Question

我试图制作一个可以暂停和恢复循环的按钮。

在代码中：

for index in range(10):
    print index
    // Runs until here, and pause
    // Button pressed
    print index + 10
    // Runs until here, and pause
    // Button pressed

在终端：

0
// Button pressed
10
// Button pressed
1
// Button pressed
11
...
9
// Button pressed
19
// Button pressed

有没有办法可以暂停并使用按钮恢复循环？

Answer 1

您可以通过在每次点击按钮时调用next()来使用生成器。

一个小例子：

import tkinter as tk

def plusten(x):
    i = 0
    while i<x:
        yield i
        yield i+10
        i += 1

def next_item():
    if gen:
        try:
            lbl["text"] = next(gen) #calls the next item of generator
        except StopIteration:
            lbl["text"] = "End of iteration" #if generator is exhausted, write an error
    else:
        lbl["text"] = "start loop by entering a number and pressing start loop button"

def start_gen():
    global gen
    try:
        gen = plusten(int(ent.get()))
        lbl["text"] = "loop started with value: " + ent.get()
    except ValueError:
        lbl["text"] = "Enter a valid value"

gen = None

root = tk.Tk()

ent = tk.Entry()
ent.pack()
tk.Button(root, text="start loop", command=start_gen).pack()

tk.Button(root, text="next item", command=next_item).pack()
lbl = tk.Label(root, text="")
lbl.pack()

root.mainloop()

Answer 2

''' 在代码中导入以下内容从tkinter导入* 导入时间

以下程序使用两个按钮创建一个tkinter窗口（暂停和退出），同时打印数字序列从1到numb（numb = 20，此处用于说明），且可控两次打印之间的时间延迟（此处为2秒）。按下暂停按钮停止打印，将按钮文本更改为“继续”。片刻后，如果按下“继续”按钮，则继续打印。要退出打印，请按退出按钮。在图中，打印数字是象征性的。也可能是显示具有时间延迟的图像。当需要查看更详细的图像，显示该图像时可以暂停显示并在需要查看剩余图像时恢复。 ''' 从tkinter导入* 导入时间

global move,stop 
move = 1 #this a variable which can take a value 1 or 0
stop='Initial-Value'  #This is a variable to control the for and while loops.
                      #Assignment of string as variable is optional. It could be
                      #integer as well

def switch():        #controls back and forth switching between Pause and Resume
    global move 
    move = not move

def come_out():      # controls the process to be running or quit
    global stop
    stop='stop'

numb=20
root = Tk()
Pause_Button=Button(root,bg='wheat',command=switch)
Pause_Button.place(relwidth=0.25,relx=0.2,rely=0.2)
Quit_Button=Button(root,bg='lightblue',text='Quit',command=come_out)
Quit_Button.place(relwidth=0.25,relx=0.5,rely=0.2)
time.sleep(2)
for s in range(numb):
    if stop=='stop':
        break
    stop='continue_while_loop'     
    while s<numb and stop=='continue_while_loop':
        stop='enter_for_loop_again'
        Pause_Button.update()
        if move==1:
            Pause_Button["text"]='Pause'
            print('s2=',s,'\n')
            time.sleep(2)
        else:
            stop='continue_while_loop'
            Pause_Button["text"]='Resume'
        Quit_Button.update()
root.mainloop()

Python暂停/恢复按钮

2 个答案: