QQmlFinalizerHook Class

Header: #include <QQmlFinalizerHook>

Detailed Description

\internal

QQmlFinalizerHook is an internal interface to run code after the current toplevel component has been completed. At first, this might look like QQmlParserStaus' componentComplete functionality by another name - however there is a difference. To understand it, consider the following QML file:

 import QtQuick
 Item {
     id: root
     Rectangle {
         id: rect
         Rectangle { id: innerRect }
     }
     property Item it: Item {id: myItem }
 }

This file will instantiate 4 (sub-)components: One for each of root, rect, innerRect and myItem. If the component gets loaded in a synchronous way, each of their componentComplete (if existent) would run directly one after another (in a non-specified order).

However, in the case of an asynchronous instantiation, e.g. via a loader, we might interrupt the (sub-)component construction partway: There can be a delay between the various componentComplete calls, and not all sub-components might have been constructed yet. QQmlFinalizerHook::componentFinalized is instead called after all asynchronously instantiated (sub-)components have been constructed. Notably, all bindings of those components have also been set up.

Note: While the engine does not use qobject_cast, tooling still relies on the interface being marked as such. Thus you should always use the Q_INTERFACES macro in classes deriving from QQmlFinalizerHook.