学习 Python 之 Pygame 开发魂斗罗（二）

魂斗罗的需求

魂斗罗游戏中包含很多个物体，现在要对这些物体进行总结

类名	包含的操作	包含的属性
玩家1类	跳跃、行走、落下、更新	生命，速度，伤害，方向，类型
玩家2类	跳跃、行走、落下、更新	生命，速度，伤害，方向，类型
敌人类	跳跃、行走、落下、更新	生命，速度，伤害，方向，类型
子弹类	移动，显示	方向，伤害，发射源，速度
桥类、陷阱类、奖励类、BOSS类	…	…
音效类	播放，停止，设置音乐	-
爆炸效果类	显示	是否可以摧毁
主类	…	…

物体总结完毕后，规划一下窗口的大小，下面是我设置的窗口大小

由于地图素材的大小限制，下面这个窗口的大小刚刚合适
在这里插入图片描述

开始编写魂斗罗

那么我们开始来编写魂斗罗吧

1. 搭建主类框架

同样地，先写主类，主类是整个游戏运作的类，我们也可以不用这样的方式，可以使用函数代替

import pygame


class MainGame:

    window = None

    def __init__(self):
        pass

    def run(self):
        pass

if __name__ == '__main__':
    pass

2. 设置游戏运行遍历和创建窗口

魂斗罗游戏不像坦克大战，坦克大战中坦克移动是把图片放到不同的位置，而魂斗罗中，人物移动有移动的动画，跳跃也有跳跃的动画，我们需要设置帧率，通过控制帧率来实现动画效果

首先创建一个常量Constants.py文件，用于存放游戏中使用的常量

from enum import Enum

# 玩家的四种状态
class State(Enum):
    STAND = 1
    WALK = 2
    JUMP = 3
    FALL = 4

# 玩家的方向
class Direction(Enum):
    RIGHT = 1
    LEFT = 2


# 设置窗口大小
SCREEN_HEIGHT = 600
SCREEN_WIDTH = 800
GROUND_HEIGHT = 63

# 玩家x方向速度
PLAYER_X_SPEED = 3

设置遍历和创建窗口

def __init__(self):
    # 初始化展示模块
    pygame.display.init()

    SCREEN_SIZE = (SCREEN_WIDTH, SCREEN_HEIGHT)
    # 初始化窗口
    MainGame.window = pygame.display.set_mode(SCREEN_SIZE)
    # 设置窗口标题
    pygame.display.set_caption('魂斗罗角色')
    # 是否结束游戏
    self.isEnd = False
    # 获取按键
    self.keys = pygame.key.get_pressed()
    # 帧率
    self.fps = 60
    self.clock = pygame.time.Clock()

修改一下run()函数

def run(self):
   while not self.isEnd:
       
       # 设置背景颜色
       pygame.display.get_surface().fill((0, 0, 0))

       # 更新窗口
       pygame.display.update()

       # 设置帧率
       self.clock.tick(self.fps)
       fps = self.clock.get_fps()
       caption = '魂斗罗 - {:.2f}'.format(fps)
       pygame.display.set_caption(caption)
   else:
       sys.exit()

完整主类代码

import sys
import pygame
from Constants import *

class MainGame:

    window = None

    def __init__(self):
        # 初始化展示模块
        pygame.display.init()

        SCREEN_SIZE = (SCREEN_WIDTH, SCREEN_HEIGHT)
        # 初始化窗口
        MainGame.window = pygame.display.set_mode(SCREEN_SIZE)
        # 设置窗口标题
        pygame.display.set_caption('魂斗罗角色')
        # 是否结束游戏
        self.isEnd = False
        # 获取按键
        self.keys = pygame.key.get_pressed()
        # 帧率
        self.fps = 60
        self.clock = pygame.time.Clock()

    def run(self):
        while not self.isEnd:

            # 设置背景颜色
            pygame.display.get_surface().fill((0, 0, 0))

            # 更新窗口
            pygame.display.update()

            # 设置帧率
            self.clock.tick(self.fps)
            fps = self.clock.get_fps()
            caption = '魂斗罗 - {:.2f}'.format(fps)
            pygame.display.set_caption(caption)
        else:
            sys.exit()

if __name__ == '__main__':
    MainGame().run()

