Python-сообщество

import appuifw, graphics, e32, key_codes  
  
BLACK = (0, 0, 0)  
WHITE = (255, 255, 255)  
key_down = None  
clicked = None  
  
def handle_event(event):  
 global clicked, key_down  
 if event['type'] == appuifw.EEventKey:  
  if key_down:  
   key_down = (event['keycode'], "down")  
  else:  
   key_down = (event['keycode'], "pressed")  
 elif event['type'] == appuifw.EEventKeyUp and key_down:  
  code, mode = key_down  
  if mode == "pressed":  
   clicked = code  
  key_down = None  
  
def key_is_down(code):  
 if key_down == (code, "down"):  
  return True  
 return False  
  
def quit():  
 global running  
 running = False  
  
def handle_redraw(rect):  
 if img: canvas.blit(img)  
  
img = None  
canvas = appuifw.Canvas(event_callback=handle_event,  
      redraw_callback=handle_redraw)  
appuifw.app.screen = 'full'  
appuifw.app.body = canvas  
appuifw.app.exit_key_handler = quit  
  
x = y = 100  
w, h = canvas.size  
img = graphics.Image.new((w, h))  
img.clear(WHITE)  
  
running = True  
while running:  
 if key_is_down(key_codes.EKeyLeftArrow): 
  x -= 2
 elif key_is_down(key_codes.EKeyRightArrow):
  x += 2
 elif key_is_down(key_codes.EKeyDownArrow):
  y += 2
 elif key_is_down(key_codes.EKeyUpArrow):
  y -= 2
      
 img.clear(WHITE)                                               - это получается,очищается экран каждую долю секунды
 img.point((x, y), outline = BLACK, width = 50)  
 handle_redraw(None)                                         - а эта функция как вызывается? (if img: canvas.blit(img)) тоже 
                                                                           каждую долю секунды?
 e32.ao_yield()