Develop Reference

I created a class for the QPushButton widget in PyQt5, but it doesn't show after I create an instance of it

I wanted to try and see if I could create a class for the QPushButton widget in PyQt5 to save some lines. But once I create to create an instance of the Button class, it doesn't appear anywhere on the win instance of the Window class.
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
import sys
class Window(QWidget):
def __init__(self):
super().__init__()
self.setWindowTitle("Nested Layouts")
self.resize(800, 200)
self.show()
class Button(QPushButton):
def __init__(self, btn_parent, btn_text, btn_width, btn_height, btn_xCor, btn_yCor):
super().__init__()
self.btn_parent = btn_parent
self.btn_text = btn_text
self.btn_width = btn_width
self.btn_height = btn_height
self.btn_xCor = btn_xCor
self.btn_yCor = btn_yCor
self.setText(self.btn_text)
self.resize(btn_width, btn_height)
self.move(btn_xCor, btn_yCor)
app = QApplication(sys.argv)
win = Window()
button = Window.Button(btn_parent=win, btn_text="This won't work", btn_width=10, btn_height=10, btn_xCor=10, btn_yCor=10)
app.exec()
I even tried to make it like this, but the results are the same:
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
import sys
class Window(QWidget):
def __init__(self):
super().__init__()
self.setWindowTitle("Nested Layouts")
self.resize(800, 200)
self.show()
class Button(QPushButton):
def __init__(self, btn_parent, btn_text, btn_width, btn_height, btn_xCor, btn_yCor):
super().__init__()
self.btn_parent = btn_parent
self.btn_text = btn_text
self.btn_width = btn_width
self.btn_height = btn_height
self.btn_xCor = btn_xCor
self.btn_yCor = btn_yCor
self.setText(self.btn_text)
self.resize(btn_width, btn_height)
self.move(btn_xCor, btn_yCor)
app = QApplication(sys.argv)
win = Window()
button = Button(btn_parent=win, btn_text="This won't work", btn_width=10, btn_height=10, btn_xCor=10, btn_yCor=10)
app.exec()
Keep in mind that I'm kind of new to OOP(and Python and programming in general), so I might have a misunderstanding about how OOP works.
How can I fix this code so that the button shows on the win instance?

PyQt5 - Detecting When Other Window Closes

I’m using PyQt5 and I need to have my main window detect when a different window closes. I read here Emit a signal from another class to main class that creating a signal class to serve as an intermediary should work. However I haven’t gotten my example to work.
In my example, clicking the button opens a QWidget window. When the QWidget is closed, the main window is supposed to change from a blue background to a red background. However, the main window remains blue using the script below.
What am I doing wrong?
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtCore import QObject, pyqtSignal
import os, sys
class MySignal(QObject):
signal = pyqtSignal()
class MyMainWindow(QMainWindow):
def __init__(self):
super().__init__()
#Make mainwindow
self.setGeometry(100,100,300,200)
self.setStyleSheet('background-color: blue')
# Make widget and button objects and set connection
self.widget = MyWidget()
self.btn = QPushButton(self)
self.btn.setText('Click')
self.btn.move(175, 150)
self.btn.setStyleSheet('background-color: white')
self.btn.clicked.connect(self.widget.showWidget)
# Make signal object and set connection
self.mySignal = MySignal()
self.mySignal.signal.connect(self.changeToRed)
# Let's start
self.show()
def changeToRed(self):
self.setStyleSheet('background-color: red')
def closeEvent(self, event):
os._exit(0)
class MyWidget(QWidget):
def __init__(self):
super().__init__()
self.setGeometry(500, 100, 200, 200)
self.sig = MySignal()
def showWidget(self):
self.show()
def closeEvent(self, event):
self.sig.signal.emit()
self.close()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MyMainWindow()
app.exec()```

The reason your code fails is that the connected signal object in MyMainWindow is not the same as the one you create in MyWidget, so the signal is never emitted. Here is a modified solution using signals in the normal way:
from PyQt5.QtWidgets import QPushButton, QMainWindow, QWidget, QApplication
from PyQt5.QtCore import QObject, pyqtSignal
import os, sys
class MyMainWindow(QMainWindow):
def __init__(self):
super().__init__()
#Make mainwindow
self.setGeometry(100,100,300,200)
self.setStyleSheet('background-color: blue')
# Make widget and button objects and set connection
self.widget = MyWidget()
self.btn = QPushButton(self)
self.btn.setText('Click')
self.btn.move(175, 150)
self.btn.setStyleSheet('background-color: white')
self.btn.clicked.connect(self.widget.showWidget)
self.widget.sig.connect(self.changeToRed)
# Let's start
self.show()
def changeToRed(self):
self.setStyleSheet('background-color: red')
class MyWidget(QWidget):
sig = pyqtSignal()
def __init__(self):
super().__init__()
self.setGeometry(500, 100, 200, 200)
def showWidget(self):
self.show()
def closeEvent(self, event):
self.sig.emit()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MyMainWindow()
app.exec()

All you need is to add the connection between the close event and the function that turn your main screen red:
self.widget.closeEvent = self.changeToRed
this line should be in your main Window class
change your changeToRed function so it will except the event too:
def changeToRed(self, e):

How to create multiple QLabels in a gui on PyQt5?

