#include <QSlider>
#include <functional>
#include <QLabel>

template<typename T = int>
class Slider : public QSlider {
public:
	explicit Slider(QLabel* label, const char *format, T * target,
					const std::function<T(int)> &convertToT = [](int v){ return T(v); },
					const std::function<int(T)> &convertFromT = [](T v){ return int(v); }) : QSlider(Qt::Horizontal) {
		this->convertToT = convertToT;
		this->convertFromT = convertFromT;
		this->target = target;

		connect(this, &QSlider::valueChanged, this, [=, this](int newValue){
			T convertedValue = convertToT(newValue);

			char buff[100];
			snprintf(buff, sizeof(buff), format, convertedValue);
			label->setText(buff);

			targetOld = *target;
			*target = convertedValue;
		});
	}

	void setFromTarget(){
		setValue(convertFromT(*target));
	}

	T targetOld;

private:
	T * target;
	std::function<T(int)> convertToT;
	std::function<int(T)> convertFromT;
};