Need to open maya scene file and do cloud rendering. A user is selecting multiple maya scene files.
I thought it will be good to submit each file in different process. It is not required to communicate between two processes. It is required though to send a message from worker process to main process i.e UI to notify, completion of work.
Two questions ?
When creating a pyqt UI interface that will accept multiple maya scene files from user, what is the best way to call maya standalone. Should it be multiprocessing or multithreading. ?
What way to communicate between worker process and main process i.e. where UI is running. ?
Is their a way to visually understand pools, queue, semaphore components of multiprocessing ?
That makes it three questions. Last is optional but it is their in the back of mind. Need to be clear.
I know that this is important as it helps optimize on the CPU. Also in non freezing the UI but can i imagine a pool to be a bridge and queue to be steps to the bridge. lost here with words ...
referring to this code from stackoverflow ( How to signal slots in a GUI from a different process? )
Instead of capitalizing, intend to call maya standalone in a subprocess
"""
Demo to show how to use PyQt5 and qt signals in combination with threads and
processes.
Description:
Text is entered in the main dialog, this is send over a queue to a process that
performs a "computation" (i.e. capitalization) on the data. Next the process sends
the data over a pipe to the Emitter which will emit a signal that will trigger
the UI to update.
Note:
At first glance it seems more logical to have the process emit the signal that
the UI can be updated. I tried this but ran into the error
"TypeError: can't pickle ChildProc objects" which I am unable to fix.
"""
import sys
from multiprocessing import Process, Queue, Pipe
from PyQt5.QtCore import pyqtSignal, QThread
from PyQt5.QtWidgets import QApplication, QLineEdit, QTextBrowser, QVBoxLayout, QDialog
class Emitter(QThread):
""" Emitter waits for data from the capitalization process and emits a signal for the UI to update its text. """
ui_data_available = pyqtSignal(str) # Signal indicating new UI data is available.
def __init__(self, from_process: Pipe):
super().__init__()
self.data_from_process = from_process
def run(self):
while True:
try:
text = self.data_from_process.recv()
except EOFError:
break
else:
self.ui_data_available.emit(text.decode('utf-8'))
class ChildProc(Process):
""" Process to capitalize a received string and return this over the pipe. """
def __init__(self, to_emitter: Pipe, from_mother: Queue, daemon=True):
super().__init__()
self.daemon = daemon
self.to_emitter = to_emitter
self.data_from_mother = from_mother
def run(self):
""" Wait for a ui_data_available on the queue and send a capitalized version of the received string to the pipe. """
while True:
text = self.data_from_mother.get()
self.to_emitter.send(text.upper())
class Form(QDialog):
def __init__(self, child_process_queue: Queue, emitter: Emitter):
super().__init__()
self.process_queue = child_process_queue
self.emitter = emitter
self.emitter.daemon = True
self.emitter.start()
# ------------------------------------------------------------------------------------------------------------
# Create the UI
# -------------------------------------------------------------------------------------------------------------
self.browser = QTextBrowser()
self.lineedit = QLineEdit('Type text and press <Enter>')
self.lineedit.selectAll()
layout = QVBoxLayout()
layout.addWidget(self.browser)
layout.addWidget(self.lineedit)
self.setLayout(layout)
self.lineedit.setFocus()
self.setWindowTitle('Upper')
# -------------------------------------------------------------------------------------------------------------
# Connect signals
# -------------------------------------------------------------------------------------------------------------
# When enter is pressed on the lineedit call self.to_child
self.lineedit.returnPressed.connect(self.to_child)
# When the emitter has data available for the UI call the updateUI function
self.emitter.ui_data_available.connect(self.updateUI)
def to_child(self):
""" Send the text of the lineedit to the process and clear the lineedit box. """
self.process_queue.put(self.lineedit.text().encode('utf-8'))
self.lineedit.clear()
def updateUI(self, text):
""" Add text to the lineedit box. """
self.browser.append(text)
if __name__ == '__main__':
# Some setup for qt
app = QApplication(sys.argv)
# Create the communication lines.
mother_pipe, child_pipe = Pipe()
queue = Queue()
# Instantiate (i.e. create instances of) our classes.
emitter = Emitter(mother_pipe)
child_process = ChildProc(child_pipe, queue)
form = Form(queue, emitter)
# Start our process.
child_process.start()
# Show the qt GUI and wait for it to exit.
form.show()
app.exec_()
Related
fellow developers! I have a question regarding Qt and multithreading.
