QThread does not update view with events - python

On menu I can trigger:
def on_git_update(self):
update_widget = UpdateView()
self.gui.setCentralWidget(update_widget)
updateGit = UpdateGit()
updateGit.progress.connect(update_widget.on_progress)
updateGit.start()
then I have:
class UpdateView(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
vbox = QVBoxLayout()
self.pbar = QProgressBar()
vbox.addWidget(self.pbar)
vbox.addStretch(1)
self.setLayout(vbox)
def on_progress(self, value):
self.pbar.setValue(int(value * 100))
class UpdateGit(QThread):
progress = pyqtSignal(float)
def __del__(self):
self.wait()
def run(self):
for i in range(10):
self.progress.emit(i / 10)
sleep(.5)
The app freezes during the processing, afaik it should work as it is in a thread using signals.
Also, it works as expected with the app updating every step when I run it in debug mode via pycharm.
How is my thread set up incorrectly?

A variable created in a function only exists until the function exists, and this is what happens with updateGit, in the case of update_widget when it is set as centralwidget it has a greater scope since Qt handles it. The solution is to extend the scope of the thread by making it a member of the class.
def on_git_update(self):
update_widget = UpdateView()
self.gui.setCentralWidget(update_widget)
self.updateGit = UpdateGit()
self.updateGit.progress.connect(update_widget.on_progress)
self.updateGit.start()

Related

Qthread isn't working Not returning signals

i have this WorkerSignals class which used to connect signals with the Qthread class worker, SaveToExcel() is a function that i used to run in Qthread.
class WorkerSignals(QObject):
finished = pyqtSignal()
error = pyqtSignal(tuple)
result = pyqtSignal(object)
progress = pyqtSignal(int)
class Worker(QThread):
def __init__(self,query,filename,choices,fileExtension,iterativeornot):
super(Worker,self).__init__()
self.signals = WorkerSignals()
self.query =query
self.filename = filename
self.choices = choices
self.fileExtension = fileExtension
self.iterativeornot =iterativeornot
#pyqtSlot()
def run(self):
try:
SaveToExcel(self.query,self.filename,self.choices,self.fileExtension,self.iterativeornot)
except:
self.signals.result.emit(1)
finally:
self.signals.finished.emit()
this is the class that i used to create the Qwidget that has ui
class AnotherWindow(QWidget):
def __init__(self,windowname):
super().__init__()
self.layout = QVBoxLayout()
self.label = QLabel()
self.setWindowTitle(windowname)
self.setWindowIcon(QIcon(os.path.join(basedir,'./images/import.png')))
self.setFixedSize(460,440)
self.layout.addWidget(self.label)
# Query
self.textinput = QPlainTextEdit()
self.layout.addWidget(self.textinput)
self.qhboxlayout1 = QHBoxLayout()
self.IterativeRadiobtn1 = QRadioButton('All Locations')
self.IterativeRadiobtn2 = QRadioButton('Current Locations')
self.IterativeRadiobtn2.setChecked(True)
self.qhboxlayout1.addWidget(self.IterativeRadiobtn1)
self.qhboxlayout1.addWidget(self.IterativeRadiobtn2)
self.layout.addLayout(self.qhboxlayout1)
# Check boxes
self.c1 = QCheckBox("sc",self)
self.c2 = QCheckBox("ad",self)
self.c3 = QCheckBox("sr",self)
self.c4 = QCheckBox("fc",self)
self.hboxlayoutchoices = QHBoxLayout()
#adding checkboxes to layout
self.checkboxlist = [self.c1,self.c2,self.c3,self.c4]
for cbox in self.checkboxlist:
self.hboxlayoutchoices.addWidget(cbox)
self.layout.addLayout(self.hboxlayoutchoices)
# filename
self.filename = QLineEdit()
self.layout.addWidget(self.filename)
# Combo box to show the filetype which need to be saved
self.extensions = QComboBox()
self.combodict = {'Excel 97-2003 Workbook (*.xls)':'xls','CSV UTF-8 (Comma delimited) (*.csv)':'csv'}
self.extensions.addItems(self.combodict)
self.layout.addWidget(self.extensions)
# import button
self.exportBtn = QPushButton('Import')
self.layout.addWidget(self.exportBtn)
#import function when button clicked
self.exportBtn.clicked.connect(self.IMPORT)
#setting layout
self.setLayout(self.layout)
def RadioButtonCheck(self):
if self.IterativeRadiobtn1.isChecked():
return True
if self.IterativeRadiobtn2.isChecked():
return False
def IMPORT(self):
self.cboxlist = []
for cbox in self.checkboxlist:
if cbox.isChecked():
self.cboxlist.append(cbox.text())
self.textinput.setReadOnly(True)
self.filename.setReadOnly(True)
self.exportBtn.setDisabled(True)
self.saveFilename = self.filename.text()
self.text = self.textinput.toPlainText()
self.inputextension = self.extensions.currentText()
self.getvalue = self.combodict.get(self.inputextension)
self.truorfalse = self.RadioButtonCheck()
# self.queryThread = threading.Thread(target=SaveToExcel,args=(self.text,self.saveFilename,self.cboxlist,self.getvalue,self.truorfalse))
# self.queryThread.start()
self.worker = Worker(self.text,self.saveFilename,self.cboxlist,self.getvalue,self.truorfalse)
self.worktherad = QThread()
self.worker.moveToThread(self.worktherad)
self.worktherad.started.connect(self.worker.run)
self.worktherad.finished.connect(self.complete)
self.worktherad.start()
def complete(self):
self.msg = QMessageBox()
self.msg.setWindowTitle("Status")
self.msg.setText("Import Done")
self.msg.exec()
self.textinput.setReadOnly(False)
self.filename.setReadOnly(False)
self.exportBtn.setDisabled(False)
self.exportBtn.setText("Import Again")
but when i click the import button the function won't run and just do nothing, I don't have a good knowledge about Qthreading but when i use the python default threading the function will run and import the datas. Still i don't have good clear idea about how to implent the Qthreading for the SaveToExcel function.
self.worker = Worker(self.text,self.saveFilename,self.cboxlist,self.getvalue,self.truorfalse)
in this line you should probably pass the parent field and you should accept the parent field in Worker __init__ method and pass it in super call
(so the thread will automatically destroyed once it's parent object is deleted)
and the Worker class is already a QThread you do not need to create another QThread and move it..
you should just run the self.worker by self.worker.start()
and don't forget to connect those Worker signals to valid pyqtSlot and if possible then connect those before starting the self.worker thread
Updated Code Snippet
self.worker = Worker(parent, self.text,self.saveFilename,self.cboxlist,self.getvalue,self.truorfalse) # Accept parent in __init__ method of Worker
self.worktherad.finished.connect(self.complete)
self.worktherad.start()
And also make complete function a pyqtSlot by adding decorator QtCore.pyqtSlot()