I've created a gui using PyQt5 in PyCharm and I've managed to get one QLabel with an image in it (Picture1.png) showing up, however, when I try to add a second QLabel with a second image (named Shutter1.png) on the same window, it seems to remove both labels and nothing shows up on the gui. I'm not sure where I'm going wrong and any help would be greatly appreciated, I'm a novice! NB I've doublechecked the filepath for both imagePath and imagePath_1 are correct. See below for attached code:
from PyQt5 import uic, QtWidgets, QtGui, QtCore
import sys
import pkg_resources
import functions.initialisation as inits
import functions.Sig2Open as S2O
import functions.Sig2Close as S2C
class Ui(QtWidgets.QMainWindow):
def __init__(self):
super(Ui, self).__init__()
self.gui = uic.loadUi('Shuttergui.ui', self)
# Creates the path of the image
self.imagePath = "C:/........../Picture1.png"
self.label = QtWidgets.QLabel(self.gui)
self.image = QtGui.QImage(self.imagePath)
self.pixmapImage = QtGui.QPixmap.fromImage(self.image)
self.label.setPixmap(self.pixmapImage)
self.label.resize(self.width(), self.height())
self.label.move(60, 170)
self.imagePath = "C:/....../Shutter1.png"
# Create label that holds the image in imagePath
self.label_1 = QtWidgets.QLabel(self.gui)
self.image_1 = QtGui.QImage(self.imagePath)
self.pixmapImage_1 = QtGui.QPixmap.fromImage(self.image_1)
self.label_1.setPixmap(self.pixmapImage_1)
self.label_1.resize(self.width(), self.height())
self.label_1.move(60, 170)
self.gui.showMaximized()
# redirect closeevent func to main self rather than inside gui
self.gui.closeEvent = self.closeEvent
# Initialise shutter functions
inits.ardopenup(self)
inits.ardshutup(self)
self.gui.show()
def closeEvent(self, event):
import time
time.sleep(0.1)
print("main thread quitting")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
app.setStyleSheet(pkg_resources.resource_stream(__name__, '/css/darktheme/style.css').read().decode())
window = Ui()
sys.exit(app.exec_())

How to destroy a QApplication and then run a new one without exiting the python script?

I want to create a QApplication which is then exited using a keyboard shortcut. Then the python script should call another QApplication.
My issues currently is that I get this error when the second QApplication is about to run:
app2 = QApplication()
RuntimeError: Please destroy the QApplication singleton before creating a new QApplication instance.
I have the following structure:
| main.py
| Q1.py
| Q2.py
This is main.py:
import Q1 as record
import Q2 as display
def main():
record.main()
display.main()
if __name__ == "__main__":
main()
This is Q1 which creates the problem:
import sys
from PySide2 import QtWidgets as qtw
from PySide2 import QtGui as qtg
from PySide2 import QtCore as qtc
from PySide2 import QtMultimedia as qtmm
class MainWindow(qtw.QMainWindow):
def __init__(self):
super().__init__()
#Create Window layout with a sound widget
soundboard = qtw.QWidget()
soundboard.setLayout(qtw.QGridLayout())
self.setCentralWidget(soundboard)
sw = SoundWidget()
soundboard.layout().addWidget(sw)
#Window Dimensions
self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.MinimumExpanding)
# Code ends here
self.show()
class SendOrderButton(qtw.QPushButton):
button_stylesheet = 'background-color: blue; color: white;'
def __init__(self):
super().__init__('Send Order')
self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.Expanding)
self.setStyleSheet(self.button_stylesheet)
#self.clicked.connect(qtc.QCoreApplication.instance().quit)
def press_button(self):
if self.isEnabled():
self.setEnabled(False)
self.setText('Send Order')
else:
self.setEnabled(True)
self.setText('Sent')
class SoundWidget(qtw.QWidget):
def __init__(self):
super().__init__()
self.setLayout(qtw.QGridLayout())
#Send Order Button
self.sendorder_button = SendOrderButton()
self.sendorder_button.setShortcut(qtg.QKeySequence('Tab'))
self.layout().addWidget(self.sendorder_button, 5, 0, 1, 2)
self.sendorder_button.clicked.connect(qtc.QCoreApplication.instance().quit)
def main():
app = qtw.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
if __name__ == '__main__':
app = qtw.QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())
This is Q2.py which has the second QApplication:
import sys
from PySide2.QtCore import (QAbstractTableModel, Slot)
from PySide2.QtWidgets import (QAction, QApplication, QMainWindow,QWidget)
class MainWindow(QMainWindow):
def __init__(self, widget):
QMainWindow.__init__(self)
# Exit QAction
exit_action = QAction("Exit", self)
exit_action.setShortcut("Ctrl+Q")
exit_action.triggered.connect(self.exit_app)
#Slot()
def exit_app(self, checked):
sys.exit()
class CustomTableModel(QAbstractTableModel):
def __init__(self, data=None):
QAbstractTableModel.__init__(self)
class Widget(QWidget):
def __init__(self):
QWidget.__init__(self)
# Getting the Model
self.model = CustomTableModel()
def main():
app2 = QApplication()
widget = Widget()
window2 = MainWindow(widget)
window2.show()
sys.exit(app2.exec_())
if __name__ == "__main__":
app = QApplication()
widget = Widget()
window = MainWindow(widget)
window.show()
sys.exit(app.exec_())

