Thanks David, I start to read the Mark summerfield' book about PyQt programming.
In fact I realized I don't need multi-threading because I can remove the Timer and just need to call the graphical application from the while loop. How can I call the "ApplicationWindow" class from my while loop? I'll try to read a bit more about PyQt to understand how it works :) thanks again! Fabien 2011/12/14 David Hoese <dho...@gmail.com>: > I'm not sure how experienced you are with multithreaded programs, but here > is some sample code (I mentioned it can get complicated). I suggest you > research Qt4 QThreads and also Qt4 Signals and slots to better understand > the code below. It is a working sample so you should be able to run it in a > terminal and notice that the GUI is responsive and that you have messages > being printed out on the terminal. The code I provided below is more > complicated than you may need for a proof-of-concept kind of program, but if > you will be communicating with physical devices I suggest something like > this. I am by no means and expert, but I have been doing something similar > to what you are doing. I also suggest maybe separating the device > communication into another module/class, especially if others are going to > (re)use your code. > > Good Luck, > Dave > > P.S. There are a lot of Qt4/PyQt4 threading examples online, but not all of > them correct. What I posted below is what I have found to be considered > "correct" by most people. > > ################# > ### Sample Code ### > ################# > > import time > from PyQt4 import QtGui,QtCore > > class MyWindow(QtGui.QWidget): > def __init__(self): > QtGui.QWidget.__init__(self) > > # Sample GUI elements to test responsiveness > the_choices = ["item"]*20 > self.choices = QtGui.QComboBox() > self.choices.addItems(the_choices) > self.layout = QtGui.QVBoxLayout(self) > self.layout.addWidget(self.choices) > self.setLayout(self.layout) > > def handle_new_data(self): > # This is where you could redraw any matplotlib plots > # Maybe send data through the signal/slot connection > print "Updating data" > > class MyInstrument(QtCore.QObject): > signal_new_data = QtCore.pyqtSignal(name="signal_new_data") > signal_closing = QtCore.pyqtSignal(name="signal_closing") > def run(self): > self._timer = QtCore.QTimer() > self._timer.timeout.connect(self._run) > self._timer.start(0) > > def _run(self): > time.sleep(1) > print "Running the instrument function" > time.sleep(1) > self.signal_new_data.emit() > > def close(self): > print "Closing instrument thread" > self._timer.stop() > # Redundant timer stop > self._timer.timeout.disconnect() > self.signal_closing.emit() > > if __name__ == "__main__": > app = QtGui.QApplication([" "]) > w = MyWindow() > w.show() > instrument = MyInstrument() > instrument_thread = QtCore.QThread() > instrument.moveToThread(instrument_thread) > > instrument_thread.started.connect(instrument.run) > instrument.signal_new_data.connect(w.handle_new_data) > > # Make the close function run in the main thread so you can "interrupt" > the sleeps > app.lastWindowClosed.connect(instrument.close, > QtCore.Qt.DirectConnection) > # You could also call quit "manually" after exec_() returns > instrument.signal_closing.connect(instrument_thread.quit) > > instrument_thread.start() > app.exec_() > #instrument_thread.quit() > > print "Waiting for instrument thread..." > instrument_thread.wait() > print "SUCCESS" > > ###################### > ### End of Sample Code ### > ###################### > > > On 12/14/11 3:51 AM, Fabien Lafont wrote: >> >> I prefer to use the multi-thread method beacause it's easier for me >> and my colaborators to have the entire acquisition process at the same >> place. Until then I use a simple one but I hope to use a more complex >> one in few weeks ( put different voltages on different devices then >> measure many voltages or current). If I use the "domino" technique >> (call the next operation by the end of the previous) it can be complex >> to read and to edit. Thank you very much anyway! >> >> How can I write a multi-thread process? I've just tried to add >> qApp.processEvents() at the end of my while loop but it doesn't change >> anything... >> >> Thanks again, >> >> Fabien >> >> 2011/12/13 David Hoese<dho...@gmail.com>: >>> >>> Yeah I didn't think about suggesting that, but I think it might get >>> complicated. I think he would have to start a one shot timer to call a >>> function to set the voltage. Then that function would also start another >>> one shot timer to call another function that would read from the sample. >>> That function then would start a one shot timer to call the first >>> function >>> again. This way he can be sure that things are called in order and that >>> timing is consistent, just in case the GUI gets complicated or something >>> makes the event loop slow down. >>> >>> He could also use multiple threads. Whatever works for Fabien I guess. >>> >>> -Dave >>> >>> On 12/13/11 1:00 PM, matplotlib-users-requ...@lists.sourceforge.net >>> wrote: >>>> >>>> From: "Drain, Theodore R (343P)"<theodore.r.dr...@jpl.nasa.gov> >>>> >>>> Subject: Re: [Matplotlib-users] [ploting data] Live data >>>> >>>> Perhaps I'm missing something, but why not use QTimer? You can't really >>>> every call sleep in a single threaded gui (for reasons you've >>>> encountered). >>>> If you need to poll something, create a QTimer for 2 seconds and have >>>> it >>>> call a measurement function to update the data. You shouldn't need any >>>> processEvents calls or sleep. >>> >>> > ------------------------------------------------------------------------------ Cloud Computing - Latest Buzzword or a Glimpse of the Future? This paper surveys cloud computing today: What are the benefits? Why are businesses embracing it? What are its payoffs and pitfalls? http://www.accelacomm.com/jaw/sdnl/114/51425149/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