Using a QTimer within a PyQt worker thread

I am working with serial device and set a flag (which is global variable) based on the received data. Now I want to reset the flag after a while (for example one second) by using a timer.
Here is the code:
class Inlet_Worker(QObject):
def __init__(self):
super(Inlet_Worker, self).__init__()
self.timer = QTimer(self)
self.timer.timeout.connect(self.Reset_Register_Barcode)
def run(self):
global Register_Barcode
while True :
if client.read_coils(address = 0x0802).bits[0]:
Register_Barcode = True
self.timer.start(1000)
def Reset_Register_Barcode(self):
global Register_Barcode
Register_Barcode = False
However the timer is not working.
I will assume from your example code that your are using a QThread and that you also use QObject.moveToThread on your worker object. This is the correct procedure, but there are some other things you must do to make your timer work.
Firstly, you should use a single-shot timer so as to avoid re-regsitration whilst the current one is active. Secondly, you must explicitly process any pending events, since your while-loop will block the thread's event-loop. Without this, the timer's timeout signal will never be emitted. Thirdly, you should ensure that the worker and thread shut down cleanly when the program exits (which will also prevent any Qt error messages). Finally, if possible, you should use signals to communicate registration changes to the main GUI thread, rather than global variables.
The demo script below (based on your example) implements all of that. After the Start button is clicked, the thread will start and periodically update the regsitration (indicated by the check-box). Hopefully you shoudld be able to see how to adapt it to your real application:
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
class Inlet_Worker(QObject):
barcodeRegistered = pyqtSignal(bool)
def __init__(self):
super().__init__()
self._stopped = False
self._registered = False
self.timer = QTimer(self)
self.timer.setSingleShot(True)
self.timer.timeout.connect(self.updateBarcodeRegistration)
def run(self):
count = 0
self._stopped = False
while not self._stopped:
#if client.read_coils(address = 0x0802).bits[0]:
count += 1
if count % 20 == 0 and not self._registered:
self.updateBarcodeRegistration(True)
self.timer.start(2000)
QCoreApplication.processEvents()
QThread.msleep(100)
self.updateBarcodeRegistration(False)
self.timer.stop()
print('Stopped')
def updateBarcodeRegistration(self, enable=False):
print('Register' if enable else 'Reset')
self._registered = enable
self.barcodeRegistered.emit(enable)
def stop(self):
self._stopped = True
class Window(QWidget):
def __init__(self):
super().__init__()
self.thread = QThread()
self.worker = Inlet_Worker()
self.worker.moveToThread(self.thread)
self.button = QPushButton('Start')
self.check = QCheckBox('Registered')
layout = QHBoxLayout(self)
layout.addWidget(self.button)
layout.addWidget(self.check)
self.thread.started.connect(self.worker.run)
self.button.clicked.connect(self.thread.start)
self.worker.barcodeRegistered.connect(self.check.setChecked)
def closeEvent(self, event):
self.worker.stop()
self.thread.quit()
self.thread.wait()
if __name__ == '__main__':
app = QApplication(['Test'])
window = Window()
window.setGeometry(600, 100, 200, 50)
window.show()
app.exec()