=== SHORT VERSION ===========================================
Is it possible to do what I want with Qt? That is (1) show a loader; (2) download a gif in the background; (3) show the downloaded gif in the main window after it has been downloaded?
=== LONG VERSION ============================================
I have this idea that when I push a button, it:
shows a loader;
activates a thread that downloads a gif from the web;
replaces the default gif hidden in the main window with the downloaded one and shows it
hides the loader;
The problem that I'm experiencing is that when the downloaded gif is show, it is "frozen" or just the first frame is shown. Other than that everything is fine. However, it need the gif to be animated after the loader is hidden.
It is mentioned here that
So the Qt event loop is responsible for executing your code in response to various things that happen in your program, but while it is executing your code, it can't do anything else.
I believe this is the heart of the problem. It is also suggested that
It is recommended to use a QThread with Qt rather than a Python thread, but a Python thread will work fine if you don't ever need to communicate back to the main thread from your function.
Since my thread replaced the contents of the default gif, I believe that it does communicates back :(
Please find my code below :)
import sys
from time import sleep
from PyQt5.QtCore import QThread
from PyQt5.QtGui import QMovie
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel
class ChangeGif(QThread):
"""
A worker that:
1 - waits for 1 second;
2 - changes the content of the default gif;
3 - shows the default gif with new contents and hide the loader.
"""
def __init__(self, all_widgets):
QThread.__init__(self)
self.all = all_widgets
def run(self):
sleep(1)
self.new_gif_file = QMovie("files/new.gif") # This is the "right" gif that freezes :(
self.new_gif_file.start()
self.all.gif_label.setMovie(self.new_gif_file)
self.all.gif_label.show()
self.all.loader_label.hide()
class MainWindow(QWidget):
"""
Main window that shows a button. If you push the button, the following happens:
1 - a loader is shown;
2 - a thread in background is started;
3 - the thread changes the contents of the default gif;
4 - when the gif is replaced, the loader disappears and the default gif with the new content is shown
"""
def __init__(self):
super(MainWindow, self).__init__()
# BUTTON
self.button = QPushButton("Push me", self)
self.button.setFixedSize(100, 50)
self.button.clicked.connect(lambda: self.change_gif())
# DEFAULT GIF
self.gif_file = QMovie("files/default.gif") # This is the "wrong" gif
self.gif_file.start()
self.gif_label = QLabel(self)
self.gif_label.setMovie(self.gif_file)
self.gif_label.move(self.button.width(), 0)
self.gif_label.hide()
# LOADER
self.loader_file = QMovie("files/loader.gif")
self.loader_file.start()
self.loader_label = QLabel(self)
self.loader_label.setMovie(self.loader_file)
self.loader_label.move(self.button.width(), 0)
self.loader_label.hide()
# WINDOW SETTINGS
self.setFixedSize(500, 500)
self.show()
def change_gif(self):
self.loader_label.show()
self.worker = ChangeGif(self)
self.worker.start()
app = QApplication(sys.argv)
window = MainWindow()
app.exec_()
Other than the fact that no UI elements should be ever accessed or created outside the main Qt thread, this is valid also for UI elements that use objects created in other threads.
In your specific case, this not only means that you cannot set the movie in the separate thread, but you cannot create the QMovie there either.
