I am trying to create new process to run separate tasks using multiprocessing. below is a simple demo:
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow
import sys
from multiprocessing import Process as mProcess
class MyWindow(QMainWindow):
def __init__(self):
super(MyWindow,self).__init__()
self.initUI()
self.processes = []
def initUI(self):
self.setGeometry(200, 200, 300, 300)
self.setWindowTitle("Tech With Tim")
self.b1 = QtWidgets.QPushButton(self)
self.b1.setText("click me!")
self.b1.clicked.connect(self.button_clicked)
def dummyFunction(self):
def f(text):
print(text)
p = mProcess(target=f, args=(100,))
self.processes.append(p)
p.start()
def button_clicked(self):
self.dummyFunction()
def window():
app = QApplication(sys.argv)
win = MyWindow()
win.show()
sys.exit(app.exec_())
if __name__ == "__main__":
window()
But I got this error:
Can't pickle local object 'MyWindow.dummyFunction.<locals>.f'
.
.
OSError: [WinError 6] The handle is invalid
Related
Force repainting does not repaint PyQt5 widget (Qlabel, QTextEdit, even QProgressBar and etc)
Tested platforms: Linux, MacOS
PyQt5 version: 5.15.7
Installed from pip
As example I created simple app that updating text in QLabel widget in for loop. Force repainting doesnt working
import sys
from time import sleep
from PyQt5.QtWidgets import (QWidget, QApplication, QPushButton, QLabel)
class Example(QWidget):
def __init__(self):
super().__init__()
self.text = QLabel('Test', self)
self.text.move(10, 10)
self.text.resize(60,20)
self.button = QPushButton('Run', self)
self.button.move(17,40)
self.button.clicked.connect(self.some_activity)
self.setGeometry(300, 300, 100, 80)
self.show()
def some_activity(self):
for i in range(100):
text = f'i = {i}'
self.text.setText(text)
# self.text.update() -> Nothing happens (it shouldnt: https://doc.qt.io/qt-5/qwidget.html#update)
self.text.repaint() # -> Nothing happens
self.repaint() # -> Nothing happens
print(f'Text updated: {text}')
sleep(0.03)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
Video demonstration: link
Just needed to use QThread to use for loop in my program
Thanks #musicamante for helping.
import sys
from time import sleep
from PyQt5 import QtCore
from PyQt5.QtWidgets import (QWidget, QApplication, QPushButton, QLabel)
class Thread(QtCore.QThread):
signal = QtCore.pyqtSignal(str)
def __init__(self, parent=None): QtCore.QThread.__init__(self, parent)
def run(self):
for i in range(100):
text = f'i = {i}'
print(f'Text updated: {text}')
self.signal.emit(text)
sleep(.3)
class Example(QWidget):
def __init__(self):
super().__init__()
self.text = QLabel('Test', self)
self.text.move(10, 10)
self.text.resize(60,20)
self.thread = Thread()
self.thread.signal.connect(self.signal, QtCore.Qt.QueuedConnection)
self.button = QPushButton('Run', self)
self.button.move(17,40)
self.button.clicked.connect(self.thread.start)
self.setGeometry(300, 300, 100, 80)
self.show()
def signal(self, text): self.text.setText(text)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
I am trying to edit the text in 'QTextEdit' but I got the error which is in the title above. I know that I shouldn't edit the widgets in the main app from another thread and I searched for some answers, But I didn't get the full answer that I want
This is a sample that produce the same error that I have
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5 import QtCore
import sys
import time
import threading
class Main(QMainWindow):
def __init__(self):
super().__init__()
self.move(50, 220)
self.resize(500, 500)
self.text_edit = QTextEdit(self)
self.text_edit.resize(200, 200)
self.btn = QPushButton('start', self)
self.btn.move(10, 250)
self.btn.clicked.connect(lambda x : self.thread_creator(self.test))
self.btn2 = QPushButton('print', self)
self.btn2.move(10, 290)
self.btn2.clicked.connect(lambda x : print('dad'))
def test(self):
for i in range(99):
self.text_edit.setText(f'dad {i}')
time.sleep(0.1)
def thread_creator(self, function):
self.thread = threading.Thread(target=function)
self.thread.start()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Main()
ex.show()
sys.exit(app.exec_())
In pyqt5 when i try to close a tread for a my program Ui freezes and stop responding.I'm new to pyqt5 couldn't find a answer for this.
