Programming WPF, 2nd Edition

FrameworkElement

System.Object
    System.Windows.Threading.DispatcherObject
        System.Windows.DependencyObject
            System.Windows.Media.Visual
                System.Windows.UIElement
                    System.Windows.FrameworkElement

FrameworkElement is the base class of the majority of visible elements in WPF. It derives from UIElement, so types that derive from FrameworkElement are able to render their own appearance and respond to user input. FrameworkElement adds data binding, styling, and resource handling, and it builds the full set of layout and animation services on top of the primitive services provided by UIElement.

FrameworkElement also provides a great deal of the infrastructure for data templates and control templates, although you must use more specialized classes to exploit these features. Only a Control (or a type derived from Control) can have a control template. You can use data templates either from a ContentPresenter or from certain control types.^[130]

FrameworkElement is arguably WPF's nearest equivalent to the Windows Forms Control class. WPF has a Control class too (which we describe later), but its role is more specialized.

Tip

Types that derive directly from FrameworkElement are typically all-code affairs. Although you could create a XAML file for a FrameworkElement with a corresponding code-behind file, you can't use this to construct the appearance of the element. This is because adding child elements at this level requires code—you need to override the GetVisualChild method and the VisualChildrenCount ...