|Microsoft DirectX 9.0|
The SetDirectDraw method passes the IDirectDraw interface to a loaded driver.
HRESULT SetDirectDraw( LPDIRECTDRAW pDirectDraw );
Pointer to the IDirectDraw interface to be passed.
Returns an HRESULT value.
To have the renderer release a DirectDraw interface previously passed in through SetDirectDraw, an application can call SetDirectDraw and pass in NULL. However, the renderer will continue using that DirectDraw interface until it is disconnected. Therefore, calling SetDirectDraw with a null parameter does not make the renderer stop using it immediately.
This method was created because only one instance of IDirectDraw could be loaded per process in versions of DirectDraw prior to DirectX 7.0. If you are using DirectX 7.0 or later, you never need to call this method. If an application wanted to load IDirectDraw but allow the Video Renderer to also allocate surfaces, the application could open IDirectDraw itself and then pass the interface to the loaded driver through IDirectDrawVideo::SetDirectDraw. Alternatively, the application could let the renderer load DirectDraw and then obtain a reference-incremented interface to it through IDirectDrawVideo::GetDirectDraw. Because DirectShow ships with the most recently shipped version of DirectDraw, however, this method is not required unless the application wants to change display modes itself and pass in a DirectDraw object, which the renderer can then use to allocate surfaces.