运行时 Tkinter window 为空白

Question

当我运行使用 Adafruit 测量温度的 tkinter 代码时。当我运行我的代码 tkinter 打开一个 window 但 window 上什么也没有出现。我以前用过 tkinter，我已经看到了应该出现的东西，但没有出现在这个特定的代码中。

#!/usr/bin/python
# -*- coding: latin-1 -*-

import Adafruit_DHT as dht
import time
from Tkinter import *

root = Tk()
k= StringVar()
num = 1
thelabel = Label(root, textvariable=k)
thelabel.pack

def READ():
    h,t = dht.read_retry(dht.DHT22, 4)
    newtext = "Temp=%s*C Humidity=%s" %(t,h)
    k.set(str(newtext))
    print newtext #I added this line to make sure that newtext actually had the values I wanted

def read30seconds():
    READ()
    root.after(30000, read30seconds)

read30seconds()
root.mainloop()

并澄清 READ 中的打印行按预期运行每 30 秒。

Answer 1

因为你没有打包在window中，而是打印在python中shell。

您应该将 print newtext 替换为：

w = Label(root, text=newtext)
w.pack()

工作代码应如下所示：

#!/usr/bin/python
# -*- coding: latin-1 -*-

import Adafruit_DHT as dht
import time
from Tkinter import *

root = Tk()
k= StringVar()
num = 1
thelabel = Label(root, textvariable=k)
thelabel.pack

def READ():
    h,t = dht.read_retry(dht.DHT22, 4)
    newtext = "Temp=%s*C Humidity=%s" %(t,h)
    k.set(str(newtext))
    w = Label(root, text=newtext)
    w.pack() 


def read30seconds():
    READ()
    root.after(30000, read30seconds)

read30seconds()
root.mainloop()

请注意，从图形上讲，这是一个非常基本的代码。要了解有关此主题的更多信息，请访问此 tkinter label tutorial 要了解有关 tkinter 本身的更多信息，请访问此 introduction to tkinter

如果你想让标签每次刷新都被覆盖，你应该使用destroy()方法删除然后替换标签，如下所示：

#!/usr/bin/python
# -*- coding: latin-1 -*-

import Adafruit_DHT as dht
import time
from Tkinter import *

root = Tk()
k= StringVar()
num = 1
thelabel = Label(root, textvariable=k)
thelabel.pack

def READ():
    global w
    h,t = dht.read_retry(dht.DHT22, 4)
    newtext = "Temp=%s*C Humidity=%s" %(t,h)
    k.set(str(newtext))
    print newtext #I added this line to make sure that newtext actually had the values I wanted

def read30seconds():
    READ()
    try: w.destroy()
    except: pass
    root.after(30000, read30seconds)

read30seconds()
root.mainloop()

运行时 Tkinter window 为空白

Tkinter window is blank when running

python

refresh

tkinter

raspberry-pi

adafruit

运行 时 Tkinter window 为空白

Tkinter window is blank when running

python

refresh

tkinter

raspberry-pi

adafruit

运行时 Tkinter window 为空白