Pyqt5 QDialog not centered on mainWindow

[dancaer69]

I've created the main window ui and dialog ui in qt designer and I have also create the .py files.
mainwindow:

import sys
from os.path import expanduser
from PyQt5 import QtWidgets
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QMainWindow, QFileDialog
from mainwindow import Ui_mainWindow
from msgDialog import MsgDialog

class MainWindow(QMainWindow, Ui_mainWindow):
    def __init__(self, parent=None):
        """
        Constructor
        @param parent reference to the parent widget
        @type QWidget
        """
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)

def run():
    app = QtWidgets.QApplication(sys.argv)
    app.setQuitOnLastWindowClosed(True)
    ui = MainWindow()
    ui.show()
    return app.exec()

dialog window:

from PyQt5 import QtCore
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QDialog
from msgDialog_ui import Ui_MsgDialog

class MsgDialog (QDialog, Ui_MsgDialog):
    def __init__(self, parent=None):
        super(MsgDialog, self).__init__(parent)
        self.setupUi(self)
        self.setWindowFlags(
            QtCore.Qt.CustomizeWindowHint |
            QtCore.Qt.FramelessWindowHint)

This is the way these 2 widgets are constructed and connected with the ui/py files.
This way works as I intended except that the dialog window changes its position when I move the main window on screen. It's not every time I called it to the main window's center. I searched about this and I found some relative topics, which suggest dialog to be child of main window, but I don't know how to make main window parent and dialog child.

[JonB]

@dancaer69
Nothing in the code you show creates or shows the dialog.

[dancaer69]

Yes, I didn't put all code, just the constructors. The main window displayed from "run" method(I added it), and the dialog by pressing a button in main window with :

msgdlg = MsgDialog(self)
msgdlg.show()

[JonB]

@dancaer69 said in Pyqt5 QDialog not centered on mainWindow:

msgdlg = MsgDialog(self)

Because you passed self (the main window) as the parent to the constructor, you are doing the

which suggest dialog to be child of main window, but I don't know how to make main window parent and dialog child.

I notice you are using show(), not exec(), so this is a non-modal, modeless dialog. Meaning that you can interact with both the dialog & the main window. I don't know whether it is supposed to appear at the centre of its parent, but I think you can move them independently.

[dancaer69]

After a lot of searching and many tries I found this thread:
https://stackoverflow.com/questions/12432740/pyqt4-what-is-the-best-way-to-center-dialog-windows
which is the only that worked with some changes. It describes two methods. In both the dialog at least displayed in same position every time and doesn't move if I move the main window. The second one is the best because with this one the dialog is centered.
So, this is the dialog' s class modification for future reference:

from PyQt5.QtWidgets import QDialog
import appMain

from msgDialog_ui import Ui_MsgDialog

class MsgDialog (QDialog, Ui_MsgDialog):
    def __init__(self, parent=None):
        super(MsgDialog, self).__init__(parent)
        self.setupUi(self)
        self.setWindowFlags(
            QtCore.Qt.CustomizeWindowHint |
            QtCore.Qt.FramelessWindowHint)
        self.centerPos()

    def centerPos(self):
        qr = appMain.MainWindow.window(self).frameGeometry()
        #cp = appMain.MainWindow.geometry(self).center()
        #qr.moveCenter(cp)
        #self.move(qr.center())
        x = (qr.width() - self.width()) / 2
        y = (qr.height() - self.height()) / 2
        self.move(x,y)