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PyQT5: how to add custom signal and slot?

i want to change slider position, when the self.factor is changed during set_parameter(). More precisely, how to update slider position as the value changes during computation?
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QPushButton, QSlider, QShortcut
from PyQt5.QtGui import QKeySequence
class Params():
def __init__(self):
self.factor = 0
def get_parameter(self):
return self.factor
def set_parameter(self, val):
self.factor =val
class SliderWidget(QWidget):
def __init__(self, param: Params):
QWidget.__init__(self)
self.params = param
layout = QVBoxLayout()
self.setLayout(layout)
self.slider = QSlider()
self.slider.valueChanged.connect(self.on_param_change)
layout.addWidget(self.slider)
self.slider.setMinimum(4)
self.slider.setMaximum(8)
def on_param_change(self):
value = self.params.get_parameter()
self.slider.setValue(value)
class Window(QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
self.box = QVBoxLayout()
self.params = Params()
self.scene = SliderWidget(self.params)
self.setCentralWidget(self.scene)
self.shortcutUp = QShortcut(QKeySequence('Ctrl+W'), self)
self.shortcutDw = QShortcut(QKeySequence('Ctrl+S'), self)
self.shortcutUp.activated.connect(self.up)
self.shortcutDw.activated.connect(self.down)
def up(self):
print('up')
value = (self.params.get_parameter() + 1)
self.params.set_parameter(value)
def down(self):
print('down')
value = (self.params.get_parameter() -1)
self.params.set_parameter(value)
import sys
if __name__ == '__main__':
app = QApplication(sys.argv)
win = Window()
win.show()
app.exec_()

You need to go through threading.
There is an exact procedure to achieve threading using PyQt5.
If you are not following it correctly, the application will crash without any error messages.
You will need the QThread lib and create workers to overwrite run method of QThread.
Here some link describing this:
https://www.youtube.com/watch?v=G7ffF0U36b0
https://realpython.com/python-pyqt-qthread/#using-qthread-to-prevent-freezing-guis
Here is the code with buttons:
from PyQt5.QtCore import QObject, QThread, pyqtSignal
class Worker(QObject): # Step 1: Create a worker class
finished = pyqtSignal()
progress = pyqtSignal(int)
def run(self):
"""Long-running task."""
for i in range(5):
sleep(1)
self.progress.emit(i + 1)
self.finished.emit()
class Window(QMainWindow):
# Snip...
def runLongTask(self):
# Step 2: Create a QThread object
self.thread = QThread()
# Step 3: Create a worker object
self.worker = Worker()
# Step 4: Move worker to the thread
self.worker.moveToThread(self.thread)
# Step 5: Connect signals and slots
self.thread.started.connect(self.worker.run)
self.worker.finished.connect(self.thread.quit)
self.worker.finished.connect(self.worker.deleteLater)
self.thread.finished.connect(self.thread.deleteLater)
self.worker.progress.connect(self.reportProgress)
# Step 6: Start the thread
self.thread.start()
# Final resets
self.longRunningBtn.setEnabled(False)
self.thread.finished.connect(
lambda: self.longRunningBtn.setEnabled(True)
)
self.thread.finished.connect(
lambda: self.stepLabel.setText("Long-Running Step: 0")
)

Using PySide2 (which is basically the same as PyQt5), I created this minor example. It displays a single QSlider. If you press Ctrl+W or Ctrl+S, the QShortcut is activated and it respectively increases or decreases the QSlider by +1 or -1.
Here's the script:
from PySide2.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QPushButton, QSlider, QShortcut
from PySide2.QtGui import QKeySequence
class Scene(QWidget):
def __init__(self):
QWidget.__init__(self)
layout = QVBoxLayout()
self.setLayout(layout)
self.slider = QSlider()
layout.addWidget(self.slider)
self.slider.setMinimum(4)
self.slider.setMaximum(8)
class Window(QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
self.scene = Scene()
self.setCentralWidget(self.scene)
self.shortcutUp = QShortcut(QKeySequence('Ctrl+W'), self)
self.shortcutDw = QShortcut(QKeySequence('Ctrl+S'), self)
self.shortcutUp.activated.connect(self.up)
self.shortcutDw.activated.connect(self.down)
def up(self):
print('up')
self.scene.slider.setValue(self.scene.slider.value()+1)
def down(self):
print('down')
self.scene.slider.setValue(self.scene.slider.value()-1)
if __name__ == '__main__':
app = QApplication()
win = Window()
win.show()
app.exec_()
I used a QShortcut so I didn't have to create a menubar, and set a shortcut there. It makes the exmaple smaller but with the same behaviour.

How to add questions into a pyqt thread

EDIT: I have attempted to add a slot to use a signal so the question box is handled by the main thread and not the worker, but it does not open the question box it just finishes the thread. I am also unsure of how to make the worker wait for the result of the question and how to return to the worker once I know what the user wants to do.
The code I have is used to test some boards and based on what happens the thread should either continue on to the next test if there was a pass or ask the user a question if there was a failure. The problem is when there is a failure the question box appears but the thread in the background continues, I don't want that to happen as the result of subsequent tests rely on the answers from the tests before.
Below is a example of what I do not want to happen.
import sys
from PyQt5.QtWidgets import QApplication, QLabel, QMainWindow, QPushButton, QVBoxLayout, QWidget, QMessageBox
from PyQt5.QtCore import QObject, pyqtSignal, QThreadPool, QRunnable, pyqtSlot
class WorkerSignals(QObject):
finished = pyqtSignal()
question = pyqtSignal()
class Worker(QRunnable):
def __init__(self, fn, *args, **kwargs):
super(Worker, self).__init__()
self.fn = fn
self.args = args
self.kwargs = kwargs
self.signals = WorkerSignals()
#pyqtSlot()
def run(self):
try:
result = self.fn(*self.args, **self.kwargs)
except:
pass
else:
self.signals.progress.emit(result)
finally:
self.signals.finished.emit()
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
layout = QVBoxLayout()
self.btnStartTest = QPushButton("Start thread")
self.labelOne = QLabel("Test one")
self.labelTwo = QLabel("Test two")
layout.addWidget(self.btnStartTest)
layout.addWidget(self.labelOne)
layout.addWidget(self.labelTwo)
w = QWidget()
w.setLayout(layout)
self.setCentralWidget(w)
self.threadpool = QThreadPool()
print("Multithreading with maximum %d threads" % self.threadpool.maxThreadCount())
self.btnStartTest.clicked.connect(self.runTestsThread)
self.show()
def runTestsThread(self):
# Pass the function to execute
worker = Worker(self.execute_this_fn)
worker.signals.question.connect(self.question_asked)
worker.signals.finished.connect(self.thread_complete)
# Execute
self.threadpool.start(worker)
def execute_this_fn(self):
resultOne = "FAIL"
resultTwo = "PASS"
if resultOne == "PASS":
self.labelOne.setStyleSheet("background-color: LightGreen")
else:
self.labelOne.setStyleSheet("background-color: Red")
self.question.emit()
if resultTwo == "PASS":
self.labelTwo.setStyleSheet("background-color: LightGreen")
else:
self.labelTwo.setStyleSheet("background-color: Red")
self.question.emit()
def thread_complete(self):
print("thread complete")
def question_asked(self):
QMessageBox.question(self, "Message Box!!", "Do you want to continue or quit")
if __name__ == "__main__":
app = QApplication(sys.argv)
Main = MainWindow()
Main.show()
sys.exit(app.exec_())
I have tried using a signal to finish the thread if there is a failure, then ask the question but this did not work. I was unsure of how to then start another thread based on the answer to the question.
Any help on how to structure this would be helpful, thanks.

How to get a child thread to close when main GUI window is closed in pyqt5 / python 3?

