keyPressEvent() method doesn't work for PyQt5 / Python 3+

Question

I'm a newbie for python. I've designed a simple calculator app using "Qt Designer" and then convert the "ui" file to "py" using "pyuic5".

But when I've added keyPressEvent() method, the method didn't work. And I don't know why. I've tried with setFocus() method to overcome this issue but failed.

can anyone help me please?

Please check my code below:

from PyQt5 import QtCore, QtGui, QtWidgets
import sys


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setMinimumSize(QtCore.QSize(330, 280))
        MainWindow.setMaximumSize(QtCore.QSize(330, 280))

        self.centralwidget = QtWidgets.QWidget(MainWindow)


        self.lineEdit_display = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_display.setGeometry(QtCore.QRect(10, 0, 311, 41))
        font = QtGui.QFont()
        font.setPointSize(14)
        font.setBold(True)
        font.setWeight(75)
        self.lineEdit_display.setFont(font)
        self.lineEdit_display.setMaxLength(15)
        self.lineEdit_display.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)
        self.lineEdit_display.setReadOnly(True)


        self.pButton_0 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_0.setGeometry(QtCore.QRect(10, 200, 51, 41))
        self.pButton_0.setCursor(QtGui.QCursor(QtCore.Qt.ArrowCursor))

        self.pButton_00 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_00.setGeometry(QtCore.QRect(70, 200, 51, 41))

        self.pButton_dot = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_dot.setGeometry(QtCore.QRect(130, 200, 51, 41))

        self.pButton_1 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_1.setGeometry(QtCore.QRect(10, 150, 51, 41))

        self.pButton_2 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_2.setGeometry(QtCore.QRect(70, 150, 51, 41))

        self.pButton_3 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_3.setGeometry(QtCore.QRect(130, 150, 51, 41))

        self.pButton_4 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_4.setGeometry(QtCore.QRect(10, 100, 51, 41))

        self.pButton_5 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_5.setGeometry(QtCore.QRect(70, 100, 51, 41))

        self.pButton_6 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_6.setGeometry(QtCore.QRect(130, 100, 51, 41))

        self.pButton_7 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_7.setGeometry(QtCore.QRect(10, 50, 51, 41))

        self.pButton_8 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_8.setGeometry(QtCore.QRect(70, 50, 51, 41))

        self.pButton_9 = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_9.setGeometry(QtCore.QRect(130, 50, 51, 41))

        self.pButton_add = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_add.setGeometry(QtCore.QRect(210, 50, 51, 41))

        self.pButton_subtract = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_subtract.setGeometry(QtCore.QRect(210, 100, 51, 41))

        self.pButton_multiplication = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_multiplication.setGeometry(QtCore.QRect(210, 150, 51, 41))

        self.pButton_divide = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_divide.setGeometry(QtCore.QRect(210, 200, 51, 41))

        self.pButton_equal = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_equal.setGeometry(QtCore.QRect(270, 150, 51, 91))

        self.pButton_ac = QtWidgets.QPushButton(self.centralwidget)
        self.pButton_ac.setGeometry(QtCore.QRect(270, 50, 51, 91))
        font = QtGui.QFont()
        font.setPointSize(14)
        self.pButton_ac.setFont(font)
        self.pButton_ac.setDefault(True)


        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 330, 27))
        self.menuMain = QtWidgets.QMenu(self.menubar)
        MainWindow.setMenuBar(self.menubar)
        self.actionExit = QtWidgets.QAction(MainWindow)
        self.actionAbout = QtWidgets.QAction(MainWindow)
        self.menuMain.addAction(self.actionExit)
        self.menuMain.addAction(self.actionAbout)
        self.menubar.addAction(self.menuMain.menuAction())

