Question

I’m using OpenCV’s highgui include to be able to get mouse click locations on my image. I’ve defined a vector<2f> that I would like to store the points that have been clicked within, but unfortunately, I think I’m doing something wrong:

void on_mouse(int mouseEvent, int x, int y, int flags, void* param)
{
    if( mouseEvent == CV_EVENT_LBUTTONDOWN) {

        printf("Clicked image at (%d,%d)\n", x, y);

        (vector<Point2f>*)param.push_back(Point2f(x,y));

    }
}

My compiler gives me an error on param and says Error: Expression must have class type.
Can anyone suggest how else to cast as a vector structure? or what I am doing incorrectly?

Answer 1

    (vector<Point2f>*)param.push_back(Point2f(x,y));

Should be:

    reinterpret_cast<vector<Point2f>*>(param)->push_back(Point2f(x,y));