#! /usr/bin/env python3
#
def bouncing_ball ( ):

  import pygame

  pygame.init()

  width = 1280
  height = 960
  screen = pygame.display.set_mode ( [ width, height ] )

  speed = [ 1, 1 ]
  black = 0, 0, 0
#
#  Get the ball image.
#
  ball = pygame.image.load ( "bouncing_ball_data/intro_ball.gif" )
#
#  Create a rectangle containing the ball image.
#  This rectangle has left, right, top and bottom coordinates.
#  It can be moved with a given speed.
#
  ballrect = ball.get_rect()

  running = True

  while running:

    for event in pygame.event.get():
      if event.type == pygame.QUIT:
        running = False

    ballrect = ballrect.move ( speed )
#
#  Reverse direction if ball hits a boundary.
#
    if ballrect.left < 0 or width < ballrect.right:
      speed[0] = - speed[0]
    if ballrect.top < 0 or height < ballrect.bottom:
      speed[1] = - speed[1]

    screen.fill ( black )
    screen.blit ( ball, ballrect )
    pygame.display.flip ( )

  pygame.quit ( )

  return

if ( __name__ == "__main__" ):
  bouncing_ball ( )