当我按下一个键时，pygame内部发生了什么？何时使用pygame.event == KEYDOWN

Question

我一直在尝试使用python编写小型2D游戏的代码。

checkp_list[0]=head_pos

pressed_key= pygame.key.get_pressed()

if pressed_key[pygame.K_ESCAPE]:
    running=False

if pressed_key[pygame.K_UP]:
    if dir_ not in ["up", "down"]:
        dir_= "up"
        checkp_no= checkp_no+1
        #head_pos_next=head_move(head_pos, dir_)
        checkp_list.insert(checkp_no,head_pos)
        log_file_obj.write("chekp_list {}, checkp_no {} after append dir {}\n".format(checkp_list,checkp_no,dir_))

if pressed_key[pygame.K_DOWN]:
    if dir_ not in ["up", "down"]:
        dir_= "down"
        checkp_no= checkp_no+1
        #head_pos_next = head_move(head_pos, dir_)
        checkp_list.insert(checkp_no,head_pos)
        log_file_obj.write("chekp_list {}, checkp_no {} after append dir {}\n".format(checkp_list,checkp_no,dir_))


if pressed_key[pygame.K_RIGHT]:
    if dir_ not in ["left", "right"]:
        dir_= "right"
        checkp_no= checkp_no+1
        #head_pos_next = head_move(head_pos, dir_)
        checkp_list.insert(checkp_no,head_pos)
        log_file_obj.write("chekp_list {}, checkp_no {} after append dir {}\n".format(checkp_list,checkp_no,dir_))

if pressed_key[pygame.K_LEFT]:
    if dir_ not in ["left", "right"]:
        dir_= "left"
        checkp_no= checkp_no+1
        #head_pos_next = head_move(head_pos, dir_)
        checkp_list.insert(checkp_no,head_pos)
        log_file_obj.write("chekp_list {}, checkp_no {} after append dir {}\n".format(checkp_list,checkp_no,dir_))

所有这些都在while True:循环内运行。基本上，每按一次箭头键，方向指示器dir_就会更改，它将在检查点编号上加1checkp_no并将当前head_pos对象的当前头部位置（在checkp_no索引位置插入该头部对象。）但是，不幸的是，所有这些checkp_list点都是最新的head_pos。该列表checkp_list是实现我的逻辑的重要因素。

chekp_list在start时[[325, 791], [325, 791], [325, 791]]，这是checkp_listwhencheckp_no是2，whenwhile循环正在开始另一个迭代（取自创建的日志文件）。所有checkp_list要附加的点都在上面。请帮助我确定问题。

Answer 1

pygame.key.get_pressed()返回包含键当前状态的列表。按住某个键时，该键的状态为True，否则为False。使用pygame.key.get_pressed()评估是否一个键被连续按下。

while True:

    pressed_key= pygame.key.get_pressed()
    if pressed_key[pygame.K_UP]:
        # the code in this condition is executed as long UP is hold down 
        # [...]

当键的状态更改时，键盘事件（请参阅pygame.event模块）仅发生一次。KEYDOWN每次按下一个键，事件就会发生一次。KEYUP每次释放钥匙时发生一次。

while True:

    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                # The following code is executed once, every time when ESC is pressed.
                # [...]

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_ESCAPE:
                # The following code is executed once, every time when ESC is released.
                # [...]