I am writing a GUI using pyqt5 (Python 3.6). I am trying to run another thread in parallel of the main GUI. I would like this child thread to terminate when I close the main application. In this example, the child thread is a simple counter. When I close the main GUI, the counter still keeps going. How can I get the thread to end when the GUI window is closed? In the real case I may have a thread that is running operations that takes a few minutes to execute. I am reluctant to use a flag within the thread to assess if it should end because it may take minutes for the thread to close after the GUI window has been closed. I would prefer the thread to end right away. Any suggestions?
Thank you.
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import (QWidget, QApplication,QPushButton,
QVBoxLayout)
import time, threading, sys
class testScriptApp(QtWidgets.QWidget):
def __init__(self, parent=None):
# initialize th widget
QtWidgets.QWidget.__init__(self, parent)
# set the window title
self.setWindowTitle("Scripting")
# manage the layout
self.mainGrid = QVBoxLayout()
self.button = QPushButton('Start')
self.button.clicked.connect(self.on_click)
self.mainGrid.addWidget(self.button)
self.setLayout(self.mainGrid)
def on_click(self):
self.worker = threading.Thread(target=Worker)
self.worker.daemon = True
self.worker.start()
def Worker(count=1):
while count>0:
print(count)
time.sleep(2)
count+=1
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
myapp = testScriptApp()
myapp.show()
app.exec_()

I tried to use the QThread but this locks up the main GUI. I am not sure if I am implementing it correctly.
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import (QWidget, QApplication,QPushButton,
QVBoxLayout)
from PyQt5.QtCore import QThread
import time, threading, sys
class testScriptApp(QtWidgets.QWidget):
def __init__(self, parent=None):
# initialize th widget
QtWidgets.QWidget.__init__(self, parent)
# set the window title
self.setWindowTitle("Scripting")
# manage the layout
self.mainGrid = QVBoxLayout()
self.button = QPushButton('Start')
self.button.clicked.connect(self.on_click)
self.mainGrid.addWidget(self.button)
self.setLayout(self.mainGrid)
def on_click(self):
self.worker = Worker()
self.worker.run()
def closeEvent(self,event):
print('Closing')
self.worker.terminate()
event.accept()
class Worker(QThread):
def __init__(self):
QThread.__init__(self)
def run(self):
count=1
while count>0:
print(count)
time.sleep(2)
count+=1
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
myapp = testScriptApp()
myapp.show()
app.exec_()

from PyQt5 import QtWidgets
from PyQt5.QtWidgets import (QWidget, QApplication,QPushButton,
QVBoxLayout)
from PyQt5.QtCore import QThread,QObject
import time, threading, sys
class testScriptApp(QtWidgets.QWidget):
def __init__(self, parent=None):
# initialize th widget
QtWidgets.QWidget.__init__(self, parent)
# set the window title
self.setWindowTitle("Scripting")
# manage the layout
self.mainGrid = QVBoxLayout()
self.button = QPushButton('Start')
self.button.clicked.connect(self.on_click)
self.mainGrid.addWidget(self.button)
self.setLayout(self.mainGrid)
def on_click(self):
self.my_thread = QThread()
self.worker = Worker()
self.worker.moveToThread(self.my_thread)
self.my_thread.started.connect(self.worker.run)
self.my_thread.start()
def closeEvent(self,event):
print('Closing')
class Worker(QObject):
def __init__(self):
super().__init__()
def run(self):
count=1
while count>0:
print(count)
time.sleep(2)
count+=1
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
myapp = testScriptApp()
myapp.show()
app.exec_()