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

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "Simple Calculator"))
        MainWindow.setToolTip(_translate("MainWindow", "Simple Calculator"))
        self.pButton_0.setToolTip(_translate("MainWindow", "0"))
        self.pButton_0.setText(_translate("MainWindow", "0"))
        self.pButton_00.setToolTip(_translate("MainWindow", "00"))
        self.pButton_00.setText(_translate("MainWindow", "00"))
        self.pButton_dot.setToolTip(_translate("MainWindow", "."))
        self.pButton_dot.setText(_translate("MainWindow", "."))
        self.pButton_1.setToolTip(_translate("MainWindow", "1"))
        self.pButton_1.setText(_translate("MainWindow", "1"))
        self.pButton_2.setToolTip(_translate("MainWindow", "2"))
        self.pButton_2.setText(_translate("MainWindow", "2"))
        self.pButton_3.setToolTip(_translate("MainWindow", "3"))
        self.pButton_3.setText(_translate("MainWindow", "3"))
        self.pButton_4.setToolTip(_translate("MainWindow", "4"))
        self.pButton_4.setText(_translate("MainWindow", "4"))
        self.pButton_5.setToolTip(_translate("MainWindow", "5"))
        self.pButton_5.setText(_translate("MainWindow", "5"))
        self.pButton_6.setToolTip(_translate("MainWindow", "6"))
        self.pButton_6.setText(_translate("MainWindow", "6"))
        self.pButton_7.setToolTip(_translate("MainWindow", "7"))
        self.pButton_7.setText(_translate("MainWindow", "7"))
        self.pButton_8.setToolTip(_translate("MainWindow", "8"))
        self.pButton_8.setText(_translate("MainWindow", "8"))
        self.pButton_9.setToolTip(_translate("MainWindow", "9"))
        self.pButton_9.setText(_translate("MainWindow", "9"))
        self.pButton_add.setToolTip(_translate("MainWindow", "+"))
        self.pButton_add.setText(_translate("MainWindow", "+"))
        self.pButton_subtract.setToolTip(_translate("MainWindow", "-"))
        self.pButton_subtract.setText(_translate("MainWindow", "-"))
        self.pButton_multiplication.setToolTip(_translate("MainWindow", "\N{MULTIPLICATION SIGN}"))
        self.pButton_multiplication.setText(_translate("MainWindow", "\N{MULTIPLICATION SIGN}"))
        self.pButton_divide.setToolTip(_translate("MainWindow", "\N{DIVISION SIGN}"))
        self.pButton_divide.setText(_translate("MainWindow", "\N{DIVISION SIGN}"))
        self.pButton_equal.setToolTip(_translate("MainWindow", "="))
        self.pButton_equal.setText(_translate("MainWindow", "="))
        self.pButton_ac.setToolTip(_translate("MainWindow", "AC"))
        self.pButton_ac.setText(_translate("MainWindow", "AC"))
        self.lineEdit_display.setToolTip(_translate("MainWindow", "Display"))
        self.lineEdit_display.setText(_translate("MainWindow", "0"))
        self.menuMain.setTitle(_translate("MainWindow", "Mai&n"))
        self.actionExit.setText(_translate("MainWindow", "&Exit"))
        self.actionAbout.setText(_translate("MainWindow", "&About"))

    def keyPressEvent(self, e):
        print(e.key())

if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)

    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()

    MainWindow.setFocus() #TRYING TO SET FOCUS FOR keyPressEvent

    sys.exit(app.exec_())

Answer 1

Sir, I couldn't find specifically what was the error in your syntax, so I edited your code to keep as much similar to yours as possible.

Here is your code working with some modifications, see if it would work for you.

from PyQt5 import QtCore, QtGui, QtWidgets
import sys

from PyQt5.QtWidgets import QAction
from PyQt5.QtWidgets import QLineEdit
from PyQt5.QtWidgets import QMainWindow
from PyQt5.QtWidgets import QMenu
from PyQt5.QtWidgets import QMenuBar
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtWidgets import QWidget


class Ui_MainWindow(QMainWindow):

    def __init__(self):
        super(Ui_MainWindow, self).__init__()
        # self.setupUi()

    def setupUi(self):
        self.setMinimumSize(QtCore.QSize(330, 280))
        self.setMaximumSize(QtCore.QSize(330, 280))

        self.centralwidget = QWidget()


