How Can I Safely Manage wxPython Progress Dialog Threading? - multithreading

Question

I have several calculations to run without any user input and without the user worrying about the program having frozen, so I am trying to show a progress bar popup to keep them aware of what's happening.
Looking around has lead me to believe that I need to use a separate thread to do this, and I came up with this example.
import threading, wx, time
MAX_INT = 10
TEST_TUPLE = [[11, 22],[33,44]]
class mainFrame(wx.Frame):
def __init__(self, parent, ID, title):
wx.Frame.__init__(self, parent, ID, title)
bt = wx.Button(self, wx.ID_OK)
self.Bind(wx.EVT_BUTTON, self.onBt, bt)
def onBt(self,event):
self.dlg = wx.ProgressDialog("title", "message", maximum=MAX_INT)
workThread = threading.Thread(target=self.doWork, args=(TEST_TUPLE,) )
workThread.start()
self.dlg.ShowModal()
def doWork(self, testArg):
# time consuming stuff that affects main GUI
print testArg
for i in range(1, MAX_INT+1):
self.SetPosition((i*4*MAX_INT, i*2*MAX_INT))
time.sleep(1)
print str(i)+" of "+str(MAX_INT)
wx.CallAfter(self.dlg.Update, i, "%i of %i"%(i, MAX_INT))
self.dlg.Destroy()
app = wx.App(False)
fr = mainFrame(None, -1, "Title")
fr.Show()
app.MainLoop()
It seems to work as intended, but is there some housekeeping that I am skipping here?
EDIT: I replaced the dialog with a miniframe so the main window would not freeze, disabled the button so there wouldn't be several frames spawned, and added a crude cancelling method.
import threading, wx, time
MAX_INT = 10
TEST_TUPLE = [[11, 22],[33,44]]
class GaugeFrame(wx.MiniFrame):
def __init__(self, parent, title, maximum):
wx.MiniFrame.__init__(self, parent, title=title, size=(200, 60) )
self.bar = wx.Gauge(self, range=maximum)
self.buCancel = wx.Button(self, label="Cancel")
self.SetBackgroundColour("LTGRAY")
siMainV = wx.BoxSizer(wx.VERTICAL)
siMainV.Add(self.bar)
siMainV.Add(self.buCancel, flag=wx.CENTER)
self.SetSizer(siMainV)
self.Fit()
self.Bind(wx.EVT_BUTTON, self.onCancel, self.buCancel)
def updateGauge(self, value, message=""):
self.bar.SetValue(value)
if message!="":
self.SetTitle(message)
def onCancel(self, e):
self.SetTitle("Cancelling...")
class MainFrame(wx.Frame):
def __init__(self, parent, ID, title):
wx.Frame.__init__(self, parent, ID, title)
self.bt = wx.Button(self, wx.ID_OK)
self.Bind(wx.EVT_BUTTON, self.onBt, self.bt)
def onBt(self, event):
self.gFr = GaugeFrame(self, title="0 of "+str(MAX_INT), maximum=MAX_INT)
self.gFr.Show()
self.gFr.Center()
self.bt.Disable()
workThread = threading.Thread(target=self.doWork, args=(TEST_TUPLE,) )
workThread.start()
def doWork(self, testArg):
# time consuming stuff that affects main GUI
print testArg
for i in range(1, MAX_INT+1):
time.sleep(1)
if self.gFr.GetTitle()=="Cancelling...":
break
print str(i)+" of "+str(MAX_INT)
wx.CallAfter(self.gFr.updateGauge, i, "%i of %i"%(i, MAX_INT))
wx.CallAfter(self.gFr.Destroy)
wx.CallAfter(self.bt.Enable)
app = wx.App(False)
fr = MainFrame(None, -1, "Title")
fr.Show()
app.MainLoop()

Answer 1

Looks pretty good, just a couple of observations.
You should not call ANY window functions on the worker thread. This includes SetPosition and Destroy. You can use wx.CallAfter to invoke these on the main thread just like you are for Update.
You probably should allow the user to cancel the processing.