Pygame animation sprite base class at Thursday, March 26, 2009

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Here's a base class for animated sprites which includes code to ensure that the images are only loaded once. It uses a dictionary of image frames keyed against the classname to achieve this.

import pygame, math, random, sys, os
from pygame.locals import *

IMAGE_PATH = '../res/images/'

class AnimationSprite(pygame.sprite.Sprite):
'''Base class for animated sprites'''

# This will hold a dict of frame lists keyed on the sprite's class name
# The images are only ever loaded once
animationFrames = {}

def __init__(self, spriteGroup):
   pygame.sprite.Sprite.__init__(self)
   self.frameCount = 0
   self.animFrameCount = 1
   self.loadImages()
   frames = AnimationSprite.animationFrames[self.__class__.__name__]
   self.image = frames[self.frameCount]
   self.rect = self.image.get_rect()
   self.spriteGroup = spriteGroup
   self.spriteGroup.add(self)

def update(self, events):
   '''Called by the SpriteGroup every tick'''
   self.doMove(events)
   self.frameCount += 1
   if not self.frameSkip == 0 and (self.frameCount % self.frameSkip) == 0:
       self.animFrameCount += 1       
       index = self.animFrameCount % self.numberOfFrames
       frames = AnimationSprite.animationFrames[self.__class__.__name__]
       self.image = frames[index]

def loadImages(self):  
   '''Load the animation frames from the composite ship image'''

   # See if we've already loaded the image for this sprite 
   if not AnimationSprite.animationFrames.has_key(self.__class__.__name__):
       print 'Loading graphics for: ', self.__class__.__name__
       compositeImage = pygame.image.load(os.path.join(IMAGE_PATH, self.imageName)).convert_alpha()
       rowOffsetY = 0
       frames = []
       for i in range(0, self.numberOfFrames):
           img = compositeImage.subsurface((self.width * i, 0), (self.width, self.height))
           frames.append(img)
       AnimationSprite.animationFrames[self.__class__.__name__] = frames