opencv调用摄像头截图保存图片

int process(VideoCapture& capture)

{
    int n = 0;
    char filename[200];
    string window_name = "video | q or esc to quit";
    cout << " \n\t按下【Space】空格键可以截图，图片将存放在工程目录下。\n\n\t【Esc】和【q】键 - 退出程序。 " << endl;
    namedWindow(window_name, CV_WINDOW_KEEPRATIO); //resizable window;
    Mat frame;
    for (;;)
    {
        capture >> frame;
        if (frame.empty())
            break;
        cv::Mat gray;
        cv::cvtColor(frame,gray,COLOR_RGB2GRAY);//转换为灰度图
        //vector<string> codes;
vector<DataMatrixCode> codes;
        Mat corners;
        findDataMatrix(gray, codes);
        drawDataMatrixCodes(codes, frame);
        imshow(window_name, frame);
        char key = (char) waitKey(1); //delay N millis, usually long enough to display and capture input
        switch (key)
        {
            case 'q':
            case 'Q':
            case 27: //escape key
                return 0;
            case ' ': //Save an image
                sprintf(filename, "视频截图%.3d.jpg", n++);
                imwrite(filename, frame);
                cout << "\n\t>保存了 " << filename <<"文件到工程目录下"<< endl;
                break;
            default:
                break;
        }
    }
    return 0;

}

//-----------------------------------【main( )函数】--------------------------------------------
// 描述：控制台应用程序的入口函数，我们的程序从这里开始
//-------------------------------------------------------------------------------------------------
int main( )  
{  
//【1】从摄像头读入视频
VideoCapture capture(0);
if (!capture.isOpened())
    {
        cerr << "Failed to open a video device or video file!\n" << endl;
        return 1;
    }
    return process(capture);  

}