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Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: http://www.gnu.org/copyleft/fdl.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \example referenceexamples/adding \title Extending QML - Adding Types Example \brief Exporting C++ Classes \ingroup qmlextendingexamples The Adding Types Example shows how to add a new object type, \c Person, to QML. The \c Person type can be used from QML like this: \snippet referenceexamples/adding/example.qml 0 \section1 Declare the Person Class All QML types map to C++ types. Here we declare a basic C++ Person class with the two properties we want accessible on the QML type - name and shoeSize. Although in this example we use the same name for the C++ class as the QML type, the C++ class can be named differently, or appear in a namespace. \snippet referenceexamples/adding/person.h 0 \section1 Define the Person Class \snippet referenceexamples/adding/person.cpp 0 The Person class implementation is quite basic. The property accessors simply return members of the object instance. The \c main.cpp file also calls the \c qmlRegisterType() function to register the \c Person type with QML as a type in the People library version 1.0, and defines the mapping between the C++ and QML class names. \section1 Running the Example The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page. */ /*! \example referenceexamples/extended \title Extending QML - Extension Objects Example \brief Extension Objects \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Adding Types Example} \endlist Shows how to use \l {QQmlEngine::}{qmlRegisterExtendedType()} to provide an \l {Registering Extension Objects}{extension object} to a \l QLineEdit without modifying or subclassing. The QML engine instantiates a \l QLineEdit and sets a property that only exists on the extension type. The extension type performs calls on the \l QLineEdit that otherwise will not be accessible to the QML engine. */ /*! \example referenceexamples/properties \title Extending QML - Object and List Property Types Example \brief Exporting C++ Properties \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Adding Types Example} \endlist The Object and List Property Types example shows how to add object and list properties in QML. This example adds a BirthdayParty type that specifies a birthday party, consisting of a celebrant and a list of guests. People are specified using the People QML type built in the previous example. \snippet referenceexamples/properties/example.qml 0 \section1 Declare the BirthdayParty The BirthdayParty class is declared like this: \snippet referenceexamples/properties/birthdayparty.h 0 \snippet referenceexamples/properties/birthdayparty.h 1 \snippet referenceexamples/properties/birthdayparty.h 2 \snippet referenceexamples/properties/birthdayparty.h 3 The class contains a member to store the celebrant object, and also a QList member. In QML, the type of a list properties - and the guests property is a list of people - are all of type QQmlListProperty. QQmlListProperty is simple value type that contains a set of function pointers. QML calls these function pointers whenever it needs to read from, write to or otherwise interact with the list. In addition to concrete lists like the people list used in this example, the use of QQmlListProperty allows for "virtual lists" and other advanced scenarios. \section2 Define the BirthdayParty The implementation of BirthdayParty property accessors is straight forward. \snippet referenceexamples/properties/birthdayparty.cpp 0 \section1 Running the Example The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page. */ /*! \example referenceexamples/coercion \title Extending QML - Inheritance and Coercion Example \brief C++ Inheritance and Coercion \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist The Inheritance and Coercion Example shows how to use base classes to assign types of more than one type to a property. It specializes the Person type developed in the previous examples into two types - a \c Boy and a \c Girl. \snippet referenceexamples/coercion/example.qml 0 \section1 Declare Boy and Girl \snippet referenceexamples/coercion/person.h 0 The Person class remains unaltered in this example and the Boy and Girl C++ classes are trivial extensions of it. As an example, the inheritance used here is a little contrived, but in real applications it is likely that the two extensions would add additional properties or modify the Person classes behavior. \section2 Define People as a base class The implementation of the People class itself has not changed since the previous example. However, as we have repurposed the People class as a common base for Boy and Girl, we want to prevent it from being instantiated from QML directly - an explicit Boy or Girl should be instantiated instead. \snippet referenceexamples/coercion/main.cpp 0 While we want to disallow instantiating Person from within QML, it still needs to be registered with the QML engine, so that it can be used as a property type and other types can be coerced to it. \section2 Define Boy and Girl The implementation of Boy and Girl is trivial. \snippet referenceexamples/coercion/person.cpp 1 All that is necessary is to implement the constructor, and to register the types and their QML name with the QML engine. \section1 Running the Example The BirthdayParty type has not changed since the previous example. The celebrant and guests property still use the People type. \snippet referenceexamples/coercion/birthdayparty.h 0 However, as all three types, Person, Boy and Girl, have been registered with the QML system, on assignment QML automatically (and type-safely) converts the Boy and Girl objects into a Person. The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page. */ /*! \example referenceexamples/default \title Extending QML - Default Property Example \brief Default Property \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist The Default Property Example is a minor modification of the \l {Extending QML - Inheritance and Coercion Example} that simplifies the specification of a BirthdayParty through the use of a default property. \snippet referenceexamples/default/example.qml 0 \section1 Declaring the BirthdayParty Class The only difference between this example and the last, is the addition of the \c DefaultProperty class info annotation. \snippet referenceexamples/default/birthdayparty.h 0 The default property specifies the property to assign to whenever an explicit property is not specified, in the case of the BirthdayParty type the guest property. It is purely a syntactic simplification, the behavior is identical to specifying the property by name, but it can add a more natural feel in many situations. The default property must be either an object or list property. \section1 Running the Example The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page. */ /*! \example referenceexamples/grouped \title Extending QML - Grouped Properties Example \brief Grouped Properties \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */ /*! \example referenceexamples/attached \title Extending QML - Attached Properties Example \brief Attached Properties \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Grouped Properties Example} \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */ /*! \example referenceexamples/signal \title Extending QML - Signal Support Example \brief Signal Support \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Attached Properties Example} \li \l {Extending QML - Grouped Properties Example} \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */ /*! \example referenceexamples/methods \title Extending QML - Methods Example \brief Methods Support \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */ /*! \example referenceexamples/valuesource \title Extending QML - Property Value Source Example \brief Property Value Source \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Signal Support Example} \li \l {Extending QML - Attached Properties Example} \li \l {Extending QML - Grouped Properties Example} \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */ /*! \example referenceexamples/binding \title Extending QML - Binding Example \brief Binding \ingroup qmlextendingexamples This example builds on: \list \li \l {Extending QML - Property Value Source Example} \li \l {Extending QML - Signal Support Example} \li \l {Extending QML - Attached Properties Example} \li \l {Extending QML - Grouped Properties Example} \li \l {Extending QML - Default Property Example} \li \l {Extending QML - Inheritance and Coercion Example} \li \l {Extending QML - Object and List Property Types Example} \li \l {Extending QML - Adding Types Example} \endlist */