Python进度条GUI

Question

I wonder if you can help me. I have seen code for creating a progress bar GUI and am trying to modify it slightly so that I can send the progress bar the value I want it to be. Below is my code

import tkinter as tk
from tkinter import ttk
import time

class progress_bar(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.progress = ttk.Progressbar(self, orient="horizontal", length=200, mode="determinate")
        self.progress.pack()
        self.val = 0
        self.maxval = 1
        self.progress["maximum"] = 1

    def updating(self, val):
        self.val = val
        self.progress["value"] = self.val
        print(self.val)

        if self.val == self.maxval:
            self.destroy()

def test():
    for i in range(0, 101):
        time.sleep(0.1)
        app.updating(i/100)

app = progress_bar()
app.after(1, test)
app.mainloop()

When I run the code the print message progresively increases from 0 - 1 as expected, however while the GUI is created it remains empty until the program has finished and it closes as required. Can you tell me what I need to modify so the GUI updates please. Thanks in advance for any help provided.

Answer 1

The issue you're having is that your test function blocks the tkinter event loop. That means that even though the progress bar's value gets updated, the progress never appears on the screen (since nothing gets redrawn until test ends).

To fix this, you need to get rid of the loop in test and instead use tkinter code to do the repeated updates.

Here's a modified version of test that should work:

def test(i=0):
    app.updating(i/100)
    if i < 100:
        app.after(100, test, i+1)

Rather than explicitly looping, it reschedules itself every 100 milliseconds. Rather than i being a loop variable, it is now an argument, and each scheduled call gets a larger i value than the one before it.