

Classes
class	PropertyPair

Public Member Functions
	QQmlContext (QQmlEngine parent, QObject objParent=nullptr)
	Create a new QQmlContext as a child of engine's root context, and the QObject parent.

	QQmlContext (QQmlContext parent, QObject objParent=nullptr)
	Create a new QQmlContext with the given parentContext, and the QObject parent.

	~QQmlContext () override
	Destroys the QQmlContext.

bool	isValid () const
	Returns whether the context is valid.

QQmlEngine *	engine () const
	Return the context's QQmlEngine, or \nullptr if the context has no QQmlEngine or the QQmlEngine was destroyed.

QQmlContext *	parentContext () const
	Return the context's parent QQmlContext, or \nullptr if this context has no parent or if the parent has been destroyed.

QObject *	contextObject () const
	Return the context object, or \nullptr if there is no context object.

void	setContextObject (QObject *)
	Set the context object.

QVariant	contextProperty (const QString &) const
	Returns the value of the name property for this context as a QVariant.

void	setContextProperty (const QString &, QObject *)
	Set the value of the name property on this context.

void	setContextProperty (const QString &, const QVariant &)
	Set a the value of the name property on this context.

void	setContextProperties (const QList< PropertyPair > &properties)

QString	nameForObject (const QObject *) const
	Returns the name of object in this context, or an empty string if object is not named in the context.

QObject *	objectForName (const QString &) const

QUrl	resolvedUrl (const QUrl &) const
	Resolves the URL src relative to the URL of the containing component.

void	setBaseUrl (const QUrl &)
	Explicitly sets the url resolvedUrl() will use for relative references to baseUrl.

QUrl	baseUrl () const
	Returns the base url of the component, or the containing component if none is set.

QJSValue	importedScript (const QString &name) 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.

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

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

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

template<typename T >
T	findChild (const QString &aName=QString(), 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 (const QString &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 >
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	QQmlEngine

class	QQmlEnginePrivate

class	QQmlExpression

class	QQmlExpressionPrivate

class	QQmlComponent

class	QQmlComponentPrivate

class	QQmlScriptPrivate

class	QQmlContextData

Additional Inherited Members
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 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
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 QQmlContext class defines a context within a QML engine.

\inmodule QtQml

Contexts hold the objects identified by id in a QML document. You can use \l{nameForObject()} and \l{objectForName()} to retrieve them.

Note: It is the responsibility of the creator to delete any QQmlContext it constructs. If a QQmlContext is no longer needed, it must be destroyed explicitly. The simplest way to ensure this is to give the QQmlContext a \l{QObject::setParent()}{parent}.

Definition at line 24 of file qqmlcontext.h.

Constructor & Destructor Documentation

◆ QQmlContext() [1/2]

QQmlContext::QQmlContext	(	QQmlEngine *	parent,
		QObject *	objParent = `nullptr`
	)

Create a new QQmlContext as a child of engine's root context, and the QObject parent.

Definition at line 98 of file qqmlcontext.cpp.

◆ QQmlContext() [2/2]

QQmlContext::QQmlContext	(	QQmlContext *	parent,
		QObject *	objParent = `nullptr`
	)

Create a new QQmlContext with the given parentContext, and the QObject parent.

Definition at line 109 of file qqmlcontext.cpp.

◆ ~QQmlContext()

QQmlContext::~QQmlContext ( )

override

Destroys the QQmlContext.

Any expressions, or sub-contexts dependent on this context will be invalidated, but not destroyed (unless they are parented to the QQmlContext object).

Definition at line 131 of file qqmlcontext.cpp.

References d.

Member Function Documentation

◆ baseUrl()

QUrl QQmlContext::baseUrl ( ) const

Returns the base url of the component, or the containing component if none is set.

Definition at line 438 of file qqmlcontext.cpp.

References d.

Referenced by QQuickCanvasItem::componentComplete(), and setBaseUrl().

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◆ contextObject()

QObject * QQmlContext::contextObject ( ) const

Return the context object, or \nullptr if there is no context object.

Definition at line 175 of file qqmlcontext.cpp.

References d.

◆ contextProperty()

QVariant QQmlContext::contextProperty ( const QString & name ) const

Returns the value of the name property for this context as a QVariant.

