Uikon -Overview

Purpose

Provides a framework for applications. -The framework is fundamental to all GUI applications.

Architectural relationships

Uikon provides a UI -library layer. It was designed to allow further higher level UI libraries -to be added that can include controls that derive from the ones provided by -Uikon. Avkon provides these higher level UI libraries in Symbian^3 and historically -in the S60 platform. Application developers can use the Uikon APIs directly, -though they should check that there is not a more appropriate Avkon API.

The -Uikon application framework extends two lower frameworks:

the Application Architecture -Framework: handles application start-up and accessing the application data -(its document).
UI Control Framework: -provides the framework for drawing and handling input to screen controls

Uikon ties these two frameworks together to provide the framework -for the standard application design.

Uikon's framework classes are -extended in turn by:

applications, to implement -appropriate behaviour for their type of data, and for their types of command
possibly by UI variant-specific -libraries, to add UI variant-specific behaviour to the application framework

Description

The API has five key concepts: application -(CEikApplication), document (CEikDocument), -app UI (CEikAppUi), UI Environment (CEikonEnv), -and utilities (EikFileUtils).

Application

The application class defines properties of the application, such as UID -and caption, and creates a new document.

The application base class -is provided by CEikApplication.

Document

The document class represents the data model for -the application. In file-based applications, it stores and restores the application's -data. It handles requests to edit a document by creating an app UI.

The -document base class is provided by CEikDocument.

App UI

The app UI is the central user interface class. It -creates and owns controls to display the application data, and centralises -handling of command input from standard controls such as menus and toolbars.

The -app UI base class is provided by CEikAppUi, which can be -customised by using the resource structure EIK_APP_INFO.

UI Environment

The UI Environment provides a large number -of assorted UI functionality, particularly simple access to information and -query dialogs, and access to standard system UI resources (bitmaps and fonts). -Every object in a GUI application can access a UI Environment (through CEikonEnv::Static()), -as a pointer to it is stored in thread-local storage.

The UI Environment -is provided by CEikonEnv.

Utilities

Utility classes provide easy access for applications -to frequently-used functionality. Notable are EikFileUtils for -file access, and EikResourceUtils for resource access.