In this article we will see how we can get the value 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. 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. This signal is emitted when the scroll bar value get changed.
In order to do this we will use valueChanged method with the scroll bar object.
Syntax : scroll.valueChanged.connect(method)
Argument : It takes method as argument
Return : It returns None
Below is the implementation
Python3
# importing librariesfrom PyQt5.QtWidgets import *from PyQt5 import QtCore, QtGuifrom PyQt5.QtGui import *from PyQt5.QtCore import *import sysclass 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) # setting value of scroll bar scroll.setValue(25) # making its background color to green scroll.setStyleSheet("background : lightgrey;") # creating a label label = QLabel("neveropen", self) # setting geometry to the label label.setGeometry(200, 100, 300, 80) # making label multi line label.setWordWrap(True) # getting value changed signal scroll.valueChanged.connect(lambda: do_action()) # method called when signal is emitted def do_action(): # getting current value value = scroll.value() # setting text to the label label.setText("Current Value : " + str(value))# create pyqt5 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
