If the value in the QDoubleSpinbox is positive, it shows no sign.
If the value is changed to a negative one, it automatically adds the "-" sign.
If the prefix is forced to "+", then the positive numbers will displayed with sign
doubleSB->setPrefix("+");
But the "+" will stay there and won't be automatically removed when the value set is negative
Is there a way to always show the correct sign?
A possible solution is to overwrite the textFromValue() method and add that character if necessary:
#include <QApplication>
#include <QDoubleSpinBox>
class DoubleSpinBox: public QDoubleSpinBox
{
public:
using QDoubleSpinBox::QDoubleSpinBox;
QString textFromValue(double value) const override
{
QString text = QDoubleSpinBox::textFromValue(value);
if(value > 0)
text.prepend(QChar('+'));
return text;
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
DoubleSpinBox w;
w.setMinimum(-100);
w.setSuffix("%");
w.show();
return a.exec();
}