windows下摄像头的使用

windows下提供了调用摄像头的相关api函数，函数定义包含在vfw.h头文件中。

http://msdn.microsoft.com/zh-cn/dd757677 这个地址提供了完整的教程。

下面贴出一个简单的例子

头文件：

#ifndef pvcamerasnapshoter_h
#define pvcamerasnapshoter_h

#include <QtGui/QWidget>
#include <QtGui/QPixmap>
#include <QtCore/QByteArray>
#include <Windows.h>
#include <Vfw.h>
#pragma comment(lib,"Vfw32.lib")

class pvCameraSnapshoter : public QWidget
{
    Q_OBJECT

public:
    pvCameraSnapshoter(QWidget *parent = 0);

    ~pvCameraSnapshoter(void);
    
    bool OpenCamera();            //初始化摄像头

    void CloseCamera();

    QPixmap GetCameraSnapshot();   //保持一帧图片数据

private:
    HWND cameraScreenHwnd;

};

#endif //pvcamerasnapshoter_h

实现文件：

#include <tchar.h>
#include <QtGui/QBitmap>
#include <QtCore/QByteArray>

#include "pvCameraSnapshoter.h"
#include "../common/pvcmuserpath.h"

LRESULT PASCAL SnapshotFrameCbProc(HWND hWnd, LPVIDEOHDR lpVHdr);        //回调函数用于处理接收到的图像数据

pvCameraSnapshoter::pvCameraSnapshoter(QWidget *parent) :
    QWidget(parent)
{

}

pvCameraSnapshoter::~pvCameraSnapshoter(void)
{
}

bool pvCameraSnapshoter::OpenCamera()
{
    LPTSTR lpszName = new TCHAR[100];
    LPTSTR lpszVer = new TCHAR[100];
    
    capGetDriverDescription(0,lpszName,100,lpszVer,100);
    cameraScreenHwnd = capCreateCaptureWindow(lpszName, WS_CHILD | WS_VISIBLE, 0, 0, width(), height(), winId(), 0); //创建一个用来显示摄像头视频的窗口
    if(cameraScreenHwnd == INVALID_HANDLE_VALUE)
    {
        return false;
    }
    if(capDriverConnect(cameraScreenHwnd,0))       //与链接摄像头
    {
        capPreview(cameraScreenHwnd,true);         //设置娱乐模式，这样与摄像头关联的窗口就可以自动显示视频数据了
        capPreviewRate(cameraScreenHwnd,60);       //每秒60帧

        BITMAPINFO bitmapinfo;
        memset(&bitmapinfo,0,sizeof(BITMAPINFO));
        bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
        bitmapinfo.bmiHeader.biWidth = 320;
        bitmapinfo.bmiHeader.biHeight = 240;
        bitmapinfo.bmiHeader.biPlanes = 1;
        bitmapinfo.bmiHeader.biBitCount = 32;
        bitmapinfo.bmiHeader.biCompression = BI_RGB;
        
        capSetVideoFormat(cameraScreenHwnd, &bitmapinfo, sizeof(bitmapinfo)); //设置摄像头的视频格式，不过这个函数好像不起作用
        capSetUserData(cameraScreenHwnd,this);   //添加用户数据，在回调函数中可能会用到
        capSetCallbackOnFrame(cameraScreenHwnd,SnapshotFrameCbProc);  //设置回调函数，摄像头的视频数据每一帧都会经过这个函数
        return true;
    }
    return false;
}

void pvCameraSnapshoter::CloseCamera()
{
    capDriverDisconnect(cameraScreenHwnd);
}

QPixmap pvCameraSnapshoter::GetCameraSnapshot()
{
    QPixmap cameraSnapshot;
    if(cameraScreenHwnd == INVALID_HANDLE_VALUE)
    {
        return cameraSnapshot;
    }
    if(capGrabFrameNoStop(cameraScreenHwnd)) //抓取一帧图像数据，与capGrabFrame相比，它不会停止预览模式和重叠
    {
        pvcmUserPath userpath;
        QString strSnapshotFile = userpath.GetUserSubPath("camerasnapshot").filePath("snapshot.bmp");
        const wchar_t* wSnapshotpath = reinterpret_cast<const wchar_t*>(strSnapshotFile.utf16());
        if(!capFileSaveDIB(cameraScreenHwnd,wSnapshotpath))   //保持摄像头快照
        {
            qDebug("save camerasnapshot fail");
            return cameraSnapshot;
        }
        cameraSnapshot.load(strSnapshotFile);
    }
    return cameraSnapshot;
}

LRESULT PASCAL SnapshotFrameCbProc(HWND hWnd, LPVIDEOHDR lpVHdr) 
{ 
　　//这里处理视频数据return (LRESULT) TRUE ; 
}

#include "moc_pvcamerasnapshoter.cpp"