QBindable Class▲
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Header: QBindable
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CMake:
find_package(Qt6 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core)
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qmake: QT += core
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Inherits: QUntypedBindable
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Group: QBindable is part of tools
Detailed Description▲
QBindable<T> helps to integrate Qt's traditional Q_PROPERTY with binding-enabled properties. If a property is backed by a QProperty, QObjectBindableProperty or QObjectComputedProperty, you can add BINDABLE bindablePropertyName to the Q_PROPERTY declaration, where bindablePropertyName is a function returning an instance of QBindable constructed from the QProperty. The returned QBindable allows users of the property to set and query bindings of the property, without having to know the exact kind of binding-enabled property used.
class MyClass : public QObject
{
Q_OBJECT
Q_PROPERTY(int x READ x WRITE setX NOTIFY xChanged BINDABLE bindableX)
public:
int x() const { return xProp; }
void setX(int x) { xProp = x; }
QBindable<int> bindableX() { return QBindable<int>(&xProp); }
signals:
void xChanged();
private:
// Declare the instance of the bindable property data.
Q_OBJECT_BINDABLE_PROPERTY(MyClass, int, xProp, &MyClass::xChanged)
};
MyClass *myObject;
QBindable<int> bindableX = myObject->bindableX();
qDebug() << bindableX.hasBinding(); // prints false
QProperty<int> y {42};
bindableX.setBinding([&](){ return 2*y.value(); });
qDebug() << bindableX.hasBinding() << myObject->x(); // prints true 84See Also▲
Member Function Documentation▲
[explicit] QBindable::QBindable(QObject *obj, const QMetaProperty &property)▲
See QBindable::QBindable(QObject *obj, const char *property)
[explicit] QBindable::QBindable(QObject *obj, const char *property)▲
Constructs a QBindable for the Q_PROPERTY property on obj. The property must have a notify signal but does not need to have BINDABLE in its Q_PROPERTY definition, so even binding unaware Q_PROPERTYs can be bound or used in binding expressions. You must use QBindable::value() in binding expressions instead of the normal property READ function (or MEMBER) to enable dependency tracking if the property is not BINDABLE. When binding using a lambda, you may prefer to capture the QBindable by value to avoid the cost of calling this constructor in the binding expression. This constructor should not be used to implement BINDABLE for a Q_PROPERTY, as the resulting Q_PROPERTY will not support dependency tracking. To make a property that is usable directly without reading through a QBindable use QProperty or QObjectBindableProperty.
QProperty<QString> displayText;
QDateTimeEdit *dateTimeEdit = findDateTimeEdit();
QBindable<QDateTime> dateTimeBindable(dateTimeEdit, "dateTime");
displayText.setBinding([dateTimeBindable](){ return dateTimeBindable.value().toString(); });See Also▲
QPropertyBinding<T> QBindable::binding() const▲
Returns the currently set binding of the underlying property. If the property does not have a binding, the returned QPropertyBinding<T> will be invalid.
See Also▲
See also setBinding, hasBinding
QPropertyBinding<T> QBindable::makeBinding(const QPropertyBindingSourceLocation &location = QT_PROPERTY_DEFAULT_BINDING_LOCATION) const▲
Constructs a binding evaluating to the underlying property's value, using a specified source location.
QPropertyBinding<T> QBindable::setBinding(const QPropertyBinding<T> &binding)▲
Sets the underlying property's binding to binding. Does nothing if the QBindable is read-only or invalid.
See Also▲
See also binding, isReadOnly(), isValid()
QPropertyBinding<T> QBindable::setBinding(Functor f)▲
This is an overloaded function.
Creates a QPropertyBinding<T> from f, and sets it as the underlying property's binding.
void QBindable::setValue(const T &value)▲
Sets the underlying property's value to value. This removes any currenltly set binding from it. This function has no effect if the QBindable is read-only or invalid.
See Also▲
See also value(), isValid(), isReadOnly(), setBinding()
QPropertyBinding<T> QBindable::takeBinding()▲
Removes the currently set binding of the underlying property and returns it. If the property does not have a binding, the returned QPropertyBinding<T> will be invalid.
See Also▲
See also binding, setBinding, hasBinding