使用DirectShow驱动摄像头

CComQIPtr m_pVW;

CComQIPtr m_pMC;

CComQIPtr m_pME;

CComPtr m_pGraph;

CComPtr m_pCapture;

DWORD m_dwGraphRegister;

bool bInit(HWND hWnd)

{

　HRESULT hr;

　//获得接口

　hr=CoCreateInstance (CLSID_FilterGraph, NULL, CLSCTX_INPROC,IID_IGraphBuilder, (void **) &m_pGraph);

　if (FAILED(hr))

　　return false;

　hr=CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC,

　IID_ICaptureGraphBuilder2, (void **) &m_pCapture);

　if (FAILED(hr))

　　return false;

　m_pMC=m_pGraph;

　m_pVW=m_pGraph;

　m_pME=m_pGraph;

　//取得消息

　m_pME->SetNotifyWindow((OAHWND)(m_hWnd=hWnd), WM_GRAPHNOTIFY, 0);

　//将过滤和捕获进行连接

　m_pCapture->SetFiltergraph(m_pGraph);

　//设备联接

　//枚举设备

　CComPtr pCde=NULL;

　CComPtr pEm=NULL;

　hr=CoCreateInstance (CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC,

　IID_ICreateDevEnum, (void **) &pCde);

　if (FAILED(hr))

　　return false;

　pCde->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pEm, 0);

　if(pEm==NULL)

　　return false;

　CComPtr pM=NULL;

　ULONG cFetched;

　CComPtr pBf=NULL;

　if(pEm->Next(1,&pM,&cFetched)==S_OK)

　{

　　pM->BindToObject(0,0,IID_IBaseFilter, (void**)&pBf);

　　pM.Release();

　}

　else

　{

　　return false;

　}

　//将设备添加到graph

　hr = m_pGraph->AddFilter(pBf, L"Video Capture");

　if (FAILED(hr))

　　return false;

　//连接一个源插口

　hr=m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW,&MEDIATYPE_Video,pBf,NULL,NULL);

　if (FAILED(hr))

　　return false;

　pBf.Release();

　//设定视频窗口

　//设定视频窗口为主窗口的一个子窗口

　hr=m_pVW->put_Owner((OAHWND)hWnd);

　if (FAILED(hr))

　　return false;

　//设定窗口样式

　m_pVW->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN);

　if (FAILED(hr))

　　return false;

　//设定窗口大小

　CRect rectClient;

　GetClientRect(hWnd,rectClient);

　m_pVW->SetWindowPosition(0, 0, 320, 240);

　//设定可视

　hr=m_pVW->put_Visible(OATRUE);

　if (FAILED(hr))

　　return false;

　　//将对象加入到运行对象列表中

　CComPtr pROT;

　GetRunningObjectTable(0,&pROT);

　WCHAR c[128];

　wsprintfW(c, L"FilterGraph %08x pid %08x\0", (DWORD_PTR)m_pGraph.p, GetCurrentProcessId());

　hr = CreateItemMoniker(L"!",c,&pM);

　if (FAILED(hr))

　　return false;

　hr = pROT->Register(ROTFLAGS_REGISTRATIONKEEPSALIVE,m_pGraph,pM,&m_dwGraphRegister);

　pM.Release();

　return false;

　}