Question

我尝试创建代码，以便在输入持续时间的范围内逐步增加直流电源的电压。我已经设置了一个用于执行此操作的GUI（这是我第一次尝试制作GUI，如果代码很奇怪就很抱歉），一切正常......除了GUI在代码执行时冻结，所以我无法阻止循环。我已经研究了几个小时了，并学会了使用root.after而不是time.sleep，但它似乎没有帮助HeatLoop功能。 GUI现在更新，但只是零星的，而且还有＃34;等待光标＆＃34;当我鼠标悬停在GUI上时出现。有办法解决这个问题吗？

我使用下面的代码修改了代码，因此它可以在任何计算机上运行而无需进行编辑。

import datetime
import time
from tkinter import *

class GUIClass:


    def __init__(self, root):
        """Initialize the GUI"""

        self.root = root
        self.percent = StringVar()
        self.percent.set("00.00 %")
        self.error = StringVar()
        self.STOP = False
        self.error.set("---")
        self.currentvoltage = StringVar()
        self.currentvoltage.set("Current Voltage: 00.00 V")
        self.DT = datetime.datetime

        # Create and attach labels
        label1 = Label(root, text='Voltage')
        label2 = Label(root, text='Ramp Duration')
        label3 = Label(root, text='Percent Done: ')
        label4 = Label(root, textvariable=self.percent)
        label5 = Label(root, text="Error Message: ")
        label6 = Label(root, textvariable=self.error)
        label7 = Label(root, textvariable=self.currentvoltage)
        label1.grid(row=0, column=0, sticky=W)
        label2.grid(row=1, column=0, sticky=W)
        label3.grid(row=2, column=0, sticky=W)
        label4.grid(row=2, column=1, sticky=W)
        label5.grid(row=3, column=0, sticky=W)
        label6.grid(row=3, column=1, sticky=W)
        label7.grid(row=3, column=2, sticky=E)



        # Create and attach entries
        self.voltage = Entry(root)
        self.duration = Entry(root)
        self.voltage.grid(row=0, column=1)
        self.duration.grid(row=1, column=1)

        # Create, bind, and attach buttons
        HeatButton = Button(root, text='Heat')
        HeatButton.bind("<Button-1>", self.Heat)
        HeatButton.grid(row=0, column=2)

        CoolButton = Button(root, text='Cool')
        CoolButton.bind("<Button-1>", self.Heat)
        CoolButton.grid(row=1, column=2)

        StopButton = Button(root, text='Stop')
        StopButton.bind("<Button-1>", self.Stop)
        StopButton.grid(row=2, column=2)


    def HeatLoop(self, condition, TimeStart, TimeDuration, MaximumVoltage, Fraction=0):
        """Heat up the cell while the condition is true"""
        if condition:
            self.percent.set("{:2.2f}%".format(Fraction * 100))
            print(MaximumVoltage)
            self.currentvoltage.set("Current Voltage: {:2.2f} V".format(Fraction*MaximumVoltage))
            self.Update()
            CurrentTime = self.DT.now()
            ElapsedTime = (CurrentTime.second/3600 + CurrentTime.minute/60 + CurrentTime.hour
                           - TimeStart.second/3600 - TimeStart.minute/60 - TimeStart.hour)
            Fraction = ElapsedTime / TimeDuration
            print(Fraction)
            self.root.after(5000)
            self.HeatLoop(bool(not self.STOP and Fraction < 1),
                                          TimeStart, TimeDuration, MaximumVoltage, Fraction)


    # Define function to heat up cell
    def Heat(self, event):
        # Initialize Parameters
        self.STOP = False
        self.error.set("---")
        self.Update()



        # Try to get voltage and duration from the GUI
        MaxVoltage = self.voltage.get()
        TimeDuration = self.duration.get()
        try:
            MaxVoltage = float(MaxVoltage)
            try:
                TimeDuration = float(TimeDuration)
            except:
                self.error.set("Please enter a valid time duration")
                self.Update()
                self.STOP = True
        except:
            self.error.set("Please enter a valid voltage value")
            self.Update()
            self.STOP = True

        TimeStart = self.DT.now()

        self.HeatLoop(True,
                      TimeStart, TimeDuration, MaxVoltage)


    def Stop(self, event):
        self.STOP = True
        print("turned off voltage")

    def Update(self):
        self.root.update_idletasks()
        self.root.update()


root1 = Tk()
a = GUIClass(root1)
root1.mainloop()

Answer 1

root.after(5000)与time.sleep(5)没有区别。它正在按照你所说的去做：冻结五秒钟。

如果你想每五秒运行一次self.HeatLoop，那么这样做的方法是这样的：

self.root.after(5000, self.HeatLoop, 
                bool(not self.STOP and Fraction < 1),
                TimeStart, TimeDuration, MaximumVoltage, 
                Fraction)

当你向after提供两个或多个参数时，tkinter会将该函数添加到队列中，并在时间到期后调用该函数。这允许事件循环在五秒间隔期间继续处理事件。

稍微好一点的方法就是检查函数内部的条件而不是传入条件，以便在完成工作之前立即评估条件，而不是在完成工作之前的五秒钟。

例如：

def HeatLoop(self, TimeStart, TimeDuration, MaximumVoltage, Fraction=0):
    if self.STOP and Fraction < 0:
        return
    ...
    self.root.after(5000, self.HeatLoop, 
                    TimeStart, TimeDuration, MaximumVoltage, 
                    Fraction)

使用root.after进行TKinter GUI冻结

1 个答案: