drawEllipse does not show nothing on GUI

Question

I have created a very simple GUI using the designer. I am now trying to draw a circle between two push buttons,but for some reason I cannot get right.. I tried a couple of methods I searched online, but none of them helped me.

this is my code:

from PyQt5 import QtCore, QtGui, QtWidgets

class ApplicationWindow(QtWidgets.QMainWindow):
   def __init__(self):
      super(ApplicationWindow, self).__init__()
      self.ui = Ui_MainWindow()
      self.ui.setupUi(self)

class Ui_MainWindow(object):
   def setupUi(self, MainWindow):
       MainWindow.setObjectName("Dialog")
       MainWindow.resize(298, 207)
       self.centralwidget = QtWidgets.QWidget(MainWindow)
       self.centralwidget.setObjectName("centralwidget")

       self.turnRed = QtWidgets.QPushButton(MainWindow)
       self.turnRed.setGeometry(QtCore.QRect(70, 90, 75, 23))
       self.turnRed.setObjectName("turnRed")

       self.turnBlue = QtWidgets.QPushButton(MainWindow)
       self.turnBlue.setGeometry(QtCore.QRect(190, 90, 75, 23))
       self.turnBlue.setObjectName("turnBlue")
       self.retranslateUi(MainWindow)
       QtCore.QMetaObject.connectSlotsByName(MainWindow)

   def paintEvent(self, e):
       painter = QtGui.QPainter(self)
       painter.setPen(QtGui.QPen(QtCore.Qt.blue, 8, QtCore.Qt.SolidLine))
       painter.drawEllipse(120,60,50,50)



   def retranslateUi(self, MainWindow):
       _translate = QtCore.QCoreApplication.translate
       MainWindow.setWindowTitle(_translate("Dialog", "Dialog"))
       self.turnRed.setText(_translate("Dialog", "RED"))
       self.turnBlue.setText(_translate("Dialog", "GREEN"))



if __name__ == "__main__":
   import sys
   app = QtWidgets.QApplication(sys.argv)
   application = ApplicationWindow()
   application.show()
   sys.exit(app.exec_())

And this is the GUI:

When I run this I see both push buttons but I can't see the ellipse/circle? What am I missing out??

note

I know it's bad to change the code generated from the designer, but all I want for this things is to see the ellipse so I can implement the same thing on my project.

Answer 1

If you know that it is bad to change the code generated from the constructor, so why do you pop it?

A class that inherits from object does not have apaintEvent method

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_MainWindow(object):
   def setupUi(self, MainWindow):
       MainWindow.setObjectName("Dialog")
       MainWindow.resize(298, 207)
       self.centralwidget = QtWidgets.QWidget(MainWindow)
       self.centralwidget.setObjectName("centralwidget")

       self.turnRed = QtWidgets.QPushButton(MainWindow)
       self.turnRed.setGeometry(QtCore.QRect(70, 90, 75, 23))
       self.turnRed.setObjectName("turnRed")

       self.turnBlue = QtWidgets.QPushButton(MainWindow)
       self.turnBlue.setGeometry(QtCore.QRect(190, 90, 75, 23))
       self.turnBlue.setObjectName("turnBlue")
       self.retranslateUi(MainWindow)
       QtCore.QMetaObject.connectSlotsByName(MainWindow)

   def retranslateUi(self, MainWindow):
       _translate = QtCore.QCoreApplication.translate
       MainWindow.setWindowTitle(_translate("Dialog", "Dialog"))
       self.turnRed.setText(_translate("Dialog", "RED"))
       self.turnBlue.setText(_translate("Dialog", "GREEN"))

class ApplicationWindow(QtWidgets.QMainWindow):
   def __init__(self):
      super(ApplicationWindow, self).__init__()
      self.ui = Ui_MainWindow()
      self.ui.setupUi(self)

   def paintEvent(self, e):
       painter = QtGui.QPainter(self)
       painter.setPen(QtGui.QPen(QtCore.Qt.blue, 8, QtCore.Qt.SolidLine))
       painter.drawEllipse(120, 60, 50, 50)


if __name__ == "__main__":
   import sys
   app = QtWidgets.QApplication(sys.argv)
   application = ApplicationWindow()
   application.show()
   sys.exit(app.exec_())

---

Update

But now that I am trying to change the color of painter, it does not let me.. So basically when I run this I get the blue circle, but when I try to change it (by clicked RED button and connect it by a function), nothing happens. could you give me a hand with that please?

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("Dialog")
        MainWindow.resize(298, 207)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")

        self.turnRed = QtWidgets.QPushButton(MainWindow)
        self.turnRed.setGeometry(QtCore.QRect(70, 90, 75, 23))
        self.turnRed.setObjectName("turnRed")

        self.turnBlue = QtWidgets.QPushButton(MainWindow)
        self.turnBlue.setGeometry(QtCore.QRect(190, 90, 75, 23))
        self.turnBlue.setObjectName("turnBlue")
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("Dialog", "Dialog"))
        self.turnRed.setText(_translate("Dialog", "RED"))
        self.turnBlue.setText(_translate("Dialog", "GREEN"))

class ApplicationWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super(ApplicationWindow, self).__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)

        self.pen = QtGui.QPen(QtCore.Qt.blue, 8, QtCore.Qt.SolidLine)
        self.ui.turnRed.clicked.connect(self.onRed)
        self.ui.turnBlue.clicked.connect(self.onGreen)

    def paintEvent(self, e):
        painter = QtGui.QPainter(self)
        painter.setPen(self.pen)
        painter.drawEllipse(120, 60, 50, 50)

    def onRed(self):
        self.pen = QtGui.QPen(QtCore.Qt.red, 8, QtCore.Qt.SolidLine)
        self.update()

    def onGreen(self):
        self.pen = QtGui.QPen(QtCore.Qt.green, 8, QtCore.Qt.SolidLine)
        self.update()


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    application = ApplicationWindow()
    application.show()
    sys.exit(app.exec_())