If you know that the property you're looking for is a QObject assigned using a QML id in the current context, \l objectForName() is more convenient and faster. In contrast to \l objectForName() and \l nameForObject(), this method does traverse the context hierarchy and searches in parent contexts if the name is not found in the current one. It also considers any \l contextObject() you may have set.

See also: objectForName(), nameForObject(), contextObject()

Definition at line 326 of file qqmlcontext.cpp.

References contextProperty(), d, QVariant::fromValue(), parentContext(), and readObjectProperty().

Referenced by contextProperty(), QQuickTumblerAttachedPrivate::init(), and QQuickTreeViewDelegatePrivate::toggleExpanded().

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◆ engine()

QQmlEngine * QQmlContext::engine ( ) const

Return the context's QQmlEngine, or \nullptr if the context has no QQmlEngine or the QQmlEngine was destroyed.

Definition at line 153 of file qqmlcontext.cpp.

References d.

Referenced by QQmlExpression::QQmlExpression(), QQmlProperty::QQmlProperty(), QQmlProperty::QQmlProperty(), QQuickPlatformColorDialog::QQuickPlatformColorDialog(), QQuickPlatformFileDialog::QQuickPlatformFileDialog(), QQuickPlatformFolderDialog::QQuickPlatformFolderDialog(), QQuickPlatformFontDialog::QQuickPlatformFontDialog(), QQuickPlatformMessageDialog::QQuickPlatformMessageDialog(), QQmlBinding::create(), QQmlPropertyBinding::createFromScriptString(), QQmlDelegateModelPrivate::emitChanges(), importedScript(), QQmlDelegateModelPrivate::object(), QQuickStyledTextPrivate::parseImageAttributes(), QQmlPrivate::propertyCapture(), QQmlXmlListModel::reload(), QuickTestImageObject::save(), and QQmlJavaScriptExpression::setupFunction().

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◆ importedScript()

QJSValue QQmlContext::importedScript ( const QString & name ) const

Definition at line 447 of file qqmlcontext.cpp.

References d, engine(), QJSValuePrivate::fromReturnedValue(), and QJSValue::UndefinedValue.

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◆ isValid()

bool QQmlContext::isValid ( ) const

Returns whether the context is valid.

To be valid, a context must have a engine, and it's contextObject(), if any, must not have been deleted.

Definition at line 143 of file qqmlcontext.cpp.

References d.

Referenced by QQmlExpression::QQmlExpression(), QQmlBinding::create(), QQmlPropertyBinding::createFromScriptString(), QtObject::createQmlObject(), QQmlDelegateModelPrivate::emitChanges(), QQmlDelegateModelPrivate::insert(), QQmlDelegateModelPrivate::object(), and QQmlTableInstanceModel::object().

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◆ nameForObject()

QString QQmlContext::nameForObject ( const QObject * object ) const

Returns the name of object in this context, or an empty string if object is not named in the context.

Objects are named by \l setContextProperty(), or as properties of a context object, or by ids in the case of QML created contexts.

If the object has multiple names, the first is returned.

In contrast to \l contextProperty(), this method does not traverse the context hierarchy. If the name is not found in the current context, an empty String is returned.

See also: contextProperty(), objectForName()

Definition at line 366 of file qqmlcontext.cpp.

References d.

Referenced by QQmlDebugTranslationServicePrivate::sendTranslatableTextOccurrences().

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◆ objectForName()

QObject * QQmlContext::objectForName ( const QString & name ) const

Since: 6.2

Returns the object for a given name in this context. Returns nullptr if name is not available in the context or if the value associated with name is not a QObject. Objects are named by \l setContextProperty(), or as properties of a context object, or by ids in the case of QML created contexts. In contrast to \l contextProperty(), this method does not traverse the context hierarchy. If the name is not found in the current context, nullptr is returned.

See also: contextProperty(), nameForObject()

Definition at line 386 of file qqmlcontext.cpp.

References d, and readObjectProperty().

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◆ parentContext()

QQmlContext * QQmlContext::parentContext ( ) const

Return the context's parent QQmlContext, or \nullptr if this context has no parent or if the parent has been destroyed.

Definition at line 163 of file qqmlcontext.cpp.

References d, and QObject::parent().

Referenced by contextProperty(), QQuickListViewPrivate::getSectionItem(), QQuickListViewPrivate::updateInlineSection(), and QQuickListViewPrivate::updateStickySections().