QWidget not loading child elements when QRunnable is also called

I'm working in a data processing desktop application with Python 3.7 and PySide2 on which requires me to load data from several large (approx 250k rows) excel files into the program's processing library. For this I've set up in my application a simple popup (called LoadingPopup) which includes a rotating gif and a simple caption, and also some code that loads the data from the excel files into a global object using pandas. Both of these things work as intended when run on their own, but if I happen to create a loading dialog and a QRunnable worker in the same scope of my codebase, the widgets contained in loading widget (a gif and a simple caption) will simply not show.
I've tried changing the parent type for my widget from QDialog to QWidget, or initializing the popup (the start() function) both outside and inside the widget. I'm not very experienced with Qt5 so I don't know what else to do.
import sys, time, traceback
from PySide2.QtWidgets import *
from PySide2.QtCore import *
from PySide2.QtGui import *
from TsrUtils import PathUtils
class WorkerSignals(QObject):
finished = Signal()
error = Signal(tuple)
result = Signal(object)
class TsrWorker(QRunnable):
def __init__(self, fn, *args, **kwargs):
super(TsrWorker, self).__init__()
self.fn = fn
self.args = args
self.kwargs = kwargs
self.signals = WorkerSignals()
#Slot()
def run(self):
try:
result = self.fn(*self.args, **self.kwargs)
except:
traceback.print_exc()
exctype, value = sys.exc_info()[:2]
self.signals.error.emit((exctype, value, traceback.format_exc()))
else:
self.signals.result.emit(result)
finally:
self.signals.finished.emit()
class LoadingPopup(QWidget):
def __init__(self):
super().__init__()
self.message = "Cargando"
self.setMinimumSize(350,300)
self.setWindowIcon(\
QIcon(PathUtils.ruta_absoluta('resources/icons/tsr.png')))
self.setWindowTitle(self.message)
self.layout = QVBoxLayout(self)
self.setLayout(self.layout)
self.movie = QMovie(self)
self.movie.setFileName("./resources/img/spinner.gif")
self.movie.setCacheMode(QMovie.CacheAll)
self.movie.start()
self.loading = QLabel(self)
self.loading.setMovie(self.movie)
self.loading.setAlignment(Qt.AlignCenter)
self.layout.addWidget(self.loading)
self.lbl = QLabel(self.message, self)
self.lbl.setAlignment(Qt.AlignCenter)
self.lbl.setStyleSheet("font: 15pt")
self.layout.addWidget(self.lbl)
class MyMainApp(QApplication):
def __init__(self, args):
super().__init__()
self.l = LoadingPopup()
self.l.show()
w = TsrWorker(time.sleep, 5)
w.signals.finished.connect(self.terminado)
w.run()
def terminado(self):
print('timer finished')
self.l.hide()
if __name__ == '__main__':
app = MyMainApp(sys.argv)
sys.exit(app.exec_())
I've changed the actual data loading part of the application in the example with a time.sleep function. MY expected results are that I should be able to have the LoadingPopup show up with a gif moving, and then it should close once the QRunnable finishes.
You should not call the run method directly since you will have the heavy task run on the GUI thread freezing it. You must launch it using QThreadPool:
class MyMainApp(QApplication):
def __init__(self, args):
super().__init__()
self.l = LoadingPopup()
self.l.show()
w = TsrWorker(time.sleep, 5)
w.signals.finished.connect(self.terminado)
# w.run()
QThreadPool.globalInstance().start(w) # <---
def terminado(self):
print('timer finished')
self.l.hide()

PyQt5: How to 'communicate' between QThread and some sub-class?

