|Microsoft DirectX 9.0|
Reports the current cooperative-level status of the Microsoft?Direct3D?device for a windowed or full-screen application.
If the method succeeds, the return value is D3D_OK, indicating that the device is operational and the calling application can continue.
If the method fails, the return value can be one of the following values (see Remarks).
D3DERR_DEVICELOST The device has been lost but cannot be reset at this time. Therefore, rendering is not possible. D3DERR_DEVICENOTRESET The device has been lost but can be reset at this time.
If the device is lost but cannot be restored at the current time, IDirect3DDevice9::TestCooperativeLevel returns the D3DERR_DEVICELOST return code. This would be the case, for example, when a full-screen device has lost focus. If an application detects a lost device, it should pause and periodically call IDirect3DDevice9::TestCooperativeLevel until it receives a return value of D3DERR_DEVICENOTRESET. The application may then attempt to reset the device by calling IDirect3DDevice9::Reset and, if this succeeds, restore the necessary resources and resume normal operation. Note that IDirect3DDevice9::Present will return D3DERR_DEVICELOST if the device is either "lost" or "not reset".
A call to IDirect3DDevice9::TestCooperativeLevel will fail if called on a different thread than that used to create the device being reset.