We Keep Coding

Qt: Dead lock detected - Sender is QPushButton(), receiver is PyQtSlotProxy() - for specific indexes in a QPushButton list

I am new to pyqt, and I tried to make an application window that contains a list of buttons that are able to toggle a different window. Since I want the number of these buttons to be of a varying quantity, I created a list of QPushButton elements for iterating over them, creating as many as defined by the length of the list, nevertheless I noticed a very weird behavior :
The following code ...
import sys
from random import randint
from PyQt5 import QtWidgets
class AnotherWindow(QtWidgets.QWidget):
"""
This "window" is a QWidget. If it has no parent,
it will appear as a free-floating window.
"""
def __init__(self):
super().__init__()
layout = QtWidgets.QVBoxLayout()
self.label = QtWidgets.QLabel("Another Window % d" % randint(0, 100))
layout.addWidget(self.label)
self.setLayout(layout)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self,windows):
super().__init__()
self.windows=[]
self.buttons=[]
l=QtWidgets.QVBoxLayout()
for i in range(len(windows)):
window=AnotherWindow()
self.windows.append(window)
button=QtWidgets.QPushButton(f'window {windows[i]}')
print(i," ",button)
self.buttons.append(button)
self.buttons[i].clicked.connect(self.toggle_window,i)
l.addWidget(self.buttons[i])
w = QtWidgets.QWidget()
w.setLayout(l)
self.setCentralWidget(w)
print(len(self.windows))
def toggle_window(self,i):
if self.windows[i].isVisible():
self.windows[i].hide()
else:
self.windows[i].show()
if __name__=="__main__":
app = QtWidgets.QApplication(sys.argv)
windows=[0,1,2,3]
windows=[str(i) for i in windows]
print(windows)
w = MainWindow(windows)
w.show()
app.exec()
produced the following error but only when the 4rth button (window 3) is pressed.
Qt: Dead lock detected while activating a BlockingQueuedConnection: Sender is QPushButton( ... ), receiver is PyQtSlotProxy( ... )
In effort to validate the code, I tried to narrow the list into a linear declaration of a static number of QPushButton instances, indicating that the issue occurs, only when I try to put the buttons on a list. For instance, the following script does not present any similar unpredictable behavior:
import sys
from random import randint
from PyQt5 import QtWidgets
class AnotherWindow(QtWidgets.QWidget):
"""
This "window" is a QWidget. If it has no parent,
it will appear as a free-floating window.
"""
def __init__(self):
super().__init__()
layout = QtWidgets.QVBoxLayout()
self.label = QtWidgets.QLabel("Another Window % d" % randint(0, 100))
layout.addWidget(self.label)
self.setLayout(layout)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.window0 = AnotherWindow()
self.window1 = AnotherWindow()
self.window2 = AnotherWindow()
self.window3 = AnotherWindow()
l = QtWidgets.QVBoxLayout()
button0 = QtWidgets.QPushButton("window 0")
button0.clicked.connect(self.toggle_window0)
l.addWidget(button0)
button1 = QtWidgets.QPushButton("window 1")
button1.clicked.connect(self.toggle_window1)
l.addWidget(button1)
button2 = QtWidgets.QPushButton("window 2")
button2.clicked.connect(self.toggle_window2)
l.addWidget(button2)
button3 = QtWidgets.QPushButton("window 3")
button3.clicked.connect(self.toggle_window3)
l.addWidget(button3)
w = QtWidgets.QWidget()
w.setLayout(l)
self.setCentralWidget(w)
def toggle_window0(self, checked):
if self.window0.isVisible():
self.window0.hide()
else:
self.window0.show()
def toggle_window1(self):
if self.window1.isVisible():
self.window1.hide()
else:
self.window1.show()
def toggle_window2(self):
if self.window2.isVisible():
self.window2.hide()
else:
self.window2.show()
def toggle_window3(self, checked):
if self.window3.isVisible():
self.window3.hide()
else:
self.window3.show()
if __name__=="__main__":
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
app.exec()
To test it further, I extended the list to a list of random lengths (more than 10), where I reassured that the issue persist for specific indexes each time. For example if I create 20 buttons using the first approach, the same bug appears for - the 4rth, the 12fth and the last index exclusively - but not for the rest of them. I even tested it on a different machine. Having also searched in forums, I could not find a solution.
Do I do anything completely wrong here? Does anyone understands better to indicate why is this happening?
I kindly thank you in advance!
Environment: Ubuntu 22.04
Pyqt version : 1.9 (under conda)

