tkinter e Adafruit IO为什么循环不工作？

Question

我最近一直在使用python……我不明白为什么while循环阻止了tkinter窗口的创建。

如果我将while循环移到move循环之前，我会显示tkinter窗口，但循环会停止。

import tkinter as tk
import time
from Adafruit_IO import Client, Feed, RequestError

ADAFRUIT_IO_USERNAME = "***********"
ADAFRUIT_IO_KEY = "**********************"
aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
loop_delay = 5
temp = 25

try:
    temperature = aio.feeds('temperature')
except RequestError: 
    feed = Feed(name="temperature")
    temperature = aio.create_feed(feed)
    
def sendtemp(temp):  
    aio.send_data(temperature.key,temp) 
    data = aio.receive(temperature.key)
    print(data.value)
    
window = tk.Tk()
window.title ("Thermometer")
window.geometry("300x100")
label = tk.Label(window, text = temp)
label.pack()

window.mainloop 

while True:
    sendtemp(temp)
    time.sleep(loop_delay)

Answer 1

我是这样解决的，你觉得呢？

import tkinter as tk

from Adafruit_IO import Client, Feed, RequestError

ADAFRUIT_IO_USERNAME = "**********"
ADAFRUIT_IO_KEY = "***************"

aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)

try:
    temperature = aio.feeds('temperature')
except RequestError: 
    feed = Feed(name="temperature")
    temperature = aio.create_feed(feed)
    
class Timer:
    
     def __init__(self, parent):
         self.temp = 25
         self.label = tk.Label(text="--,- °C", font="Arial 30", width=10)
         self.label.pack()
         self.label.after(5000, self.sendtemp)

     def sendtemp(self):
         aio.send_data(temperature.key,self.temp) 
         data = aio.receive(temperature.key)
         print(data.value)
         self.label.configure(text="%i°C" % self.temp)
         self.temp +=1
         self.label.after(5000, self.sendtemp)       

if __name__ == "__main__":
     window = tk.Tk()
     window.title ("Thermometer")
     window.geometry("300x100")
     timer = Timer(window)
     window.mainloop()

Answer 2

你的while循环阻塞了程序。从字面上看，它除了调用sendtemp并休眠之外什么也不做。

while True:
    sendtemp(temp)
    time.sleep(loop_delay)

在TK窗口上没有响应事件的空间，Python正忙于做这两件事。

要定期执行操作，您需要设置一个计时器，该计时器在TK的主事件循环(使用.mainloop()启动的循环)上运行。这是通过the .after() method完成的。

这个方法需要一个毫秒的延迟和一个你想要调用的函数。

window = tk.Tk()
window.title ("Thermometer")
window.geometry("300x100")
timer_id = None
timer_delay = 5000

def sendtemp(temp):  
    aio.send_data(temperature.key,temp) 
    data = aio.receive(temperature.key)
    print(data.value)
    if timer_id is not None:
        start_timer()

def start_timer():
    global timer_id
    timer_id = window.after(timer_delay, sendtemp)

def stop_timer():
    global timer_id
    if timer_id is not None:
        window.after_cancel(timer_id)
        timer_id = None

start_timer()
window.mainloop()

您可以将停止和启动计时器绑定到一个按钮上。