Pygame中的Sprite类

Sprite源代码

pygame中sprite模块的Sprite类是一个简单的基类，它的源代码如下：

class Sprite(object):
    def __init__(self, *groups):
        self.__g = {} # The groups the sprite is in
        if groups:
            self.add(*groups)

    def add(self, *groups):
        has = self.__g.__contains__
        for group in groups:
            if hasattr(group, '_spritegroup'):
                if not has(group):
                    group.add_internal(self)
                    self.add_internal(group)
            else:
                self.add(*group)

    def remove(self, *groups):
        has = self.__g.__contains__
        for group in groups:
            if hasattr(group, '_spritegroup'):
                if has(group):
                    group.remove_internal(self)
                    self.remove_internal(group)
            else:
                self.remove(*group)

    def add_internal(self, group):
        self.__g[group] = 0

    def remove_internal(self, group):
        del self.__g[group]

    def update(self, *args):
        pass

    def kill(self):
        for c in self.__g:
            c.remove_internal(self)
        self.__g.clear()

    def groups(self):
        return list(self.__g)

    def alive(self):
        return truth(self.__g)

    def __repr__(self):
        return "<%s sprite(in %d groups)>" % (self.__class__.__name__, len(self.__g))

派生类一般是要重写Sprite类的update方法 ，并给Sprite类的image属性和rect属性赋值。

• update方法，适用于控制sprite对象行为的方法。基类中该方法没有任何实现，这是等着我们自己去覆盖的。
• add方法，将该sprite对象增加到group中，存疑。
• remove方法。sprite对象会从group中删掉。
• kill方法，将该sprite对象从所有groups中删掉。
• groups方法，返回sprite对象所在的所有组。
• alive方法，判断sprite方法是否还在组中。

简单的例子

它的实例我们参考这个博主的代码：
Sprite使用代码示例

这个博主是写了一个简单的小球弹弹弹的代码。

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
bWFnZVJlYWR5ccllPAAABBJJREFUeNqsVj2PG1UUvfPp8XictXfHa+9mlyJCNEQRWiToqACJAgGC
LqJNlQZR0IFEj8RPSJkGGooUpEWJkGhR0tAAElI2tsfjjxnPjIdz7oyDF2wSUK72yN43793z7rkf
Y8N2HFmbbVliGIYiyzIpy1Isy3oHeMswzLOyXJ2tVit9VhTFAxz5Cfge+A7IZIcZmySObQudwIE0
veanraB1w/O8l5x6D9eXy6UkSaJYLBa6BvsNuAV8uY3sCQlvX4LANM0Xw/Dgdhj2Xm02m+K6LqPR
PXmeS5qmMp/PZTabyXQ6lclkosS1/QJcB+5vkthrAkoAuc4uHx//0B8MvCAIxG/5jEg0kpIkmcwX
icTxBIhlHWEURXoedgW4B3wIfHuBJM9yMQ3j5PTk5N7g6MjtdrrS3e9Ku90GUUvc2hkdMYJx5Ivn
NRC19UReRlRLR/sGeB34UUkMJBcJlcHg6K4SdDvS7/el1+tJp7MnQdCWRqMhDGWZLmWCCFog9rBm
GBYc50rOKON4uqkSC+IQSC3moeX7N09PX/i4AwLkAoQDxeFhHziU8CCUzt6e+EFLc2QaJi4mFQHy
kQLZMpME+WJF1sabdYA7Nq4jQbv9OZPs+75cgkSMYH9/X6PhJ9dpTLjruFLkBRyjACBd1BoLzzY8
T3O0IRntJvCZDXsTTnq262CzrzmgRHu4+QEIQhAxNzRWU1mTxfjOwvBIAOlIYNnWtja5bqM33mN/
sBEdx9bNPOQ1PWlqZJdAFKoMrEI6R+9gj6t7cUl1zjKnjFvsfaybr1Uqlv94ypXSKCud+aefpezs
7O3LL9s4c5U65gCrhGDDpUkqyWIuU1STweNlJRe7nAlmA+ZaVbnmiD4KFNEWC+3VqjB5YImDdMA+
YKONx2OVgxefojRL8CzmCxkOhxLhWYy+mGIvz6RKmv096X91PErP4Byazapbs3vZB45bVQqTzBzQ
kjQBQSTnjx7JcDTCRSLkKNY9SbKACsttHKZdrIqHILnGCNhoDU0qG83U5mNUVTOKShRPYo3m8fAc
nT/S/3mWFy2KrXKNOFbuI+Rr1FvLsB731Ho2m2pU7I1Sx8pSHTLaESIZjob6nfso2w77mSR3IMsN
zh4mmLOIBAkO6fjAgESdV1MYiV4kiUZHRDjD3E0Qza580D+rjsUdAQEj4fRl8wUkqBttPeo5RlJI
uB71jIASc8D+i4W8IoX8CviC5cuI+JlgpLsgcF1ng6RQyaoX1oWX1i67DTxe9w+9/EHW9VOrngCW
ZfNFpmvVWOfUzZ/mfG0HwHBz4ZV1kz8nvLuL+YPnRPDJ00J8A/j9fzrnW+sjeUbjbP8amDyj86z+
tXL5PwzOC4njj4K3gavA8cazczYacLd+p/+6y8mfAgwAsRuLfp/zVLMAAAAASUVORK5CYII="""))
        self.image = pygame.image.load(ball_file, 'file').convert_alpha()
        self.rect = self.image.fill(color, None, BLEND_ADD)
        self.rect.topleft = initial_position

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.speed[0]
            self.rect.y += self.speed[1]
            self.update_time = current_time+10
        pass



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

#ball = Ball((255, 0, 0), (100, 100))
balls = []
for color,location,speed in [([255, 0, 0], [50, 50],[2,3]),
                        ([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()

可以看到代码中Ball类继承类Sprite基类，然后MoveBall类继承了Ball类，这里只是用了Sprite类的update方法，还没有用到Group相关的方法。