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◆ resolvedUrl()

QUrl QQmlContext::resolvedUrl ( const QUrl & src ) const

Resolves the URL src relative to the URL of the containing component.

See also: QQmlEngine::baseUrl(), setBaseUrl()

Definition at line 413 of file qqmlcontext.cpp.

References d.

Referenced by QQuickStackElement::fromString().

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◆ setBaseUrl()

void QQmlContext::setBaseUrl ( const QUrl & baseUrl )

Explicitly sets the url resolvedUrl() will use for relative references to baseUrl.

Calling this function will override the url of the containing component used by default.

See also: resolvedUrl()

Definition at line 427 of file qqmlcontext.cpp.

References baseUrl(), d, and QUrl::toString().

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◆ setContextObject()

void QQmlContext::setContextObject ( QObject * object )

Set the context object.

Note: You should not use context objects to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 187 of file qqmlcontext.cpp.

References d, and qWarning.

Referenced by QQuickLoaderPrivate::_q_sourceLoaded().

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◆ setContextProperties()

void QQmlContext::setContextProperties ( const QList< PropertyPair > & properties )

Since: 5.11

Set a batch of properties on this context.

Setting all properties in one batch avoids unnecessary refreshing expressions, and is therefore recommended instead of calling \l setContextProperty() for each individual property.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

See also: QQmlContext::setContextProperty()

Definition at line 275 of file qqmlcontext.cpp.

References d, properties, property, and setContextProperty().

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◆ setContextProperty() [1/2]

void QQmlContext::setContextProperty	(	const QString &	name,
		const QVariant &	value
	)

Set a the value of the name property on this context.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 213 of file qqmlcontext.cpp.

References QMetaObjectPrivate::absoluteSignalCount(), QMetaObject::activate(), QObject::connect(), d, QObject::destroyed(), and qWarning.

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◆ setContextProperty() [2/2]

void QQmlContext::setContextProperty	(	const QString &	name,
		QObject *	value
	)

Set the value of the name property on this context.

QQmlContext does not take ownership of value.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 256 of file qqmlcontext.cpp.

References QVariant::fromValue(), and setContextProperty().

Referenced by main(), main(), quick_test_main_with_setup(), setContextProperties(), and setContextProperty().

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Friends And Related Symbol Documentation

◆ QQmlComponent

friend class QQmlComponent

friend

Definition at line 64 of file qqmlcontext.h.

◆ QQmlComponentPrivate

friend class QQmlComponentPrivate

friend

Definition at line 65 of file qqmlcontext.h.

◆ QQmlContextData

friend class QQmlContextData

friend

Definition at line 67 of file qqmlcontext.h.

◆ QQmlEngine

friend class QQmlEngine

friend

Definition at line 60 of file qqmlcontext.h.

◆ QQmlEnginePrivate

friend class QQmlEnginePrivate

friend

Definition at line 61 of file qqmlcontext.h.

◆ QQmlExpression

friend class QQmlExpression

friend

Definition at line 62 of file qqmlcontext.h.

◆ QQmlExpressionPrivate

friend class QQmlExpressionPrivate

friend

Definition at line 63 of file qqmlcontext.h.

◆ QQmlScriptPrivate

friend class QQmlScriptPrivate

friend

Definition at line 66 of file qqmlcontext.h.

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

qtdeclarative/src/qml/qml/qqmlcontext.h
qtdeclarative/src/qml/qml/qqmlcontext.cpp

Classes

Public Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QQmlContext() [1/2]

◆ QQmlContext() [2/2]

◆ ~QQmlContext()

Member Function Documentation

◆ baseUrl()

◆ contextObject()

◆ contextProperty()

◆ engine()

◆ importedScript()

◆ isValid()

◆ nameForObject()

◆ objectForName()

◆ parentContext()

◆ resolvedUrl()

◆ setBaseUrl()

◆ setContextObject()

◆ setContextProperties()

◆ setContextProperty() [1/2]

◆ setContextProperty() [2/2]

Friends And Related Symbol Documentation

◆ QQmlComponent

◆ QQmlComponentPrivate

◆ QQmlContextData

◆ QQmlEngine

◆ QQmlEnginePrivate

◆ QQmlExpression

◆ QQmlExpressionPrivate

◆ QQmlScriptPrivate