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_PROPERTY(QString name READ name WRITE setName)
     Q_PROPERTY(int shoeSize READ shoeSize WRITE setShoeSize)
     Person(QObject *parent = nullptr);

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

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

     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.

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 project @ code.qt.io