As noted in the comments a Qt application can only and should have a QApplication (you might not follow this rule but nothing guarantees that it works correctly) so you will have to restructure your code.
Assuming that you want the Q1 window to be first and when that window is closed then the Q2 window opens that does not imply at any time that you have to use several QApplication. The idea is to know when a window is closed and to be notified of it, to know when a window is closed then you must override the closeEvent method of the window and to make the notification you must send a signal.
Considering the above, the solution is:
├── main.py
├── Q1.py
└── Q2.py
main.py
import sys
from PySide2 import QtWidgets as qtw
import Q1 as record
import Q2 as display
def main():
app = qtw.QApplication(sys.argv)
w1 = record.get_mainwindow()
w2 = display.get_mainwindow()
w1.closed.connect(w2.show)
w1.show()
sys.exit(app.exec_())
if __name__ == "__main__":
main()
Q1.py
from PySide2 import QtWidgets as qtw
from PySide2 import QtGui as qtg
from PySide2 import QtCore as qtc
class MainWindow(qtw.QMainWindow):
closed = qtc.Signal()
def __init__(self):
super().__init__()
# Create Window layout with a sound widget
soundboard = qtw.QWidget()
soundboard.setLayout(qtw.QGridLayout())
self.setCentralWidget(soundboard)
sw = SoundWidget()
soundboard.layout().addWidget(sw)
# Window Dimensions
self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.MinimumExpanding)
sw.sendorder_button.clicked.connect(self.close)
def closeEvent(self, event):
self.closed.emit()
super().closeEvent(event)
class SendOrderButton(qtw.QPushButton):
button_stylesheet = "background-color: blue; color: white;"
def __init__(self):
super().__init__("Send Order")
self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.Expanding)
self.setStyleSheet(self.button_stylesheet)
def press_button(self):
if self.isEnabled():
self.setEnabled(False)
self.setText("Send Order")
else:
self.setEnabled(True)
self.setText("Sent")
class SoundWidget(qtw.QWidget):
def __init__(self):
super().__init__()
self.setLayout(qtw.QGridLayout())
# Send Order Button
self.sendorder_button = SendOrderButton()
self.sendorder_button.setShortcut(qtg.QKeySequence("Tab"))
self.layout().addWidget(self.sendorder_button, 5, 0, 1, 2)
def get_mainwindow():
window = MainWindow()
return window
if __name__ == "__main__":
import sys
app = qtw.QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())
Q2.py
from PySide2 import QtCore as qtc
from PySide2 import QtWidgets as qtw
class MainWindow(qtw.QMainWindow):
def __init__(self, widget):
super().__init__()
file_menu = self.menuBar().addMenu("&File")
# Exit QAction
exit_action = qtw.QAction("Exit", self)
exit_action.setShortcut("Ctrl+Q")
exit_action.triggered.connect(self.close)
file_menu.addAction(exit_action)
class CustomTableModel(qtc.QAbstractTableModel):
pass
class Widget(qtw.QWidget):
def __init__(self):
super().__init__()
# Getting the Model
self.model = CustomTableModel()
def get_mainwindow():
widget = Widget()
window2 = MainWindow(widget)
return window2
if __name__ == "__main__":
import sys
app = qtw.QApplication()
widget = Widget()
window = MainWindow(widget)
window.show()
sys.exit(app.exec_())

first argument of unbound method must have type 'QWidget' [duplicate]