hope self.my_thread.requestInterruption() won't qualify as flag, otherwise is not the sought answer :
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import (QWidget, QApplication,QPushButton,
QVBoxLayout)
from PyQt5.QtCore import QThread,QObject
import time, threading, sys
class testScriptApp(QtWidgets.QWidget):
def __init__(self, parent=None):
# initialize th widget
QtWidgets.QWidget.__init__(self, parent)
# set the window title
self.setWindowTitle("Scripting")
# manage the layout
self.mainGrid = QVBoxLayout()
self.button = QPushButton('Start')
self.button.clicked.connect(self.on_click)
self.mainGrid.addWidget(self.button)
self.setLayout(self.mainGrid)
def on_click(self):
self.my_thread = QThread()
self.worker = Worker(self.my_thread)
self.worker.moveToThread(self.my_thread)
self.my_thread.started.connect(self.worker.run)
self.my_thread.start()
def closeEvent(self,event):
self.my_thread.requestInterruption()
print('Closing')
self.my_thread.quit()
self.my_thread.wait()
print('is thread running ?', self.my_thread.isRunning())
class Worker(QObject):
def __init__(self, thread):
super().__init__()
self.thread = thread
def run(self):
count=1
while count>0:
print(count)
time.sleep(2)
count+=1
if self.thread.isInterruptionRequested():
break
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
myapp = testScriptApp()
myapp.show()
app.exec_()
see PySide6.QtCore.QThread.isInterruptionRequested()
Using threading.thread like in your question, I used threading.Event() and I set it (= True) to stop your Worker loop, but once again I hope is not a flag:
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import (QWidget, QApplication,QPushButton,
QVBoxLayout)
import time, threading, sys
class testScriptApp(QtWidgets.QWidget):
def __init__(self, parent=None):
# initialize th widget
QtWidgets.QWidget.__init__(self, parent)
# set the window title
self.setWindowTitle("Scripting")
# manage the layout
self.mainGrid = QVBoxLayout()
self.button = QPushButton('Start')
self.button.clicked.connect(self.on_click)
self.mainGrid.addWidget(self.button)
self.setLayout(self.mainGrid)
self.event = threading.Event()
def on_click(self):
self.worker = threading.Thread(target=Worker, args = (self.event,))
self.worker.daemon = True
self.worker.start()
def closeEvent(self, event):
if 'worker' in self.__dict__:
self.event.set() ## sets event: threading.Event() = True
self.worker.join() ## waits self.worker to complete ***
print('is worker alive, self.worker.is_alive() : ', self.worker.is_alive())
pass
def Worker(event, count=1 ):
print(event)
while count>0:
print(count)
time.sleep(2)
count+=1
if event.is_set():
break
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
myapp = testScriptApp()
myapp.show()
app.exec_()
try the code commenting and uncommentig out self.event.set() & self.worker.join() in
def closeEvent(self, event):
if 'worker' in self.__dict__:
self.event.set() ## sets event: threading.Event() = True
self.worker.join() ## waits self.worker to complete ***
print('is worker alive, self.worker.is_alive() : ', self.worker.is_alive())
pass
*** Wait until the thread terminates. This blocks the calling thread until the thread whose join() method is called terminates –

What is the proper way of opening a child dialog in a second thread in PyQt?