In the following example, I'm opening a local file, and use a signal to send the data to the main thread. From there, I create a QBuffer to store the data in a IO device that can be used by QMovie. Note that both the buffer and the movie must have a persistent reference, otherwise they will be garbage collected as soon as the function returns.
from PyQt5.QtCore import QThread, QByteArray, QBuffer
class ChangeGif(QThread):
dataLoaded = pyqtSignal(QByteArray)
def __init__(self, all_widgets):
QThread.__init__(self)
self.all = all_widgets
def run(self):
sleep(1)
f = QFile('new.gif')
f.open(f.ReadOnly)
self.dataLoaded.emit(f.readAll())
f.close()
class MainWindow(QWidget):
# ...
def change_gif(self):
self.loader_label.show()
self.worker = ChangeGif(self)
self.worker.dataLoaded.connect(self.applyNewGif)
self.worker.start()
def applyNewGif(self, data):
# a persistent reference must be kept for both the buffer and the movie,
# otherwise they will be garbage collected, causing the program to
# freeze or crash
self.buffer = QBuffer()
self.buffer.setData(data)
self.newGif = QMovie()
self.newGif.setCacheMode(self.newGif.CacheAll)
self.newGif.setDevice(self.buffer)
self.gif_label.setMovie(self.newGif)
self.newGif.start()
self.gif_label.show()
self.loader_label.hide()
Note that the example above is just for explanation purposes, as the downloading process can be done using QtNetwork modules, which work asynchronously and provide simple signals and slots to download remote data:
from PyQt5.QtCore import QUrl
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
class MainWindow(QWidget):
def __init__(self):
# ...
self.downloader = QNetworkAccessManager()
def change_gif(self):
self.loader_label.show()
url = QUrl('https://path.to/animation.gif')
self.device = self.downloader.get(QNetworkRequest(url))
self.device.finished.connect(self.applyNewGif)
def applyNewGif(self):
self.loader_label.hide()
self.newGif = QMovie()
self.newGif.setDevice(self.device)
self.gif_label.setMovie(self.newGif)
self.newGif.start()
self.gif_label.show()
The main rule working with Qt is that only one main thread is responsible for manipulating UI widgets. It is often referred to as GUI thread. You should never try to access widgets from another threads. For example, Qt timers won't start activated from another thread and Qt would print warning in the runtime console. In your case - if you put all the manipulation with the QMovie in the GUI Thread, most probably everything will work as expected.
What to do? Use the signals and slots - they are also designed to work between threads.
What your code should do:
Show a loader form the main thread.
Activate a thread that downloads a gif from the web.
After the download is ready - emit a signal and capture it in main GUI thread'. Remember to use Qt::QueuedConnection` when connecting the signal and the slot, though it will be used automatically in some cases.
In the receiving slot replace the default gif in main window with the downloaded one and show it and hide the loader.
You'll have to use some synchronization mechanism to avoid data-racing. A mutex will be enough. Or you could pass the data as the signal-slot parameter, but in case of a gif it probably would be too big.
I have a UI that I am wanting to use threading with inside of Maya. The reason for doing this is so I can run Maya.cmds without hanging/freezing the UI while updating the UI with progress bars, etc.
I have read a few examples from StackOverflow but my code is crashing every second time I run it. Examples I have followed are here and here
import maya.cmds as cmds
from PySide2 import QtWidgets, QtCore, QtGui, QtUiTools
import mainWindow #Main window just grabs the Maya main window and returns the object to use as parent.
class Tool(QtWidgets.QMainWindow):
def __init__(self, parent=mainWindow.getMayaMainWindow()):
super(Tool, self).__init__(parent)
UI = "pathToUI/UI.ui"
loader = QtUiTools.QUiLoader()
ui_file = QtCore.QFile(UI)
ui_file.open(QtCore.QFile.ReadOnly)
self.ui = loader.load(ui_file, self)
#Scans all window objects and if one is open with the same name as this tool then close it so we don't have two open.
mainWindow.closeUI("Tool")
###HERE'S WHERE THE THREADING STARTS###
#Create a thread
thread = QtCore.QThread()
#Create worker object
self.worker = Worker()
#Move worker object into thread (This creates an automatic queue if multiples of the same worker are called)
self.worker.moveToThread(thread)
#Connect buttons in the UI to trigger a method inside the worker which should run in a thread
self.ui.first_btn.clicked.connect(self.worker.do_something)
self.ui.second_btn.clicked.connect(self.worker.do_something_else)
self.ui.third_btn.clicked.connect(self.worker.and_so_fourth)
#Start the thread
thread.start()
#Show UI
self.ui.show()
class Worker(QtCore.QObject):
def __init__(self):
super(Worker, self).__init__() #This will immediately crash Maya on tool launch
#super(Worker).__init__() #This works to open the window but still gets an error '# TypeError: super() takes at least 1 argument (0 given)'
def do_something(self):
#Start long code here and update progress bar as needed in a still active UI.
myTool.ui.progressBar.setValue(0)
print "doing something!"
myTool.ui.progressBar.setValue(100)
def do_something_else(self):
#Start long code here and update progress bar as needed in a still active UI.
myTool.ui.progressBar.setValue(0)
print "doing something else!"
myTool.ui.progressBar.setValue(100)
def and_so_fourth(self):
#Start long code here and update progress bar as needed in a still active UI.
myTool.ui.progressBar.setValue(0)
print "and so fourth, all in the new thread in a queue of which method was called first!"
myTool.ui.progressBar.setValue(100)
#A Button inside Maya will import this code and run the 'launch' function to setup the tool
def launch():
global myTool
myTool = Tool()
I'm expecting the UI to stay active (not locked up) and the threads to be running Maya cmds without crashing Maya entirely while updating the UIs progress bars.
Any insight on this would be amazing!
From what I see it has the following errors:
thread is a local variable that is deleted when the constructor is finished executing causing what is executed to be done in the main thread which is not desired, the solution is to extend the life cycle and for this there are several solutions: 1) make class attribute, 2) pass a parent to the cycle of life they are managed by the parent. In this case use the second solution.
You should not modify the GUI from another thread, in your case you have modified the progressBar from another thread, in Qt you must use signals.
You must use the #Slot decorator in the methods that are executed in another thread.
You indicate that you want to modify myTool but you have not declared it, soglobal myTool will not work by making myTool a local variable to be deleted. The solution is to declare myTool:myTool = None
Considering the above, the solution is:
import maya.cmds as cmds
from PySide2 import QtWidgets, QtCore, QtGui, QtUiTools
import mainWindow # Main window just grabs the Maya main window and returns the object to use as parent.
class Tool(QtWidgets.QMainWindow):
def __init__(self, parent=mainWindow.getMayaMainWindow()):
super(Tool, self).__init__(parent)
UI = "pathToUI/UI.ui"
loader = QtUiTools.QUiLoader()
ui_file = QtCore.QFile(UI)
ui_file.open(QtCore.QFile.ReadOnly)
self.ui = loader.load(ui_file, self)
# Scans all window objects and if one is open with the same name as this tool then close it so we don't have two open.
mainWindow.closeUI("Tool")
# Create a thread
thread = QtCore.QThread(self)
# Create worker object
self.worker = Worker()
# Move worker object into thread (This creates an automatic queue if multiples of the same worker are called)
self.worker.moveToThread(thread)
# Connect buttons in the UI to trigger a method inside the worker which should run in a thread
self.ui.first_btn.clicked.connect(self.worker.do_something)
self.ui.second_btn.clicked.connect(self.worker.do_something_else)
self.ui.third_btn.clicked.connect(self.worker.and_so_fourth)
self.worker.valueChanged.connect(self.ui.progressBar.setValue)
# Start the thread
thread.start()
# Show UI
self.ui.show()
class Worker(QtCore.QObject):
valueChanged = QtCore.Signal(int)
#QtCore.Slot()
def do_something(self):
# Start long code here and update progress bar as needed in a still active UI.
self.valueChanged.emit(0)
print "doing something!"
