Qt QQuick consists of multiple interacting sets of components: the scene graph abstraction and the renderers for various graphics architectures; the declarative QML language; the QQuickItem (Item) hierarchy of classes that are usually instantiated declaratively, which in turn create and manage scene graph nodes; various model classes that can drive creation of Item instances at runtime; event-handling classes; and the V4 implementation of JavaScript that can be used for adding imperative scripting to the objects that are declared in QML.

QML Runtime Engine

The QML language includes a JavaScript interpreter, runtime and compiler. Here we go into some runtime implementation details.

Garbage Collection in the V4 engine