how to use cv::setMouseCallback

Question

I\'m trying to use cv::setMouseCallback in my c++ project. I just don\'t get it. let that I habe a class Stuff how can tell this class you got a frame and run the cv::se

Answer 1

you must declare a mouse handler as static inside your class. For instance, I have a dragger with a member mouser, that I want to be called. I declare an helper static void mouser, that cast the void* received and calls the member:

class dragger {

void mouser(int event, int x, int y) {
  current_img = original_img.clone();
  Point P(x, y);
  ...
}
static void mouser(int event, int x, int y, int, void* this_) {
  static_cast(this_)->mouser(event, x, y);
}

and instance in dragger constructor in this way

dragger(string w, Mat m) :
    window_id(w), status(0), original_img(m), /*black(0, 0, 0),*/ K(5, 5)
{
   ...
   setMouseCallback(w, mouser, this);
}

...
}