PyQt application crashes the second time it calls error message - python

Context:
I'm creating a GUI using QtDesigner and PyCharm. The issue I am having occurs when the main window (win1) calls a second windows (win2) through a QPushButton, and then opens an error message due to lack of user input. I am using an external file (main.py) to handle the logic and events of all the windows, rather than editing code generated by QtDesigner.
Issue:
The way I have things set up, the user needs to pick an option from a comboBox, based on the user's selection, the application launches either win2 or win3
User picks no option from comboBox --> Error message
User picks option 1 --> win2 opens, win1 closes
User picks option 2 --> win3 opens, win1 closes
The problem occurs after user exits win 2/3 and goes back to win1
User picks option 1/2 --> correct window opens, no issues
User picks no option --> error message --> user closes error
message --> crash (or sudden application exit)
Note: The crash produces no errors/warnings
Here's the code I'm using to handle the opening/closing:
class win1(QtGui.QMainWindow, pg1.Ui_MainWindow):
def __init__(self, parent=None):
super(win1, self).__init__(parent)
self.setupUi(self)
self.btn1.clicked.connect(self.checkuserselection)
self.addnew = win2(self)
def checkuserselection(self):
user_str = str(self.comboBox.currentText())
if user_str == "Select Option":
self.errMsg()
elif user_str == "Option 1":
self.runaddnew("Window title for option 1")
else:
self.runaddnew("window title for option 2")
def runaddnew(self, title):
self.addnew.setWindowTitle(title)
self.addnew.show()
self.hide()
#staticmethod
def errMsg():
w = QtGui.QMessageBox()
QtGui.QMessageBox.critical(w, "No Option Selected!")
The code for win2:
class win2(QtGui.QMainWindow, pg2.Ui_MainWindow):
def __init__(self, parent=None):
super(win2, self).__init__(parent)
self.setupUi(self)
self.actionExit.triggered.connect(self.closeWindow)
def closeWindow(self):
self.close()
w = win1(self)
w.show()
The user can get the error message many times without the application suddenly quitting, as long as they haven't opened one of the other windows. This leads me to think that the issue is with the closeWindow method in win2. My knowledge in python/pyQt is limited, so I don't know if that's indeed where the issue is.

Thanks to #ekhumoro, I'm posting the response that worked here in case anyone else has this issue.
In the code for win2:
def closeWindow(self):
self.parent().show()
self.close()
This works because win1 passed self to win2 when win2 was created

Related

How to pause window to turn on another window?

I use tkinter and CTK:
I have created a page for login and I want to stop or use this page when the user is logged in, I want to show a new window and I want to resume the window when I want? How can I do that, I didn't know how to make it
I'll bite. Here's an example application that opens a second window when the user clicks a button on the main window, and disables interaction with the main window until the second window is closed.
Some configuration has been omitted for brevity, and I'm not using CTk here because I don't know how you've implemented it in your specific application - however, it should be easy enough to modify this example to work with CTk.
import tkinter as tk
from tkinter import ttk
class App(tk.Tk):
def __init__(self):
super().__init__()
self.open_button = ttk.Button(
self,
text='Open 2nd Window',
command=self.modal
)
self.open_button.pack()
def modal(self):
self.window = tk.Toplevel(self) # create new window
# bind a handler for when the user closes this window
self.window.protocol('WM_DELETE_WINDOW', self.on_close)
# disable interaction with the main (root) window
self.attributes('-disabled', True)
self.close_button = ttk.Button(
self.window,
text='Close Modal',
command=self.on_close
)
self.close_button.pack()
def on_close(self):
# re-enable interaction the root window
self.attributes('-disabled', False)
# close the modal window
self.window.destroy()
if __name__ == '__main__':
app = App()
app.mailoop() # run the app
In the future:
Provide code that shows you made a good-faith effort to solve the problem on your own
Don't post the same question multiple times within hours - if you need to make changes, edit the original question
If you mean you want to open up another window to do something before going back to the original window, you should consider using message box. Here is a link that goes over the types of messageboxes: https://docs.python.org/3/library/tkinter.messagebox.html.

