QDoubleSpinBox with leading zeros (always 4 digits)

Question

I have a QDoubleSpinBox in range 0-7000, but want the value always displayed as 4 digits (0-> 0000, 1 -> 0001 , 30 -> 0030, 3333 -> 3333).

I understand I can add a prefix, but a prefix is always added. What are my options?

Answer 1

If you use integers, then QSpinBox will be enough.

You can simply inherit from QSpinBox and re-implement the textFromValue function:

class MySpinBox: public QSpinBox 
{
    Q_OBJECT

public:
    MySpinBox( QWidget * parent = 0) :
        QSpinBox(parent)
    {
    }

    virtual QString textFromValue ( int value ) const
    {
        /* 4 - number of digits, 10 - base of number, '0' - pad character*/
        return QString("%1").arg(value, 4 , 10, QChar('0'));
    }
};

Filling QString this way does the trick.