Your problem is the following:
self.buttons[i].clicked.connect(self.toggle_window,i)
You are passing i as second argument to connect and expect the toggle_window function to be called with this argument. This is not happening. In toggle_window, i will always be False. See musicamente's comment regarding what this second argument to connect does.
What you should do instead is connect the button click to a function of your window object. From there, you can of course do a callback to a function of your main window as illustrated below:
import sys
from random import randint
from PyQt5 import QtWidgets
class AnotherWindow(QtWidgets.QWidget):
def __init__(self, parent, i):
super().__init__()
self.parent = parent
self.i = i
layout = QtWidgets.QVBoxLayout()
self.label = QtWidgets.QLabel("Another Window {}".format(i))
layout.addWidget(self.label)
self.setLayout(layout)
def toggle(self):
print("Toggling windows {}".format(self.i))
if self.isVisible():
self.hide()
self.parent.window_toggled(self.i, False)
else:
self.show()
self.parent.window_toggled(self.i, True)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, windows):
super().__init__()
self.windows=[]
self.buttons=[]
l=QtWidgets.QVBoxLayout()
for i,title in enumerate(windows):
window=AnotherWindow(self, i)
self.windows.append(window)
button=QtWidgets.QPushButton(title)
button.clicked.connect(window.toggle)
l.addWidget(button)
self.buttons.append(button)
w = QtWidgets.QWidget()
w.setLayout(l)
self.setCentralWidget(w)
def window_toggled(self, i, visible):
print("Window {} is now {}".format(i, "visible" if visible else "hidden"))
if __name__=="__main__":
app = QtWidgets.QApplication(sys.argv)
windows = ["window {}".format(i) for i in range(12)]
w = MainWindow(windows)
w.show()
app.exec()

How to add Today Button in QDateEdit Pop-up QCalendarWidget

Today Button like this
Image of my pop-up calendar widget:
I am trying to create simple Gui using PyQt5 in Python with date picker option. I need to add today button in QDateEdit in pop-up QCalendarWidget.

You must add the button to the QCalendarWidget through the layout, and when the button is pressed set the QDate::currentDate() as selectedDate of the QCalendarWidget:
import sys
from PyQt5 import QtCore, QtWidgets
class DateEdit(QtWidgets.QDateEdit):
def __init__(self, parent=None):
super().__init__(parent, calendarPopup=True)
self._today_button = QtWidgets.QPushButton(self.tr("Today"))
self._today_button.clicked.connect(self._update_today)
self.calendarWidget().layout().addWidget(self._today_button)
#QtCore.pyqtSlot()
def _update_today(self):
self._today_button.clearFocus()
today = QtCore.QDate.currentDate()
self.calendarWidget().setSelectedDate(today)
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
w = DateEdit()
w.show()
sys.exit(app.exec_())

