PyQt5 QScrollBar – 价值改变的信号

在这篇文章中，我们将看到如何获得QScrollBar的值改变信号。QScrollBar是一个控件，它使用户能够访问文档中比用来显示它的小部件更大的部分。滑块是滚动条内可滚动的对象。值基本上取决于滑块的位置，滚动条的值根据滑块的位置而变化，当滑块向下移动时值增加，当滑块向上移动时值减少。它可以在setValue方法的帮助下以编程方式设置。当滚动条的值发生变化时，就会发出这个信号。

为了做到这一点，我们将使用滚动条对象的valueChanged方法。

语法： roll.valueChanged.connect(method)

参数： 它把方法作为参数

返回： 它返回无

下面是实现

# 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)
 
        # setting value of scroll bar
        scroll.setValue(25)
 
        # making its background color to green
        scroll.setStyleSheet("background : lightgrey;")
 
        # creating a label
        label = QLabel("GeeksforGeeks", 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 app
App = QApplication(sys.argv)
 
# create the instance of our Window
window = Window()
 
# start the app
sys.exit(App.exec())