        self.lineEdit_display = QLineEdit(self.centralwidget)
        self.lineEdit_display.setGeometry(QtCore.QRect(10, 0, 311, 41))
        font = QtGui.QFont()
        font.setPointSize(14)
        font.setBold(True)
        font.setWeight(75)
        self.lineEdit_display.setFont(font)
        self.lineEdit_display.setMaxLength(15)
        self.lineEdit_display.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)
        self.lineEdit_display.setReadOnly(True)


        self.pButton_0 = QPushButton(self.centralwidget)
        self.pButton_0.setGeometry(QtCore.QRect(10, 200, 51, 41))
        self.pButton_0.setCursor(QtGui.QCursor(QtCore.Qt.ArrowCursor))

        self.pButton_00 = QPushButton(self.centralwidget)
        self.pButton_00.setGeometry(QtCore.QRect(70, 200, 51, 41))

        self.pButton_dot = QPushButton(self.centralwidget)
        self.pButton_dot.setGeometry(QtCore.QRect(130, 200, 51, 41))

        self.pButton_1 = QPushButton(self.centralwidget)
        self.pButton_1.setGeometry(QtCore.QRect(10, 150, 51, 41))

        self.pButton_2 = QPushButton(self.centralwidget)
        self.pButton_2.setGeometry(QtCore.QRect(70, 150, 51, 41))

        self.pButton_3 = QPushButton(self.centralwidget)
        self.pButton_3.setGeometry(QtCore.QRect(130, 150, 51, 41))

        self.pButton_4 = QPushButton(self.centralwidget)
        self.pButton_4.setGeometry(QtCore.QRect(10, 100, 51, 41))

        self.pButton_5 = QPushButton(self.centralwidget)
        self.pButton_5.setGeometry(QtCore.QRect(70, 100, 51, 41))

        self.pButton_6 = QPushButton(self.centralwidget)
        self.pButton_6.setGeometry(QtCore.QRect(130, 100, 51, 41))

        self.pButton_7 = QPushButton(self.centralwidget)
        self.pButton_7.setGeometry(QtCore.QRect(10, 50, 51, 41))

        self.pButton_8 = QPushButton(self.centralwidget)
        self.pButton_8.setGeometry(QtCore.QRect(70, 50, 51, 41))

        self.pButton_9 = QPushButton(self.centralwidget)
        self.pButton_9.setGeometry(QtCore.QRect(130, 50, 51, 41))

        self.pButton_add = QPushButton(self.centralwidget)
        self.pButton_add.setGeometry(QtCore.QRect(210, 50, 51, 41))

        self.pButton_subtract = QPushButton(self.centralwidget)
        self.pButton_subtract.setGeometry(QtCore.QRect(210, 100, 51, 41))

        self.pButton_multiplication = QPushButton(self.centralwidget)
        self.pButton_multiplication.setGeometry(QtCore.QRect(210, 150, 51, 41))

        self.pButton_divide = QPushButton(self.centralwidget)
        self.pButton_divide.setGeometry(QtCore.QRect(210, 200, 51, 41))

        self.pButton_equal = QPushButton(self.centralwidget)
        self.pButton_equal.setGeometry(QtCore.QRect(270, 150, 51, 91))

        self.pButton_ac = QPushButton(self.centralwidget)
        self.pButton_ac.setGeometry(QtCore.QRect(270, 50, 51, 91))
        font = QtGui.QFont()
        font.setPointSize(14)
        self.pButton_ac.setFont(font)
        self.pButton_ac.setDefault(True)

        self.setCentralWidget(self.centralwidget)
        self.menubar = QMenuBar(self)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 330, 27))
        self.menuMain = QMenu(self.menubar)
        self.setMenuBar(self.menubar)
        self.actionExit = QAction(self)
        self.actionAbout = QAction(self)
        self.menuMain.addAction(self.actionExit)
        self.menuMain.addAction(self.actionAbout)
        self.menubar.addAction(self.menuMain.menuAction())

