How to call a function and pass variable in tkinter scale widget?

Question

I am trying to use tkinter scale widget to increase or decrease a Label widget text size on the canvas. I am using the the scale widget variable value to do so. The text size changing when the button is clicked (my_btn) but I want it to change and I would like to increase or decrease the text size by dragging the scale widget left or right. When I am dragging the scale widget the program is prompting an error:

TypeError: <lambda>() takes 0 positional arguments but 1 was given.

The code is shown below. Please tell me how can I control the text size by dragging the scale widget directly.

    ##### Imports #####
from tkinter import *
from tkinter import ttk

###################################################################
                         # FUNCTIONS #
###################################################################
def slide(mainCanvas, textSlider):
    slide.textLayer.place_forget()
    slide.textLayer = Label(mainCanvas, text="TEST", font=('Arial', int(textSlider.get())), bg='white', fg='red')
    slide.textLayer.place(relx=0.5, rely=0.5, anchor='center')

###################################################################
                           # MAIN #
###################################################################
def main():
    root = Tk()
    rootWidth = 500
    rootHeight = 510
    root.minsize(rootWidth, rootHeight)

    mainFrameCanvas = Frame(root, bg='white', width=rootWidth, height=350)
    mainFrameCanvas.pack(anchor='n')
    mainCanvas = Canvas(mainFrameCanvas, width=rootWidth, height=350, bg='white', relief='solid', borderwidth=1)
    mainCanvas.pack(fill='x', expand=1)

    mainFrameSlider = Frame(root, bg='white', width=rootWidth, height=150, relief='solid', borderwidth=1)
    mainFrameSlider.pack(anchor='s')


    slide.textLayer = Label(mainCanvas, text="TEST", bg='white', fg='red')
    slide.textLayer.place(relx=0.5, rely=0.5, anchor='center')


    var = DoubleVar()
    textSlider = Scale(mainFrameSlider, from_=10, to=30, variable=var, orient=HORIZONTAL, length=rootWidth*0.9, troughcolor='white', showvalue=1, bg='white', highlightbackground='white')
    textSlider.bind("<Button-1>", lambda: slide(mainCanvas, textSlider))
    textSlider.place(x=20, y=40)


    my_btn = Button(root, text="Click Me!", command=lambda: slide(mainCanvas, textSlider)).pack()


    root.mainloop()

###################################################################
                           # RUN #
###################################################################

def run():
    print('\nStart script')
    main()
    print('Finished script')

run()

acw1668 · Accepted Answer · 2022-03-23 15:16:40Z

1

Callback for an event binding expects an argument, the Event object. So

textSlider.bind("<Button-1>", lambda: slide(mainCanvas, textSlider))

should be changed to:

textSlider.bind("<Button-1>", lambda e: slide(mainCanvas, textSlider))

Note that you don't need to remove and recreate the label inside slide(), just update the font for the label:

def slide(mainCanvas, textSlider):
    slide.textLayer.config(font=('Arial', int(textSlider.get())))

edited Mar 23, 2022 at 15:16

answered Mar 23, 2022 at 15:10

acw1668

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