Tkinter条目小部件:如果在一段时间内没有键入任何内容，如何不断检查活动并删除字段

Question

试着写一个小程序，你输入一个Tkinter Entry小部件，如果你不输入5秒，它会删除所有东西。我能做的最好的事情就是让它在五秒钟后删除第一个按键上的所有内容，但我不知道如果没有额外的按键，如何让它做到这一点。

import time
from tkinter import *

def click(key):
global click_before_last_click, last_click
# print(key.char)
click_before_last_click = last_click
last_click = time.time()
# print(click_before_last_click)
# print(last_click)
delete_shit()

def disappearing_text_start():
global click_before_last_click, last_click
click_before_last_click = time.time()
last_click = time.time()
entry.delete(1.0, END)
entry.bind("<Key>", click)

def disappearing_text_end():
text_file = open("result.txt", "w")
text_file.write(entry.get(1.0, END))
text_file.close()
entry.delete(1.0, END)

def delete_shit():
if last_click > click_before_last_click + 5:
print("TOO LONG")
entry.delete(1.0, END)

if __name__ == "__main__":
click_before_last_click = time.time()
last_click = time.time()
window = Tk()
window.title("Disappearing Text")
window.config(padx=50, pady=20, bg="#D3D3D3")
title_label = Label(text="Disappearing Text App", fg="black", bg="#D3D3D3", font=("Courier", 24))
title_label.grid(column=1, row=0, columnspan=2)
label = Label(text="Click start to begin, and end to save your text.  "
"If you stop typing for 5 seconds, you lose everything.",
bg="#D3D3D3", font=("Courier", 14))
label.grid(column=1, row=1, columnspan=2)
entry = Text(width=100, height=30)
entry.grid(column=1, columnspan=2, row=3)
start_button = Button(text="Start", command=disappearing_text_start)
start_button.grid(column=1, row=4, pady=20)
end_button = Button(text="Save", command=disappearing_text_end)
end_button.grid(column=2, row=4, pady=20)
window.mainloop()

Answer 1

可以使用after删除时间间隔后的字符。每次用户按下一个键，删除旧的预定功能，然后重新安排。

另外，顺便说一句，您使用了无效的1.0索引。Tkinter将接受它，但是索引是字符串而不是浮点数。

让我们从编写一个函数开始，该函数将安排在5秒内删除文本。它还将取消任何挂起的作业，有效地将计时器重置为零。它需要接受一个event参数，因为它将从键绑定调用。

after_id = None
def schedule_delete(event=None):
global after_id
if after_id:
window.after_cancel(after_id)
after_id = window.after(5000, delete_shit)

接下来，安排它在用户单击"开始"时被调用按钮。disappearing_text_start可能看起来像这样:

def disappearing_text_start():
schedule_delete()
entry.delete("1.0", END)

你可以在你的程序主体中调用这个bind命令一次，让reschedule_delete在每次按下键时都被调用:

entry.bind("<Any-KeyPress>", reschedule_delete)

最后，我们需要在用户点击"停止"按钮时取消所有挂起的作业。按钮:

def disappearing_text_end():
global after_id
if after_id:
window.after_cancel(after_id)
after_id = None
... the rest of your code here ...

---

下面是一个完整的工作示例:

from tkinter import *

def click(key):
schedule_delete()
def disappearing_text_start():
schedule_delete()
entry.delete("1.0", END)
def schedule_delete(event=None):
global after_id
if after_id:
window.after_cancel(after_id)
after_id = window.after(5000, delete_shit)
def disappearing_text_end():
global after_id
if after_id:
window.after_cancel(after_id)
after_id = None
text_file = open("result.txt", "w")
text_file.write(entry.get(1.0, END))
text_file.close()
entry.delete("1.0", END)
def delete_shit():
entry.delete("1.0", END)

if __name__ == "__main__":
# this is used to keep track of the scheduled function call
after_id = None
window = Tk()
window.title("Disappearing Text")
window.config(padx=50, pady=20, bg="#D3D3D3")
title_label = Label(text="Disappearing Text App", fg="black", bg="#D3D3D3", font=("Courier", 24))
title_label.grid(column=1, row=0, columnspan=2)
label = Label(text="Click start to begin, and end to save your text.  "
"If you stop typing for 5 seconds, you lose everything.",
bg="#D3D3D3", font=("Courier", 14))
label.grid(column=1, row=1, columnspan=2)
entry = Text(width=100, height=30)
entry.grid(column=1, columnspan=2, row=3)
start_button = Button(text="Start", command=disappearing_text_start)
start_button.grid(column=1, row=4, pady=20)
end_button = Button(text="Save", command=disappearing_text_end)
end_button.grid(column=2, row=4, pady=20)
entry.bind("<Any-KeyPress>", schedule_delete)
window.mainloop()