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Question

我的目标是创建一个vector<Rect>，现在我只从一个Rect开始，包含用户在一个框架中创建的任意数量的ROI，最初是从摄像机拍摄的。通过在按下并抬起鼠标时抓取点来创建ROI。

我知道填充投资回报率的代码正在onMouse使用已注释的cout。如果我尝试在setup函数的while循环中打印出ROI，则它为空。我搞砸了指针还是别的什么？

using namespace std;
using namespace cv;

//Global Variables
Point P1(0,0);
Point P2(0,0);
bool complete = false;

struct MouseParams
{
    Mat img;
    Point pt;
    int lucky;
};


void onMouse ( int event, int x, int y, int d, void *ptr ){
    switch(event){
        //mouse pressed (get coordinate of first point)
        case CV_EVENT_LBUTTONDOWN:
            cout << "press" << endl;
            P1.x=x;
            P1.y=y;
            break;
        //mouse lifted (get coordinate of final point)
        case CV_EVENT_LBUTTONUP:
            cout << "lift" << endl;
            P2.x=x;
            P2.y=y;
            complete = true;
            break;
        default:
            break;
    }
    //If lifted mosue and have two valid points()
    if(complete && P1 != P2){
        cout << "Building ROI" << endl;
        Rect*ROI = (Rect*)ptr;
        int w,h;
        h= P2.y-P1.y;
        w = P2.x-P1.x;

        ROI->x=x;
        ROI->y=y;
        ROI->width=w;
        ROI->height=h;
        cout << ROI << endl;
        complete = false;
    }
}

Rect setup(Mat frame){
    Rect ROI;
    while(true){
        namedWindow("ROI");
        setMouseCallback("ROI",onMouse, &ROI);
        cout << ROI << endl;
        //draw ROI grabbed in onMouse
        rectangle( frame, ROI, Scalar(0,255,0), 1, 8, 0 );
        imshow("ROI",frame);
        moveWindow("ROI", 0,50);
        waitKey(0);
        return ROI;
    }

}

UPDATE：修改waitkey（），因为它正在等待输入向前移动的while循环。现在代码可以保留最新的ROI（可以在设置框架中绘制很多）但需要适应保留向量，但感觉使用指针很难做到。

key = (char)waitKey(0);   // explicit cast
        if (key == 27) break;                // break if `esc' key was pressed.
        if (key == ' ') continue;;
    }
    destroyAllWindows();
    return ROI;