Class structure for the toolbar API

The Toolbar API consists of following classes: CAknToolbar, CAknToolbarExtension, and MAknToolbarObserver. The Toolbar API class structure and its simplified environment is described in the figure below.

Figure: Toolbar API class structure

CAknToolbar is the API main class that provides the most of the API functionality. The UI framework classes CEikAppUiFactory, CAknView, and CAknAppUi take care of creating and destructing the CAknToolbar object. Moreover, you can access the toolbar in your application through these UI framework classes.

CAknToolbar is a compound (window-owning) control that contains simple (non-window-owning) controls that are the toolbar items. Toolbar items can be for example CAknButton type controls. Each toolbar can also have one extension that expands the toolbar. The extension contains also for example CAknButton type controls.

MAknToolbarObserver is an interface that can be used to observe toolbar events. The application class can implement this interface and register itself as the toolbar observer. CAknToolbar then informs the observer when toolbar events occur (when toolbar is about to be shown and when some toolbar item state has changed e.g. a button is pressed).