Smooth scrolling ?

Guys,

I'm just about to give up on smooth scrolling with pygame. I tried many different ways but getting jerky motions no matter what I do.

The code is below and it simply blits the pic on a screen and flips the screen when the vsync backtrace is up. Then it repeats. In my assumption it should be smooth, but it is not :(

Any helping hand ?

Thanks a lot,

Dmitry/

 

pygame-1.6

WinXP, P4-1.8

 

# ----------------------------------------------------------------------------

import pygame
pygame.init()

 

screen= pygame.display.set_mode( (800,600), pygame.DOUBLEBUF|pygame.HWSURFACE, 32 )

 

i= 0
f= pygame.font.Font( 'data/arialn.ttf', 80 )
s= f.render( 'Scrolling', 1, (0xff,0xee,0x00) )
surf= pygame.Surface( s.get_size(), pygame.SRCALPHA, 32 )
surf.blit( s, (0,0) )
screen.fill( (255,255,255) )
pygame.display.update()
while i< 800:
  screen.fill( (255,255,255), (0,200,800,surf.get_height()) )
  screen.blit( surf, ( i, 200 ) )
  pygame.display.flip()
  pygame.event.poll()
  i+= 1

 

pygame.quit()

# ----------------------------------------------------------------------------