Using a wx.gauge in a wx.wizard

Question

I'm having trouble getting the gauge in the second page of my wizard to appear and update. It doesn't show until it's at 100%. It seems to me that the EVT_WIZARD_PAGE_CHANGED event gets handled before objects on the page are displayed.

The code below is a simplified version of what I'm trying to do. When I run it, the second page just hangs until the fill_gauge method is finished and the gauge is at 100%, then it finally appears on the screen. Does anyone have any ideas of how to display the gauge as soon as I change to the second page and have it dynamically update.

import time
import wx.wizard

class Wizard(wx.wizard.Wizard):
    def __init__(self, parent, title):
        wx.wizard.Wizard.__init__(self, parent, wx.ID_ANY, title )
        self.pages = []
        self.Bind(wx.wizard.EVT_WIZARD_PAGE_CHANGED, self.on_page_changed)

    def add_page(self, page):
        """Add a WizardPage to the pages list"""
        self.pages.append(page)

    def chain_pages(self):
        i = 0
        while 1:
            if i == len(self.pages) - 1:
                break
            else:
                wx.wizard.WizardPageSimple_Chain(self.pages[i], self.pages[i + 1])
                i += 1

    def run(self):
        self.RunWizard(self.pages[0])

    def on_page_changed(self, evt):
        #if coming from self.pages[0]
        #and direction is forward
        if evt.GetDirection(): direction = 'forward'
        else:                  direction = 'backward'

        if evt.GetPage() is self.pages[1]\
        and direction == "forward":
            self.pages[1].fill_gauge()

class StartPage(wx.wizard.WizardPageSimple):

    def __init__(self, parent, title):
        wx.wizard.WizardPageSimple.__init__(self, parent)
        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.text = wx.StaticText(self, -1,
        "This is the First Page")
        #self.text.Wrap(parent.GetClientSizeTuple()[0])
        self.sizer.Add(self.text, 0, wx.ALIGN_CENTER|wx.ALL, 5)

class UpdatePage(wx.wizard.WizardPageSimple):
    def __init__(self, parent, title):
        wx.wizard.WizardPageSimple.__init__(self, parent)
        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.status = wx.StaticText(self, -1, "This is the Second Page")
        self.gauge = wx.Gauge(self, -1, name = "Guage")

        self.sizer.Add(self.status, 0, wx.ALIGN_CENTER|wx.ALL, 5)
        self.sizer.Add(self.gauge, 0, wx.EXPAND|wx.ALIGN_CENTER_HORIZONTAL|wx.ALL, 10)
        self.SetSizer(self.sizer)

    def update(self, percent, status):
        self.status.SetLabel(status)
        self.gauge.SetValue(percent)
        #self.Refresh()

    def fill_gauge(self):
        x = 0
        while x <=100:
            self.update(x, "Gauge is at %d" % x)
            x += 10
            time.sleep(1)

if __name__ == '__main__':
    app = wx.App()
    wizard = Wizard(None, "Updater")
    wizard.add_page(StartPage(wizard, "Updater"))
    wizard.add_page(UpdatePage(wizard, "Updater"))
    wizard.chain_pages()
    wizard.run()
    wizard.Destroy()
    app.MainLoop()

Answer 1

Your method of updating the gauge is blocking the gui's event loop. You could use a wx.Timer to call the update so it doesn't block. See the following example of your modifed code.

import time 
import wx.wizard


class Wizard(wx.wizard.Wizard):
    def __init__(self, parent, title):
        wx.wizard.Wizard.__init__(self, parent, wx.ID_ANY, title)
        self.pages = []
        self.Bind(wx.wizard.EVT_WIZARD_PAGE_CHANGED, self.on_page_changed)

    def add_page(self, page):
        """Add a WizardPage to the pages list"""
        self.pages.append(page)

    def chain_pages(self):
        i = 0
        while 1:
            if i == len(self.pages) - 1:
                break
            else:
                wx.wizard.WizardPageSimple_Chain(self.pages[i],
                                                 self.pages[i + 1])
                i += 1

    def run(self):
        self.RunWizard(self.pages[0])

    def on_page_changed(self, evt):
        # if coming from self.pages[0]
        # and direction is forward
        if evt.GetDirection():
            direction = 'forward'
        else:
            direction = 'backward'

        if evt.GetPage() is self.pages[1]\
        and direction == "forward":
#             self.pages[1].fill_gauge()
            self.pages[1].timer.Start(1000)


class StartPage(wx.wizard.WizardPageSimple):

    def __init__(self, parent, title):
        wx.wizard.WizardPageSimple.__init__(self, parent)
        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.text = wx.StaticText(self, -1,
        "This is the First Page")
        # self.text.Wrap(parent.GetClientSizeTuple()[0])
        self.sizer.Add(self.text, 0, wx.ALIGN_CENTER | wx.ALL, 5)


class UpdatePage(wx.wizard.WizardPageSimple):
    def __init__(self, parent, title):
        wx.wizard.WizardPageSimple.__init__(self, parent)
        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.status = wx.StaticText(self, -1, "This is the Second Page")
        self.gauge = wx.Gauge(self, -1, name="Guage")

        self.sizer.Add(self.status, 0, wx.ALIGN_CENTER | wx.ALL, 5)
        self.sizer.Add(self.gauge, 0,
                       wx.EXPAND | wx.ALIGN_CENTER_HORIZONTAL | wx.ALL, 10)
        self.SetSizer(self.sizer)

        self.gauge_pos = 0  # Added
        self.timer = wx.Timer(self)  # Added
        self.Bind(wx.EVT_TIMER, self.on_gauge_timer)  # Added

    def update(self, percent, status):
        self.status.SetLabel(status)
        self.gauge.SetValue(percent)
        # self.Refresh()

#     def fill_gauge(self):
#         x = 0
#         while x <= 100:
#             self.update(x, "Gauge is at %d" % x)
#             x += 10
#             time.sleep(1)

    def on_gauge_timer(self, event):  # Added method
        if self.gauge_pos < 100:
            self.gauge_pos += 10
            self.update(self.gauge_pos, "Gauge is at %d" % self.gauge_pos)
        else:
            self.timer.Stop()
            self.gauge_pos = 0


if __name__ == '__main__':
    app = wx.App()
    wizard = Wizard(None, "Updater")
    wizard.add_page(StartPage(wizard, "Updater"))
    wizard.add_page(UpdatePage(wizard, "Updater"))
    wizard.chain_pages()
    wizard.run()
    wizard.Destroy()
    app.MainLoop()

Note: it needs better code adding to stop the timer and reset the gauge if you go back a page, but i only made it basicly work.