Tkinter – scales

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The Tkinter Scale widget is a graphical slider that allows a user to select a numerical value within a specified range. It provides an interactive way to input integer or float values, often used for controls like volume or brightness.

Key Concepts:

• Function: The Scale widget presents a slider knob that users can drag along a trough to adjust a value.
• Orientation: It can be arranged either horizontally or vertically using the orient option.
• Range: The minimum and maximum values are defined by the from_ (note the trailing underscore because from is a Python keyword) and to options.
• Value Retrieval: The current value of the slider can be retrieved at any time using the .get() method.
• Callbacks: A Python function can be specified with the command option, which will be called every time the slider is moved.
• Control Variables: The value can be linked to a Tkinter variable (e.g., IntVar or DoubleVar) using the variable option, automatically reflecting changes in the widget and the program. 

Common Options

Option	Description
orient	Sets the orientation to tk.HORIZONTAL or tk.VERTICAL.
from_	The starting value of the range (uses an underscore).
to	The ending value of the range.
command	A function to call when the slider is moved.
tickinterval	Displays numerical tick marks along the scale at specified intervals (e.g., tickinterval=10).
resolution	Sets the smallest increment by which the value can change (e.g., resolution=0.5 for half steps).
length	The length of the scale (width for horizontal, height for vertical).
label	Text label to display within the widget.

Lets create a scale to show the temperature.

from tkinter import *
window = Tk()

scale = Scale(window, from_=0, to=100)  # we can specify the scale start and end values
scale.pack()

window.mainloop()

This code outputs a very basic looking scale:

Now lets flip the scale so the 0 is at the bottom, then we’ll add a submit button so we can get the current value.

from tkinter import *

def submit():
    print("The temperature is: "+ str(scale.get())+ " degrees C")

window = Tk()

scale = Scale(window,from_=100, to=0)
scale.pack()

button = Button(window,text="Submit",command=submit)
button.pack()

window.mainloop()

If we want to store the current temperature displayed on the slider when the button submit is “pressed”

from tkinter import *

def submit():
    temp = scale.get()
    print(f"The temperature is: {temp} degrees C")  # Could also use str(temp)

window = Tk()

scale = Scale(window,from_=100, to=0)
scale.pack()

button = Button(window,text="Submit",command=submit)
button.pack()

window.mainloop()

We can make our scale horizontal:

from tkinter import *

def show_value():
    # Get the current value from the scale and print it
    print(f"Current value: {scale.get()}")

window = Tk()

# Create a horizontal scale from 0 to 100
scale = Scale(window, from_=0, to=100, orient=HORIZONTAL)
scale.pack()

# Create a button to show the value
button = Button(window, text='Show Value', command=show_value)
button.pack()

# Initialize the slider to a specific value (optional)
scale.set(20)

window.mainloop()

We can make size changes to our scale to make more useable:

from tkinter import *

def submit():
    temp = scale.get()
    print(f"The temperature is: {str(temp)} degrees C")

window = Tk()

scale = Scale(window,
              from_=100,
              to=0,
              length=600,
              orient=VERTICAL,   # can also us HORIZONTAL
              font=("Consolas",20),
              tickinterval = 10, # adds numeric indicators for value
              showvalue = 1,     # 0 - hides current value, 1- default shows value
              resolution = 5    # increment of slider
              )
scale.set(((scale['from']-scale['to'])/2)+scale["to"]) # centre start position of slider

scale.pack()

button = Button(window,text="Submit",command=submit)
button.pack()

We can make cosmetic changes to our scale to make it look significantly nicer by injecting some colour into the picture:

from tkinter import *

def submit():
    temp = scale.get()
    print(f"The temperature is: {str(temp)} degrees C")

window = Tk()

scale = Scale(window,
              from_=100,
              to=0,
              length=600,
              orient=HORIZONTAL,   # can also us VERTICAL (the default)
              font=("Consolas",20),
              tickinterval = 10, # adds numeric indicators for value
              showvalue = 1,     # 0 - hides current value, 1- default shows value
              resolution = 5,     # increment of slider
              troughcolor = '#69EAFF', # makes the slider trough and icy blue colour
              fg='#FF1C00',            # sets the text (foreground) colour
              bg='#111111'             # sets the background colour
              )
scale.set(((scale['from']-scale['to'])/2)+scale["to"]) # centre start position of slider

scale.pack()

button = Button(window,text="Submit",command=submit)
button.pack()

window.mainloop()

Here’s a final output of our scale turned horizontal:

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