运行一下，看看窗口

在这里插入图片描述

3. 获取窗口中的事件

在魂斗罗中，玩家移动是必不可少的操作，因此键盘事件响应是必不可少的

def getPlayingModeEvent(self):
    # 获取事件列表
    for event in pygame.event.get():
        # 点击窗口关闭按钮
        if event.type == pygame.QUIT:
            self.isEnd = True
        # 键盘按键按下
        elif event.type == pygame.KEYDOWN:
            self.keys = pygame.key.get_pressed()
        # 键盘按键抬起
        elif event.type == pygame.KEYUP:
            self.keys = pygame.key.get_pressed()

获取窗口中的事件，用于玩家角色移动、发射子弹等操作

在这个游戏中，我规定aswd操控玩家移动，j攻击，k跳跃

import sys
import pygame
from Constants import *

class MainGame:

    window = None

    def __init__(self):
        # 初始化展示模块
        pygame.display.init()

        SCREEN_SIZE = (SCREEN_WIDTH, SCREEN_HEIGHT)
        # 初始化窗口
        MainGame.window = pygame.display.set_mode(SCREEN_SIZE)
        # 设置窗口标题
        pygame.display.set_caption('魂斗罗角色')
        # 是否结束游戏
        self.isEnd = False
        # 获取按键
        self.keys = pygame.key.get_pressed()
        # 帧率
        self.fps = 60
        self.clock = pygame.time.Clock()

    def run(self):
        while not self.isEnd:

            # 设置背景颜色
            pygame.display.get_surface().fill((0, 0, 0))

            # 获取窗口中的事件
            self.getPlayingModeEvent()

            # 更新窗口
            pygame.display.update()

            # 设置帧率
            self.clock.tick(self.fps)
            fps = self.clock.get_fps()
            caption = '魂斗罗 - {:.2f}'.format(fps)
            pygame.display.set_caption(caption)
        else:
            sys.exit()

    def getPlayingModeEvent(self):
        # 获取事件列表
        for event in pygame.event.get():
            # 点击窗口关闭按钮
            if event.type == pygame.QUIT:
                self.isEnd = True
            # 键盘按键按下
            elif event.type == pygame.KEYDOWN:
                self.keys = pygame.key.get_pressed()
            # 键盘按键抬起
            elif event.type == pygame.KEYUP:
                self.keys = pygame.key.get_pressed()

if __name__ == '__main__':
    MainGame().run()

4. 创建角色

创建一个玩家类，实现玩家的移动和射击，玩家类需要继承
pygame.sprite.Sprite类，用来实现物体的碰撞检测

import pygame
from Constants import *


class PlayerOne(pygame.sprite.Sprite):

    def __init__(self, currentTime):
        pygame.sprite.Sprite.__init__(self)
        pass

    def update(self, playerBulletList, keys, currentTime):
        pass

创建玩家类后，先把玩家图片加载进来，这里需要写一个函数，用来处理图片

在常量Constants.py文件中，写一个函数，用来加载图片

def loadImage(filename, hReverse = False):
    image = pygame.image.load(filename)
    if hReverse:
        image = pygame.transform.flip(image, True, False)
    rect = image.get_rect()
    image = pygame.transform.scale(
        image,
        (int(rect.width * 2.5), int(rect.height * 2.5))
    )
    image = image.convert_alpha()
    return image

这个函数用来设置图片放缩和水平翻转

因为素材中大多数图片都是向右的，如果要得到向左的，必须要进行翻转，为了方便，我就没有处理素材，直接使用了翻转

文件中翻转和缩放代码，在学习 Python 之 Pygame 开发魂斗罗（一）中已经见过了

完整的常量文件

from enum import Enum
import pygame

class State(Enum):
    STAND = 1
    WALK = 2
    JUMP = 3
    FALL = 4
    SQUAT = 5

class Direction(Enum):
    RIGHT = 1
    LEFT = 2

def loadImage(filename, hReverse = False):
    image = pygame.image.load(filename)
    if hReverse:
        image = pygame.transform.flip(image, True, False)
    rect = image.get_rect()
    image = pygame.transform.scale(
        image,
        (int(rect.width * 2.5), int(rect.height * 2.5))
    )
    image = image.convert_alpha()
    return image