self.valueChanged.emit(100)
#QtCore.Slot()
def do_something_else(self):
# Start long code here and update progress bar as needed in a still active UI.
self.valueChanged.emit(0)
print "doing something else!"
self.valueChanged.emit(100)
#QtCore.Slot()
def and_so_fourth(self):
# Start long code here and update progress bar as needed in a still active UI.
self.valueChanged.emit(0)
print "and so fourth, all in the new thread in a queue of which method was called first!"
self.valueChanged.emit(100)
myTool = None
def launch():
global myTool
myTool = Tool()
Is it possible to get Python to launch a PyQt5 GUI application using the main thread of execution, and then leave the thread open to do other things?
Here is the simplest example I can think of:
from PyQt5.QtWidgets import *
def infinite_useless_loop():
while True:
pass
app = QApplication([])
doodad = QMainWindow()
doodad.show()
infinite_useless_loop()
If you run this code, it freezes because the 'mainloop' is not activated as it normally would be if I didn't make a call to the useless infinite loop, and instead put a call to app.exec_(). The call to infinite_useless_loop is meant to substitute the main thread being used to do other useful work WHILE the GUI is running correctly.
To do this correctly, I'd have to imagine one would make a separate thread and use that to run the GUI, while launching that thread with the main thread, and just continuing on from there; able to communicate if necessary in the future.
EDIT
I wrote some code that gets the main event loop working in a seperate thread, but I am still not able to fully interact with the GUI object that is created in another thread. This code effectively solves half of my problem:
from PyQt5.QtWidgets import *
from threading import Thread
import sys
def makeGUI():
app = QApplication([])
doodad = QMainWindow()
doodad.show()
sys.exit(app.exec_())
def infinite_useless_loop():
while True:
pass
if __name__ == '__main__':
thread = Thread(target=makeGUI)
thread.start()
infinite_useless_loop()
This code spawns the blank window, able to be clicked on and resized correctly (because the event loop is working), but is on its own. Do I have to revert to signals and slots to communicate with the object, or can I somehow get the GUI object back into the main thread and use it's methods from there?
EDIT 2
I do not wish to do any actual GUI manipulation outside of the GUI's thread, just call methods on the GUI object that I HAVE MADE. The entire GUI structure would be made by the GUI object.
EDIT 3
This new code now makes it able to be communicated with, but only with raw bits of information, and not by one thread accessing another thread's GUI object's methods. This is close, but its still not what I want. Calling the GUI object's methods would have to be done by passing the raw information through the queue, and then being processed at the other side. Then an exec() function would have to be called. That is not acceptable. Here is the code:
from PyQt5.QtWidgets import *
import multiprocessing
import threading
import sys
import time
import queue
class Application(QMainWindow):
def __init__(self, comms):
super(Application, self).__init__()
self.comms = comms
self.fetchingThread = threading.Thread(target=self.fetchingLoop)
self.labelOne = QLabel(self)
self.layout = QVBoxLayout()
self.layout.addWidget(self.labelOne)
self.setLayout(self.layout)
self.fetchingThread.start()
def fetchingLoop(self):
while True:
try:
obj = self.comms.get()
self.processItem(obj)
except queue.Empty:
pass
def processItem(self, item):
self.labelOne.setText(str(item))
print(self.labelOne.text())
class Launcher(multiprocessing.Process):
def __init__(self, Application):
super(Launcher, self).__init__()
self.comms = multiprocessing.Queue()
self.Application = Application
def get_comms(self):
return self.comms
def run(self):
app = QApplication([])
window = self.Application(self.comms)
window.show()
sys.exit(app.exec_())
def no_thread():
app = QApplication([])
window = Application(False)
window.show()
sys.exit(app.exec_())
if __name__ == '__main__':
thread = Launcher(Application)
comms = thread.get_comms()
thread.start()
c = 0
while True:
c += 1
time.sleep(1)
comms.put(c)
Let's say I have a PyQt program that goes through a given directory, looks for *JPEG images, and does some processing every time it finds one. Depending on the size of the selected directory, this may take from some seconds to minutes.
