Main
|--------------\
| |
DIB Fake Z-Buffer
|
|------\---------\
| | |
User DGA2 DIBTexture
Main provides a very simple base class that does not implement any of
the image-related functions. Therefore it does not place any
constraints on how the surface data is stored.
DIB stores the surface data in a DIB section. It is used by the Main
DirectDraw driver to create off-screen surfaces.
User implements primary and backbuffer surfaces for the User DirectDraw
driver. If it is a primary surface, it will attempt to keep itself
synchronized to the window.
DGA2 surfaces claims an appropriate section of framebuffer space and
lets DIB build its DIB section on top of it.
Fake Z-Buffer surfaces are used by Direct3D to indicate that a primary
surface has an associated z-buffer. For a first implementation, it
doesn't need to store any image data since it is just a placeholder.
(Actually 3D programs will rarely use Lock or GetDC on primary
surfaces, backbuffers or z-buffers so we may want to arrange for
lazy allocation of the DIB sections.)