# 设置窗口大小
SCREEN_HEIGHT = 600
SCREEN_WIDTH = 800
GROUND_HEIGHT = 63

# 玩家x方向速度
PLAYER_X_SPEED = 3

这里需要注意一点，由于玩家移动时有动画效果，所有我们载入的图片是连续的好几张

下面是图片的素材

链接：https://pan.baidu.com/s/1X7tESkes_O6nbPxfpHD6hQ?pwd=hdly
提取码：hdly

有了素材，开始读取图片吧，修改玩家类的__init__()函数

def __init__(self, currentTime):
    pygame.sprite.Sprite.__init__(self)
    # 加载角色图片
    self.standRightImage = loadImage('../Image/Player/Player1/Right/stand.png')
    self.standLeftImage = loadImage('../Image/Player/Player1/Left/stand.png')
    self.upRightImage = loadImage('../Image/Player/Player1/Up/upRight(small).png')
    self.upLeftImage = loadImage('../Image/Player/Player1/Up/upLeft(small).png')
    self.downRightImage = loadImage('../Image/Player/Player1/Down/down.png')
    self.downLeftImage = loadImage('../Image/Player/Player1/Down/down.png', True)
    self.obliqueUpRightImages = [
        loadImage('../Image/Player/Player1/Up/rightUp1.png'),
        loadImage('../Image/Player/Player1/Up/rightUp2.png'),
        loadImage('../Image/Player/Player1/Up/rightUp3.png'),
    ]
    self.obliqueUpLeftImages = [
        loadImage('../Image/Player/Player1/Up/rightUp1.png', True),
        loadImage('../Image/Player/Player1/Up/rightUp2.png', True),
        loadImage('../Image/Player/Player1/Up/rightUp3.png', True),
    ]
    self.obliqueDownRightImages = [
        loadImage('../Image/Player/Player1/ObliqueDown/1.png'),
        loadImage('../Image/Player/Player1/ObliqueDown/2.png'),
        loadImage('../Image/Player/Player1/ObliqueDown/3.png'),
    ]
    self.obliqueDownLeftImages = [
        loadImage('../Image/Player/Player1/ObliqueDown/1.png', True),
        loadImage('../Image/Player/Player1/ObliqueDown/2.png', True),
        loadImage('../Image/Player/Player1/ObliqueDown/3.png', True),
    ]
    # 角色向右的全部图片
    self.rightImages = [
        loadImage('../Image/Player/Player1/Right/run1.png'),
        loadImage('../Image/Player/Player1/Right/run2.png'),
        loadImage('../Image/Player/Player1/Right/run3.png')
    ]
    # 角色向左的全部图片
    self.leftImages = [
        loadImage('../Image/Player/Player1/Left/run1.png'),
        loadImage('../Image/Player/Player1/Left/run2.png'),
        loadImage('../Image/Player/Player1/Left/run3.png')
    ]
    # 角色跳跃的全部图片
    self.upRightImages = [
        loadImage('../Image/Player/Player1/Jump/jump1.png'),
        loadImage('../Image/Player/Player1/Jump/jump2.png'),
        loadImage('../Image/Player/Player1/Jump/jump3.png'),
        loadImage('../Image/Player/Player1/Jump/jump4.png'),
    ]
    self.upLeftImages = [
        loadImage('../Image/Player/Player1/Jump/jump1.png', True),
        loadImage('../Image/Player/Player1/Jump/jump2.png', True),
        loadImage('../Image/Player/Player1/Jump/jump3.png', True),
        loadImage('../Image/Player/Player1/Jump/jump4.png', True),
    ]
    self.rightFireImages = [
        loadImage('../Image/Player/Player1/Right/fire1.png'),
        loadImage('../Image/Player/Player1/Right/fire2.png'),
        loadImage('../Image/Player/Player1/Right/fire3.png'),
    ]
    self.leftFireImages = [
        loadImage('../Image/Player/Player1/Right/fire1.png', True),
        loadImage('../Image/Player/Player1/Right/fire2.png', True),
        loadImage('../Image/Player/Player1/Right/fire3.png', True),
    ]

图片读取好后，我们需要设置一些索引，用来记录当前应该加载哪一张图片

举个简单的例子，人物向右行走的图片有三张，如下图

在这里插入图片描述
我们需要在人物跑动的时候，循环加载这三张图片，所以要设置一个索引，用来记录当前加载到了哪一张，如果是第三张，那么把索引再变为0，这样下次就又开始加载第一张图片了，循环下去，就可以看到人物跑动的动画了

好，那我们就来设置索引

def __init__(self, currentTime):
	...
    # 角色左右移动下标
    self.imageIndex = 0
    # 角色跳跃下标
    self.upImageIndex = 0
    # 角色斜射下标
    self.obliqueImageIndex = 0
    ...

