当我按下一个键时，pygame内部发生了什么?何时使用pygame.event == KEYDOWN [英] What all things happens inside pygame when I press a key? When to use pygame.event==KEYDOWN

问题描述

我一直在尝试使用python编写一个小型2D游戏.

I have been trying to code a small 2D game using python.

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True:循环的中运行.基本上，每当按下箭头键时，方向指示器dir_都会更改，它将在检查点编号 checkp_no 上加1，然后在<中插入head对象的当前头部位置( head_pos code> checkp_no 索引位置.但是不幸的是，所有 checkp_list 点中的所有内容都是最新的 head_pos .列表 checkp_list 是实现我的逻辑的重要因素.

All this is running inside a while True: loop. Basically, whenever an arrow key is pressed, direction indicator dir_ changes and it'll add 1 to checkpoint number checkp_no and insert current head position(head_pos of the head object in checkp_no index position. But unfortunately, all in the checkp_list points turns out to be the latest head_pos. The list checkp_list is an important factor to implement my logic.

chekp_list ，同时启动 [[325，791]，[325，791]，[325，791]] ，这是当 checkp_no 为2且 while 循环开始另一个迭代(取自创建的日志文件)时的 checkp_list .上面附有 checkp_list 的所有要点.请帮助我确定问题所在.

chekp_list while start [[325, 791], [325, 791], [325, 791]], this is the checkp_list when checkp_no is 2 and when while loop is starting another iteration (taken from log file created). All the points where checkp_list is getting appended are above. Please help me to identify the issue.

推荐答案

pygame.key.get_pressed() returns a list with the current states of a key. When a key is hold down, the state for the key is True, else it is False. Use pygame.key.get_pressed() to evaluate if a key is continuously pressed.

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 
        # [...]

键盘事件(请参阅 pygame.event 模块)仅发生一次当键的状态改变时.每次按下一个键，都会发生一次 KEYDOWN 事件. KEYUP 会在每次释放键时发生一次.

The keyboard events (see pygame.event module) occur only once when the state of a key changes. The KEYDOWN event occurs once every time a key is pressed. KEYUP occurs once every time a key is released.

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.
                # [...]

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