CCoeFep Class Reference

Detailed Description

Abstract base class for all FEPs.

FEP authors must derive a class from CCoeFep. The CCoeFep-derived class should implement all of its pure virtual functions including the ones which CCoeFep inherits from its base classes. For information on these functions, see the documentation of the base classes. The global NewFepL() function is used to create a fully initialised object of the derived class.

FEPs that need to intercept key events should own a CCoeControl-derived object. This object is referred to as the FEP control. The FEP control should be added to the control stack at a priority of ECoeStackPriorityFep, so that it receives first refusal of key events from the window server.

In general, focus is retained by the underlying application. This has the advantage that the user can see where the output produced by the FEP will go. When focus is switched between controls, the FEP must be notified in case the input capability of the focussed control changes. For instance, the FEP needs to prevent the user composing a large amount of text only for it to be passed to a newly focussed control that cannot accept text input. CCoeFep derives from MCoeFocusObserver, which enables FEPs to receive notification when the focus for the underlying control changes. The implementation of MCoeFocusObserver's functions can call the enquiry functions of class TCoeInputCapabilities to find out what input capabilities are supported by the new target control (you need to get the TCoeInputCapabilities object from the application UI first: see CCoeAppUi::InputCapabilities()).

See also: NewFepL()