You can decide to create a custom button to handle the popup even.
import sys
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
class EditDate:
def __init__(self):
super(EditDate, self).__init__()
self.app_runner()
def date_gui(self):
self.app = QApplication(sys.argv)
self.win = QDialog()
self.win.setFixedSize(280, 40)
self.dateEdit = QDateEdit(self.win)
self.dateEdit.setFixedSize(230, 40)
self.dateEdit.move(5, 0)
self.hideCalendar = QPushButton(self.win)
self.hideCalendar.setText("Hide")
self.hideCalendar.move(231, 0)
self.hideCalendar.setFixedSize(45, 40)
self.displayCalendar = QPushButton(self.win)
self.displayCalendar.setText("Date..")
self.displayCalendar.move(231, 0)
self.displayCalendar.setFixedSize(45, 40)
self.calender = QCalendarWidget(self.win)
self.calender.move(5, 40)
self.todayButton = QPushButton(self.win)
self.todayButton.setText("Today")
self.todayButton.setFixedSize(100, 30)
self.todayButton.move(5, 200)
self.calender.hide()
self.todayButton.hide()
def button_handling(self):
self.todayButton.clicked.connect(self.todays_date)
self.displayCalendar.clicked.connect(self.display_cal)
self.hideCalendar.clicked.connect(self.hide_cal)
def hide_cal(self):
self.calender.hide()
self.displayCalendar.show()
self.todayButton.hide()
self.hideCalendar.hide()
self.win.setFixedSize(280, 40)
def display_cal(self):
self.win.setFixedSize(280, 300)
self.calender.show()
self.todayButton.show()
self.hideCalendar.show()
self.displayCalendar.hide()
def todays_date(self):
self.date = QDate.currentDate()
self.dateEdit.setDate(self.date)
self.calender.setSelectedDate(self.date)
def app_runner(self):
self.date_gui()
self.win.show()
self.button_handling()
sys.exit(self.app.exec_())
main = EditDate()

Resize multiple labels containing images with changing window size

I have a window that has six symmetrically placed labels, all showing images (designed using qt-designer with the help of layouts). I would like to resize these images according to the changing window size. I have found some help in previous questions like: PyQt: Detect resizing in Widget-window resized signal
At present, using resizeEvent() in my case does not shrink the images according to the resize function. It is already triggered with the display of my form window thereby making the pushButton useless. Above all, the resulting execution is very slow. My images are of 2058x1536 dimension and displayed transparently.
My qt-designer code is given here: https://pastebin.com/TzM6qiKZ
import Ui_ImageCrop_Test
import sys
from PyQt5.QtWidgets import QMainWindow, QApplication
from PyQt5.QtGui import QPixmap, QImage, QPainter, QColor
from PyQt5.QtCore import Qt
class ImageCrop(Ui_ImageCrop_Test.Ui_MainWindow, QMainWindow):
def __init__(self, parent=None):
super(ImageCrop, self).__init__()
self.setupUi(self)
self.transparency = 220
with open("Img_files.txt") as file:
self.img_files = file.read().splitlines()
self.length = len(self.img_files)
self.pushButton_1.clicked.connect(self.click1)
self.label_1.resizeEvent = self.click1
def click1(self, event):
for i in range(6):
image = QImage(self.img_files[i])
image = image.convertToFormat(QImage.Format_ARGB8565_Premultiplied)
p = QPainter(image)
p.setCompositionMode(QPainter.CompositionMode_DestinationIn)
p.fillRect(image.rect(), QColor(0, 0, 0, self.transparency))
p.end()
pixmap = QPixmap(image)
w = int(self.label_1.width() - 4.0)
h = int(self.label_1.height() - 4.0)
smaller_pixmap = pixmap.scaled(w, h, Qt.IgnoreAspectRatio, Qt.FastTransformation)
if i == 0:
self.label_1.setPixmap(smaller_pixmap)
if i == 1:
self.label_2.setPixmap(smaller_pixmap)
if i == 2:
self.label_3.setPixmap(smaller_pixmap)
if i == 3:
self.label_4.setPixmap(smaller_pixmap)
if i == 4:
self.label_5.setPixmap(smaller_pixmap)
if i == 5:
self.label_6.setPixmap(smaller_pixmap)
def main():
app = QApplication(sys.argv)
form1 = ImageCrop()
form1.show()
app.exec_()
if __name__ == '__main__': main()
Is there any solution to run this code faster? For example, I was thinking to make all my labels turn blank during a mouse click at the edge of my window and then images reappear after the mouse button is released. This does not seem so neat. Also, I am not sure if using paintEvent can reduce my lag. Thank you for your suggestions and comments.

