PyQt5 QSpinBox – 检查边距是否为 NULL ？

在本文中，我们将看到如何检查旋转框的边距是否为 NULL，默认情况下它设置为零，尽管我们可以使用旋转框对象的setContentsMargins方法来更改它。如果任何边距值大于 0，则旋转框边距不为 NULL。

注意：当每个边距值设置为 0 时，表示它们为 NULL

为此，我们使用isNull方法。

Syntax : margin.isNull()
Here margin is the QMargin object of the spin box

Argument : It takes no argument

Return : It returns bool

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, 600, 400)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
        # method for widgets
    def UiComponents(self):
        # creating spin box
        self.spin = QSpinBox(self)
  
        # setting geometry to spin box
        self.spin.setGeometry(100, 100, 250, 40)
  
        # setting range to the spin box
        self.spin.setRange(0, 999999)
  
        # setting prefix to spin
        self.spin.setPrefix("Prefix ")
  
        # setting suffix to spin
        self.spin.setSuffix(" Suffix")
  
        # creating label
        label = QLabel(self)
  
        # setting geometry to the label
        label.setGeometry(100, 200, 200, 70)
  
        # making it multi line label
        label.setWordWrap(True)
  
        # setting content margins
        self.spin.setContentsMargins(1, 0, 0, 0)
  
        # getting content margins
        margin = self.spin.contentsMargins()
  
        # checking if margin is NULL
        check = margin.isNull()
  
        # setting text to the label
        label.setText("BMargin is NULL ? : " + str(check))
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
window.spin.setFocus()
# start the app
sys.exit(App.exec())

输出 ：