Windows Presentation Foundation

Windows Presentation Foundation (WPF) provides developers with a unified programming model for building rich Windows smart client user experiences that incorporate UI, media, and documents.

The primary WPF programming model is exposed through managed code. Early in the design phase of WPF there were a number of debates about where the line should be drawn between the managed components of the system and the unmanaged ones. The CLR provides a number of features that make development more productive and robust (including memory management, error handling, common type system, etc.) but they come at a cost.

The major components of WPF are illustrated in the figure below. The red sections of the diagram (PresentationFramework, PresentationCore, and milcore) are the major code portions of WPF. Of these, only one is an unmanaged component – milcore. Milcore is written in unmanaged code in order to enable tight integration with DirectX. All display in WPF is done through the DirectX engine, allowing for efficient hardware and software rendering. WPF also required fine control over memory and execution. The composition engine in milcore is extremely performance sensitive, and required giving up many advantages of the CLR to gain performance.

Communication between the managed and unmanaged portions of WPF is discussed later in this topic. The remainder of the managed programming model is described below.

Taken From :http://msdn.microsoft.com/en-us/library/ms750441.aspx