The following diagram shows the relationships between DirectDraw, the graphics device interface (GDI), the hardware abstraction layer (HAL), hardware emulation layer (HEL) and the hardware.
As the preceding diagram shows, a DirectDraw object exists alongside GDI, and both have direct access to the hardware through a device-dependent abstraction layer. Unlike GDI, DirectDraw makes use of special hardware features whenever possible. If the hardware does not support a feature, DirectDraw attempts to emulate it by using the HEL. DirectDraw can provide surface memory in the form of a device context, making it possible for you to use GDI functions to work with surface objects.