有了下标还要考虑加载图片的间隔，这个游戏中，在前面我们已经设置了游戏的帧率，为60，就是一秒加载60张图片，如果不设置时间间隔，玩家移动的时候，加载的图片是闪的，因为太快了，看不清楚，所以要设置间隔

首先记录下上次加载的图片的时间，然后在显示玩家图片时，用当前的时间减去上次加载图片的时间，如果相差一定的间隔，那么就让索引+1，超过图片个数就把索引置为0

下面是设置上一次加载图片的时间变量

def __init__(self, currentTime):
	...
    # 上一次显示图片的时间
    self.runLastTimer = currentTime
    self.fireLastTimer = currentTime
    ...

这里要区分一下，因为玩家移动的时候也可以射击，所以移动射击的图片和移动不射击的图片要分开索引，防止混淆

之后设置一下玩家的其他属性

	# 选择当前要显示的图片
    self.image = self.standRightImage
    # 获取图片的rect
    self.rect = self.image.get_rect()
    # 设置角色的状态
    self.state = State.FALL
    # 角色的方向
    self.direction = Direction.RIGHT
    # 速度
    self.xSpeed = PLAYER_X_SPEED
    self.ySpeed = 0
    self.jumpSpeed = -11
    # 人物当前的状态标志
    self.isStanding = False
    self.isWalking = False
    self.isJumping = True
    self.isSquating = False
    self.isFiring = False
    # 重力加速度
    self.gravity = 0.7
	# 玩家上下的朝向
    self.isUp = False
    self.isDown = False

角色一开始是降落的状态，是因为开始的时候角色从天而降

# 人物当前的状态标志
self.isStanding = False
self.isWalking = False
self.isJumping = True
self.isSquating = False
self.isFiring = False

# 玩家上下的朝向
self.isUp = False
self.isDown = False

这两组属性，用来画出当前角色的图片

完整的角色类代码

import pygame
from Constants import *


class PlayerOne(pygame.sprite.Sprite):

    def __init__(self, currentTime):
        pygame.sprite.Sprite.__init__(self)
        # 加载角色图片
        self.standRightImage = loadImage('../Image/Player/Player1/Right/stand.png')
        self.standLeftImage = loadImage('../Image/Player/Player1/Left/stand.png')
        self.upRightImage = loadImage('../Image/Player/Player1/Up/upRight(small).png')
        self.upLeftImage = loadImage('../Image/Player/Player1/Up/upLeft(small).png')
        self.downRightImage = loadImage('../Image/Player/Player1/Down/down.png')
        self.downLeftImage = loadImage('../Image/Player/Player1/Down/down.png', True)
        self.obliqueUpRightImages = [
            loadImage('../Image/Player/Player1/Up/rightUp1.png'),
            loadImage('../Image/Player/Player1/Up/rightUp2.png'),
            loadImage('../Image/Player/Player1/Up/rightUp3.png'),
        ]
        self.obliqueUpLeftImages = [
            loadImage('../Image/Player/Player1/Up/rightUp1.png', True),
            loadImage('../Image/Player/Player1/Up/rightUp2.png', True),
            loadImage('../Image/Player/Player1/Up/rightUp3.png', True),
        ]
        self.obliqueDownRightImages = [
            loadImage('../Image/Player/Player1/ObliqueDown/1.png'),
            loadImage('../Image/Player/Player1/ObliqueDown/2.png'),
            loadImage('../Image/Player/Player1/ObliqueDown/3.png'),
        ]
        self.obliqueDownLeftImages = [
            loadImage('../Image/Player/Player1/ObliqueDown/1.png', True),
            loadImage('../Image/Player/Player1/ObliqueDown/2.png', True),
            loadImage('../Image/Player/Player1/ObliqueDown/3.png', True),
        ]
        # 角色向右的全部图片
        self.rightImages = [
            loadImage('../Image/Player/Player1/Right/run1.png'),
            loadImage('../Image/Player/Player1/Right/run2.png'),
            loadImage('../Image/Player/Player1/Right/run3.png')
        ]
        # 角色向左的全部图片
        self.leftImages = [
            loadImage('../Image/Player/Player1/Left/run1.png'),
            loadImage('../Image/Player/Player1/Left/run2.png'),
            loadImage('../Image/Player/Player1/Left/run3.png')
        ]
        # 角色跳跃的全部图片
        self.upRightImages = [
            loadImage('../Image/Player/Player1/Jump/jump1.png'),
            loadImage('../Image/Player/Player1/Jump/jump2.png'),
            loadImage('../Image/Player/Player1/Jump/jump3.png'),
            loadImage('../Image/Player/Player1/Jump/jump4.png'),
        ]
        self.upLeftImages = [
            loadImage('../Image/Player/Player1/Jump/jump1.png', True),
            loadImage('../Image/Player/Player1/Jump/jump2.png', True),
            loadImage('../Image/Player/Player1/Jump/jump3.png', True),
            loadImage('../Image/Player/Player1/Jump/jump4.png', True),
        ]
        self.rightFireImages = [
            loadImage('../Image/Player/Player1/Right/fire1.png'),
            loadImage('../Image/Player/Player1/Right/fire2.png'),
            loadImage('../Image/Player/Player1/Right/fire3.png'),
        ]
        self.leftFireImages = [
            loadImage('../Image/Player/Player1/Right/fire1.png', True),
            loadImage('../Image/Player/Player1/Right/fire2.png', True),
            loadImage('../Image/Player/Player1/Right/fire3.png', True),
        ]
        # 角色左右移动下标
        self.imageIndex = 0
        # 角色跳跃下标
        self.upImageIndex = 0
        # 角色斜射下标
        self.obliqueImageIndex = 0
        # 上一次显示图片的时间
        self.runLastTimer = currentTime
        self.fireLastTimer = currentTime

