突然发现下面这个东西，一点也不懂。

DECLARE_INTERFACE_(IDirect3D9, IUnknown)
{
/*** IUnknown methods ***/
STDMETHOD(QueryInterface)(THIS_ REFIID riid, void** ppvObj) PURE;
STDMETHOD_(ULONG,AddRef)(THIS) PURE;
STDMETHOD_(ULONG,Release)(THIS) PURE;

/*** IDirect3D9 methods ***/
STDMETHOD(RegisterSoftwareDevice)(THIS_ void* pInitializeFunction) PURE;
STDMETHOD_(UINT, GetAdapterCount)(THIS) PURE;
STDMETHOD(GetAdapterIdentifier)(THIS_ UINT Adapter,DWORD Flags,D3DADAPTER_IDENTIFIER9* pIdentifier) PURE;
STDMETHOD_(UINT, GetAdapterModeCount)(THIS_ UINT Adapter,D3DFORMAT Format) PURE;
STDMETHOD(EnumAdapterModes)(THIS_ UINT Adapter,D3DFORMAT Format,UINT Mode,D3DDISPLAYMODE* pMode) PURE;
STDMETHOD(GetAdapterDisplayMode)(THIS_ UINT Adapter,D3DDISPLAYMODE* pMode) PURE;
STDMETHOD(CheckDeviceType)(THIS_ UINT iAdapter,D3DDEVTYPE DevType,D3DFORMAT DisplayFormat,D3DFORMAT BackBufferFormat,BOOL bWindowed) PURE;
STDMETHOD(CheckDeviceFormat)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT AdapterFormat,DWORD Usage,D3DRESOURCETYPE RType,D3DFORMAT CheckFormat) PURE;
STDMETHOD(CheckDeviceMultiSampleType)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT SurfaceFormat,BOOL Windowed,D3DMULTISAMPLE_TYPE MultiSampleType,DWORD* pQualityLevels) PURE;
STDMETHOD(CheckDepthStencilMatch)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT AdapterFormat,D3DFORMAT RenderTargetFormat,D3DFORMAT DepthStencilFormat) PURE;
STDMETHOD(CheckDeviceFormatConversion)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT SourceFormat,D3DFORMAT TargetFormat) PURE;
STDMETHOD(GetDeviceCaps)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DCAPS9* pCaps) PURE;
STDMETHOD_(HMONITOR, GetAdapterMonitor)(THIS_ UINT Adapter) PURE;
STDMETHOD(CreateDevice)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,HWND hFocusWindow,DWORD BehaviorFlags,D3DPRESENT_PARAMETERS* pPresentationParameters,IDirect3DDevice9** ppReturnedDeviceInterface) PURE;
};