These are the methods in main window(GUI) file
def clickButton_on(self):
print("clicked on/off")
ControlPanel.start()
def clickButton_Off(self):
print("clicked on/off")
ControlPanel.stop()
This is the controlPanel class methods
#classmethod
def start(cls):
print('start method fired')
cls.th = threading.Thread(target=cls.test,args=(cls.attr,))
cls.th.start()
#classmethod
def stop(cls):
print('stop method fired')
cls.th.join()
Full code to recreate the issue
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.uic import loadUi
import sys
import threading
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super(MainWindow,self).__init__()
self.b1 = QtWidgets.QPushButton(self)
self.b1.setText("on")
self.b2 = QtWidgets.QPushButton(self)
self.b2.setText("off")
self.b2.move(50,50)
self.b1.clicked.connect(self.clickButton_on)
self.b2.clicked.connect(self.clickButton_Off)
def clickButton_on(self):
print("clicked on/off")
ControlPanel.start()
def clickButton_Off(self):
print("clicked on/off")
ControlPanel.stop()
class ControlPanel:
n=2
#classmethod
def start(cls):
print('start method fired')
cls.th = threading.Thread(target=cls.test,args=(cls.n,))
cls.th.start()
#classmethod
def stop(cls):
print('stop method fired')
cls.th.join()
#classmethod
def test(cls,n):
print('test method fired')
n= 0
while True:
n += 0.1
print(f'thread running n = {n}')
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
windows completely freezes. It doesnt close the thread with .join() it thread keeps running.
I want to use startup function which should have while loop.
but I run the code my gui doesn't appear until while loop ends.
I tried with self.show() it can make show gui but it doesn't allow to use sys.exit()
import sys
from PyQt5.QtWidgets import QApplication
from PyQt5 import uic
import time
form_class,QMainWindow=uic.loadUiType('youhua.ui')
class MyWindow(QMainWindow,form_class):
def __init__(self):
super().__init__()
self.setupUi(self)
#self.show()
self.myfunc()
def myfunc(self):
k=1
stat=True
while stat:
k=k+1
time.sleep(1)
self.statusMessage.append(str(k))
QApplication.processEvents()
if k>10:
stat=False
#sys.exit()
if __name__=='__main__':
app=QApplication(sys.argv)
myWindow=MyWindow()
myWindow.show()
app.exec_()
If you need to perform an action again, you have several options.
For example, if each iteration takes very little time, without the possibility of blocking the main loop, you can replace the cycle with a timer (QTimer) and call the method each time, which is responsible for obtaining new data and updating the necessary interface elements in accordance with them:
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5 import uic
from PyQt5.QtCore import QThread, QTimer
import time
#form_class, QMainWindow = uic.loadUiType('youhua.ui')
class MyWindow(QMainWindow): #, form_class):
def __init__(self):
super().__init__()
self.k = 0
centralWidget = QtWidgets.QWidget(self)
self.setCentralWidget(centralWidget)
self.button = QtWidgets.QPushButton('Start', self)
self.button.clicked.connect(self.read_data)
self.label_data = QtWidgets.QLabel(self, alignment=QtCore.Qt.AlignCenter)
self.label_data.setText('Pending')
layout = QtWidgets.QGridLayout(centralWidget)
layout.addWidget(self.label_data)
layout.addWidget(self.button)
self.timer = QtCore.QTimer(self)
self.timer.setInterval(1000)
self.timer.timeout.connect(self.read_data_from_sensor)
#QtCore.pyqtSlot()
def read_data(self):
''' Start / Stop reading at the touch of a button '''
if not self.timer.isActive():
self.timer.start()
self.button.setText("Stop")
else:
self.timer.stop()
self.button.setText("Start")
self.label_data.setText("Pending")
#QtCore.pyqtSlot()
def read_data_from_sensor(self):
dt = time.strftime("%Y-%m-%d %H:%M:%S")
self.label_data.setText(dt)
self.label_data.adjustSize()
self.k += 1
self.statusBar().showMessage('{} item(s)'.format(self.k))
if self.k > 10:
self.timer.stop()
self.button.setText("Start")
self.label_data.setText("Pending")
self.k = 0
if __name__=='__main__':
app = QApplication(sys.argv)
myWindow = MyWindow()
myWindow.show()
app.exec_()
What you wrote may also work, but this is not very good. You can compare.
import sys
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5 import uic
from PyQt5.QtCore import QThread
#import time
#form_class, QMainWindow = uic.loadUiType('youhua.ui')
class MyWindow(QMainWindow): #, form_class):
def __init__(self):
super().__init__()
# self.setupUi(self)
self.show()
self.myfunc()
def myfunc(self):
k = 0
stat = True
while stat:
k += 1
# time.sleep(1)
# self.statusMessage.append(str(k))
self.statusBar().showMessage('{} item(s)'.format(k))
QThread.msleep(1000)
QApplication.processEvents()
if k>10:
stat=False
#sys.exit()
if __name__=='__main__':
app = QApplication(sys.argv)
myWindow = MyWindow()
# myWindow.show()
app.exec_()
In your loop you are sleeping for 10 second, since you are creating a while loop on the main thread, the GUI wont show until the loop is done because it would be blocking the main thread. You can test this by removing time.sleep(1).
Without changing your code much, try this:
import sys,threading, time
from PyQt5.QtWidgets import QApplication
from PyQt5 import uic
form_class,QMainWindow=uic.loadUiType('youhua.ui')
class MyWindow(QMainWindow,form_class):
def __init__(self):
super().__init__()
self.setupUi(self)
#self.show()
t = threading.Thread(target=self.myfunc)
t.start()
def myfunc(self):
k=1
stat=True
while stat:
k=k+1
time.sleep(1)
self.statusMessage.append(str(k))
QApplication.processEvents()
if k>10:
stat=False
#sys.exit() - if you are trying to close the window here use self.close()
if __name__=='__main__':
app=QApplication(sys.argv)
myWindow=MyWindow()
myWindow.show()
sys.exit(app.exec_())
i'm new in Python and PyQt4.
I want to ask "How to back to previous Window ?"
i have 2 file in here, file 'login' and 'signup'
here file login.py
import sys
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \
QApplication, QGridLayout
from signup import SignUp
class Login(QWidget):
def __init__(self):
super(Login, self).__init__()
self.setWindowTitle("Login")
self.login_window()
def login_window(self):
self.login_layout = QGridLayout()
self.login_button = QPushButton("Login")
self.signup_button = QPushButton("Sign Up")
self.login_layout.addWidget(self.login_button, 2, 0)
self.login_layout.addWidget(self.signup_button, 2, 1)
self.signup_button.clicked.connect(self.signup_show)
self.setLayout(self.login_layout)
self.show()
def signup_show(self):
self.signupshow = SignUp()
self.hide()
self.signupshow.show()
def check_signup(self):
SignUp.check_signup()
self.show()
def main():
app = QApplication(sys.argv)
login = Login()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
and here is signup.py
import sys
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \
QApplication, QGridLayout
class SignUp(QWidget):
def __init__(self):
super(SignUp, self).__init__()
self.setWindowTitle("Sign Up")
self.signup_window()
def signup_window(self):
self.signup_layout = QGridLayout()
self.signup_button = QPushButton("Sign Up")
self.signup_layout.addWidget(self.signup_button, 2, 0, 1, 0)
self.signup_button.clicked.connect(self.check_signup)
self.setLayout(self.signup_layout)
self.show()
def check_signup(self):
self.close()
def main():
app = QApplication(sys.argv)
signup = SignUp()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
my problem is, when i push button signup from signup.py, it's close but window Login is not show.
