[英]PyQt5 self reference
我使用Qt Designer來設計GUI,並使用PyQt5中的命令將.ui文件轉換為.py。 由此,我想在單擊按鈕時輸出一個消息框。 我已經在按鈕偵聽器的功能上使用此行代碼成功完成了此操作:
QtWidgets.QMessageBox.about(MainWindow, "Result", "Invalid number entered!")
我已經在互聯網上進行搜索,但是我不明白為什么這一項不起作用。
QtWidgets.QMessageBox.about(self, "Result", "Invalid number entered!")
他們自己也引用MainWindow嗎?
這是完整的源代碼。
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
是引用相同實例的類的方法的第一個參數(名稱是按慣例,不是必需的)。
對於另一個QMessageBox.about()
需要一個繼承自QWidget
或None的某種對象作為第一個參數。
如果我們查看由Qt Designer生成的類,我們會清楚地看到它不是小部件,實際上,該類的唯一目的是成為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
因此,要傳遞的self
,即Ui_MainWindow
的實例是Ui_MainWindow
,因為它不引用窗口小部件,但是MainWindow
是窗口小部件,因此它可以正確地使用此更改。 此外,在生成的文件中,您還會顯示以下消息:
# WARNING! All changes made in this file will be lost!
該消息是因為,如果您要更改設計,則必須覆蓋您編寫的邏輯,例如basicArithmetic
方法,這會使項目無法使用。
PyQt我建議創建另一個使用生成QtDesigner的類的類,我假設生成的文件名為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_())
該新類可以具有以下形式:
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_())
這就是為什么在很多情況下, self
被視為第一個參數的原因。
您可以在以下鏈接中找到更多信息:
沒有自引用指向MainWindow
繼承於QtWidgets.QMainWindow()
Ui_MainWindow
類,因此,當您說QtWidgets.QMessageBox.about(self, "Result", toDisplay)
,會將Ui_MainWindow
視為不正確的父QWidget
。
這次調用QtWidgets.QMessageBox.about(MainWindow, "Result", toDisplay)
時,您的代碼將運行良好,因為MainWindow
是有效的QWidget
即QtWidgets.QMainWindow()
希望這可以幫助。
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