结构体调用

#include "FrameProducer.h"
#include <iostream>

class FrameFromCamera: public FrameProducer {
public:
    FrameFromCamera();
    virtual ~FrameFromCamera();

    cv::Mat giveFrame();
    bool isend();

    std::string getFilename() {
        return "camera";
    }
private:
    cv::VideoCapture cap;
};

#endif /* FRAMEFROMCAMERA_H_ */

#include "FrameFromCamera.h"

FrameFromCamera::FrameFromCamera() {
    cap.open(0);

    if( !cap.isOpened() )
    {
        std::cerr << "Failed to open capture device" << std::endl;
        exit(2);
    }

}

FrameFromCamera::~FrameFromCamera() {

}

cv::Mat FrameFromCamera::giveFrame() {
    cv::Mat frame;

    // keep hoping to receive a frame
    do {
        cap >>frame;
        std::cout << "." << std::endl;
    } while(frame.empty());

    return frame;
}

bool FrameFromCamera::isend() {
    return false;
}

调用先申明结构体变量，再通过->或者 .来调用结构体成员函数 give frame

FrameFromCamera a;

cv::Mat Frame = a.giveFrame();