This question already has an answer here:
How to fix error in my pyqt programm (first argument of unbound method must have type 'QDialog') ?
(1 answer)
Closed 3 years ago.
I'm trying to build a GUI app using PyQt5 and Python 3.7 and I've decided to break the code in different modules. When i try to import a function that creates an instance of a custom widget, an error related to 'sis'. What I read is that 'sis' is a way of encapsulation C/C++ code to be run in python. But how can I work with that?
This is the code that runs the app:
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.setGeometry(10,35,1500,800)
self.setWindowTitle("Cotizador TuCheff")
#self.setWindowIcon(QtGui.QIcon(''))
mainWindow(self)
def mainWindow(self):
from PyQt5 import QtCore, QtGui, QtWidgets
from Pages.Quote import quote
barMenu = QtWidgets.QTabWidget(self)
tab1 = QtWidgets.QWidget()
quoteLayout = QtWidgets.QVBoxLayout()
quoteGenerator = quote.makeQuoteWindow()
quoteLayout.addWidget(quoteGenerator)
tab1.setLayout(quoteLayout)
barMenu.addTab(tab1, "&Nueva Cotización")
self.setCentralWidget(barMenu)
if __name__ == "__main__":
app = QApplication([])
window = MainWindow()
window.show()
app.exec_()
And file, where I try to get a custom widget, is:
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication
import sys
def makeQuoteWindow():
quoteWindow = QuoteWindow
quoteWindow.create()
#app = QApplication([])
#window = quoteWindow()
#window.show()
#status = app.exec_()
#sys.exit(status)
class QuoteWindow(QtWidgets.QWidget):
def __init__(self):
super(QuoteWindow, self).__init__()
def create(self):
mainWidget = QtWidgets.QWidget()
vLayout1 = QtWidgets.QVBoxLayout()
#=======------------------------ UPPER SIDE -------------------
hLayout1 = QtWidgets.QHBoxLayout()
##A LOT OF WIDGETS AND LAYOUTS
hLayout2 = QtWidgets.QHBoxLayout()
#display content
vLayout1.addLayout(hLayout1)
vLayout1.addLayout(hLayout2)
hLayout2.addItem(vSpacer1)
mainWidget.setLayout(vLayout1)
return mainWidget
if __name__ == "__main__":
makeQuoteWindow()
The error is:
TypeError: create(self, window: sip.voidptr = 0, initializeWindow: bool = True, destroyOldWindow: bool = True): first argument of unbound method must have type 'QWidget'

Try it:
main.py
import sys
from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtWidgets import QApplication, QMainWindow
# from Pages.Quote import quote
from Quote import QuoteWindow
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.setGeometry(10,35,1500,800)
self.setWindowTitle("Cotizador TuCheff")
self.setWindowIcon(QtGui.QIcon('im.png'))
# mainWindow(self)
self.mainWindow()
def mainWindow(self):
# from Pages.Quote import quote
self.quoteWindow = QuoteWindow() # +++
barMenu = QtWidgets.QTabWidget(self)
tab1 = QtWidgets.QWidget()
quoteLayout = QtWidgets.QVBoxLayout()
# quoteGenerator = quote.makeQuoteWindow()
# quoteLayout.addWidget(quoteGenerator)
quoteLayout.addWidget(self.quoteWindow) # +++
tab1.setLayout(quoteLayout)
barMenu.addTab(tab1, "&Nueva Cotización")
self.setCentralWidget(barMenu)
if __name__ == "__main__":
app = QApplication([])
window = MainWindow()
window.show()
app.exec_()
Quote.py
from PyQt5 import QtCore, QtWidgets, QtGui
class QuoteWindow(QtWidgets.QWidget):
def __init__(self):
super(QuoteWindow, self).__init__()
def create(self):
mainWidget = QtWidgets.QWidget()
vLayout1 = QtWidgets.QVBoxLayout()
#=======------------------------ UPPER SIDE -------------------
hLayout1 = QtWidgets.QHBoxLayout()
##A LOT OF WIDGETS AND LAYOUTS
hLayout2 = QtWidgets.QHBoxLayout()
#display content
vLayout1.addLayout(hLayout1)
vLayout1.addLayout(hLayout2)
hLayout2.addItem(vSpacer1)
mainWidget.setLayout(vLayout1)
return mainWidget