PocketMatrix

What does this mean:

>>Since DirectDraw only supports unsigned coordinates however it's not that useful in most cases however.



You can certainly blit surfaces to destinations which are referenced by signed coordinate values. The RECT structure has members which are typed as LONG.

Where the DDraw clipper does come in handy is when you're running in a window and your window is partially obscured by another window or a pop-up menu. DDraw does the right thing in this instance and will turn your full-window-sized Blt into a series of multiple blits which keeps the blitter from stomping over the occluded regions. GAPIDraw will never be able to do something like this on Pocket PC because it doesn't have hooks into GWES to know when and where the occluded areas are of the destination window.