#include <qqmlbind_p.h>

Inheritance diagram for QQmlBind:

Collaboration diagram for QQmlBind:

Public Types
enum	RestorationMode { RestoreNone = 0x0 , RestoreBinding = 0x1 , RestoreValue = 0x2 , RestoreBindingOrValue = RestoreBinding \| RestoreValue }

Signals
void	restoreModeChanged ()

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
	QQmlBind (QObject *parent=nullptr)

bool	when () const
	\qmlproperty bool QtQml::Binding::when

void	setWhen (bool)

QObject *	object ()
	\qmlproperty QtObject QtQml::Binding::target

void	setObject (QObject *)

QString	property () const
	\qmlproperty string QtQml::Binding::property

void	setProperty (const QString &)

QVariant	value () const
	\qmlproperty var QtQml::Binding::value

void	setValue (const QVariant &)

bool	delayed () const
	\qmlproperty bool QtQml::Binding::delayed

void	setDelayed (bool)

RestorationMode	restoreMode () const
	\qmlproperty enumeration QtQml::Binding::restoreMode

void	setRestoreMode (RestorationMode)

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`.

Public Member Functions inherited from QQmlPropertyValueSource
	QQmlPropertyValueSource ()
	Constructs a QQmlPropertyValueSource.

virtual	~QQmlPropertyValueSource ()
	Destroys the value source.

Public Member Functions inherited from QQmlParserStatus
	QQmlParserStatus ()

virtual	~QQmlParserStatus ()

Protected Member Functions
void	setTarget (const QQmlProperty &) override
	Set the target property for the value source.

void	classBegin () override
	Invoked after class creation, but before any properties have been set.

void	componentComplete () override
	Invoked after the root component that caused this instantiation has completed construction.

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
QObject *	target

QString	property

QVariant	value

bool	when

bool	delayed

RestorationMode	restoreMode

Properties inherited from QObject
QString	objectName
	the name of this object

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

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

Definition at line 26 of file qqmlbind_p.h.

Member Enumeration Documentation

◆ RestorationMode

enum QQmlBind::RestorationMode

Enumerator
RestoreNone
RestoreBinding
RestoreValue
RestoreBindingOrValue

Definition at line 29 of file qqmlbind_p.h.

Constructor & Destructor Documentation

◆ QQmlBind()

QQmlBind::QQmlBind ( QObject * parent = nullptr )

\qmltype Binding
\instantiates QQmlBind
\inqmlmodule QtQml
\ingroup qtquick-interceptors
\brief Enables the arbitrary creation of property bindings.

In QML, property bindings result in a dependency between the properties of
different objects.

\section1 Binding to an Inaccessible Property

Sometimes it is necessary to bind an object's property to
that of another object that isn't directly instantiated by QML, such as a
property of a class exported to QML by C++. You can use the Binding type
to establish this dependency; binding any value to any object's property.

For example, in a C++ application that maps an "app.enteredText" property
into QML, you can use Binding to update the enteredText property.

\qml
TextEdit { id: myTextField; text: "Please type here..." }
Binding { app.enteredText: myTextField.text }
\endqml

When \c{text} changes, the C++ property \c{enteredText} will update
automatically.

\section1 Conditional Bindings

In some cases you may want to modify the value of a property when a certain
condition is met but leave it unmodified otherwise. Often, it's not possible
to do this with direct bindings, as you have to supply values for all
possible branches.

For example, the code snippet below results in a warning whenever you
release the mouse. This is because the value of the binding is undefined
when the mouse isn't pressed.

\qml

produces warning: "Unable to assign [undefined] to double value" value: if (mouse.pressed) mouse.mouseX \endqml

The Binding type can prevent this warning.

\qml Binding on value { when: mouse.pressed value: mouse.mouseX } \endqml

The Binding type restores any previously set direct bindings on the property.

See also: {Qt Qml}

Definition at line 389 of file qqmlbind.cpp.