I would like to keep my user updated with the status - preferably with something like "x files processed out of y files" . If not, a simple running pulse progress bar by setting progressbar.setRange(0,0) works too.
From my understanding, in order to prevent my GUI from freezing, I will need a seperate thread that process the images, and the original thread that updates the GUI every interval.
But I am wondering if there is any possible way for me to do both in the same thread?
Yes, you can easily do this using processEvents, which is provided for this exact purpose.
I have used this technique for implementing a simple find-in-files dialog box. All you need to do is launch the function that processes the files with a single-shot timer, and then periodically call processEvents in the loop. This is should be good enough to update a counter with the number of files processed, and also allow the user to cancel the process, if necessary.
The only real issue is deciding on how frequently to call processEvents. The more often you call it, the more responsive the GUI will be - but this comes at the cost of considerably slowing the processing of the files. So you may have to experiment a little bit in order to find an acceptable compromise.
UPDATE:
Here's a simple demo that shows how the code could be structured:
import sys, time
from PyQt5 import QtWidgets, QtCore
class Window(QtWidgets.QWidget):
def __init__(self):
super().__init__()
self.button = QtWidgets.QPushButton('Start')
self.progress = QtWidgets.QLabel('0')
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
layout.addWidget(self.progress)
self.button.clicked.connect(self.test)
self._stop = False
self._stopped = True
def test(self):
if self._stopped:
self._stop = False
self.progress.setText('0')
self.button.setText('Stop')
QtCore.QTimer.singleShot(1, self.process)
else:
self._stop = True
def process(self):
self._stopped = False
for index in range(1, 1000):
time.sleep(0.01)
self.progress.setText(str(index))
if not index % 20:
QtWidgets.qApp.processEvents(
QtCore.QEventLoop.AllEvents, 50)
if self._stop:
break
self._stopped = True
self.button.setText('Start')
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
window = Window()
window.show()
sys.exit(app.exec_())
I could not achieve the thing you need without multi threading and this is not possible because gui can be only updated in main thread. Below is an algorithm how I did this with multithreading.
Let's say you have your application processing images. Then there are the following threads:
Main thread (that blocks by GUI/QApplication-derived classes.exec())
Timer with, for example, 1 second interval which updates a variable and calls a slot in GUI thread which updates a variable in user interface.
A thread which is processing images on your pc.
def process(self):
self._status = "processing image 1"
....
def _update(self):
self.status_label.setText(self._status)
def start_processing(self, image_path):
# create thread for process and run it
# create thread for updating by using QtCore.QTimer()
# connect qtimer triggered signal to and `self._update()` slot
# connect image processing thread (use connect signal to any slot, in this example I'll stop timer after processing thread finishes)
#pyqtSlot()
def _stop_timer():
self._qtimer.stop()
self._qtimer = None
_update_thread.finished.connect(_stop_timer)
In pyqt5 it is possible to assign a pyqtvariable from a one nested thread(first level). So you can make your variable a pyqtvariable with setter and getter and update gui in a setter or think how you can do this by yourself.
You could just use the python threading module and emit a signal in your threaded routine.