i think i don't have any trigger in signup.py for check_signup in login.py
in this code, i delete some Line Edit and Label. I think it's not a problem.
i hope someone will help, Thank you before :)
and if you answer this questtion, i hope you will explain a little bit of the logic, thank you again :)
I'm not really sure what you are trying to achieve (your description is kind of confusing), but let's start here. I put all your code in one file, since you need to import each other (which leads to cyclic import). Then, I just added these two lines
self.login = Login()
self.login.show()
into check_signup method of SignUp class, which pops-up Login window. If this is not your desired result, please let us know and provide us a better description. The code follows:
import sys
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \
QApplication, QGridLayout
class Login(QWidget):
def __init__(self):
super(Login, self).__init__()
self.setWindowTitle("Login")
self.login_window()
def login_window(self):
self.login_layout = QGridLayout()
self.login_button = QPushButton("Login")
self.signup_button = QPushButton("Sign Up")
self.login_layout.addWidget(self.login_button, 2, 0)
self.login_layout.addWidget(self.signup_button, 2, 1)
self.signup_button.clicked.connect(self.signup_show)
self.setLayout(self.login_layout)
self.show()
def signup_show(self):
self.signupshow = SignUp()
self.hide()
self.signupshow.show()
def check_signup(self):
SignUp.check_signup()
self.show()
class SignUp(QWidget):
def __init__(self):
super(SignUp, self).__init__()
self.setWindowTitle("Sign Up")
self.signup_window()
def signup_window(self):
self.signup_layout = QGridLayout()
self.signup_button = QPushButton("Sign Up")
self.signup_layout.addWidget(self.signup_button, 2, 0, 1, 0)
self.signup_button.clicked.connect(self.check_signup)
self.setLayout(self.signup_layout)
self.show()
def check_signup(self):
self.login = Login()
self.login.show()
self.close()
def main():
app = QApplication(sys.argv)
signup = SignUp()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
You should rather use signal-slot connections:
import sys
from PyQt4 import QtGui, QtCore
class WidgetA(QtGui.QWidget):
open_b = QtCore.pyqtSignal()
def __init__(self, parent=None):
super(WidgetA, self).__init__(parent)
self.resize(100, 100)
self.l = QtGui.QVBoxLayout()
self.close_btn = QtGui.QPushButton('Close')
self.b_btn = QtGui.QPushButton('Open B')
self.b_btn.clicked.connect(self.b_btn_clicked)
self.l.addWidget(self.close_btn)
self.l.addWidget(self.b_btn)
self.setLayout(self.l)
def b_btn_clicked(self):
self.open_b.emit()
self.hide()
class WidgetB(QtGui.QWidget):
open_a = QtCore.pyqtSignal()
def __init__(self, parent=None):
super(WidgetB, self).__init__(parent)
self.resize(100, 100)
self.l = QtGui.QVBoxLayout()
self.close_btn = QtGui.QPushButton('Close')
self.close_btn.clicked.connect(self.hide)
self.a_btn = QtGui.QPushButton('Open A')
self.a_btn.clicked.connect(self.a_btn_clicked)
self.l.addWidget(self.close_btn)
self.l.addWidget(self.a_btn)
self.setLayout(self.l)
def a_btn_clicked(self):
self.open_a.emit()
self.hide()
def main():
app = QtGui.QApplication(sys.argv)
a = WidgetA()
b = WidgetB()
a.open_b.connect(lambda: b.show())
b.open_a.connect(lambda: a.show())
a.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()