Set string to QDoubleSpinBox

Question

Regarding some task I must do the following. Consider I have a QDoubleSpinBox with positive values from 0 to 1000. And every time when user tries to lower the value of spinbox, f.e. to click the down button when value is 0, the value of spinbox must be string "unset". I tried to do this, to clear the value of spinbox and then setPrefix. But it did not worked. Any other solutions?

Hm, but QDoubleSpinBox is to display floating point numbers. However you want to set a string? Maybe using a label along with the spin box would be better idea? — vahancho, Nov 14 '14 at 08:24

score 11 · Accepted Answer · answered Nov 14 '14 at 08:40

11

You can try specialValueText.

This is a example:

#include <QApplication>
#include <QDoubleSpinBox>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QDoubleSpinBox doubleSpinBox;
    doubleSpinBox.setRange(0.f, 1000.f);
    doubleSpinBox.setValue(1.f);
    doubleSpinBox.setSpecialValueText("unset");

    doubleSpinBox.show();
    return a.exec();
}

when value is 0, the value of spinbox must be string "unset".

answered Nov 14 '14 at 08:40

pezy

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Nice functionality: Using Qt quite a while and never thought something like this exists. Thanks for your tip! – Robert Nov 14 '14 at 08:47
For those wondering, to unset this just call doubleSpinBox.setSpecialValueText("") – nicolaum Sep 02 '23 at 11:55

score 6 · Answer 2 · edited May 23 '17 at 12:21

There are two solutions to achieve what you want.

As pezy in the other answer says using setSpecialValueText where the text is shown when the current value() == minimum() of the spinbox

or a bit more powerful: subclass QSpinBox and override following functions:

int valueFromText(const QString &text) const;
QString textFromValue(int value) const;
QValidator::State validate(QString & input, int & pos) const;

Have a look here, trying something similar QSpinBox enter NaN as a valid value.

score -1 · Answer 3 · answered Nov 14 '14 at 08:26

-1

Sub class QSpinBox and define your behavior.
Take a look at this example

answered Nov 14 '14 at 08:26

Pratham

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Set string to QDoubleSpinBox

3 Answers3