A wxPython-based sample clock app.

wx-clock.py

#!/usr/bin/env python
from __future__ import (absolute_import,
                        division,
                        print_function,
                        unicode_literals)
import math
import time

import wx


class ClockWindow(wx.Window):
    
    def __init__(self, parent, id=-1,
                 pos=wx.DefaultPosition, size=wx.DefaultSize,
                 style=0, name=wx.PanelNameStr):

        wx.Window.__init__(self, parent, id, pos, size, style, name)

        self.SetBackgroundColour(wx.WHITE)

        self.lr_clock = 128
        self._bmp = wx.EmptyBitmap(self.lr_clock*2, self.lr_clock*2)
        self._timer = wx.Timer(self)

        self.Bind(wx.EVT_PAINT, self.OnPaint)
        self.Bind(wx.EVT_TIMER, self.OnTimer)

        ms_resolution = 1000/30
        self._timer.Start(ms_resolution)

    def OnPaint(self, evt):
        
        dc = wx.PaintDC(self)
        dw_client, dh_client = self.GetClientSizeTuple()
        dc.DrawBitmap(self._bmp, 0, 0)

    def OnTimer(self, evt):
        
        wx.CallAfter(self.draw_clock_on_bitmap)

    def draw_clock_on_bitmap(self):

        lr_clock = self.lr_clock 
        lx_center = ly_center = lr_clock
        lr_bezel = self.lr_clock * 0.95
        lr_shaft = lr_clock / 2 * 0.1
        lr_hour_hand = lr_clock * 0.7
        lr_min_hand = lr_clock * 0.8
        lr_sec_hand = lr_clock * 0.9
        tm = time.localtime()
        tm_sec = time.time() % 60
        tm_min = tm.tm_min + tm_sec / 60
        tm_hour = tm.tm_hour + tm_min / 60
        rad_hour = tm_hour / 6 * math.pi - math.pi/2
        rad_min = tm_min / 30 * math.pi - math.pi/2
        rad_sec = tm_sec / 30 * math.pi - math.pi/2
        lx_hour = lx_center + lr_hour_hand * math.cos(rad_hour)
        ly_hour = ly_center + lr_hour_hand * math.sin(rad_hour)
        ly_min = ly_center + lr_min_hand * math.sin(rad_min)
        lx_min = lx_center + lr_min_hand * math.cos(rad_min)
        lx_sec = lx_center + lr_sec_hand * math.cos(rad_sec)
        ly_sec = ly_center + lr_sec_hand * math.sin(rad_sec)

        mdc = wx.MemoryDC(self._bmp)
        mdc.Clear()

        gc = wx.GraphicsContext.Create(mdc)
        
        gc.SetFont(self.GetFont())
        label = '%02d:%02d:%02d' % (tm_hour, tm_min, tm_sec)
        lw_label, lh_label = gc.GetTextExtent(label)
        lx_label = lx_center - lw_label / 2
        ly_label = lr_clock * 1.7
        gc.DrawText(label, lx_label, ly_label)

        gc.SetPen(wx.BLACK_PEN)
        gc.SetBrush(wx.TRANSPARENT_BRUSH)
        gc.DrawEllipse(lr_clock-lr_bezel, lr_clock-lr_bezel, 
                       lr_bezel*2, lr_bezel*2)
        gc.DrawLines(((lx_center, ly_center), (lx_hour, ly_hour)))
        gc.DrawLines(((lx_center, ly_center), (lx_min, ly_min)))
        gc.SetPen(wx.RED_PEN)
        gc.DrawLines(((lx_center, ly_center), (lx_sec, ly_sec)))
        gc.SetPen(wx.BLACK_PEN)
        gc.SetBrush(wx.BLACK_BRUSH)
        gc.DrawEllipse(lx_center-lr_shaft, ly_center-lr_shaft,
                       lr_shaft*2, lr_shaft*2)
        
        self.Refresh()
        mdc.SelectObject(wx.NullBitmap)


def main():

    app = wx.App()
    frame = wx.Frame(None)
    child = ClockWindow(frame)
    frame.Show()

    app.MainLoop()


if __name__ == '__main__':
    main()