Member Function Documentation

◆ classBegin()

void QQmlBind::classBegin ( )

overrideprotectedvirtual

Invoked after class creation, but before any properties have been set.

Implements QQmlParserStatus.

Definition at line 704 of file qqmlbind.cpp.

References d.

◆ componentComplete()

void QQmlBind::componentComplete ( )

overrideprotectedvirtual

Invoked after the root component that caused this instantiation has completed construction.

At this point all static values and binding values have been assigned to the class.

Implements QQmlParserStatus.

Definition at line 976 of file qqmlbind.cpp.

References d, and qmlContext().

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◆ delayed()

bool QQmlBind::delayed ( ) const

\qmlproperty bool QtQml::Binding::delayed

Since: 5.8

This property holds whether the binding should be delayed.

A delayed binding will not immediately update the target, but rather wait until the event queue has been cleared. This can be used as an optimization, or to prevent intermediary values from being assigned.

Binding {
    contactName.text.value: givenName + " " + familyName
    when: list.ListView.isCurrentItem
    delayed: true
}

Note: Using the \l delayed property incurs a run time cost as the Binding element has to create a proxy for the value, so that it can delay its application to the actual target. When using the \l target and \l property properties, this cost is lower because the \l value property can be re-used as proxy. When using the form shown above, Binding will allocate a separate object with a dynamic meta-object to hold the proxy values.

Definition at line 599 of file qqmlbind.cpp.

References d.

◆ object()

QObject * QQmlBind::object ( )

\qmlproperty QtObject QtQml::Binding::target

The object to be updated. You need to use this property if the binding target does not have an id attribute (for example, when the target is a singleton). Otherwise, the following two pieces of code are equivalent:

\qml Binding { contactName.text: name } \endqml

\qml Binding { target: contactName property: "text" value: name } \endqml

The former one is much more compact, but you cannot replace the target object or property at run time. With the latter one you can.

Definition at line 452 of file qqmlbind.cpp.

References d.

◆ property()

QString QQmlBind::property ( ) const

\qmlproperty string QtQml::Binding::property

The property to be updated.

This can be a group property if the expression results in accessing a property of a \l {QML Value Types}{value type}. For example:

\qml Item { id: item

property rect rectangle: Qt.rect(0, 0, 200, 200) }

Binding { target: item property: "rectangle.x" value: 100 } \endqml

You only need to use this property if you can't supply the binding target declaratively. The following snippet of code is equivalent to the above binding, but more compact:

\qml Binding { item.rectangle.x: 100 } \endqml

Definition at line 522 of file qqmlbind.cpp.

References d.

◆ restoreMode()

QQmlBind::RestorationMode QQmlBind::restoreMode ( ) const

\qmlproperty enumeration QtQml::Binding::restoreMode

Since: 5.14

This property can be used to describe if and how the original value should be restored when the binding is disabled.

The possible values are:

\value Binding.RestoreNone The original value is not restored at all \value Binding.RestoreBinding The original value is restored if it was another binding. In that case the old binding is in effect again. \value Binding.RestoreValue The original value is restored if it was a plain value rather than a binding. \value Binding.RestoreBindingOrValue The original value is always restored.

The default value is Binding.RestoreBindingOrValue.

Note: This property exists for backwards compatibility with earlier versions of Qt. Don't use it in new code.

Definition at line 660 of file qqmlbind.cpp.

References d, RestoreBinding, RestoreNone, and RestoreValue.

◆ restoreModeChanged

void QQmlBind::restoreModeChanged ( )

signal

Referenced by setRestoreMode().

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◆ setDelayed()

void QQmlBind::setDelayed ( bool delayed )

Definition at line 605 of file qqmlbind.cpp.

References Binding, d, delayed, i, QQmlBindEntry::previousKind, and QQmlAnyBinding::removeBindingFrom().

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◆ setObject()

void QQmlBind::setObject ( QObject * obj )

Definition at line 458 of file qqmlbind.cpp.