QLabel has the scaledContents property that allows the image to scale automatically:
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
import Ui_ImageCrop_Test
class ImageCrop(QtWidgets.QMainWindow, Ui_ImageCrop_Test.Ui_MainWindow):
def __init__(self, parent=None):
super(ImageCrop, self).__init__()
self.setupUi(self)
self.pushButton_1.clicked.connect(self.click1)
self.transparency = 220
with open("Img_files.txt") as file:
self.img_files = file.read().splitlines()
#QtCore.pyqtSlot()
def click1(self):
labels = [self.label_1, self.label_2, self.label_3,
self.label_4, self.label_5, self.label_6]
for label, filename in zip(labels, self.img_files):
image = QtGui.QImage(filename)
image = image.convertToFormat(QtGui.QImage.Format_ARGB8565_Premultiplied)
p = QtGui.QPainter(image)
p.setCompositionMode(QtGui.QPainter.CompositionMode_DestinationIn)
p.fillRect(image.rect(), QtGui.QColor(0, 0, 0, self.transparency))
p.end()
pixmap = QtGui.QPixmap(image)
w = int(label.width() - 4.0)
h = int(label.height() - 4.0)
smaller_pixmap = pixmap.scaled(w, h, QtCore.Qt.IgnoreAspectRatio, QtCore.Qt.FastTransformation)
label.setPixmap(smaller_pixmap)
label.setScaledContents(True)
def main():
app = QtWidgets.QApplication(sys.argv)
form1 = ImageCrop()
form1.show()
app.exec_()
if __name__ == '__main__': main()

PyQt5 - How to add a scrollbar to a QMessageBox

I have a list which is generated based on user-input.
I am trying to display this list in a QMessageBox. But, I have no way of knowing the length of this list. The list could be long.
Thus, I need to add a scrollbar to the QMessageBox.
Interestingly, I looked everywhere, but I haven’t found any solutions for this.
Below is, what I hope to be a “Minimal, Complete and Verifiable Example”, of course without the user input; I just created a list as an example.
I appreciate any advice.
import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class W(QWidget):
def __init__(self):
super().__init__()
self.initUi()
def initUi(self):
self.btn = QPushButton('Show Message', self)
self.btn.setGeometry(10, 10, 100, 100)
self.btn.clicked.connect(self.buttonClicked)
self.lst = list(range(2000))
self.show()
def buttonClicked(self):
result = QMessageBox(self)
result.setText('%s' % self.lst)
result.exec_()
if __name__ == "__main__":
app = QApplication(sys.argv)
gui = W()
sys.exit(app.exec_())

You can not add a scrollbar directly since the widget in charge of displaying the text is a QLabel. The solution is to add a QScrollArea. The size may be inadequate so a stylesheet has to be used to set minimum values.
class ScrollMessageBox(QMessageBox):
def __init__(self, l, *args, **kwargs):
QMessageBox.__init__(self, *args, **kwargs)
scroll = QScrollArea(self)
scroll.setWidgetResizable(True)
self.content = QWidget()
scroll.setWidget(self.content)
lay = QVBoxLayout(self.content)
for item in l:
lay.addWidget(QLabel(item, self))
self.layout().addWidget(scroll, 0, 0, 1, self.layout().columnCount())
self.setStyleSheet("QScrollArea{min-width:300 px; min-height: 400px}")
class W(QWidget):
def __init__(self):
super().__init__()
self.btn = QPushButton('Show Message', self)
self.btn.setGeometry(10, 10, 100, 100)
self.btn.clicked.connect(self.buttonClicked)
self.lst = [str(i) for i in range(2000)]
self.show()
def buttonClicked(self):
result = ScrollMessageBox(self.lst, None)
result.exec_()
if __name__ == "__main__":
app = QApplication(sys.argv)
gui = W()
sys.exit(app.exec_())
Output:

Here is another way to override the widgets behavior.
You can get references to the children of the widget by using 'children()'.
Then you can manipulate them like any other widget.
Here we add a QScrollArea and QLabel to the original widget's QGridLayout. We get the text from the original widget's label and copy it to our new label, finally we clear the text from the original label so it is not shown (because it is beside our new label).
Our new label is scrollable. We must set the minimum size of the scrollArea or it will be hard to read.
import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class ScrollMessageBox(QMessageBox):
def __init__(self, *args, **kwargs):
QMessageBox.__init__(self, *args, **kwargs)
chldn = self.children()
scrll = QScrollArea(self)
scrll.setWidgetResizable(True)
grd = self.findChild(QGridLayout)
lbl = QLabel(chldn[1].text(), self)
lbl.setWordWrap(True)
scrll.setWidget(lbl)
scrll.setMinimumSize (400,200)
grd.addWidget(scrll,0,1)
chldn[1].setText('')
self.exec_()
class W(QWidget):
def __init__(self):
super(W,self).__init__()
self.btn = QPushButton('Show Message', self)
self.btn.setGeometry(10, 10, 100, 100)
self.btn.clicked.connect(self.buttonClicked)
self.message = ("""We have encountered an error.
The following information may be useful in troubleshooting:
1
2
3
4
5
6
7
8
9
10
Here is the bottom.
""")
self.show()
def buttonClicked(self):
result = ScrollMessageBox(QMessageBox.Critical,"Error!",self.message)
if __name__ == "__main__":
app = QApplication(sys.argv)
gui = W()
sys.exit(app.exec_())

PYQT Accessing and changing dynamically added controls

I am a beginner with GUI's and PYQT. What I am trying to do is dynamically set up a grid of QComboBox's and QLineEdit's. From the QComboBox you can select a choice and from that choice, it will fill in the corresponding QLineEdit with some numbers. The problem I'm having is creating the link between the first QComboBox and the first QLineEdit box. I could make a function for each row but I would like to know a better way. I will post some sample code. Thank you for any help or advice that you might have.
import sys
from PyQt5.QtCore import QCoreApplication
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class window(QMainWindow):
def __init__(self):
super(window, self).__init__()
self.setGeometry(50, 50, 700, 600)
self.home()
def home(self):
Test1Choices = ['Test1:','Choice1', 'Choice2', 'Choice3', 'Choice4','Choice5', 'Choice6', 'Choice7', 'Choice8', 'Choice9']
Test2Choices= ['Test2:','1','2','3','4','5','6','7','8','9','10','11','12','13','14','15']
for i in range(0,10):
Choice1ComboBox = QComboBox(self)
Choice1ComboBox.addItems(Test1Choices)
Choice1ComboBox.resize(150,25)
Choice1ComboBox.move(30,(150+(i*35)))
Choice1ComboBox.setCurrentIndex(2)
Choice2ComboBox = QComboBox(self)
Choice2ComboBox.setObjectName("Choice2ComboBox"+str(i))
Choice2ComboBox.addItems(Test2Choices)
Choice2ComboBox.resize(75,25)
Choice2ComboBox.move(200,(150+(i*35)))
Choice2ComboBox.setCurrentIndex(2)
Choice2ComboBox.activated[str].connect(self.doSomething)
numTextBox = QLineEdit(self)
numTextBox.setObjectName("numBox"+str(i))
numTextBox.move(325,(150+(i*35)))
numTextBox.resize(35,25)
result1TextBox = QLineEdit(self)
result1TextBox.setObjectName("result1Box"+str(i))
result1TextBox.move(400,(150+(i*35)))
result1TextBox.resize(100,25)
result1TextBox.setEnabled(0)
result2TextBox = QLineEdit(self)
result2TextBox.setObjectName("result2Box"+str(i))
result2TextBox.move(525,(150+(i*35)))
result2TextBox.resize(100,25)
result2TextBox.setEnabled(0)
self.show()
def doSomething(self):
numbers=['result1','result2','result3','result4','result5','result6','result7','result8','result9','result10','result11','result12','result13','result14','result15']
def run():
app = QApplication(sys.argv)
Gui = window()
sys.exit(app.exec_())
run()
To summarize I would like to bring in the index of the selected QComboBox. Then use that index number to reference the answer that is in the "numbers" array. Then print that result in the QLineEdit that is in the same row