        # 选择当前要显示的图片
        self.image = self.standRightImage
        # 获取图片的rect
        self.rect = self.image.get_rect()
        # 设置角色的状态
        self.state = State.FALL
        # 角色的方向
        self.direction = Direction.RIGHT
        # 速度
        self.xSpeed = PLAYER_X_SPEED
        self.ySpeed = 0
        self.jumpSpeed = -11
        # 人物当前的状态标志
        self.isStanding = False
        self.isWalking = False
        self.isJumping = True
        self.isSquating = False
        self.isFiring = False
        # 重力加速度
        self.gravity = 0.7

        self.isUp = False
        self.isDown = False

    def update(self, playerBulletList, keys, currentTime):
        pass

5. 完成角色更新函数

先根据状态读取下一次操作，再更新玩家位置，再根据方向和状态标志觉得玩家显示的图片

def update(self, keys, currentTime):
    # 更新站或者走的状态
    # 根据状态响应按键
    if self.state == State.STAND:
        self.standing(keys, currentTime)
    elif self.state == State.WALK:
        self.walking(keys, currentTime)
    elif self.state == State.JUMP:
        self.jumping(keys, currentTime)
    elif self.state == State.FALL:
        self.falling(keys, currentTime)

    # 更新位置
    # 记录前一次的位置坐标
    pre = self.rect.x
    self.rect.x += self.xSpeed
    self.rect.y += self.ySpeed
    # 如果x位置小于0了，就不能移动，防止人物跑到屏幕左边
    if self.rect.x <= 0:
        self.rect.x = pre

根据状态标志设置角色图片

    # 更新动画
    # 跳跃状态
    if self.isJumping:
        # 根据方向
        if self.direction == Direction.RIGHT:
            # 方向向右，角色加载向右跳起的图片
            self.image = self.upRightImages[self.upImageIndex]
        else:
            # 否则，方向向左，角色加载向左跳起的图片
            self.image = self.upLeftImages[self.upImageIndex]

    # 角色蹲下
    if self.isSquating:
        if self.direction == Direction.RIGHT:
            # 加载向右蹲下的图片
            self.image = self.downRightImage
        else:
            # 加载向左蹲下的图片
            self.image = self.downLeftImage

