[英]PyQt5 self reference
I used Qt Designer to design a GUI and use the command in PyQt5 to convert the .ui file to .py. 我使用Qt Designer来设计GUI,并使用PyQt5中的命令将.ui文件转换为.py。 From that, I want to output a messagebox when a button is clicked.
由此,我想在单击按钮时输出一个消息框。 I have successfully done it using this line of code on the function of the button listener:
我已经在按钮侦听器的功能上使用此行代码成功完成了此操作:
QtWidgets.QMessageBox.about(MainWindow, "Result", "Invalid number entered!")
I have searched around the internet but I don't understand why this one don't work. 我已经在互联网上进行搜索,但是我不明白为什么这一项不起作用。
QtWidgets.QMessageBox.about(self, "Result", "Invalid number entered!")
Does the self their refer to the MainWindow also? 他们自己也引用MainWindow吗?
Here is the full source code. 这是完整的源代码。
from PyQt5 import QtCore, QtGui, QtWidgets
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName("MainWindow")
MainWindow.setWindowModality(QtCore.Qt.WindowModal)
#MainWindow.resize(310, 185)
MainWindow.setFixedSize(310, 185)
MainWindow.setStyleSheet("#MainWindow\n"
"{\n"
" background-color:qradialgradient(spread:pad, cx:0.5, cy:0.5,
radius:1.696, fx:0.5, fy:0.505682, stop:0 rgba(0, 85, 255, 255), stop:1
rgba(255, 255, 255, 255))\n"
"}\n"
"\n"
"#firstNo_lineedit, #secondNo_lineedit\n"
"{\n"
" \n"
" background-color: rgb(28, 255, 123);\n"
"}\n"
"\n"
"")
self.centralwidget = QtWidgets.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.firstNo_lineedit = QtWidgets.QLineEdit(self.centralwidget)
self.firstNo_lineedit.setGeometry(QtCore.QRect(130, 40, 113, 20))
self.firstNo_lineedit.setObjectName("firstNo_lineedit")
self.secondNo_lineedit = QtWidgets.QLineEdit(self.centralwidget)
self.secondNo_lineedit.setGeometry(QtCore.QRect(130, 70, 113, 20))
self.secondNo_lineedit.setObjectName("secondNo_lineedit")
self.calculate_button = QtWidgets.QPushButton(self.centralwidget)
self.calculate_button.setGeometry(QtCore.QRect(170, 100, 75, 23))
self.calculate_button.setObjectName("calculate_button")
self.label = QtWidgets.QLabel(self.centralwidget)
self.label.setGeometry(QtCore.QRect(60, 40, 81, 20))
self.label.setObjectName("label")
self.label_2 = QtWidgets.QLabel(self.centralwidget)
self.label_2.setGeometry(QtCore.QRect(60, 70, 61, 20))
self.label_2.setObjectName("label_2")
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtWidgets.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 310, 21))
self.menubar.setObjectName("menubar")
self.menuAbout = QtWidgets.QMenu(self.menubar)
self.menuAbout.setObjectName("menuAbout")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtWidgets.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.menubar.addAction(self.menuAbout.menuAction())
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
# ================= Listeners ===================
self.calculate_button.clicked.connect(self.basicArithmetic)
# ============================================
# ================= Events ===================
def basicArithmetic(self):
try:
firstNo=float(self.firstNo_lineedit.text())
secondNo=float(self.secondNo_lineedit.text())
resSum=firstNo+secondNo
resDiff=firstNo-secondNo
resMul=firstNo*secondNo
resDiv=round(firstNo/secondNo,2)
print("Sum: {}".format(resSum))
print("Difference: {}".format(resDiff))
print("Product: {}".format(resMul))
print("Quotient: {}".format(resDiv))
toDisplay="Sum: {}".format(resSum)
toDisplay+="\n"
toDisplay+="Difference: {}".format(resDiff)
toDisplay+="\n"
toDisplay+="Product: {}".format(resMul)
toDisplay+="\n"
toDisplay+="Quotient: {}".format(resDiv)
#QtWidgets.QMessageBox.about(self, "Result", toDisplay)
QtWidgets.QMessageBox.about(MainWindow, "Result", toDisplay)
except ValueError:
#QtWidgets.QMessageBox.about(self, "Result", toDisplay)
QtWidgets.QMessageBox.about(MainWindow, "Result", "Invalid number entered!")
# ============================================
def retranslateUi(self, MainWindow):
_translate = QtCore.QCoreApplication.translate
MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
self.calculate_button.setText(_translate("MainWindow", "Calculate"))
self.label.setText(_translate("MainWindow", "First No.:"))
self.label_2.setText(_translate("MainWindow", "Second No.:"))
self.menuAbout.setTitle(_translate("MainWindow", "About"))
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
self
is the first parameter of the methods (the name is by convention, is not mandatory) of a class that refers to the instance of the same. self
是引用相同实例的类的方法的第一个参数(名称是按惯例,不是必需的)。
For another QMessageBox.about()
requires as first parameter an object of some kind that inherits from QWidget
or also None. 对于另一个
QMessageBox.about()
需要一个继承自QWidget
或None的某种对象作为第一个参数。
If we review the class generated by Qt Designer, we clearly see that it is not a widget, in fact the only objective of that class is to be an interface to fill in another widget: 如果我们查看由Qt Designer生成的类,我们会清楚地看到它不是小部件,实际上,该类的唯一目的是成为填充其他小部件的接口:
MainWindow = QtWidgets.QMainWindow() # create widget
ui = Ui_MainWindow() # create interface
ui.setupUi(MainWindow) # fill widget
Therefore the self
, the instance of Ui_MainWindow
, you want to pass is not appropriate because it does not refer to the widget, but the MainWindow
is a widget, so it works correctly with that change. 因此,要传递的
self
,即Ui_MainWindow
的实例是Ui_MainWindow
,因为它不引用窗口小部件,但是MainWindow
是窗口小部件,因此它可以正确地使用此更改。 Also within the generated file you have the following message: 此外,在生成的文件中,您还会显示以下消息:
# WARNING! All changes made in this file will be lost!
That message is because if you want to change the design you will have to overwrite the logic that you wrote, such as your basicArithmetic
method, which makes the project untenable. 该消息是因为,如果您要更改设计,则必须覆盖您编写的逻辑,例如
basicArithmetic
方法,这会使项目无法使用。
PyQt I recommend to create another class that uses the class that generates QtDesigner, I assume that the generated file is called design.py PyQt我建议创建另一个使用生成QtDesigner的类的类,我假设生成的文件名为design.py
design.py: design.py:
# -*- coding: utf-8 -*-
# Form implementation generated from reading ui file 'design.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
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName("MainWindow")
MainWindow.setWindowModality(QtCore.Qt.WindowModal)
#MainWindow.resize(310, 185)
MainWindow.setFixedSize(310, 185)
MainWindow.setStyleSheet("#MainWindow\n"
"{\n"
" background-color:qradialgradient(spread:pad, cx:0.5, cy:0.5,"
"radius:1.696, fx:0.5, fy:0.505682, stop:0 rgba(0, 85, 255, 255), stop:1"
"rgba(255, 255, 255, 255))\n"
"}\n"
"\n"
"#firstNo_lineedit, #secondNo_lineedit\n"
"{\n"
" \n"
" background-color: rgb(28, 255, 123);\n"
"}\n"
"\n"
"")
self.centralwidget = QtWidgets.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.firstNo_lineedit = QtWidgets.QLineEdit(self.centralwidget)
self.firstNo_lineedit.setGeometry(QtCore.QRect(130, 40, 113, 20))
self.firstNo_lineedit.setObjectName("firstNo_lineedit")
self.secondNo_lineedit = QtWidgets.QLineEdit(self.centralwidget)
self.secondNo_lineedit.setGeometry(QtCore.QRect(130, 70, 113, 20))
self.secondNo_lineedit.setObjectName("secondNo_lineedit")
self.calculate_button = QtWidgets.QPushButton(self.centralwidget)
self.calculate_button.setGeometry(QtCore.QRect(170, 100, 75, 23))
self.calculate_button.setObjectName("calculate_button")
self.label = QtWidgets.QLabel(self.centralwidget)
