"Python主循環內的While循環導致延遲"

Question

当我运行包含在root.mainloop()中的while True:循环的代码时，这会使我的GUI严重滞后，代码的运行也不如我希望的那么顺利。我想知道我如何使我的代码运行平稳，没有滞后。在

为了这个测试的目的，我已经注释掉了大部分代码，这些代码只有在连接到我的raspberry pi时才起作用。在

提前谢谢你的帮助。在

import os
import glob
import time
#import RPi.GPIO as GPIO
from datetime import datetime
from tkinter import *

'''
#Set gpio's
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(17,GPIO.OUT)#RED
GPIO.setup(22,GPIO.OUT)#GREEN
GPIO.setup(27,GPIO.OUT)#BLUE


#grab temp probe information
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'


# Read temperature from device

def read_temp_raw():
    f = open(device_file, 'r')
    lines = f.readlines()
    f.close()
    return lines

def read_temp():
    lines=read_temp_raw()
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.1)
        lines = read_temp_raw()
    equals_pos = lines[1].find('t=')
    if equals_pos != -1:
        temp_string = lines[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000
        #temp_f = temp_c * 9.0 / 5.0 + 32.0
        return temp_c#, temp_f

'''
temp = 18
desiredtemp = 17
deg = u'\xb0'#utf code for degree

#increase button press
def increase():
    global desiredtemp
    desiredtemp += 0.5
    tmpstr.set("%s" % desiredtemp)


#Decrease button press
def decrease():
    global desiredtemp
    desiredtemp -= 0.5
    tmpstr.set("%s" % desiredtemp)




#Tkinter start 
root = Tk()
root.wm_title("Temp") #Name the title bar

#code to add widgets will go here....

#make 3 frames for text and buttons
topFrame = Frame(root)
topFrame.pack(side=TOP)

middleFrame = Frame(root)
middleFrame.pack()

bottomFrame = Frame(root)
bottomFrame.pack(side=BOTTOM)

tmpstr = StringVar(value="%s" % desiredtemp)
crtmpstr = StringVar(value="%s" % temp)

#Set labels
label1 = Label(topFrame, text="Desired Temp = ", fg="black")
label2 = Label(middleFrame, text="Actual Temp = ", fg="black")
label3 = Label(topFrame, textvariable=tmpstr, fg="black")
label4 = Label(middleFrame, textvariable=crtmpstr, fg="black")

#use to put labels on screen
label1.pack(side=LEFT)
label2.pack(side=LEFT)
label3.pack(side=LEFT)
label4.pack(side=LEFT)

#Set buttons
button1 = Button(bottomFrame, text="Increase (0.5"+ deg +"C)", fg="black", command=increase)
button2 = Button(bottomFrame, text="Decrease (0.5"+ deg +"C)", fg="black", command=decrease)

#use to put buttons on screen
button1.pack(side=LEFT)
button2.pack(side=LEFT)


#Tkinter End


# Open file to be logged
'''
file = open("/home/pi/Desktop/Templog.csv", "a")

if os.stat("/home/pi/Desktop/Templog.csv").st_size == 0:
    file.write("Date, Time, TemperatureSensor1\n")

'''


# Continuous print loop
while 1:
    print(temp)
    if(temp<=desiredtemp):
        #GPIO.output(17,GPIO.LOW)
        #GPIO.output(22,GPIO.HIGH)
        temp += 5
        crtmpstr.set("%s" % temp)
    else:
        #GPIO.output(17,GPIO.HIGH)
        #GPIO.output(22,GPIO.LOW)
        temp -=0.5
        crtmpstr.set("%s" % temp)

    #now = datetime.now()
    #file.write(str(now.day)+"-"+str(now.month)+"-"+str(now.year)+","+str(now.hour)+":"+str(now.minute)+":"+str(now.second)+","+str(read_temp())+"\n")
    #file.flush()
    time.sleep(1)
    root.update()



root.mainloop()

Answer 1

只需使用TK对象的after方法。这不会影响重绘，也不需要调用任何手动更新函数，因为它会推迟代码的执行，直到gui线程不忙为止。在

将要独立执行的代码拆分为一个单独的函数，并将其与一个时间延迟一起传递给root.after。我第一次使用延迟0，所以它立即执行。然后在函数的末尾再次调用它，这次传递值1000（毫秒）作为延迟。它将重复执行，直到您结束tkinter应用程序。在

# ... other code here

def gpiotask():

    global temp

    print(temp)
    if(temp <= desiredtemp):
        GPIO.output(17, GPIO.LOW)
        GPIO.output(22, GPIO.HIGH)
        temp += 5 # <- did you mean 0.5 here ?
        crtmpstr.set("%s" % temp)
    else:
        GPIO.output(17, GPIO.HIGH)
        GPIO.output(22, GPIO.LOW)
        temp -= 0.5
        crtmpstr.set("%s" % temp)

    root.after(1000, gpiotask)

root.after(0, gpiotask)
root.mainloop()