'C++ - Qt Creator - /How to have DOT and COMMA as decimal separator on a QDoubleSpinBox?

I am building a C++ GUI application on QT Creator. I changed the location to Portuguese/Brazil, now only comma is the decimal separator.

I need the QDoubleSpinBox to get as decimal separator dot and comma. Officialy comma is the separator in Portuguese, but some keyboard only have points in the numeric part.

Please help,

c++qt


Solution 1:[1]

subClass QDoubleSpinBox and reimplement the virtual method validate

full solution here :

customSpinBox.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QRegExpValidator>
#include <QDoubleSpinBox>



class CustomSpinBox : public QDoubleSpinBox {
    Q_OBJECT

public:
    explicit CustomSpinBox(QWidget* parent =0);
    virtual QValidator::State validate(QString & text, int & pos) const;

private:
    QRegExpValidator* validator;

};
#endif // WIDGET_H

customSpinBox.cpp

CustomSpinBox::CustomSpinBox(QWidget *parent):QDoubleSpinBox(parent),
  validator(new QRegExpValidator(this))
{
    validator->setRegExp(QRegExp("\\d{1,}(?:[,.]{1})\\d*"));
}

QValidator::State CustomSpinBox::validate(QString &text, int &pos) const
{
    return validator->validate(text,pos);
}

Solution 2:[2]

I tried to converted the solution from basslo to Qt 6.0 but it failed to accept integer numbers. The following solution works fine for me with Qt 6.0

#pragma once
#include <qtWidgets>

class CRelaxedDoubleSpinBox : public QDoubleSpinBox {
    Q_OBJECT

public:
    explicit CRelaxedDoubleSpinBox(QWidget* parent =0) : QDoubleSpinBox(parent)
    {
    }

    virtual QValidator::State validate(QString & text, int & pos) const
    {
        QString s = QString(text).replace(".", ",");
        return QDoubleSpinBox::validate(s,pos);
    }

    double valueFromText(const QString& text) const
    {
        QString s = QString(text).replace(",", ".");
        return s.toDouble();
    }
};

Solution 3:[3]

You can subclass QDoubleSpinBox and reimplement the validate method to accept both the dot and the comma as the decimal separator. I think you can get by with just adding a special check when the input is a period and allow it to be accepted (provided there are no other periods or commas in the string), but otherwise call the base class implementation. I haven't compiled or tested this, but I think this is pretty close:

MyDoubleSpinBox::validate (QString &input, int &pos)
{
    if (input == ".")
        {
        return (text ().contains (".") || text ().contains (",")) ? QValidator::Invalid : QValidator::Acceptable;
        }

     return QDoubleSpinBox::validate (input, pos);
}

Solution 4:[4]

I'm using PySide6 and I adapted to the Python language the wonderful solution provided by @RED SOFT ADAIR to Python:

from PySide6.QtWidgets import QDoubleSpinBox,

class CustomDoubleSpinbox(QDoubleSpinBox):
    def validate(self, text: str, pos: int) -> object:
        text = text.replace(".", ",")
        return QDoubleSpinBox.validate(self, text, pos)

    def valueFromText(self, text: str) -> float:
        text = text.replace(",", ".")
        return float(text)

Here it is in case anyone ended up here in a similar situation.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 basslo
Solution 2 RED SOFT ADAIR
Solution 3 goug
Solution 4 Kastakin

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