self.label.setGeometry(QtCore.QRect(60, 40, 81, 20))
self.label.setObjectName("label")
self.label_2 = QtWidgets.QLabel(self.centralwidget)
self.label_2.setGeometry(QtCore.QRect(60, 70, 61, 20))
self.label_2.setObjectName("label_2")
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtWidgets.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 310, 21))
self.menubar.setObjectName("menubar")
self.menuAbout = QtWidgets.QMenu(self.menubar)
self.menuAbout.setObjectName("menuAbout")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtWidgets.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.menubar.addAction(self.menuAbout.menuAction())
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
def retranslateUi(self, MainWindow):
_translate = QtCore.QCoreApplication.translate
MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
self.calculate_button.setText(_translate("MainWindow", "Calculate"))
self.label.setText(_translate("MainWindow", "First No.:"))
self.label_2.setText(_translate("MainWindow", "Second No.:"))
self.menuAbout.setTitle(_translate("MainWindow", "About"))
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
This new class can have the following form: 该新类可以具有以下形式:
main.py: main.py:
from PyQt5 import QtCore, QtGui, QtWidgets
from design import Ui_MainWindow
class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
def __init__(self, *args, **kwargs):
QtWidgets.QMainWindow.__init__(self, *args, **kwargs)
self.setupUi(self)
# ================= Listeners ===================
self.calculate_button.clicked.connect(self.basicArithmetic)
# ============================================
# ================= Events ===================
def basicArithmetic(self):
try:
firstNo=float(self.firstNo_lineedit.text())
secondNo=float(self.secondNo_lineedit.text())
resSum=firstNo+secondNo
resDiff=firstNo-secondNo
resMul=firstNo*secondNo
resDiv=round(firstNo/secondNo,2)
print("Sum: {}".format(resSum))
print("Difference: {}".format(resDiff))
print("Product: {}".format(resMul))
print("Quotient: {}".format(resDiv))
toDisplay="Sum: {}".format(resSum)
toDisplay+="\n"
toDisplay+="Difference: {}".format(resDiff)
toDisplay+="\n"
toDisplay+="Product: {}".format(resMul)
toDisplay+="\n"
toDisplay+="Quotient: {}".format(resDiv)
#QtWidgets.QMessageBox.about(self, "Result", toDisplay)
QtWidgets.QMessageBox.about(self, "Result", toDisplay)
except ValueError:
#QtWidgets.QMessageBox.about(self, "Result", toDisplay)
QtWidgets.QMessageBox.about(self, "Result", "Invalid number entered!")
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
And that is the reason why, in many cases, self
is seen as the first parameter. 这就是为什么在很多情况下,
self
被视为第一个参数的原因。
You can find more information at the following link: 您可以在以下链接中找到更多信息:
No self refers to Ui_MainWindow
class where MainWindow
reffers to QtWidgets.QMainWindow()
So when you say QtWidgets.QMessageBox.about(self, "Result", toDisplay)
it will treat Ui_MainWindow
as a parent QWidget
which is not correct. 没有自引用指向
MainWindow
继承于QtWidgets.QMainWindow()
Ui_MainWindow
类,因此,当您说QtWidgets.QMessageBox.about(self, "Result", toDisplay)
,会将Ui_MainWindow
视为不正确的父QWidget
。
when you call QtWidgets.QMessageBox.about(MainWindow, "Result", toDisplay)
this time your code will run fine because MainWindow
is a valid QWidget
ie QtWidgets.QMainWindow()
这次调用
QtWidgets.QMessageBox.about(MainWindow, "Result", toDisplay)
时,您的代码将运行良好,因为MainWindow
是有效的QWidget
即QtWidgets.QMainWindow()
hope this helps. 希望这可以帮助。
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