The Visual class is the basic abstraction from which every FrameworkElement object derives. It also serves as the entry point for writing new controls in WPF, and in many ways can be thought of as an equivalent of a window handle (HWND) in the Win32 application model.
The Visual object is a core WPF object, whose primary role is to provide rendering support. User interface controls, such as Button and TextBox, derive from the Visual class, and use the Visual defined properties for persisting their rendering data. The Visual object provides support for the following:
Output display: Rendering the persisted, serialized drawing content of a visual.
Transformations: Performing transformations on a visual.
Clipping: Providing clipping region support for a visual.
Hit testing: Determining whether a specified coordinate (point) or geometry is contained within the bounds of a visual.
Bounding box calculations: Determining the bounding rectangle of a visual.
Architecturally, the Visual object does not include support for other application development requirements / WPF features that are not immediately related to its rendering, such as the following:
Event handling
Layout
Styles
Data binding
Globalization
Visual is provided as a public abstract class from which further classes can be derived. The following illustration shows the hierarchy of the existing visual objects that are defined in the WPF architecture.
Visual class hierarchy
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In some cases, members that are defined as protected in Visual are exposed as more readily accessible members with similar names in the derived UIElement class.
For more information, see Windows Presentation Foundation Graphics Rendering Overview.