Multiple messages in screen PyQt5

Here is my code
app = QApplication(sys.argv)
loginWindow = loadUi('~/mainwindow.ui')
okconnect = loadUi('~/okconnect.ui')
def prueba2(test):
print(test + " Testing2")
def prueba(test):
print (test)
okconnect.show()
okconnect.getvmsButton.clicked.connect(lambda: prueba2(test))
loginWindow.show()
loginWindow.connectButton.clicked.connect(lambda: prueba("test"))
sys.exit(app.exec_())
When I press "connect" button, a new window is opened, with a button, "getvmsButton", when I press this button, its show in console the print line in def prueba2(test), but if I close the window, and then I click again in connect button, the window open again and "getvmsButton" is pressed again, the console show 2 messages instead of 1. If I repeat the process, more messages are showed.
What should I change to show only one messages when I close and open several times the window?
When you close your GUI by 'x' doesn't mean you disconnected the button click signal, therefore, every time you click the 'connect' button, the loginWindow will create a new button.clicked event and keep the old ones. A quick solution to this is to define a close-event for the 'x' clicks. Here provided is just a way to close the old signal events.
from PyQt5.QtWidgets import QWidget
OKConnect(QWidget):
def __init__(self):
super().__init__()
self.okconnect = loadUi('~/okconnect.ui')
self.okconnect.closeEvent = self.closeEvent
def closeEvent(self, event):
print("testing2 closing")
# to close the old getvmsButton signals
self.okconnect.getvmsButton.disconnect()
# Here below is exactly your code
app = QApplication(sys.argv)
loginWindow = loadUi('~/mainwindow.ui')
okconnect = OKConnect()
def prueba2(test):
print(test + " Testing2")
def prueba(test):
print (test)
okconnect.show()
okconnect.getvmsButton.clicked.connect(lambda: prueba2(test))
loginWindow.show()
loginWindow.connectButton.clicked.connect(lambda: prueba("test"))
sys.exit(app.exec_())
I am not sure about your .ui files, the code may not work on yours.

PyQt WebEngineView interferes with MainMenu

I'm trying to create an application that contains a web browser within it, but when I add the web browser my menu bar visually disappears but functionally remains in place. The following are two images, one showing the "self.centralWidget(self.web_widget)" commented out, and the other allows that line to run. If you run the example code, you will also see that while visually the entire web page appears as if the menu bar wasn't present, you have to click slightly below each entry field and button in order to activate it, behaving as if the menu bar was in fact present.
Web Widget Commented Out
Web Widget Active
Example Code
import os
import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtWebEngineWidgets import *
class WebPage(QWebEngineView):
def __init__(self, parent=None):
QWebEngineView.__init__(self)
self.current_url = ''
self.load(QUrl("https://facebook.com"))
self.loadFinished.connect(self._on_load_finished)
def _on_load_finished(self):
print("Url Loaded")
class MainWindow(QMainWindow):
def __init__(self, parent=None):
# Initialize the Main Window
super(MainWindow, self).__init__(parent)
self.create_menu()
self.add_web_widet()
self.show()
def create_menu(self):
''' Creates the Main Menu '''
self.main_menu = self.menuBar()
self.main_menu_actions = {}
self.file_menu = self.main_menu.addMenu("Example File Menu")
self.file_menu.addAction(QAction("Testing Testing", self))
def add_web_widet(self):
self.web_widget = WebPage(self)
self.setCentralWidget(self.web_widget)
if __name__ == "__main__":
app = QApplication(sys.argv)
main_window = MainWindow()
main_window.showMaximized()
sys.exit(app.exec_()) # only need one app, one running event loop
Development Environment
Windows 10, PyQt5, pyqt5-5.9
EDIT
The problem doesn't seem to be directly related to the menu bar. Even removing the menu bar the issue still occurs. That said, changing from showMaximized() to showFullScreen() does seem to solve the problem.
I no longer believe this is an issue with PyQt5 specifically but rather a problem with the graphics driver. Specifically, if you look at Atlassian's HipChat application it has a similar problem which is documented here:
https://jira.atlassian.com/browse/HCPUB-3177
Some individuals were able to solve the problem by running the application from the command prompt with the addendum "--disable-gpu" but that didn't work for my python application. On the other hand, rolling back the Intel(R) HD Graphics Driver did solve my problem. Version 21.20.16.4627 is the one that seems to be causing problems.

Why is my PyQt4 program exiting the main loop for no apparent reason?

