pygame经典sprite精灵类

import cStringIO, base64
import pygame
from pygame.locals import *

class Ball(pygame.sprite.Sprite):
    def __init__(self, color, initial_position):
        pygame.sprite.Sprite.__init__(self)
        ball_file = cStringIO.StringIO(base64.decodestring(
"""iVBORw0KGgoAAAANSUhEUgAAABkAAAAZCAYAAADE6YVjAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJ
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        self.image = pygame.image.load(ball_file, 'file').convert_alpha()
        self.rect = self.image.fill(color, None, BLEND_ADD)
        self.rect.topleft = initial_position

pygame.init()
# screen = pygame.display.set_mode([350, 350])

# ball = Ball((255, 0, 0), (100, 100))
# screen.blit(ball.image, ball.rect)
# pygame.display.update()
# while pygame.event.poll().type != KEYDOWN:
#     pygame.time.delay(10)
class MoveBall(Ball):
    def __init__(self, color, initial_position, speed, border):
        super(MoveBall, self).__init__(color, initial_position)
        self.speed = speed
        self.border = border
        self.update_time = 0
 
    def update(self, current_time):
        if self.update_time < current_time:
            if self.rect.left < 0 or self.rect.left > self.border[0] - self.rect.w:
                self.speed[0] *= -1
            if self.rect.top < 0 or self.rect.top > self.border[1] - self.rect.h:
                self.speed[1] *= -1
 
            self.rect.x, self.rect.y = self.rect.x + self.speed[0], self.rect.y + self.speed[1]
            self.update_time = current_time + 10
 
pygame.init()
screen = pygame.display.set_mode([350, 350])
 
balls = []
for color, location, speed in [([255, 0, 0], [50, 50], [2,4]),
                        ([0, 255, 0], [100, 100], [3,2]),
                        ([0, 0, 255], [150, 150], [4,3])]:
    balls.append(MoveBall(color, location, speed, (350, 350)))
 
while True:
    if pygame.event.poll().type == QUIT: break
 
    screen.fill((0,0,0,))
    current_time = pygame.time.get_ticks()
    for b in balls:
        b.update(current_time)
        screen.blit(b.image, b.rect)
    pygame.display.update()