前面的知識和案例中我們也用了一下鍵盤，那時候是用了pygame.event.get()獲取所有的事件，當(dāng)event.type == KEYDOWN的時候，再判斷event.key的種類。今天我們再介紹一個方法，pygame.key.get_pressed()來獲得所有按下的鍵值，它會返回一個元組。這個元組的索引就是鍵值，對應(yīng)的就是是否按下，比如說：

當(dāng)我們按下右鍵時，得到的 get_pressed 元組列表如下（注意有一個1）：

(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)

pygame.K_RIGHT 是一個常量, 值是275.

key_pressed[pygame.K_RIGHT] 實質(zhì)上就是key_pressed[275]==1代表右鍵被按下

當(dāng)然key模塊下還有很多函數(shù)：

key.get_focused —— 返回當(dāng)前的pygame窗口是否激活

key.get_pressed —— 剛剛解釋過了

key.get_mods —— 按下的組合鍵（Alt, Ctrl, Shift）

key.set_mods —— 你也可以模擬按下組合鍵的效果（KMOD_ALT, KMOD_CTRL, KMOD_SHIFT）

key.set_repeat —— 無參數(shù)調(diào)用設(shè)置pygame不產(chǎn)生重復(fù)按鍵事件，二參數(shù)(delay, interval)調(diào)用設(shè)置重復(fù)事件發(fā)生的時間

key.name —— 接受鍵值返回鍵名

使用鍵盤控制方向

根據(jù)坐標(biāo)變化規(guī)律，通過這張圖幫助理解鍵盤如何控制方向：

我們使用key.get_pressed()修改之前的程序：

background_image_filename = './img/Underwater.png'
sprite_image_filename = './img/fish-b.png'

import pygame
from pygame.locals import *
from sys import exit
from Vec2d import *
 
pygame.init()
 
screen = pygame.display.set_mode((640, 480), 0, 32)
 
background = pygame.image.load(background_image_filename).convert()
sprite = pygame.image.load(sprite_image_filename).convert_alpha()
 
clock = pygame.time.Clock()
sprite_pos = Vec2d(200, 150)
sprite_speed = 300.
 
while True:
 
    for event in pygame.event.get():
        if event.type == QUIT:
            exit()
 
    pressed_keys = pygame.key.get_pressed()

    key_direction = Vec2d(0, 0)
    if pressed_keys[K_LEFT]:
        print(pressed_keys)
        key_direction.x = -1
    elif pressed_keys[K_RIGHT]:
        key_direction.x = +1
    if pressed_keys[K_UP]:
        key_direction.y = -1
    elif pressed_keys[K_DOWN]:
        key_direction.y = +1

    key_direction.normalized()

    screen.blit(background, (0,0))
    screen.blit(sprite, sprite_pos)

    time_passed = clock.tick(30)
    time_passed_seconds = time_passed / 1000.0

    sprite_pos+= key_direction * sprite_speed * time_passed_seconds

    pygame.display.update()

如果你不知道Vec2d是什么，傳送門-->pygame游戲編程入門-向量類的使用

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