CODEWITHSUNDEEP
pythonpyqtpyqt4
Hongzheng
Hongzheng

Reputation: 23

How to constrain a QSpinBox to valid values

Suppose I want a QSpinBox to have valid values from 0 to 10 with a step of 2 (i.e., 0, 2, 4, 6, 8, 10). I can set the QSpinBox to have minimum of 0 and maximum of 10, with a singleStep of 2. If users click the up/down arrows, it works well. However, if user type in an odd number (say 3), the spinbox still think it is valid and accepts it. Whatelse should I do so that my QSpinBox will not allow odd numbers in this case?

Upvotes: 2

Views: 2224

Answers (1)

eyllanesc
eyllanesc

Reputation: 244301

To correct this problem you can implement the valueChanged signal, verify if the value is correct, if it is not modicas nothing, in contrast if not, you place the previous value.

Example:

import sys

from PyQt4.QtCore import pyqtSignal
from PyQt4.QtGui import QApplication, QSpinBox


class SpinBox(QSpinBox):
    # Replaces the valueChanged signal
    newValueChanged = pyqtSignal(int)

    def __init__(self, parent=None):
        super(SpinBox, self).__init__(parent=parent)

        self.valueChanged.connect(self.onValueChanged)
        self.before_value = self.value()
        self.newValueChanged.connect(self.slot)

    def onValueChanged(self, i):
        if not self.isValid(i):
            self.setValue(self.before_value)
        else:
            self.newValueChanged.emit(i)
            self.before_value = i

    def isValid(self, value):
        if (self.minimum() - value % self.singleStep()) == 0:
            return True
        return False

    def slot(self, value):
        print(value)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    w = SpinBox()
    w.setMinimum(0)
    w.setMaximum(10)
    w.setSingleStep(2)
    w.show()
    sys.exit(app.exec_())

Upvotes: 2

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