We use sender() to get the object that emits the signal, then we look for the name of that object with setObjectName(), and we search the index, then we get the other objects with findChildren(), for example the output will be the union of the selected texts.
add name to Choice1ComboBox:
Choice1ComboBox.setObjectName("Choice1ComboBox"+str(i))
doSomething function:
def doSomething(self, _):
sender = self.sender()
l = sender.objectName().split("Choice1ComboBox")
if len(l) > 1:
number = l[1]
else:
number = sender.objectName().split("Choice2ComboBox")[1]
combo1 = self.findChildren(QComboBox, "Choice1ComboBox"+number)[0]
combo2 = self.findChildren(QComboBox, "Choice2ComboBox"+number)[0]
obj = self.findChildren(QLineEdit, "numBox"+number)[0]
obj.setText(combo1.currentText() + " " + combo2.currentText())
Complete code:
import sys
from PyQt5.QtCore import QCoreApplication
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class window(QMainWindow):
def __init__(self):
super(window, self).__init__()
self.setGeometry(50, 50, 700, 600)
self.home()
def home(self):
Test1Choices = ['Test1:','Choice1', 'Choice2', 'Choice3', 'Choice4','Choice5', 'Choice6', 'Choice7', 'Choice8', 'Choice9']
Test2Choices= ['Test2:','1','2','3','4','5','6','7','8','9','10','11','12','13','14','15']
for i in range(0,10):
Choice1ComboBox = QComboBox(self)
Choice1ComboBox.setObjectName("Choice1ComboBox"+str(i))
Choice1ComboBox.addItems(Test1Choices)
Choice1ComboBox.resize(150,25)
Choice1ComboBox.move(30,(150+(i*35)))
Choice1ComboBox.setCurrentIndex(2)
Choice1ComboBox.activated[str].connect(self.doSomething)
Choice2ComboBox = QComboBox(self)
Choice2ComboBox.setObjectName("Choice2ComboBox"+str(i))
Choice2ComboBox.addItems(Test2Choices)
Choice2ComboBox.resize(75,25)
Choice2ComboBox.move(200,(150+(i*35)))
Choice2ComboBox.setCurrentIndex(2)
Choice2ComboBox.activated[str].connect(self.doSomething)
numTextBox = QLineEdit(self)
numTextBox.setObjectName("numBox"+str(i))
numTextBox.move(325,(150+(i*35)))
numTextBox.resize(35,25)
result1TextBox = QLineEdit(self)
result1TextBox.setObjectName("result1Box"+str(i))
result1TextBox.move(400,(150+(i*35)))
result1TextBox.resize(100,25)
result1TextBox.setEnabled(0)
result2TextBox = QLineEdit(self)
result2TextBox.setObjectName("result2Box"+str(i))
result2TextBox.move(525,(150+(i*35)))
result2TextBox.resize(100,25)
result2TextBox.setEnabled(0)
self.show()
def doSomething(self, _):
sender = self.sender()
l = sender.objectName().split("Choice1ComboBox")
if len(l) > 1:
number = l[1]
else:
number = sender.objectName().split("Choice2ComboBox")[1]
combo1 = self.findChildren(QComboBox, "Choice1ComboBox"+number)[0]
combo2 = self.findChildren(QComboBox, "Choice2ComboBox"+number)[0]
obj = self.findChildren(QLineEdit, "numBox"+number)[0]
obj.setText(combo1.currentText() + " " + combo2.currentText())
def run():
app = QApplication(sys.argv)
Gui = window()
sys.exit(app.exec_())
run()