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

    def retranslateUi(self):
        _translate = QtCore.QCoreApplication.translate
        self.setWindowTitle(_translate("MainWindow", "Simple Calculator"))
        self.setToolTip(_translate("MainWindow", "Simple Calculator"))
        self.pButton_0.setToolTip(_translate("MainWindow", "0"))
        self.pButton_0.setText(_translate("MainWindow", "0"))
        self.pButton_00.setToolTip(_translate("MainWindow", "00"))
        self.pButton_00.setText(_translate("MainWindow", "00"))
        self.pButton_dot.setToolTip(_translate("MainWindow", "."))
        self.pButton_dot.setText(_translate("MainWindow", "."))
        self.pButton_1.setToolTip(_translate("MainWindow", "1"))
        self.pButton_1.setText(_translate("MainWindow", "1"))
        self.pButton_2.setToolTip(_translate("MainWindow", "2"))
        self.pButton_2.setText(_translate("MainWindow", "2"))
        self.pButton_3.setToolTip(_translate("MainWindow", "3"))
        self.pButton_3.setText(_translate("MainWindow", "3"))
        self.pButton_4.setToolTip(_translate("MainWindow", "4"))
        self.pButton_4.setText(_translate("MainWindow", "4"))
        self.pButton_5.setToolTip(_translate("MainWindow", "5"))
        self.pButton_5.setText(_translate("MainWindow", "5"))
        self.pButton_6.setToolTip(_translate("MainWindow", "6"))
        self.pButton_6.setText(_translate("MainWindow", "6"))
        self.pButton_7.setToolTip(_translate("MainWindow", "7"))
        self.pButton_7.setText(_translate("MainWindow", "7"))
        self.pButton_8.setToolTip(_translate("MainWindow", "8"))
        self.pButton_8.setText(_translate("MainWindow", "8"))
        self.pButton_9.setToolTip(_translate("MainWindow", "9"))
        self.pButton_9.setText(_translate("MainWindow", "9"))
        self.pButton_add.setToolTip(_translate("MainWindow", "+"))
        self.pButton_add.setText(_translate("MainWindow", "+"))
        self.pButton_subtract.setToolTip(_translate("MainWindow", "-"))
        self.pButton_subtract.setText(_translate("MainWindow", "-"))
        self.pButton_multiplication.setToolTip(_translate("MainWindow", "\N{MULTIPLICATION SIGN}"))
        self.pButton_multiplication.setText(_translate("MainWindow", "\N{MULTIPLICATION SIGN}"))
        self.pButton_divide.setToolTip(_translate("MainWindow", "\N{DIVISION SIGN}"))
        self.pButton_divide.setText(_translate("MainWindow", "\N{DIVISION SIGN}"))
        self.pButton_equal.setToolTip(_translate("MainWindow", "="))
        self.pButton_equal.setText(_translate("MainWindow", "="))
        self.pButton_ac.setToolTip(_translate("MainWindow", "AC"))
        self.pButton_ac.setText(_translate("MainWindow", "AC"))
        self.lineEdit_display.setToolTip(_translate("MainWindow", "Display"))
        self.lineEdit_display.setText(_translate("MainWindow", "0"))
        self.menuMain.setTitle(_translate("MainWindow", "Mai&n"))
        self.actionExit.setText(_translate("MainWindow", "&Exit"))
        self.actionAbout.setText(_translate("MainWindow", "&About"))

    def keyPressEvent(self, e):
        print(e.key())

if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)

    ui = Ui_MainWindow()
    ui.setupUi()
    ui.show()

    sys.exit(app.exec_())

Hope it works ^^

Answer 2

It looks like you need to connect each widget with an event. GUIs are event-driven programming. As you've seen, they just sit there looking at you until the user takes some action, and it is your (the programmer's) responsibility to define what happens for each action.

For example, you have buttons for your calculator. I assume when you press a number button you want that number to show up in a text box representing the display. If so then you need to handle the "clicked" event. Something similar to

 self.pButton_9.clicked.connect(self.click_9) # connects button to action by defining a callback - an action to handle the event.

def click_9(self):
    self.lineEdit_display.text += '9 '

One of the best intro tutorials I've seen is Here . I usually have all my Python classes go through it to start learning GUI programming.

Answer 3

I had this problem too. use this code in setupUI function:

MainWindow.keyPressEvent = self.keyPressEvent