This is an abstract class for specifying an interface for receiving notifications when an icon's frame buffer has been updated. An object of derived class implementing this interface should be registered for a given icon to the AknIcon framework using function AknIconUtils::SetObserver().

AknIcon framework calls this function whenever the frame buffer of the observed icon changes. This observer mechanism is mainly useful in animated icons cases. The observer e.g. can redraw the icon on the screen when the frame of the animated icon has changed.