CODEWITHSUNDEEP
pythonuser-interfaceprocesswxpython
user1927638
user1927638

Reputation: 1173

Simple wxPython post event from Process

I am trying to create a window that receives simple event notifications from a Process. Here is the code that I have so far:

import wx, wx.lib.newevent, time, sys
from multiprocessing import Process

size_width = 320
size_height = 240
background_color = (226,223,206)

SomeNewEvent, EVT_SOME_NEW_EVENT = wx.lib.newevent.NewEvent()


class StatusWindow(wx.Frame):
    def __init__(self, parent):
        super(StatusWindow, self).__init__(parent, title='Monitor', size=(size_width, size_height))

        self.Bind(EVT_SOME_NEW_EVENT, self.updateStatus)

        staticBox = wx.StaticBox(self, label='Monitor Status:', pos=(5, 105), size=(size_width - 28, size_height/3))
        self.statusLabel = wx.StaticText(staticBox, label='None', pos=(10, 35), size=(size_width, 20), style=wx.ALIGN_LEFT)
        self.count = 0
        self.InitUI()

        self.monitor = cMonitor()
        self.monitor.start()

    def InitUI(self):
        panel = wx.Panel(self)    
        self.SetBackgroundColour(background_color)
        self.Centre()
        self.Show()

    def updateStatus(self, evt):
        self.statusLabel.SetLabel(evt.attr1)

class cMonitor(Process):
    def __init__(self):
        super(cMonitor, self).__init__()

    def run(self):
        time.sleep(2)
        print 'This is an update'
        #create the event
        evt = SomeNewEvent(attr1="Some event has just occured")
        #post the event
        wx.PostEvent(EVT_SOME_NEW_EVENT, evt)

if __name__ == '__main__':
    app = wx.App()
    window = StatusWindow(None)
    app.MainLoop()

The window gets created, but the Process does not appear to be either executing or sending the post event notification correctly. I should note that the print statement in the run method is not showing up either. What is causing the GUI to not be updated?? This was what I used as a reference:

http://wiki.wxpython.org/CustomEventClasses

Upvotes: 2

Views: 2735

Answers (1)

NorthCat
NorthCat

Reputation: 9937

First of all, your code throws an error:

Traceback (most recent call last):
  File "C:\Python27\lib\multiprocessing\process.py", line 232, in _bootstrap
    self.run()
  File "C:\PyProgs\stackoverflow_answers\wx_answers\wx_events1.py", line 44, in run
    wx.PostEvent(EVT_SOME_NEW_EVENT, evt)
  File "C:\Python27\lib\site-packages\wx-3.0-msw\wx\_core.py", line 8410, in PostEvent
    return _core_.PostEvent(*args, **kwargs)
TypeError: in method 'PostEvent', expected argument 1 of type 'wxEvtHandler *'

According the docs, PostEvent(dest, event) send an event to a window or other wx.EvtHandler to be processed later, but in your code first parameter has type PyEventBinder. Your code would have to look something like this:

wx.PostEvent(self.wxWindow, evt)

where self.wxWindow - object of StatusWindow class. But there is another problem: you can not use wxPython objects as multiprocessor arguments(link).

One way to do what you want - using threading module instead multiprocessing:

import wx, wx.lib.newevent, time, sys
from threading import *
size_width = 320
size_height = 240
background_color = (226,223,206)

SomeNewEvent, EVT_SOME_NEW_EVENT = wx.lib.newevent.NewEvent()


class StatusWindow(wx.Frame):
    def __init__(self, parent):
        super(StatusWindow, self).__init__(parent, title='Monitor', size=(size_width, size_height))

        self.Bind(EVT_SOME_NEW_EVENT, self.updateStatus)

        staticBox = wx.StaticBox(self, label='Monitor Status:', pos=(5, 105), size=(size_width - 28, size_height/3))
        self.statusLabel = wx.StaticText(staticBox, label='None', pos=(10, 35), size=(size_width, 20), style=wx.ALIGN_LEFT)
        self.count = 0
        self.InitUI()

        # Set up event handler for any worker thread results
        self.monitor = cMonitor(self)
        self.monitor.start()

    def InitUI(self):
        panel = wx.Panel(self)    
        self.SetBackgroundColour(background_color)
        self.Centre()
        self.Show()

    def updateStatus(self, evt):
        self.statusLabel.SetLabel(evt.attr1)



class cMonitor(Thread):
    def __init__(self, wxWindow):
        super(cMonitor, self).__init__()
        self.wxWindow = wxWindow


    def run(self):
        time.sleep(2)
        print 'This is an update'
        #create the event
        evt = SomeNewEvent(attr1="Some event has just occured")
        #post the event
        wx.PostEvent(self.wxWindow, evt)

if __name__ == '__main__':

    app = wx.App()
    window = StatusWindow(None)
    app.MainLoop()

Upvotes: 1

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