Bouncing ball with rotation

gistfile1.py

"""Simple bouncing ball demo."""

import sys

import pygame

pygame.init()

size = (1024, 768)
speed = [1, 1]
black = (0, 0, 0)

screen = pygame.display.set_mode(size)

ball = pygame.image.load('ball2.png')
ballrect = ball.get_rect()

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

    ballrect = ballrect.move(speed)
    if ballrect.left < 0 or ballrect.right > size[0]:
        speed[0] = -speed[0]
    if ballrect.top < 0 or ballrect.bottom > size[1]:
        speed[1] = -speed[1]

    screen.fill(black)

    if speed == [1, 1]:
        angle = -45
    if speed == [1, -1]:
        angle = 45
    if speed == [-1, -1]:
        angle = -225
    if speed == [-1, 1]:
        angle = -135

    rotated_ball = pygame.transform.rotate(ball, angle)
    screen.blit(rotated_ball, ballrect)

    pygame.display.flip()