Question

When I start the program, it runs fine. But when I press the Countdown Button, and then attempt to activate the Action Button, it freezes.

import wx
import time


class LeftPanel(wx.Panel):
    def __init__(self, parent, id):
        wx.Panel.__init__(self, parent, id, style=wx.BORDER_SUNKEN)
        self.text = parent.GetParent().rightPanel.text
        self.text_2 = parent.GetParent().rightPanel.text_2
        button1 = wx.Button(self, -1, 'Count', (10, 10))
        button2 = wx.Button(self, -1, 'Countdown', (10, 60))
        button3 = wx.Button(self, -1, 'Action', (10, 110))
        self.Bind(wx.EVT_BUTTON, self.OnPlus, id=button1.GetId())
        self.Bind(wx.EVT_BUTTON, self.OnMinus, id=button2.GetId())
        self.Bind(wx.EVT_BUTTON, self.button_Pressed, id=button3.GetId())
        self.timed_Out = 1     


    def OnPlus(self, event):
        value = 1
        for t in range(5000):
            value = value + 1
            time.sleep(1)
            self.text.SetLabel(str(value))

    def OnMinus(self, event):
        import math
        value = 60
        for t in range(value):
            value = value - 1
            time.sleep(1)
            self.text.SetLabel(str(value/60) + ':' + str(value%60))

        self.timed_Out = 0
        self.text_2.SetLabel(str('End o\'line.'))

    def button_Pressed(self, event):
        if self.timed_Out == 1:
            if self.text_2 == 'First':
                self.text_2.SetLabel('Second')

            elif self.text_2 == 'Second':
                 self.text_2.SetLabel('First')



class RightPanel(wx.Panel):
    def __init__(self, parent, id):
        wx.Panel.__init__(self, parent, id, style=wx.BORDER_SUNKEN)
        self.text = wx.StaticText(self, -1, '0', (10,60))
        self.text_2 = wx.StaticText(self,-1,'First',(10, 120))

class Communicate(wx.Frame):
    def __init__(self, parent, id, title):
        wx.Frame.__init__(self, parent, id, title, size=(600, 200))
        panel = wx.Panel(self, -1)
        self.rightPanel = RightPanel(panel, -1)
        leftPanel = LeftPanel(panel, -1)
        hbox = wx.BoxSizer()
        hbox.Add(leftPanel, 1, wx.EXPAND | wx.ALL, 4)
        hbox.Add(self.rightPanel, 1, wx.EXPAND | wx.ALL, 5)
        panel.SetSizer(hbox)
        self.Centre()
        self.Show(True)



app = wx.App()
Communicate(None, -1, 'widgets communicate')
app.MainLoop()

Answer 1

That’s because you are putting time.sleep calls in the button event handler function. This will cause the user interface to freeze. It may get visually updated as the counter label gets updated (it doesn’t for me) but no interface elements will work until the event handler finishes.

What you need to do is to run the timer in a separate thread; then, each second, send an event to the main window to tell it to update its counter. You can do that with the wx.PostEvent function.

Or, for a simpler and better solution, you can use wx.Timer built for this very purpose. Here is a tutorial about it. You can use it for repeating events too, which is the case for this countdown.

There is a more generic tutorial about having long-running tasks activated by UI events; I am putting this link because I am guessing people on Google will be looking for this when they search for why their application is freezing, and it will probably not be because of a timer.