Views

diff -r 43e37759235e -r 51a74ef9ed63 Symbian3/SDK/Source/GUID-DAC32BB9-C0EB-42FF-A596-C2F1A90A4BD7.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-DAC32BB9-C0EB-42FF-A596-C2F1A90A4BD7.dita Wed Mar 31 11:11:55 2010 +0100 @@ -0,0 +1,85 @@ + + + + + +Views +

The term view refers to the MVC +design (Model-View-Controller) component that has the following attributes:

displays the application state known by the application
+
receives user input
is owned by the UI +controller
observes application state changes either directly or through +the UI controller and updates the screen accordingly

In practice, views are collections of interface elements, such as controls, +menus, command button areas (CBAs), key events, that make up one top-level +window in an application. Applications may have one or more views. If an application +has more than one view and if the status pane behavior is organized in this +manner, then each view in an application can have its own tab. Applications +can have only a single view active at any one time. The current view is the +view that interacts with the user, receiving events and menu choices as if +it were the only set of UI elements.

Multiple view architectures are widely used in application development +on the Symbian platform. Multiple view architectures:

provide developers with an efficient way to build multiple +views within an application and switch between them easily and simply.
+
allow applications to bundle their user interface requirements +into a single element (a view). The view architecture then provides the capability +to switch quickly between the views.
allow applications to take advantage of object orientation +to encapsulate code, keeping it simple and clear.
provide the ability for one application to activate the view +of another. This is particularly useful when you want to use an existing display +or editing capability without going to the expense of integrating a component +into your application.
allow applications to register views, with one view being +active in each running application at any one time. It does not dictate what +a view is; however, it does provide support for a view being a display page +on the screen

+Controller-view hierarchy in traditional and Symbian architectures +

In practice, the view concept varies depending upon your chosen architecture +approach:

Traditional architecture +views +

In a traditional architecture, the view is derived from CCoeControl, +which typically constructs a top-level window-owning control that draws itself +and contains other controls.

For more information on views in tradition architecture approaches, +see Traditional +Symbian UI application architecture.

Symbian architecture +views +

In Symbian view architecture, a view controller is added between the UI controller and +the view that draws itself and contains other controls. For example, view +controllers can be used to specify CBAs that are specific to specific views.

In a Symbian architecture, the view controller is derived from CAknView, +which is derived directly from CBase and not from CCoeControl. +This means the CAknView-derived views are not controls. CAknView-derived +views need to contain CCoeControl-derived classes to provide +visual representation on the display.

For more information on views in Symbian architecture approaches, see View +architecture.

Dialog architecture +views +

In dialog architectures, views are implemented in modeless dialog boxes. +Multiple views can be constructed using nested dialogs or a tabbed dialog +pane.

For more information on views in dialog architecture approaches, see Dialog +architecture.

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