IDirectDrawSurface3::SetOverlayPosition

DDraw vtable[30] → HRESULT

IDirectDrawSurface3::SetOverlayPosition is a method of the COM interface IDirectDrawSurface3 in DirectDraw. Its function pointer sits at vtable index 30 — the zero-based slot in that interface's virtual method table, counted from QueryInterface and including every entry inherited from a base interface. It takes 2 parameters (lX, lY) and returns HRESULT.

COM methods are reached through that table rather than by an exported name, so the slot index is what a wrapper, an interface hook or a disassembly listing has to resolve against. The parameter order and types below are the ones this interface declares.