I'm (trying to) make a small program that resides in the system tray and checks a list of Twitch channels to see if they're online every once in a while.
I'm currently doing the GUI (in PyQt4), but it's exiting for no reason.
Here's my code so far:
import sys
from PyQt4 import QtGui
from PyQt4 import QtCore
class TwitchWatchTray(QtGui.QSystemTrayIcon):
def __init__(self, icon, parent=None):
super(TwitchWatchTray, self).__init__(icon, parent)
self.menu = QtGui.QMenu(parent)
settings_action = self.menu.addAction("Settings")
settings_action.triggered.connect(self.open_settings)
self.menu.addSeparator()
exit_action = self.menu.addAction("Exit")
exit_action.triggered.connect(QtCore.QCoreApplication.instance().quit)
self.setContextMenu(self.menu)
self.show()
def open_settings(self):
settings = SettingsDialog()
settings.show()
class SettingsDialog(QtGui.QWidget):
def __init__(self):
super(SettingsDialog, self).__init__()
self.resize(300, 300)
self.setWindowTitle('TwitchWatch Settings')
vbox = QtGui.QHBoxLayout()
self.channels_list = QtGui.QListView(self)
vbox.addWidget(self.channels_list)
self.add_box = QtGui.QLineEdit(self)
vbox.addWidget(self.add_box)
self.setLayout(vbox)
self.show()
def main():
app = QtGui.QApplication(sys.argv)
widget = QtGui.QWidget()
tw = TwitchWatchTray(QtGui.QIcon("icon.png"), widget)
app.exec_()
print("Done!")
if __name__ == '__main__':
main()
When I right click the tray icon and click "Settings", it flashes a white box (my dialog), then immediately exits and prints "Done!".
Why is this, and how do I fix it?
There are two reasons why your code exits immediately after you open the settings dialog.
The first problem is with your open_settings method:
def open_settings(self):
settings = SettingsDialog()
settings.show()
This creates a dialog and makes it visible. show() returns immediately after showing the window; it doesn't wait for the window to be closed. The settings variable goes out of scope at the end of the method, and this causes the reference count of your SettingsDialog to drop to zero and hence become eligible for garbage collection. When Python deletes the SettingsDialog object, PyQt will delete the underlying C++ object, and this is what causes the dialog to close again.
I would recommend having your settings dialog subclass QDialog rather than QWidget (it is a dialog, after all). Instead of calling settings.show() you can then call settings.exec_(). settings.exec_() does wait for the dialog to be closed before it returns. It also returns QDialog.Accepted or QDialog.Rejected depending on whether the user clicked OK or Cancel. I'd also recommend getting rid of the call to self.show() in your SettingsDialog constructor.
The second problem is that your QApplication is set to quit when the last window is closed. This is the default behaviour, which is what a lot of applications need, but not yours. Even if your dialog stayed open and you could close it, you wouldn't want your application to exit immediately after you close the settings dialog. Call app.setQuitOnLastWindowClosed(False) to fix this.

QDialog - Prevent Closing in Python and PyQt

I have a login screen dialog written using pyqt and python and it shows a dialog pup up when it runs and you can type in a certin username and password to unlock it basicly. It's just something simple I made in learning pyqt. I'm trying to take and use it somewhere else but need to know if there is a way to prevent someone from using the x button and closing it i would like to also have it stay on top of all windows so it cant be moved out of the way? Is this possible? I did some research and couldn't find anything that could help me.
Edit:
as requested here is the code:
from PyQt4 import QtGui
class Test(QtGui.QDialog):
def __init__(self):
QtGui.QDialog.__init__(self)
self.textUsername = QtGui.QLineEdit(self)
self.textPassword = QtGui.QLineEdit(self)
self.loginbuton = QtGui.QPushButton('Test Login', self)
self.loginbuton.clicked.connect(self.Login)
layout = QtGui.QVBoxLayout(self)
layout.addWidget(self.textUsername)
layout.addWidget(self.textPassword)
layout.addWidget(self.loginbuton)
def Login(self):
if (self.textUsername.text() == 'Test' and
self.textPassword.text() == 'Password'):
self.accept()
else:
QtGui.QMessageBox.warning(
self, 'Wrong', 'Incorrect user or password')
class Window(QtGui.QMainWindow):
def __init__(self):
QtGui.QMainWindow.__init__(self)
if __name__ == '__main__':
import sys
app = QtGui.QApplication(sys.argv)
if Test().exec_() == QtGui.QDialog.Accepted:
window = Window()
window.show()
sys.exit(app.exec_())
Bad news first, it is not possible to remove the close button from the window, based on the Riverbank mailing system
You can't remove/disable close button because its handled by the
window manager, Qt can't do anything there.
Good news, you can override and ignore, so that when the user sends the event, you can ignore or put a message or something.
Read this article for ignoring the QCloseEvent
Also, take a look at this question, How do I catch a pyqt closeEvent and minimize the dialog instead of exiting?
Which uses this:
class MyDialog(QtGui.QDialog):
# ...
def __init__(self, parent=None):
super(MyDialog, self).__init__(parent)
# when you want to destroy the dialog set this to True
self._want_to_close = False
def closeEvent(self, evnt):
if self._want_to_close:
super(MyDialog, self).closeEvent(evnt)
else:
evnt.ignore()
self.setWindowState(QtCore.Qt.WindowMinimized)
You can disable the window buttons in PyQt5.
The key is to combine it with "CustomizeWindowHint",
and exclude the ones you want to be disabled.
Example:
#exclude "QtCore.Qt.WindowCloseButtonHint" or any other window button
self.setWindowFlags(
QtCore.Qt.Window |
QtCore.Qt.CustomizeWindowHint |
QtCore.Qt.WindowTitleHint |
QtCore.Qt.WindowMinimizeButtonHint
)
Result with QDialog:
Reference: https://doc.qt.io/qt-5/qt.html#WindowType-enum
Tip: if you want to change flags of the current window, use window.show()
after window.setWindowFlags,
because it needs to refresh it, so it calls window.hide().
Tested with QtWidgets.QDialog on:
Windows 10 x32,
Python 3.7.9,
PyQt5 5.15.1
.
I don't know if you want to do this but you can also make your window frameless. To make window frameless you can set the window flag equal to QtCore.Qt.FramelessWindowHint

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