I have an application where I run some process in a second thread and at some point, given a certain condition, another dialog window opens, which halts the process until you confirm something. This causes the following error message:
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x1f9c82383d0), parent's thread is QThread(0x1f9c7ade2a0), current thread is QThread(0x1f9c8358800)
Interestingly, if you also move your cursor over the MainWindow while the process is running, and before the new dialog pops up, it also produces this error message a couple of times:
QBasicTimer::stop: Failed. Possibly trying to stop from a different thread
Very strange. Because it only occurs if you move your cursor over the MainWindow.
Now, in my application, I actually load an interface for the new dialog that pops up using PyQt5.uic.loadUi, and this hasn't caused any problems. However, when I was creating the example for this post, another issue occurred, due to the fact that I was setting the layout of the new dialog during its initialization:
QObject::setParent: Cannot set parent, new parent is in a different thread
Which results in the application crashing:
Process finished with exit code -1073741819 (0xC0000005)
I'm obviously doing something wrong here regarding the threading I would guess, but I don't know what. I am especially baffled by the fact that I cannot set the layout of the new dialog during its initialization, while using loadUi is totally fine. Here is my example code:
import sys
import time
import numpy as np
from PyQt5.QtCore import QObject, pyqtSignal, QThread
from PyQt5.QtWidgets import (
QDialog, QApplication, QPushButton, QGridLayout, QProgressBar, QLabel
)
class SpecialDialog(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton('pass variable')
btn.clicked.connect(self.accept)
layout = QGridLayout()
layout.addWidget(btn)
# self.setLayout(layout)
self.variable = np.random.randint(0, 100)
class Handler(QObject):
progress = pyqtSignal(int)
finished = pyqtSignal(int)
def __init__(self):
super().__init__()
self._isRunning = True
self._success = False
def run(self):
result = None
i = 0
while i < 100 and self._isRunning:
if i == 50:
dialog = SpecialDialog()
dialog.exec_()
result = dialog.variable
time.sleep(0.01)
i += 1
self.progress.emit(i)
if i == 100:
self._success = True
self.finished.emit(result)
def stop(self):
self._isRunning = False
class MainWindow(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton('test')
btn.clicked.connect(self.run_test)
self.pbar = QProgressBar()
self.resultLabel = QLabel('Result:')
layout = QGridLayout(self)
layout.addWidget(btn)
layout.addWidget(self.pbar)
layout.addWidget(self.resultLabel)
self.setLayout(layout)
self.handler = None
self.handler_thread = QThread()
self.result = None
def run_test(self):
self.handler = Handler()
self.handler.moveToThread(self.handler_thread)
self.handler.progress.connect(self.progress)
self.handler.finished.connect(self.finisher)
self.handler_thread.started.connect(self.handler.run)
self.handler_thread.start()
def progress(self, val):
self.pbar.setValue(val)
def finisher(self, result):
self.result = result
self.resultLabel.setText(f'Result: {result}')
self.pbar.setValue(0)
self.handler.stop()
self.handler.progress.disconnect(self.progress)
self.handler.finished.disconnect(self.finisher)
self.handler_thread.started.disconnect(self.handler.run)
self.handler_thread.terminate()
self.handler = None
if __name__ == '__main__':
app = QApplication(sys.argv)
GUI = MainWindow()
GUI.show()
sys.exit(app.exec_())
EDIT
I forgot to mention that I already found this post, which may be related to my problem, however, I don't undestand the reasoning of the solution in the top answer, and more importantly, I don't speak what I believe is C++.

You cannot create or modify a GUI element from a secondary thread and this is signaled by the error message.
You have to redesign the Handler class, with your requirement you must divide run into 2 methods, the first method will generate progress up to 50% where the GUI will open the dialogue, obtain the result and launch the second method.
import sys
import time
import numpy as np
from functools import partial
from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot, QThread, QTimer
from PyQt5.QtWidgets import (
QDialog,
QApplication,
QPushButton,
QGridLayout,
QProgressBar,
QLabel,
)
class SpecialDialog(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton("pass variable")
btn.clicked.connect(self.accept)
layout = QGridLayout()
layout.addWidget(btn)
# self.setLayout(layout)
self.variable = np.random.randint(0, 100)
class Handler(QObject):
progress = pyqtSignal(int)
finished = pyqtSignal(int)
def __init__(self):
super().__init__()
self._isRunning = True
self._success = False
#pyqtSlot()
def task1(self):
i = 0
while i <= 50 and self._isRunning:
time.sleep(0.01)
i += 1
self.progress.emit(i)
#pyqtSlot(int)
def task2(self, result):
i = 50
while i < 100 and self._isRunning:
time.sleep(0.01)
i += 1
self.progress.emit(i)
if i == 100:
self._success = True
self.finished.emit(result)
def stop(self):
self._isRunning = False
class MainWindow(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton("test")
btn.clicked.connect(self.run_test)
self.pbar = QProgressBar()
self.resultLabel = QLabel("Result:")
layout = QGridLayout(self)
layout.addWidget(btn)
layout.addWidget(self.pbar)
layout.addWidget(self.resultLabel)
self.setLayout(layout)
self.handler = None
self.handler_thread = QThread()
self.result = None
def run_test(self):
self.handler = Handler()
self.handler.moveToThread(self.handler_thread)
self.handler.progress.connect(self.progress)
self.handler.finished.connect(self.finisher)
self.handler_thread.started.connect(self.handler.task1)
self.handler_thread.start()
#pyqtSlot(int)
def progress(self, val):
self.pbar.setValue(val)
if val == 50:
dialog = SpecialDialog()
dialog.exec_()
result = dialog.variable
wrapper = partial(self.handler.task2, result)
QTimer.singleShot(0, wrapper)
def finisher(self, result):
self.result = result
self.resultLabel.setText(f"Result: {result}")
self.pbar.setValue(0)
self.handler.stop()
self.handler_thread.quit()
self.handler_thread.wait()
if __name__ == "__main__":
app = QApplication(sys.argv)
GUI = MainWindow()
GUI.show()
sys.exit(app.exec_())