To this question I am referring to the answer from #eyllanesc in PyQt5: How to scroll text in QTextEdit automatically (animational effect)?
There #eyllanesc shows how to make the text auto scrolls smoothly using verticalScrollBar(). It works great.
For this question, I have added some extra lines, to use QThread to get the text.
What I want to achieve here: to let the QThread class 'communicate' with the AnimationTextEdit class, so that the scrolling time can be determined by the text-length. So that the programm stops, when the scrolling process ends.
I must say it is very very tricky task for me. I would like to show the programm flow first, as I imagined.
UPDATE: My code is as follows. It works, but...
Problem with the code: when the text stops to scroll, the time.sleep() still works. The App wait there till time.sleep() stops.
What I want to get: When the text stops to scroll, the time.sleep() runs to its end value.
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys
import time
import sqlite3
class AnimationTextEdit(QTextEdit):
# signal_HowLongIsTheText = pyqtSignal(int) # signal to tell the QThread, how long the text is
def __init__(self, *args, **kwargs):
QTextEdit.__init__(self, *args, **kwargs)
self.animation = QVariantAnimation(self)
self.animation.valueChanged.connect(self.moveToLine)
# def sent_Info_to_Thread(self):
# self.obj_Thread = Worker()
# self.signal_HowLongIsTheText.connect(self.obj_Thread.getText_HowLongIsIt)
# self.signal_HowLongIsTheText.emit(self.textLength)
# self.signal_HowLongIsTheText.disconnect(self.obj_Thread.getText_HowLongIsIt)
#pyqtSlot()
def startAnimation(self):
self.animation.stop()
self.animation.setStartValue(0)
self.textLength = self.verticalScrollBar().maximum()
# self.sent_Info_to_Thread()
self.animation.setEndValue(self.textLength)
self.animation.setDuration(self.animation.endValue()*4)
self.animation.start()
#pyqtSlot(QVariant)
def moveToLine(self, i):
self.verticalScrollBar().setValue(i)
class Worker(QObject):
finished = pyqtSignal()
textSignal = pyqtSignal(str)
# #pyqtSlot(int)
# def getText_HowLongIsIt(self, textLength):
# self.textLength = textLength
#pyqtSlot()
def getText(self):
longText = "\n".join(["{}: long text - auto scrolling ".format(i) for i in range(100)])
self.textSignal.emit(longText)
time.sleep(10)
# time.sleep(int(self.textLength / 100))
# My question is about the above line: time.sleep(self.textLength)
# Instead of giving a fixed sleep time value here,
# I want let the Worker Class know,
# how long it will take to scroll all the text to the end.
self.finished.emit()
class MyApp(QWidget):
def __init__(self):
super(MyApp, self).__init__()
self.setFixedSize(600, 400)
self.initUI()
self.startThread()
def initUI(self):
self.txt = AnimationTextEdit(self)
self.btn = QPushButton("Start", self)
self.layout = QHBoxLayout(self)
self.layout.addWidget(self.txt)
self.layout.addWidget(self.btn)
self.btn.clicked.connect(self.txt.startAnimation)
def startThread(self):
self.obj = Worker()
self.thread = QThread()
self.obj.textSignal.connect(self.textUpdate)
self.obj.moveToThread(self.thread)
self.obj.finished.connect(self.thread.quit)
self.thread.started.connect(self.obj.getText)
self.thread.finished.connect(app.exit)
self.thread.start()
def textUpdate(self, longText):
self.txt.append(longText)
self.txt.moveToLine(0)
if __name__ == "__main__":
app = QApplication(sys.argv)
window = MyApp()
window.show()
sys.exit(app.exec_())
Thanks for the help and hint. What have I done wrong?
Although in the animation the duration is established it is necessary to understand that this is not exact, this could vary for several reasons, so calculating using the sleep to wait for it to end in a certain time and just closing the application may fail.
If your main objective is that when the animation is finished the program execution is finished then you must use the finished QVariantAnimation signal to finish the execution of the thread, this signal is emited when it finishes executing.
class AnimationTextEdit(QTextEdit):
def __init__(self, *args, **kwargs):
QTextEdit.__init__(self, *args, **kwargs)
self.animation = QVariantAnimation(self)
self.animation.valueChanged.connect(self.moveToLine)
#pyqtSlot()
def startAnimation(self):
self.animation.stop()
self.animation.setStartValue(0)
self.textLength = self.verticalScrollBar().maximum()
self.animation.setEndValue(self.textLength)
self.animation.setDuration(self.animation.endValue()*4)
self.animation.start()
#pyqtSlot(QVariant)
def moveToLine(self, i):
self.verticalScrollBar().setValue(i)
class Worker(QObject):
textSignal = pyqtSignal(str)
#pyqtSlot()
def getText(self):
longText = "\n".join(["{}: long text - auto scrolling ".format(i) for i in range(100)])
self.textSignal.emit(longText)
class MyApp(QWidget):
def __init__(self):
super(MyApp, self).__init__()
self.setFixedSize(600, 400)
self.initUI()
self.startThread()
def initUI(self):
self.txt = AnimationTextEdit(self)
self.btn = QPushButton("Start", self)
self.layout = QHBoxLayout(self)
self.layout.addWidget(self.txt)
self.layout.addWidget(self.btn)
self.btn.clicked.connect(self.txt.startAnimation)
def startThread(self):
self.obj = Worker()
self.thread = QThread()
self.obj.textSignal.connect(self.textUpdate)
self.obj.moveToThread(self.thread)
self.txt.animation.finished.connect(self.thread.quit)
self.thread.started.connect(self.obj.getText)
self.thread.finished.connect(app.exit)
self.thread.start()
def textUpdate(self, longText):
self.txt.append(longText)
self.txt.moveToLine(0)
if __name__ == "__main__":
app = QApplication(sys.argv)
window = MyApp()
window.show()
sys.exit(app.exec_())

