I've worked with DirectX 9 a fair amount, and just recently switched to DirectX 10. I've noticed that a lot of 9's device methods have gone missing or been changed. For instance, in DX9, the method StretchRect was used to draw a surface to the screen.
My problem is this: I have a IDirect3DSurface9 that I need to draw to the screen, but I am using DirectX 10. Can 10's graphics device do this? Or do I need to get 9's graphics device and do it with that one? Is it even possible to have both an IDirect3D9Device and an IDirect3D10Device at the same time??
I've implemented DirectX 9 code for drawing on top of the DirectX 10 code, and the results are... interesting. It looks like the devices actually compete for the screen. DX10's device seems to win this competition more often than not, as well, probably because i'm using the swap chain with it. Anyways, part of the question is still open for answering. If there is a way to draw DX9 surfaces using a DX10 device, i will award that answer.