View +architecture

diff -r 000000000000 -r 89d6a7a84779 Symbian3/SDK/Source/GUID-68B999C2-0993-4804-9624-42C3D88BE5C7.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-68B999C2-0993-4804-9624-42C3D88BE5C7.dita Thu Jan 21 18:18:20 2010 +0000 @@ -0,0 +1,88 @@ + + + + + +View +architecture +

The following image illustrates the components of the view architecture +approach.

+View architecture classes +

Symbian platform applications that follow the view architecture require:

a UI +controller derived from CAknViewAppUi
+
a view +controller derived from CAknView
+
a view or +views derived from CCoeControl
+

The view architecture only allows one view to be active in each application. +If a new view is switched to within an application, the current view is immediately +deactivated, so this architectural approach is not appropriate in the +following cases:

Applications with any view that cannot cleanly handle unexpected +activation of another view in that application.
Applications that provide views that can be nested over other +applications, except where embedding is used.
Applications that provide controls that can be used inside +other applications (for example, using a Web control inside an e-mail viewer +to show an e‑mail with HTML content).

Typical responsibilities in this architecture are:

CAknViewAppUi-derived +class acts as a UI +controller:
+
+
- It creates one or more CAknView-derived +view controllers.
- It handles events that +are not handled by the view controllers.
- To switch between views, it activates and deactivates views.
  +
- It handles menu commands passed +to it by the view controllers.
- It receives events such as layout and foreground notifications +from the run-time environment.
+
+
CAknView-derived +class acts as a view +controller
+
+
- It creates one of more CCoeControl-derived +views.
- It handles registering controls for key +event handling.
- It handles menu commands.
  +
+
+
CCoeControl-derived +view:
+
+
- Shows application data and state on the screen.
+
+

For information on the CAknApplication and CAknDocument-derived +classes, see Framework +requirements for GUI applications.

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