The Major components of WPF Architecture are Presentation Framework, Presentation Core and Media Integration Layer. The architecture divides in three major groups Managed Layer, Media Integration Layer (Unmanaged code) and Core Operating System.
Managed layer contains WindowsBase, Presentation Framework and Presentation Core assembly. Media Integration Layer contains Milcore(Media Integration Library Core) and WindowsCodecs modules and both are unmanaged code. Media Integration Layer interacts with Direct3D and Direct3D interacts with Device Driver.
Presentation Framework – Holds top level WPF types includes Window, Controls, Styles, and Layout Panels etc. The code and controls written in WPF Application is mostly interacting with this layer.
Presentation Core – Holds base types such as UI Element and Visual. Almost all the controls you are directly interacting with are derived from these types. Presentation Framework uses most of the types defined in this layer.
MilCore – Media Integration Library is core rendering system. MIL is unmanaged code. This layer converts WPF elements into the format that Direct3D expects. Windows7 and Windows Vista uses this assembly to render its Desktop.
WindowsCodecs– provides supports for imaging like image processing, image displaying and scaling etc.
Direct3D – This layer is used to render graphics created using WPF Applications.