Implement QThread with QProgressBar in PySide (or PyQt) during calculation

I would like to know how to implement QProgressBar, which shows the progress of calculation in main thread.
Please refer to below codes.
import sys
from PySide2.QtWidgets import QApplication, QWidget, QPushButton, QVBoxLayout, QProgressBar
from PySide2.QtCore import QThread
class BarThread(QThread):
# Progress Bar UI Definition
def __init__(self):
QThread.__init__(self)
self.window = QWidget()
self.pgsb = QProgressBar()
self.lay = QVBoxLayout()
self.lay.addWidget(self.pgsb)
self.window.setLayout(self.lay)
self.isRun = False
# Thread Function Definition
def run(self):
self.window.show()
while self.isRun:
self.pgsb.setValue(self.percent)
print(self.percent)
if self.percent == 100:
self.isRun = False
class Tool(QWidget):
# Main UI Definition
def __init__(self):
windowWidth = 300
windowHeight = 300
QWidget.__init__(self)
self.setWindowTitle("Example")
self.resize(windowWidth, windowHeight)
self.bt = QPushButton('Numbering')
self.layout = QVBoxLayout()
self.layout.addWidget(self.bt)
self.setLayout(self.layout)
# Main Function Link Definition
self.bt.clicked.connect(self.numbering)
# Main Function Definition
def numbering(self):
bth = BarThread()
bth.start()
bth.isRun = True
for x in range(0,100000):
bth.percent = x/1000
print(x)
if __name__ == "__main__":
app = QApplication(sys.argv)
widget = Tool()
widget.show()
sys.exit(app.exec_())
You can copy and paste directly onto your python IDE.
(it needs PySide2. It can be installed with 'pip install pyside2' in your prompt).
This code executes simple numbering, however, this doesn't show numbering progress.
How can I solve this problem? Thank you in advance.
P.S. I'm using Windows 10 with PyCharm.

You have at least the following errors:
You must not modify the GUI from another thread, in your case the run method is executed in another thread but you try to modify the value of the QProgressBar, in addition to displaying a widget which is not allowed. If you want to modify the GUI with the information provided in the execution in the secondary thread you must do it through signals since they are thread-safe
The for loop is the blocking task so it must be executed in another thread.
Considering the above, the solution is:
import sys
from PySide2.QtWidgets import (
QApplication,
QWidget,
QPushButton,
QVBoxLayout,
QProgressBar,
)
from PySide2.QtCore import QThread, Signal
class ProgressWidget(QWidget):
def __init__(self, parent=None):
super(ProgressWidget, self).__init__(parent)
self.pgsb = QProgressBar()
lay = QVBoxLayout(self)
lay.addWidget(self.pgsb)
class BarThread(QThread):
progressChanged = Signal(int)
def run(self):
percent = 0
for x in range(0, 100000):
percent = x / 100
self.progressChanged.emit(percent)
class Tool(QWidget):
"""Main UI Definition"""
def __init__(self, parent=None):
super(Tool, self).__init__(parent)
self.setWindowTitle("Example")
self.resize(300, 300)
self.bt = QPushButton("Numbering")
layout = QVBoxLayout(self)
layout.addWidget(self.bt)
# Main Function Link Definition
self.bt.clicked.connect(self.numbering)
self.bar_thread = BarThread(self)
self.progress_widget = ProgressWidget()
self.bar_thread.progressChanged.connect(self.progress_widget.pgsb.setValue)
# Main Function Definition
def numbering(self):
self.bar_thread.start()
self.progress_widget.show()
def closeEvent(self, event):
super(Tool, self).closeEvent(event)
self.bar_thread.quit()
self.bar_thread.wait()
if __name__ == "__main__":
app = QApplication(sys.argv)
widget = Tool()
widget.show()
sys.exit(app.exec_())