How to make a Tkinter Scale count from 0 to 100 to 0

Question

I want to create a Python3 programm that contains a Tkinter Scale. And I want it to scale it in percent from 0(left) to 100 (middle) and back to 0 (on the right). How do I get rid of the '-' without breaking the code? Here's what I got so far:

Here's what I got so far:

#!/usr/bin/python3

import tkinter as tk
from tkinter import ttk
...
scale = tk.Scale(root, from_=-100, to=100, orient="horizontal", length=300, sliderlength=10)
...

it does nearly what I want, but I want to count from 0 to 100 and back to to 0.

Answer 1

If you want to show the current value above the slider from 0 to 100 to 0, you can set showvalue=0 and use another label to show the value you want:

def show_value(value):
    value = int(value)
    x, y = scale.coords()
    value_label["text"] = 100 - abs(value)
    value_label.place(x=scale.winfo_x()+x, y=scale.winfo_y(), anchor="s")


# label for showing the scale value
value_label = tk.Label(root, font=("", 8))

scale = tk.Scale(root, from_=-100, to=100, orient="horizontal", length=300, sliderlength=10,
                 showvalue=0, command=show_value)

...

# show the initial value
root.update()
show_value(0)

Note that the above solution just change the value displayed but the value returned by scale.get() is still from -100 to 100.

Result:

Answer 2

If you want to customize the display of the Tkinter Scale widget to show percent values from 100 to 0 and back to 100, you can use the from_ and to options. Here's an example code for your Python3 program:

import tkinter as tk

def scale_changed(value):
    # Do something with the scaled value
    print(f"Scaled Value: {value}%")

# Create the main window
root = tk.Tk()
root.title("Percent Scale")

# Create a scale widget
scale = tk.Scale(root, from_=100, to=0, orient=tk.HORIZONTAL, command=scale_changed)
scale.pack(pady=20)

# Start the Tkinter event loop
root.mainloop()

In this code, the from_ option is set to 100, and the to option is set to 0. This will create a Scale widget that goes from 100 to 0 horizontally. The scale_changed function is called whenever the scale value changes, and you can modify it to suit your needs.

Feel free to adjust the code as necessary for your specific requirements.

Answer 3

you can directly handle the transformation within the lambda function attached to the Scale widget's command parameter. The scale will still technically run from 0 to 200, but the value will be transformed on the fly to the desired range (100 to 0 to 100) whenever the slider is moved.

import tkinter as tk

root = tk.Tk()
root.title("Custom Scale")

# Create the scale and handle value transformation in a lambda function
scale = tk.Scale(root, from_=0, to=200, orient="horizontal", length=300, sliderlength=10,
                 command=lambda value: print(100 - abs(100 - int(value))))

scale.set(100)  # Initialize at the middle position
scale.pack()

root.mainloop()