Symbian OS Developers

Uikon 1

Uikon can be thought of as the common core on top of which are built the variant user interfaces that actually appear on phones.

Uikon provides a framework for creating user interfaces including the base classes which interface to lower-level system services such as application launching; key mapping and command handling; alarms and notifications; and graphics services.

Uikon supplies the base classes from which user interface variants derive essential application classes (Application, Document and AppUI) and encapsulates the relationships between them.

Uikon supplies the factory classes used by the user interface variant to create the hierarchy of custom concrete user interface control classes, including list boxes, scroll bars, buttons, dialogs and popups. (Basic menus are not controls but windows.)

Uikon loads a static library implementation (interface defined by the UI Look and Feel component) of the core library look-and-feel (LAF) component, which is supplied by the user interface variant. The UI Look and Feel component defines a standard set of methods which the variant user interface implements to define the concrete behavior of user interface elements, for example, layout and behavior of windows; choice of fonts and bitmaps; default location of resource files; system font and text rendering defaults; and the look and feel of toolbar, dialog, button and button container classes. The Uikon Error Resolver Plug-in is a small component that is used by the user interface variant to map system error codes to localized strings. Strictly speaking it is not a plug-in, but a resource file which is built as a dummy DLL.

Uikon provides a server stub which is run to launch other servers expected by the framework or by applications (the alarm server, notifier server, and server-side support for user-interface status panes) and to load implementations specific to a user interface variant for password and alarm notifications. (The Notifier is run inside the Uikon server thread to ensure that memory is always preallocated for those notification dialogs which must never fail, for example the 'Out of memory' dialog itself.)

Uikon provides servers to manage backup and shutdown (used to close running applications when the user starts a backup, and to handle shutdown when the user switches off the device). In earlier releases of the operating system (up to Symbian OS v7.0) Uikon also supplied a core library of concrete controls and dialogs, EikCoeControl; these are now supplied in the customization toolkit, and may be selectively re-implemented by the user interface variant or discarded.