PyQt: Progress bar and label disappear

I am new to Python and PyQt. When I start my program, after a few seconds, the progress bar and label disappear. The progress bar starts appearing and disappearing (the label is gone) when the mouse hovers over the progress bar, showing up once more before disappearing. But if I comment the line where I set up the progress bar value, the label does not disappear.
Here is the code:
from PyQt4 import QtCore, QtGui, Qt
from PyQt4.Qt import QDialog, QApplication
import sys
import sensors
from sensors import *
import threading
class tmp():
def main(self):
global test
global name
sensors.init()
try:
for chip in sensors.iter_detected_chips():
#print (chip)
#print('Adapter:', chip.adapter_name)
for feature in chip:
if feature.label == 'Physical id 0':
test = feature.get_value()
name = feature.label
#print ('%s (%r): %.1f' % (feature.name, feature.label, feature.get_value()))
threading.Timer(5.0, self.main).start()
return test
print
finally:
sensors.cleanup()
zz = tmp()
zz.main()
class MainWindow(QtGui.QWidget):
def __init__(self):
super(MainWindow, self).__init__()
self.setGeometry(50, 50, 250, 150)
self.setWindowTitle("Title here")
#lay = QtGui.QVBoxLayout()
#lay.addWidget(self.prgB)
#lay.addWidget(self.lbl)
#self.setLayout(lay)
self.home()
def home(self):
self.prgB = QtGui.QProgressBar(self)
self.prgB.setGeometry(20, 20, 210, 20)
self.lbl = QtGui.QLabel(self)
self.lbl.setGeometry(20, 40, 210, 20)
lay = QtGui.QVBoxLayout()
lay.addWidget(self.prgB)
lay.addWidget(self.lbl)
self.setLayout(lay)
self.update()
def update(self):
textas = ('%s : %.1f' % (name, test))
self.lbl.setText(str(textas))
self.prgB.setValue(test)
threading.Timer(5.0, self.update).start()
QtGui.QApplication.processEvents()
self.show()
def run():
QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_X11InitThreads)
app = QtGui.QApplication(sys.argv)
GUI = MainWindow()
sys.exit(app.exec_())
run()
What I am trying to do is just get the temp value (pysensors) and pass it to the label text and progress bar value. It is working, just as I said, but after a few seconds the label is gone and the progress bar disappears.
I know (or I guess) there is something wrong with the update function. I just can't find out whats wrong.
First of all you don't need the separate class tmp(). Delete it and just move the main() function in MainWindow class. After doing this name,test variables should not be global any more. Define them in your init (for example self.test = 0, self.name='something') and refer to them in the rest of the code as self.test and self.name.
Now the most important mistake in your code is that you are trying to update GUI components from a different thread. GUI components should be handled only by the main thread using the signal/slot mechanism that pyqt provides.
The steps for doing this in your case are
Define a new signal in MainWindow class
Connect this signal to the update() function
Emit this signal from main() function
In the end your code should look like this
class MainWindow(QtGui.QWidget):
signalUpdateBar = QtCore.pyqtSignal()
def __init__(self):
...
self.test = 0
self.name = "0"
...
def home(self):
...
self.signalUpdateBar.connect(self.update)
self.main()
self.show()
def main():
try:
...
self.test = feature.get_value()
self.name = feature.label
threading.Timer(5.0, self.main).start()
self.signalUpdateBar.emit()
finally:
...
Moreover in your update() function
self.prgB.setValue(self.test)
should be the last statement. Anything below that is not necessary.

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