PyQt5 - 02 对closeEvent()重写，添加关闭窗口触发的事件

对《PyQt5 - 01 使用qt creator创建第一个pyqt5界面程序》中的程序进行修改，通过重写closeEvent()方法实现退出时给出提示框

对.ui文件生成的代码修改：

《PyQt5 - 01 使用qt creator创建第一个pyqt5界面程序》中的源码：

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'dialog.ui'
#
# Created by: PyQt5 UI code generator 5.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets
import sys

class Ui_Dialog(object):
def setupUi(self, Dialog):
Dialog.setObjectName("Dialog")
Dialog.resize(640, 480)
self.pushButton = QtWidgets.QPushButton(Dialog)
self.pushButton.setGeometry(QtCore.QRect(370, 80, 113, 32))
self.pushButton.setObjectName("pushButton")
self.lineEdit = QtWidgets.QLineEdit(Dialog)
self.lineEdit.setGeometry(QtCore.QRect(140, 80, 113, 21))
self.lineEdit.setObjectName("lineEdit")
self.textBrowser = QtWidgets.QTextBrowser(Dialog)
self.textBrowser.setGeometry(QtCore.QRect(180, 200, 256, 192))
self.textBrowser.setObjectName("textBrowser")
self.label = QtWidgets.QLabel(Dialog)
self.label.setGeometry(QtCore.QRect(30, 80, 111, 16))
self.label.setObjectName("label")
self.label_2 = QtWidgets.QLabel(Dialog)
self.label_2.setGeometry(QtCore.QRect(30, 220, 141, 16))
self.label_2.setObjectName("label_2")

self.retranslateUi(Dialog)
QtCore.QMetaObject.connectSlotsByName(Dialog)

def retranslateUi(self, Dialog):
_translate = QtCore.QCoreApplication.translate
Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
self.pushButton.setText(_translate("Dialog", "PushButton"))
self.label.setText(_translate("Dialog", "这是Line Edit ->"))
self.label_2.setText(_translate("Dialog", "这是Text Browser ->"))

def main():
"""
主函数，用于运行程序
:return: None
"""
app = QtWidgets.QApplication(sys.argv)
dialog = QtWidgets.QDialog()
ui = Ui_Dialog()
ui.setupUi(dialog)
dialog.show()
sys.exit(app.exec_())

if __name__ == '__main__':
main()

分析main()函数：

def main():
"""
主函数，用于运行程序
:return: None
"""
app = QtWidgets.QApplication(sys.argv)
dialog = QtWidgets.QDialog()  # 创建一个QDialog窗口对象，
ui = Ui_Dialog()  # 创建一个自定义的控件布局对象
ui.setupUi(dialog)  # 将布局传入QDialog窗口
dialog.show()  # 显示QDialog窗口
sys.exit(app.exec_())

从main()方法中看到我们最终显示的是QDialog类创建的窗口对象，如果想要实现关闭窗口触发弹窗提示或执行一些其他方法，需要重写的是QDialog类中的closeEvent()方法，而不是重写我们创建的Ui_Dialog类的closeEvent()方法。

原理：关闭窗口时会执行类的close()方法，并触发QCloseEvent信号，进而执行closeEvent(self, QCloseEvent)方法。

添加代码如下：

class Dialog(QtWidgets.QDialog):
"""对QDialog类重写，实现一些功能"""

def closeEvent(self, event):
"""
重写closeEvent方法，实现dialog窗体关闭时执行一些代码
:param event: close()触发的事件
:return: None
"""
reply = QtWidgets.QMessageBox.question(self,
'本程序',
"是否要退出程序？",
QtWidgets.QMessageBox.Yes | QtWidgets.QMessageBox.No,
QtWidgets.QMessageBox.No)
if reply == QtWidgets.QMessageBox.Yes:
event.accept()
else:
event.ignore()

完整代码如下：

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'dialog.ui'
#
# Created by: PyQt5 UI code generator 5.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets
import sys

class Ui_Dialog(object):
def setupUi(self, Dialog):
Dialog.setObjectName("Dialog")
Dialog.resize(640, 480)
self.pushButton = QtWidgets.QPushButton(Dialog)
self.pushButton.setGeometry(QtCore.QRect(370, 80, 113, 32))
self.pushButton.setObjectName("pushButton")
self.lineEdit = QtWidgets.QLineEdit(Dialog)
self.lineEdit.setGeometry(QtCore.QRect(140, 80, 113, 21))
self.lineEdit.setObjectName("lineEdit")
self.textBrowser = QtWidgets.QTextBrowser(Dialog)
self.textBrowser.setGeometry(QtCore.QRect(180, 200, 256, 192))
self.textBrowser.setObjectName("textBrowser")
self.label = QtWidgets.QLabel(Dialog)
self.label.setGeometry(QtCore.QRect(30, 80, 111, 16))
self.label.setObjectName("label")
self.label_2 = QtWidgets.QLabel(Dialog)
self.label_2.setGeometry(QtCore.QRect(30, 220, 141, 16))
self.label_2.setObjectName("label_2")

self.retranslateUi(Dialog)
QtCore.QMetaObject.connectSlotsByName(Dialog)

def retranslateUi(self, Dialog):
_translate = QtCore.QCoreApplication.translate
Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
self.pushButton.setText(_translate("Dialog", "PushButton"))
self.label.setText(_translate("Dialog", "这是Line Edit ->"))
self.label_2.setText(_translate("Dialog", "这是Text Browser ->"))

class Dialog(QtWidgets.QDialog):
"""对QDialog类重写，实现一些功能"""

def closeEvent(self, event):
"""
重写closeEvent方法，实现dialog窗体关闭时执行一些代码
:param event: close()触发的事件
:return: None
"""
reply = QtWidgets.QMessageBox.question(self,
'本程序',
"是否要退出程序？",
QtWidgets.QMessageBox.Yes | QtWidgets.QMessageBox.No,
QtWidgets.QMessageBox.No)
if reply == QtWidgets.QMessageBox.Yes:
event.accept()
else:
event.ignore()

def main():
"""
主函数，用于运行程序
:return: None
"""
app = QtWidgets.QApplication(sys.argv)
dialog = Dialog()  # 注意修改为了自己重写的Dialog类
ui = Ui_Dialog()
ui.setupUi(dialog)
dialog.show()  # 显示了自己重写的Dialog类
sys.exit(app.exec_())

if __name__ == '__main__':
main()