Python基础：第017课——鼠标拖动小球移动(1)

视频

观看视频

完善上次课代码

import pygame, sys

pygame.init()

screen_width , screen_height = 600,480
screen = pygame.display.set_mode((screen_width,screen_height))

pygame.display.set_caption("小小工坊")

ball = pygame.image.load('pygame/images/ball.gif')
ball_rect = ball.get_rect()

fclock = pygame.time.Clock()

speed = [1,1]
orientation = [1,1]

still = False
while True:

    for e in pygame.event.get():
        if e.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        elif e.type == pygame.KEYDOWN:
            if e.key == pygame.K_UP:
                speed[1] = speed[1] - 1 if speed[1] > 0 else 0
            elif e.key == pygame.K_DOWN:
                speed[1] = speed[1] + 1
            elif e.key == pygame.K_RIGHT:
                speed[0] = speed[0] + 1
            elif e.key == pygame.K_LEFT:
                speed[0] = speed[0] - 1 if speed[0] >0 else 0
    
    if ball_rect.bottom >= screen_height or ball_rect.top < 0:
        orientation[1] = -orientation[1]
    if ball_rect.right >= screen_width or ball_rect.left < 0:
        orientation[0] = -orientation[0]

    ball_rect = ball_rect.move(speed[0]*orientation[0],speed[1]*orientation[1])

    # if ball_rect.bottom >= screen_height:
    #     speed[1] = -1
    #     # ball_rect.bottom = screen_height
    # if ball_rect.top <= 0:
    #     speed[1] = 1
    #     # ball_rect.top = 0
    # if ball_rect.right >= screen_width:
    #     speed[0] = -1
    #     # ball_rect.right = screen_width
    # if ball_rect.left <= 0:
    #     speed[0] = 1
    #     # ball_rect.left = 0

    screen.fill((0,0,255))
    screen.blit(ball,ball_rect)

    pygame.display.update()
    fclock.tick(200)

处理鼠标事件

事件完整解析

鼠标是计算机最重要外接设备之一，同时它也是游戏玩家必不可少的工具之一。

Pygame 提供了三个鼠标事件，分别是鼠标移动
（MOUSEMOTION）、鼠标按下（MOUSEBUTTONDOWN）、鼠标释放（MOUSEBUTTONUP），不同事件类型对应着不同的成员属性。如下所示：

pygame.event.MOUSEMOTION鼠标移动事件

• event.pos 相对于窗口左上角，鼠标的当前坐标值(x,y)
• event.rel 鼠标相对运动距离(x,y)，相对于上次事件
• event.buttons 鼠标按钮初始状态(0,0,0)，分别对应(左键,滑轮,右键)，移动过程中点击那个键，相应位置变会为1

pygame.event.MOUSEBUTTONUP鼠标键释放事件

• event.pos 相对于窗口左上角，鼠标的当前坐标值(x,y)
• event.button 鼠标释放键编号（整数）左键为1，按下滚动轮2、右键为3

pygame.event.MOUSEBUTTONDOWN 鼠标键按下事件

• event.pos 相对于窗口左上角，鼠标的当前坐标值(x,y)
• event.button 鼠标按下键编号（整数），左键为1，按下滚动轮2、右键为3，向前滚动滑轮4、向后滚动滑轮5

通过一组简单的示例对鼠标事件进行演示，示例代码如下：

import pygame
from random import randint
# 初始化程序
pygame.init()
screen = pygame.display.set_mode((450,400))
pygame.display.set_caption("鼠标拖拽演示")
# 更新显示

pygame.display.flip()
while True:
    #等待事件发生
    event = pygame.event.wait()
    if event.type == pygame.QUIT:
        exit("成功退出")
    if event.type == pygame.MOUSEBUTTONDOWN:
        # pos 获取鼠标当前位置
        print('鼠标按下',event.pos)
        mx,my = event.pos
        # 调用 pygame.draw 模块画圆
        pygame.draw.circle(screen,(255,255,0),(mx,my),50)

    if event.type == pygame.MOUSEBUTTONUP:
        print('鼠标弹起')
        pass
    if event.type == pygame.MOUSEMOTION:
        print('鼠标移动')
        mx, my = event.pos
        # 随机生成 RGB 颜色值
        r = randint(0,255)
        g = randint(0,255)
        b = randint(0,255)
        pygame.draw.circle(screen, (r,g,b,),(mx, my), 50)
        
	# 处理完，更新显示
	pygame.display.update()

用鼠标拖动小球移动

如何让小球移动

边界处理

关键是：

1. 水平方向，只要小球超过右边的边界，就需要保证让小球向左运动，即运动方向向左。
2. 纵向，只要小球超出下边界，就需要保证小球向上运动，即运动方向向上。

本次课代码

import pygame, sys

pygame.init()

screen_width , screen_height = 600,480
screen = pygame.display.set_mode((screen_width,screen_height))

pygame.display.set_caption("小小工坊")

ball = pygame.image.load('pygame/images/ball.gif')
ball_rect = ball.get_rect()

fclock = pygame.time.Clock()

speed = [1,1]
orientation = [1,1]

still = False
while True:

    for e in pygame.event.get():
        if e.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        elif e.type == pygame.KEYDOWN:
            if e.key == pygame.K_UP:
                speed[1] = speed[1] - 1 if speed[1] > 0 else 0
            elif e.key == pygame.K_DOWN:
                speed[1] = speed[1] + 1
            elif e.key == pygame.K_RIGHT:
                speed[0] = speed[0] + 1
            elif e.key == pygame.K_LEFT:
                speed[0] = speed[0] - 1 if speed[0] >0 else 0
        elif e.type == pygame.MOUSEBUTTONDOWN:
            if e.button == 1:
                still = True
        elif e.type == pygame.MOUSEBUTTONUP:
            still = False
            ball_rect.left,ball_rect.top = e.pos
        elif e.type == pygame.MOUSEMOTION:
            if e.buttons[0] == 1:
                ball_rect.left, ball_rect.top = e.pos
    
    if ball_rect.bottom >= screen_height or ball_rect.top < 0:
        orientation[1] = -orientation[1]
    if ball_rect.right >= screen_width or ball_rect.left < 0:
        orientation[0] = -orientation[0]
    if not still:
        ball_rect = ball_rect.move(speed[0]*orientation[0],speed[1]*orientation[1])

    # if ball_rect.bottom >= screen_height:
    #     speed[1] = -1
    #     # ball_rect.bottom = screen_height
    # if ball_rect.top <= 0:
    #     speed[1] = 1
    #     # ball_rect.top = 0
    # if ball_rect.right >= screen_width:
    #     speed[0] = -1
    #     # ball_rect.right = screen_width
    # if ball_rect.left <= 0:
    #     speed[0] = 1
    #     # ball_rect.left = 0

    screen.fill((0,0,255))
    screen.blit(ball,ball_rect)

    pygame.display.update()
    fclock.tick(200)