References d, QQmlBinding::evaluate(), QQmlJavaScriptExpression::hasValidContext(), QQmlAnyBinding::ofProperty(), qmlContext(), setTarget(), and when.

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◆ setProperty()

void QQmlBind::setProperty ( const QString & p )

Definition at line 528 of file qqmlbind.cpp.

References d, qmlContext(), and setTarget().

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◆ setRestoreMode()

void QQmlBind::setRestoreMode ( RestorationMode newMode )

Definition at line 671 of file qqmlbind.cpp.

References d, emit, RestoreBinding, restoreMode, restoreModeChanged(), and RestoreValue.

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◆ setTarget()

void QQmlBind::setTarget ( const QQmlProperty & property )

overrideprotectedvirtual

Set the target property for the value source.

This method will be called by the QML engine when assigning a value source.

Implements QQmlPropertyValueSource.

Definition at line 681 of file qqmlbind.cpp.

References d.

Referenced by setObject(), and setProperty().

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◆ setValue()

void QQmlBind::setValue ( const QVariant & v )

Definition at line 565 of file qqmlbind.cpp.

References QQmlBindEntry::current, QQmlBindEntry::currentKind, d, and QQmlBindEntryContent::set().

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◆ setWhen()

void QQmlBind::setWhen ( bool v )

Definition at line 418 of file qqmlbind.cpp.

References d.

◆ value()

QVariant QQmlBind::value ( ) const

\qmlproperty var QtQml::Binding::value

The value to be set on the target object and property. This can be a constant (which isn't very useful), or a bound expression.

You only need to use this property if you can't supply the binding target declaratively. Otherwise you can directly bind to the target.

Definition at line 556 of file qqmlbind.cpp.

References d, Q_ASSERT, and Variant.

◆ when()

bool QQmlBind::when ( ) const

\qmlproperty bool QtQml::Binding::when

This property holds when the binding is active. This should be set to an expression that evaluates to true when you want the binding to be active.

\qml Binding { contactName.text: name when: list.ListView.isCurrentItem } \endqml

By default, any binding or value that was set perviously is restored when the binding becomes inactive. You can customize the restoration behavior using the \l restoreMode property.

See also: restoreMode

Definition at line 412 of file qqmlbind.cpp.

References d.

Property Documentation

◆ delayed

bool QQmlBind::delayed

readwrite

Definition at line 45 of file qqmlbind_p.h.

Referenced by setDelayed().

◆ property

QString QQmlBind::property

readwrite

Definition at line 42 of file qqmlbind_p.h.

◆ restoreMode

RestorationMode QQmlBind::restoreMode

readwrite

Definition at line 46 of file qqmlbind_p.h.

Referenced by setRestoreMode().

◆ target

QObject * QQmlBind::target

readwrite

Definition at line 41 of file qqmlbind_p.h.

◆ value

QVariant QQmlBind::value

readwrite

Definition at line 43 of file qqmlbind_p.h.

◆ when

bool QQmlBind::when

readwrite

Definition at line 44 of file qqmlbind_p.h.

Referenced by setObject().

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

qtdeclarative/src/qml/types/qqmlbind_p.h (5c5a2c24847c636857153078e4716fcb242f394d)
qtdeclarative/src/qml/types/qqmlbind.cpp (98ecc9adbbb0f032f4ef4341d4cdd896158d4409)

Public Types

Signals

Public Member Functions

Protected Member Functions

Properties

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ RestorationMode

Constructor & Destructor Documentation

◆ QQmlBind()

Member Function Documentation

◆ classBegin()

◆ componentComplete()

◆ delayed()

◆ object()

◆ property()

◆ restoreMode()

◆ restoreModeChanged

◆ setDelayed()

◆ setObject()

◆ setProperty()

◆ setRestoreMode()

◆ setTarget()

◆ setValue()

◆ setWhen()

◆ value()

◆ when()

Property Documentation

◆ delayed

◆ property

◆ restoreMode

◆ target

◆ value

◆ when