why do my sliders disappear in python tkinter?

Question

I've been working on a tkinter project that uses three sliders to customize an RGB output. The code bellow works just fine:

from tkinter import*


Window = Tk()
Window.title("Edit Color")
Window.geometry('1270x680')
Window.configure(background = "black")

#sliders
Slider_1 = Scale(activebackground='pink',
                 orient=HORIZONTAL,
                 relief=GROOVE,
                 length = 500,
                 from_=0,to_=255,
                 bg='red',
                 tickinterval=51,
                 troughcolor='pink')
Slider_1.grid(row=0, column=0,padx=60, pady=70)


Slider_2 = Scale(activebackground='lightGreen',
                 orient=HORIZONTAL,
                 relief=GROOVE,
                 length = 500,
                 from_=0,to_=255,
                 bg='Green',
                 tickinterval=51,
                 troughcolor='lightGreen')
Slider_2.grid(row=2,  column=0, pady=70)


Slider_3 = Scale(activebackground= 'light blue',
                 orient=HORIZONTAL,relief=GROOVE,
                 length = 500, from_=0, to_=255,
                 bg='blue',
                 tickinterval=51,
                 troughcolor= 'light blue')
Slider_3.grid(row=4, column=0, pady=70)


Window.mainloop()

Then I added two things in order to be able to print the values of the sliders. The first is near the top. It is a function which is associated with a parameter called ”command”, that can be found at the end of the parentheses of each slider function:

from tkinter import*


Window = Tk()
Window.title("Edit Color")
Window.geometry('1270x680')
Window.configure(background = "black")

def print_value(val):
    print val

#sliders
    Slider_1 = Scale(activebackground='pink',
                 orient=HORIZONTAL,
                 relief=GROOVE,
                 length = 500,
                 from_=0,to_=255,
                 bg='red',
                 tickinterval=51,
                 troughcolor='pink',command=print_value)
    Slider_1.grid(row=0, column=0,padx=60, pady=70)


    Slider_2 = Scale(activebackground='lightGreen',
                 orient=HORIZONTAL,
                 relief=GROOVE,
                 length = 500,
                 from_=0,to_=255,
                 bg='Green',
                 tickinterval=51,
                 troughcolor='lightGreen',command=print_value)
    Slider_2.grid(row=2,  column=0, pady=70)


    Slider_3 = Scale(activebackground= 'light blue',
                 orient=HORIZONTAL,relief=GROOVE,
                 length = 500, from_=0, to_=255,
                 bg='blue',
                 tickinterval=51,
                 troughcolor= 'light blue',command=print_value)
    Slider_3.grid(row=4, column=0, pady=70)


Window.mainloop()

When I added this and executed the program the screen was black and I had no Sliders.

what do I do?

Answer 1

创建滑块的代码位于函数print_value ，您永远不会调用print_value 。