Qt 5.11 | Qt QML | Qt QML Examples | Extending QML - Adding Types Example

Qt 5.11.3 Reference Documentation

# Extending QML - Adding Types Example

Exporting C++ Classes.

The Adding Types Example shows how to add a new object type, `Person`, to QML. The `Person` type can be used from QML like this:

      import People 1.0

      Person {
          name: "Bob Jones"
          shoeSize: 12
      }

## 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.

      class Person : public QObject
      {
          Q_OBJECT
          Q_PROPERTY(QString name READ name WRITE setName)
          Q_PROPERTY(int shoeSize READ shoeSize WRITE setShoeSize)
      public:
          Person(QObject *parent = 0);

          QString name() const;
          void setName(const QString &);

          int shoeSize() const;
          void setShoeSize(int);

      private:
          QString m_name;
          int m_shoeSize;
      };

## Define the Person Class

      Person::Person(QObject *parent)
      : QObject(parent), m_shoeSize(0)
      {
      }

      QString Person::name() const
      {
          return m_name;
      }

      void Person::setName(const QString &n)
      {
          m_name = n;
      }

      int Person::shoeSize() const
      {
          return m_shoeSize;
      }

      void Person::setShoeSize(int s)
      {
          m_shoeSize = s;
      }

The Person class implementation is quite basic. The property accessors simply return members of the object instance.

The `main.cpp` file also calls the `qmlRegisterType()` function to register the `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.

## 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.

Files:

- referenceexamples/adding/adding.pro
- referenceexamples/adding/adding.qrc
- referenceexamples/adding/example.qml
- referenceexamples/adding/main.cpp
- referenceexamples/adding/person.cpp
- referenceexamples/adding/person.h