Here's a working example
from PyQt4 import QtGui, QtCore
import threading
import time
class MyWidget(QtGui.QWidget):
valueChanged = QtCore.pyqtSignal(int)
def __init__(self, parent=None):
super(MyWidget, self).__init__(parent)
self.computeButton = QtGui.QPushButton("Compute", self)
self.progressBar = QtGui.QProgressBar()
layout = QtGui.QVBoxLayout(self)
layout.addWidget(self.computeButton)
layout.addWidget(self.progressBar)
self.computeButton.clicked.connect(self.compute)
self.valueChanged.connect(self.progressBar.setValue)
def compute(self):
nbFiles = 10
self.progressBar.setRange(0, nbFiles)
def inner():
for i in range(1, nbFiles+1):
time.sleep(0.5) # Process Image
self.valueChanged.emit(i) # Notify progress
self.thread = threading.Thread(target = inner)
self.thread.start()
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
widget = MyWidget()
widget.show()
sys.exit(app.exec_())
I have a problem i can't quite figure out for some time. I have a main window application and a QDialog that should pop out after clicking one of the buttons, but the show() method on QDialog seems to be waiting for the funcion connected to the "clicked()" signal to end!
I want the dialog to show right after calling the QDialog.show() method, not after all the other code instructions in that function...
Of course in my code I am going to replace the sleep(5) part with much more complicated code, but this pictures the problem and the code I put there is irrelevant to the issue, i think (database connections and updates)
being more specific:
# -*- coding: utf-8 -*-
import sys
import PyQt4
from PyQt4 import QtCore, QtGui
from twython import Twython, TwythonError
from project import Ui_MainWindow
from time import sleep
import psycopg2, globalvals, updater
import updating, noconnection
class UpWindow(QtGui.QDialog):
def __init__(self, parent=None):
QtGui.QDialog.__init__(self, parent, QtCore.Qt.WindowStaysOnTopHint)
self.ui = updating.Ui_updating()
self.ui.setupUi(self)
class NoConnection(QtGui.QDialog):
def __init__(self, parent=None):
QtGui.QDialog.__init__(self, parent, QtCore.Qt.WindowStaysOnTopHint)
self.ui = noconnection.Ui_noConnection()
self.ui.setupUi(self)
QtCore.QObject.connect(self.ui.noConnectionClose, QtCore.SIGNAL("clicked()"), self.close)
class MyCounter(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.noConn = NoConnection(self)
self.upWin = UpWindow(self)
QtCore.QObject.connect(self.ui.refreshButton,QtCore.SIGNAL("clicked()"), self.refresh)
QtCore.QObject.connect(self.ui.manageButton,QtCore.SIGNAL("clicked()"), self.manage)
def refresh(self):
self.upWin.show()
self.upWin.show
self.upWin.setVisible(True)
self.setEnabled(False)
self.upWin.setEnabled(True)
#Thats the issue - the sleep instruction is being held
#BEFORE the showing of upWin QDialog
sleep(5)
def manage(self):
print 'ok'
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
myapp = MyCounter()
myapp.upcontent()
myapp.show()
sys.exit(app.exec_())
Think of the any Qt program as a cooperative-multitasking system. Graphics and events in general are handled by the main loop. You don't want to stay long in any slot, because the library won't process signals (say button clicks, repaints, but also other stuff) in the mean time.
If you want to do some heavy processing, or anything that needs to wait for resources while the rest of the program is chugging along, use a QThread.
Another option is to force the event processing with qApp.processEvents() (you can find qApp in QtGui), just before your sleep(5) (or whatever code you're going to put in place of it).
Edit: Now, keep in mind that forcing the event processing will just show the QDialog you're trying to popup. You can't do anything with it (remember, no event processing) without calling again qApp.processEvents() or returning from the slot.
If MyCounter represents a widget that does a long computation and updates a dialog during that time, then sleep(5) is not representative of it, because during those 5 seconds the GUI can't handle events. For a "long running" function you would move the blocking part to a QThread and either poll the thread or connect to a signal it emits as it progresses, either way you would not hold up the GUI event loop during that time (for example, the polling, which takes very little time, would occur in an idle callback). The simplest way to create your test would be to use a timed callback into your MyCounter:
def refresh(self):
... show stuff, then:
self.timer = QTimer()
self.timer.timeout.connect(self.updateDialog)
timer.start(100) # 10 times per sec
def updateDialog(self):
#get thread status
if self.thread.status != self.oldStatus:
self.upWin.updateStatus( self.thread.status )