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PyQt5 QScrollBar – Getting Range Changed Signal

  • Last Updated : 29 Jul, 2020
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In this article we will see how we can get the range changed signal of QScrollBar. QScrollBar is a control that enables the user to access parts of a document that is larger than the widget used to display it. Slider is the scroll-able object inside the bar. By default value range from 0 to 99. Value is basically depend upon the slider position, scroll bar value changes according to the position of the slider, value increases when slider goes down and decreases when slider moves up. It can be programmatically set with the help of setValue method. Range is basically a combination of minimum and maximum value which can be set with the help of setRange method. This signal is emitted when the slider range has changed, with min being the new minimum, and max being the new maximum.

In order to do this we will use rangeChanged method with the scroll bar object.

Syntax : scroll.rangeChanged.connect(method)

Argument : It takes method as argument

Return : It returns None



Below is the implementation




# importing libraries
from PyQt5.QtWidgets import * 
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import * 
from PyQt5.QtCore import * 
import sys
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Python ")
  
        # setting geometry
        self.setGeometry(100, 100, 500, 400)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
  
  
    # method for components
    def UiComponents(self):
  
        scroll = QScrollBar(self)
  
        # setting geometry of the scroll bar
        scroll.setGeometry(100, 50, 30, 200)
  
        # making its background color to green
        scroll.setStyleSheet("background : lightgrey;")
  
        # creating a label
        label = QLabel("GeesforGeeks", self)
  
        # setting geometry to the label
        label.setGeometry(200, 100, 300, 80)
  
        # making label multi line
        label.setWordWrap(True)
  
        # getting range changed signal
        scroll.rangeChanged.connect(lambda: do_action())
  
        # method called when signal is emitted
        def do_action():
              
            # setting text to the label
            label.setText("Range Changed Signal Emitted")
              
  
        # setting range of scroll bar
        scroll.setRange(200, 250)
  
  
  
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

Output :

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