PyQt QSpinBox

Summary: in this tutorial, you’ll learn how to use the PyQt QSpinBox widget to create a spin box.

Introduction to the PyQt QSpinBox widget

A spin box combines a text entry and an up-down control. The up-down control allows you to spin through a set of incremental values:

 PyQt QSpinBox

The values of a spin box can be integers or discrete sets of values e.g., days of weeks and months of years.

A spin box allows you to increase or decrease a value by clicking the up/down buttons or pressing the up/down key on the keyboard. Also, you can type a value manually in the spin box.

To create a spin box, you use the QSpintBox class:

QSpinBox()
Code language: Python (python)

Whenever the value of a spin box changes, it emits the valueChanged() signal that sends the current value as an integer.

In addition, the QSpinBox emits the textChanged signal that provides a spin box’s value as an instance of the QString.

The following table lists some useful properties of the QSpinBox:

PropertyDescription
valueThe current integer value of the spin box.
cleanTextThe current string value of the spin box (excludes the prefix and suffix).
maximumThe maximum integer value of the spin box
minimumThe minimum integer value of the spin box.
prefixA string that prepends to the displayed value.
suffixA string that appends to the displayed value.
singleStepAn increment/decrement integer value when up/down arrows are clicked
wrappingis a boolean value that determines whether to wrap from one end of the range to the other when the up/down arrows are clicked.

Let’s take an example of using the PyQt QSpinBox class.

PyQt QSpinBox example

The following program displays a spin box that allows you to enter an amount between one and 100:

import sys from PyQt6.QtWidgets import QApplication, QWidget, QSpinBox, QLabel, QFormLayout from PyQt6.QtCore import Qt class MainWindow(QWidget): def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self.setWindowTitle('PyQt QSpinBox') self.setMinimumWidth(300) # create a grid layout layout = QFormLayout() self.setLayout(layout) amount = QSpinBox(minimum=1, maximum=100, value=20, prefix='$') amount.valueChanged.connect(self.update) self.result_label = QLabel('', self) layout.addRow('Amount:', amount) layout.addRow(self.result_label) # show the window self.show() def update(self, value): self.result_label.setText(f'Current Value: {value}') if __name__ == '__main__': app = QApplication(sys.argv) window = MainWindow() sys.exit(app.exec())
Code language: Python (python)

How it works.

First, create a QSpinBox object with the minimum, maximum, value, and prefix options:

amount = QSpinBox(minimum=1, maximum=100, value=20, prefix='$')
Code language: Python (python)

Second, connect the valueChanged signal to the update() method:

amount.valueChanged.connect(self.update)
Code language: Python (python)

Third, create a QLabel for displaying the current value of the spin box:

self.result_label = QLabel('', self)
Code language: Python (python)

Finally, define the update() method that changes the value of the result label whenever the value of the spin box changes:

def update(self, value): self.result_label.setText(f'Current Value: {value}')
Code language: Python (python)

Summary

  • Use QSpinBox class to create a spin box.
  • Connect to the valueChanged signal to trigger an action when the current value of a spin box changes
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