QSlider PyQt - Python

Introduction

In PyQt, QSlider is a widget used to implement a slider control that allows the user to select a value by sliding a handle horizontally or vertically.

Installing PyQt

To use QSlider in Python, you need to install PyQt. To do this, you can use pip:

pip install PyQt5

Alternatively, if you prefer to use PyQt4, you can install it with:

pip install PyQt4

Creating a QSlider

To create a slider control in your PyQt application, you first need to create an instance of the QSlider class. You can do this using the following code:

# Import required modules
from PyQt5.QtWidgets import QApplication, QWidget, QSlider
from PyQt5.QtCore import Qt

# Create an instance of the QSlider class
slider = QSlider(Qt.Horizontal)

This creates a horizontal slider control. You can also create a vertical slider by passing Qt.Vertical as the argument to the QSlider constructor.

Setting the Range and Value

The range of a slider is the minimum and maximum values that it can represent. By default, the minimum value is 0 and the maximum value is 99. To set the range of a slider, you can use the setRange method:

slider.setRange(0, 100)

To set the initial value of a slider, you can use the setValue method:

slider.setValue(50)

This sets the value of the slider to 50.

Getting the Value

To get the current value of a slider, you can use the value method:

value = slider.value()

This returns the current value of the slider.

Responding to Changes

To respond to changes in the value of a slider, you can connect its valueChanged signal to a slot function:

# Slot function to handle value changes
def on_value_changed(value):
    print('Value: {}'.format(value))

# Connect the signal to the slot
slider.valueChanged.connect(on_value_changed)

This connects the valueChanged signal of the slider to the on_value_changed function. Whenever the value of the slider changes, the on_value_changed function will be called with the new value as its argument.

Conclusion

QSlider is a powerful widget in PyQt that allows you to add slider controls to your application. With the methods and signals available in QSlider, you can easily set the range, value, and respond to changes in the slider value.