使用dshow捕获摄像头图像

#include "stdafx.h"
#include <DShow.h>
#include <Guiddef.h>
#include <strmif.h>  

#define CHECK_HR(s) if (FAILED(s)) {return 1;}
#define SAFE_RELEASE(p)     do { if ((p)) { (p)->Release(); (p) = NULL; } } while(0)  

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

#pragma comment(lib, "Dxguid.lib")
#pragma comment(lib, "Strmiids.lib")  

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    CoInitialize(NULL);
    int nRes = ;

    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = ;
    wcex.cbWndExtra = ;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + );
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = _T("dshow capture");
    wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(NULL, _T("Call to RegisterClassEx failed!"), _T("Win32 Guided Tour"), NULL);

        return ;
    }

    HWND m_hWnd = ::CreateWindowA("STATIC", "ds_video_preview", WS_POPUP, , , , , NULL, NULL, NULL, NULL);
    ShowWindow(m_hWnd, nCmdShow);
    UpdateWindow(m_hWnd);

    if (m_hWnd == NULL)
    {
        nRes = ;
    }

    //----------------------用dshow获取摄像头---start--------------------------

    IGraphBuilder         *m_pGraph;//filter总图表管理器
    ICaptureGraphBuilder2 *m_pBuild;//捕获图表管理器
    IVideoWindow          *m_pVidWin;//窗口接口
    HRESULT hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&m_pGraph);
    CHECK_HR();
    hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&m_pBuild);
    CHECK_HR();
    hr = m_pBuild->SetFiltergraph(m_pGraph);//给捕获图表管理器指定一个可用的图表管理器来进行使用
    CHECK_HR();
    hr = m_pGraph->QueryInterface(IID_IVideoWindow, (void **)&m_pVidWin);//通过此函数来查询某个组件是否支持某个特定的接口,如果支持就返回这些接口的指针
    CHECK_HR();

    ICreateDevEnum *pDevEnum = NULL;
    IEnumMoniker *pClsEnum = NULL;
    IMoniker *pMoniker = NULL;
    //创建设备枚举COM对象
    hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC, IID_ICreateDevEnum, (void **)&pDevEnum);
    CHECK_HR();
    //创建视频采集设备枚举COM对象
    hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pClsEnum, );
    CHECK_HR();

    int i = ;
    while (i <= )
    {
        hr = pClsEnum->Next(, &pMoniker, NULL);
        ++i;
    }
    CHECK_HR();

    IBaseFilter           *m_pSrc;
    hr = pMoniker->BindToObject(, , IID_IBaseFilter, (void **)&m_pSrc);//就是这句获得Filter
    CHECK_HR();

    SAFE_RELEASE(pMoniker);
    SAFE_RELEASE(pClsEnum);
    SAFE_RELEASE(pDevEnum);

    //将设备添加到filter管理器graph
    hr = m_pGraph->AddFilter(m_pSrc, L"Video Capture");
    CHECK_HR();

    hr = m_pBuild->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, m_pSrc, NULL, NULL);
    CHECK_HR();

    m_pVidWin->put_Owner((OAHWND)m_hWnd);
    m_pVidWin->SetWindowPosition(, , , );
    m_pVidWin->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS);

    //IMediaControl接口,用来控制流媒体在Filter Graph中的流动,例如流媒体的启动和停止
    IMediaControl         *m_pMediaControl;
    hr = m_pGraph->QueryInterface(IID_IMediaControl, (void **)&m_pMediaControl);
    CHECK_HR();

    hr = m_pMediaControl->Run();

    //----------------------用dshow获取摄像头---end--------------------------

    MSG msg;
    while (GetMessage(&msg, NULL, , ))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;

}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR greeting[] = _T("Hello, World!");

    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        TextOut(hdc, , , greeting, _tcslen(greeting));
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage();
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return ;
}