CODEWITHSUNDEEP
c++opencv
tschale
tschale

Reputation: 975

OpenCV Trackbar - show double value instead of int

I'm using createTrackbar(const string& trackbarname, const string& winname, int* value, int count, TrackbarCallback onChange=0, void* userdata=0) in openCV to get an input value, which needs to be a double in the range between 0 and 1. I can easily calculate the needed value from the trackbar position, but obviously the GUI only shows the int-value for the slider, which is a little bit irritating.

Is there any way to change the value the trackbar shows? I can't find any information about this in the documentation or tutorials...

Upvotes: 3

Views: 6670

Answers (3)

Martin R.
Martin R.

Reputation: 1642

Like already stated, this is not possible. Here is a little wrapper which calculates double values for you conveniently:

class DoubleTrack{
public:

    int int_value = 0;
    double precision;
    void(*user_callback)(double);

    void setup(const std::string& field_name, const std::string& window_name, void(*function)(double), double max_value, double default_value = 0, unsigned precision = 100){
            int_value = default_value * precision;
            createTrackbar(field_name, window_name, &int_value, max_value * precision, DoubleTrack::callback, this);
            user_callback = function;
            this->precision = precision;
    }

    static void callback(int, void* object){
        DoubleTrack* pObject = static_cast<DoubleTrack*>(object);
        pObject->user_callback(pObject->int_value / pObject->precision);
    }

};

static void test(double value){
    std::cout << value << std::endl;
}

DoubleTrack().setup("field_name", "window_name", test, 4.5);

Upvotes: 0

marol
marol

Reputation: 4074

AFAIK there is not possibility to pass double or other floating point value but still if you are okay let's say with 0.001 precision you can create a trackbar with max value 1000 and then simply treat its value as a double betwen 0 and 1 by dividing trackbar value by max value.

Upvotes: 0

Яois
Яois

Reputation: 3858

No, there is not. Unfortunately, the way the trackbar is implemented (with or without Qt) it does not support that.

Upvotes: 4

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