Problems with outputing console to GUI in tkinter

Question

I am using tkinter. I have the following code printing out the console output to GUI in live mode. Now it simple prints the numbers (delay is needed so that I can see that it is in real-life).

import tkinter as tk
import time
import sys

class Display(tk.Frame):
    def __init__(self):
       tk.Frame.__init__(self)
       self.doIt = tk.Button(self,text="Start", command=self.start, background = 'black', fg='white')
       self.doIt.pack()
       self.output = tk.Text(self, width=100, height=15, background = 'black', fg='white')
       self.output.pack()
       sys.stdout = self
       self.configure(background='black')
       self.pack()


    def start(self):
        for i in range (1, 1000):
            print (i)
            time.sleep(2)


    def write(self, txt):
        self.output.insert(tk.END,str(txt))
        self.update_idletasks()


if __name__ == '__main__':
    Display().mainloop()

However, when I try to fold the window or switch to another application it freezes. Another thing is that I want it to scroll down and show new output as it reaches the end of the window. I would appreciate any help on these issues.

I don't see how you can get any output from the posted code, but maybe am I missing something? — Reblochon Masque
– Reblochon Masque, Commented Apr 22, 2016 at 13:50
well, I took this code from the web and modified it a bit and it works. It prints the output of the console to the text widget — Kate
– Kate, Commented Apr 22, 2016 at 13:56
Good for you, I could not make it work... but I see that your question was edited, maybe the first paste was not good...edit No luck :( — Reblochon Masque
– Reblochon Masque, Commented Apr 22, 2016 at 13:57
I am not stick to this one, so if you can suggest any other way of putting output to the console in real-time, I would be very grateful — Kate
– Kate, Commented Apr 22, 2016 at 13:58

Matt · Accepted Answer · 2016-04-22 15:47:49Z

2

I recommend you don't use time.sleep() in the Tkinter event loop as it will cause the application to go unresponsive during the sleep call. Because of this I suggest you use the .after() call.

Regarding the scrolling, you simply need to add a scrollbar to your text widget. Here's an example:

import tkinter as tk
import time
import sys

class Display(tk.Frame):
    def __init__(self):
       tk.Frame.__init__(self)
       self.doIt = tk.Button(self,text="Start", command=self.start, background = 'black', fg='white')
       self.doIt.pack()

       self.output = tk.Text(self, width=100, height=15, background = 'black', fg='white')
       self.output.pack(side=tk.LEFT)

       self.scrollbar = tk.Scrollbar(self, orient="vertical", command = self.output.yview)
       self.scrollbar.pack(side=tk.RIGHT, fill="y")

       self.output['yscrollcommand'] = self.scrollbar.set

       self.count = 1
       self.configure(background='black')
       self.pack()


    def start(self):
        if self.count < 1000:
            self.write(str(self.count) + '\n')
            print (self.count)
            self.count += 1
            self.after(2000, self.start)


    def write(self, txt):
        self.output.insert(tk.END,str(txt))
        self.update_idletasks()


if __name__ == '__main__':
    Display().mainloop()

answered Apr 22, 2016 at 15:47

Matt

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1 Comment

Kate Over a year ago

Thank you! I was using sleep() just to test if it works and could never think that it will cause issues haha

Reblochon Masque · Accepted Answer · 2016-04-22 14:40:21Z

This now outputs both in the console and in the output tk window: What was missing is a call to self.write(). I also suppressed the diverting of sysout to the window.

import tkinter as tk
import time
import sys

class Display(tk.Frame):
    def __init__(self):
       tk.Frame.__init__(self)
       self.doIt = tk.Button(self,text="Start", command=self.start, background = 'black', fg='white')
       self.doIt.pack()
       self.output = tk.Text(self, width=100, height=15, background = 'black', fg='white')
       self.output.pack()
#       sys.stdout = self
       self.configure(background='black')
       self.pack()


    def start(self):
        for i in range (1, 1000):
            self.write(str(i) + '\n')
            print (i)
            time.sleep(2)


    def write(self, txt):
        self.output.insert(tk.END,str(txt))
        self.update_idletasks()


if __name__ == '__main__':
    Display().mainloop()

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