Multiprocessing in wxpython - python-2.7

Question

I have a GUI with buttons 'OK' and 'Cancel' clicking on which creates a child threads which pops up a dialog box saying 'OK/Cancel button is pressed'. Now when i click on OK button, i want child thread calling it must wait for another process(may be another dialogbox saying wait) and then must pop up message 'OK button is pressed'.
I used wx.timer for childthread to wait but could not get it worked.
How to make a child thread pause and continue(like an interrupt) when the process is done?
Below find my trials!
import wx, time
from threading import Thread
ID_RUN = 101
ID_RUN2 = 102
class ChildThread_OK(Thread):
def __init__(self, myframe):
"""Init Worker Thread Class."""
Thread.__init__(self)
self.myframe = myframe
self._want_abort = True
def run(self):
if self._want_abort is True:
self.waitevent()
wx.CallAfter(self.myframe.AfterRun, 'Ok button pressed')
def waitevent(self):
wx.CallAfter(self.myframe.message,"Oops!!there is another process running wait for it to finish. Closing this dialog box in 2s...")
def closeit(self, event):
self.dialogBox.Destroy()
class ChildThread_Cancel(Thread):
def __init__(self, myframe):
Thread.__init__(self)
self.myframe = myframe
def run(self):
wx.CallAfter(self.myframe.AfterRun, "Cancel button pressed")
class MyFrame(wx.Frame):
def __init__(self, parent, ID, title):
wx.Frame.__init__(self, parent, ID, title)
panel = wx.Panel(self, -1)
mainSizer = wx.BoxSizer(wx.HORIZONTAL)
mainSizer.Add(wx.Button(panel, ID_RUN, "OK"))
mainSizer.Add(wx.Button(panel, ID_RUN2, "Cancel"))
panel.SetSizer(mainSizer)
mainSizer.Fit(self)
wx.EVT_BUTTON(self, ID_RUN, self.onRun)
wx.EVT_BUTTON(self, ID_RUN2, self.onRun2)
def onRun(self, event):
self.child = ChildThread_OK(myframe=self)
self.child.daemon = True
self.child.start()
def onRun2(self, event):
self.child2 = ChildThread_Cancel(myframe = self)
self.child2.daemon = True
self.child2.start()
def AfterRun(self, msg):
dlg = wx.MessageDialog(self, msg, "Message", wx.OK | wx.ICON_INFORMATION)
dlg.ShowModal()
dlg.Destroy()
def message(self,msg):
dlg = wx.BusyInfo(msg)
time.sleep(5)
class MyApp(wx.App):
def OnInit(self):
frame = MyFrame(None, -1, "My GUI")
frame.Show(True)
frame.Centre()
return True
app = MyApp(0)
app.MainLoop()

Answer 1

First: You cannot use timer or message box in a child thread, you can only use them in main thread. So the methods below are not meaningful.
def waitevent(self):
self.timer = wx.Timer(self, 1)
self.Bind(wx.EVT_TIMER, self.closeit, self.timer)
self.timer.Start(2000, wx.TIMER_ONE_SHOT)
wx.CallAfter(self.AfterRun, 'Ok button pressed')
print 'Oops!!there is another process running wait for it to finish. Closing this dialog box in 2s...'
def closeit(self, event):
self.dialogBox.Destroy()
Second: If you use message boxes to display something, main thread is suspended and your code after message box is run after message box is closed. You can use wx.StaticText or wx.TextCtrl on main panel to show the messages or you can create new frames mimicing message boxes and they dont suspend the program and can be easily destroyed OR you can make a custom message dialog waiting for a variable to change (e.g. True/False). There is a custom message dialog example in wxPython demo.
Third: You should learn the events and queues in python's multithreading module to help you control the child threads. Child thread can sleep until an event is set or can wait until there is something in a queue.