    # 角色站着
    if self.isStanding:
        if self.direction == Direction.RIGHT:
            if self.isUp:
                # 加载向右朝上的图片
                self.image = self.upRightImage
            elif self.isDown:
                # 加载向右蹲下的图片
                self.image = self.downRightImage
            else:
                # 加载向右站着的图片
                self.image = self.standRightImage
        else:
            # 向左也是同样的效果
            if self.isUp:
                self.image = self.upLeftImage
            elif self.isDown:
                self.image = self.downLeftImage
            else:
                self.image = self.standLeftImage

    # 角色移动
    if self.isWalking:
        if self.direction == Direction.RIGHT:
            if self.isUp:
                # 加载斜右上的图片
                self.image = self.obliqueUpRightImages[self.obliqueImageIndex]
            elif self.isDown:
                # 加载斜右下的图片
                self.image = self.obliqueDownRightImages[self.obliqueImageIndex]
            else:
                # 加载向右移动的图片，根据开火状态是否加载向右开火移动的图片
                if self.isFiring:
                    self.image = self.rightFireImages[self.imageIndex]
                else:
                    self.image = self.rightImages[self.imageIndex]
        else:
            if self.isUp:
                self.image = self.obliqueUpLeftImages[self.obliqueImageIndex]
            elif self.isDown:
                self.image = self.obliqueDownLeftImages[self.obliqueImageIndex]
            else:
                if self.isFiring:
                    self.image = self.leftFireImages[self.imageIndex]
                else:
                    self.image = self.leftImages[self.imageIndex]

完整的update()函数

def update(self, playerBulletList, keys, currentTime):
    # 更新站或者走的状态
    # 根据状态响应按键
    if self.state == State.STAND:
        self.standing(keys, currentTime, playerBulletList)
    elif self.state == State.WALK:
        self.walking(keys, currentTime, playerBulletList)
    elif self.state == State.JUMP:
        self.jumping(keys, currentTime, playerBulletList)
    elif self.state == State.FALL:
        self.falling(keys, currentTime, playerBulletList)

    # 更新位置
    # 记录前一次的位置坐标
    pre = self.rect.x
    self.rect.x += self.xSpeed
    self.rect.y += self.ySpeed
    # 如果x位置小于0了，就不能移动，防止人物跑到屏幕左边
    if self.rect.x <= 0:
        self.rect.x = pre

    # 更新动画
    # 跳跃状态
    if self.isJumping:
        # 根据方向
        if self.direction == Direction.RIGHT:
            # 方向向右，角色加载向右跳起的图片
            self.image = self.upRightImages[self.upImageIndex]
        else:
            # 否则，方向向左，角色加载向左跳起的图片
            self.image = self.upLeftImages[self.upImageIndex]

    # 角色蹲下
    if self.isSquating:
        if self.direction == Direction.RIGHT:
            # 加载向右蹲下的图片
            self.image = self.downRightImage
        else:
            # 加载向左蹲下的图片
            self.image = self.downLeftImage

    # 角色站着
    if self.isStanding:
        if self.direction == Direction.RIGHT:
            if self.isUp:
                # 加载向右朝上的图片
                self.image = self.upRightImage
            elif self.isDown:
                # 加载向右蹲下的图片
                self.image = self.downRightImage
            else:
                # 加载向右站着的图片
                self.image = self.standRightImage
        else:
            # 向左也是同样的效果
            if self.isUp:
                self.image = self.upLeftImage
            elif self.isDown:
                self.image = self.downLeftImage
            else:
                self.image = self.standLeftImage

    # 角色移动
    if self.isWalking:
        if self.direction == Direction.RIGHT:
            if self.isUp:
                # 加载斜右上的图片
                self.image = self.obliqueUpRightImages[self.obliqueImageIndex]
            elif self.isDown:
                # 加载斜右下的图片
                self.image = self.obliqueDownRightImages[self.obliqueImageIndex]
            else:
                # 加载向右移动的图片，根据开火状态是否加载向右开火移动的图片
                if self.isFiring:
                    self.image = self.rightFireImages[self.imageIndex]
                else:
                    self.image = self.rightImages[self.imageIndex]
        else:
            if self.isUp:
                self.image = self.obliqueUpLeftImages[self.obliqueImageIndex]
            elif self.isDown:
                self.image = self.obliqueDownLeftImages[self.obliqueImageIndex]
            else:
                if self.isFiring:
                    self.image = self.leftFireImages[self.imageIndex]
                else:
                    self.image = self.leftImages[self.imageIndex]

之后就是对四个状态函数进行完善啦