Question

我试图在玩家按下任意键后删除标签。但是，Python Shell显示错误消息。我该如何解决？

我尝试过label.destroy()，但是由于我已经有一个调用此函数的标签，因此label.destroy()函数不起作用。

from tkinter import *

root = Tk()

def testing(event):
    print("You have pressed a key.")
    root.unbind_all('<Key>')
    label.destroy() # There are two of these.


def countdown(count, label):
    label['text'] = count
    if count > -1:
        root.after(1000, countdown, count-1, label)
    elif count == 0:
        label['text'] = 'Time \nExpired'
    elif count < 0:
        label.destroy() # The second "label.destroy()"

# any_key = root.create_text(250, 400, anchor=CENTER, font=('Calibri', 20), text='Press any key to start.')
# I commented the previous line out because that was my previous code.

any_key = Label(root, anchor=CENTER, font=('Calibri', 20), text='Press any key to start.')
any_key.place(250, 400) # Error 2

root.bind('<Key>', testing)
label = Label(root, anchor=CENTER, font=('Calibri', 48))
label.place(x=50, y=100)
countdown(10, label)

root.bind_all('<Key>', testing)

root.pack()
root.mainloop()

我希望该程序可以删除名为any_key的标签，但是在按下键之前它甚至没有显示出来。此外，即使我只给出了两个用于放置TypeError: place_configure() takes from 1 to 2 positional arguments but 3 were given标签的参数，Tkinter也会显示一个显示any_key的错误。如果您注释掉any_key.place()，则会显示另一个错误，正在读取。 Tkinter回调中的异常

Traceback (most recent call last):
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1705, in __call__
    return self.func(*args)
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 749, in callit
    func(*args)
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\Programs\Tests\test 8.py", line 22, in countdown
    label['text'] = count
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1492, in __setitem__
    self.configure({key: value})
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1485, in configure
    return self._configure('configure', cnf, kw)
  File "C:\Users\kevin\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1476, in _configure
    self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
_tkinter.TclError: invalid command name ".!canvas.!label2"

如何解决这些错误？

Answer 1

经过我在注释中描述的更改，我得到了工作代码

place需要名称为place(x=..., y=...)的参数

root.pack()不起作用-root没有方法pack()。您不能将窗口root放在窗口root内。

我还使用count > 0代替了count > -1，现在它可以检查count == 0

from tkinter import *

def testing(event):
    print("You have pressed a key.")
    root.unbind_all('<Key>')
    label.destroy() # There are two of these.

def countdown(count, label):
    label['text'] = count
    if count > 0: # not -1
        root.after(1000, countdown, count-1, label)
    elif count == 0:
        label['text'] = 'Time \nExpired'
        # to destroy after 1s
        root.after(1000, countdown, count-1, label)
    elif count < 0:
        label.destroy() # The second "label.destroy()"

root = Tk()

any_key = Label(root, anchor=CENTER, font=('Calibri', 20), text='Press any key to start.')
any_key.place(x=250, y=400) # need x=, y=

label = Label(root, anchor=CENTER, font=('Calibri', 48))
label.place(x=50, y=100)
countdown(10, label)

root.bind_all('<Key>', testing)
#root.pack() # you try to put window `root` inside window `root`

root.mainloop()

因为您可以在testing()结束倒计时之前销毁标签，所以最好通知countdown该小部件不存在。我将为此使用label = None

def testing(event):
    global label

    print("You have pressed a key.")

    root.unbind_all('<Key>')

    if label is not None:
         label.destroy() # There are two of these.
         label = None


def countdown(count, label):
    global label

    if label is not None:
        label['text'] = count
        if count > 0: # not -1
            root.after(1000, countdown, count-1, label)
        elif count == 0:
            label['text'] = 'Time \nExpired'
            # to destroy after 1s
            root.after(1000, countdown, count-1, label)
        elif count < 0:
            label.destroy() # The second "label.destroy()"
            label = None

Answer 2

要解决错误2，您应该执行以下操作：

any_key.place(x=250, y=400) # SOLVE ERROR

我对此也有一个错误：“ root.pack（）”，因为应该是“ label.pack（）”

进行两次销毁，因为有两行“ root.bind（''，测试）”和“ root.bind_all（”，测试）”仅保留其中一个。

控制台中发生错误是因为“测试”和“倒数”这两种方法是异步的，因此倒数在测试之前开始，并在销毁之后尝试在标签上做一些事情。因此，您需要同步此方法并共享标签的状态（也使用label == null）

from tkinter import *
import threading
import functools

root = Tk()
state = True

def synchronized(wrapped):
    lock = threading.Lock()
    @functools.wraps(wrapped)
    def _wrap(*args, **kwargs):
        print("Calling '%s' with Lock %s" % (wrapped.__name__, id(lock)))
        with lock:
            return wrapped(*args, **kwargs)
    return _wrap

@synchronized
def testing(event):
    global state
    print(event)
    print("You have pressed a key.")
    root.unbind_all('<Key>')
    state = False
    label.destroy() # There are two of these.

@synchronized
def countdown(count, label):
    global state
    print(count)
    print(state)
    if state: 
        label['text'] = count
        if count > 0:
            root.after(1000, countdown, count-1, label)
        elif count == 0:
            label['text'] = 'Time \nExpired'
        elif count < 0:
            label.destroy() # The second "label.destroy()"

# any_key = root.create_text(250, 400, anchor=CENTER, font=('Calibri', 20), text='Press any key to start.')
# I commented the previous line out because that was my previous code.

any_key = Label(root, anchor=CENTER, font=('Calibri', 20), text='Press any key to start.')
any_key.place(x=250, y=400) # SOLVE ERROR

root.bind('<Key>', testing)
label = Label(root, anchor=CENTER, font=('Calibri', 48))
label.place(x=50, y=100)
countdown(10, label)



label.pack() # SOLVE ERROR
root.mainloop()

按键后如何删除标签

2 个答案: