how do I dynamically change ttk button font color and background

Question

I have tried various ways to do it but I miss something. in the beggining I thought I need to create a style and than assign it to the button

st = ttk.Style()
st.configure('blueTButton', foreground="white", background="blue")
Btn.configure(style='blueTButton')

but I got an error: _tkinter.TclError: Layout blueTButton not found

so I tried this:

Btn.configure(foreground = 'red')
# and also
Btn.config(foreground = 'red')

and many other stupid attempts.

can anyone assist?

Answer 1

Since you are using ttk package, you have to use a Style to apply any modifications to widgets used from that package.

To dynamically change them, such as with a button press, pass a reference to the widget to a function to do whatever you like. I personally decided to also pass a reference to the Style object so it doesn't need to be recreated with each function call. Modify this example code to fit your needs.

import tkinter as tk
# Using cycle for demonstration purposes
from itertools import cycle
from tkinter import ttk

class TKTEST:

    def __init__(self) -> None:
        self.tkapp()

    def tkapp(self) -> None:

        root = tk.Tk()
        root.title("Test Dynamic Color Change")
        root.geometry("300x300")

        # Create style object before button
        style = ttk.Style()

        # Create a collection of colors to cycle through
        colors = cycle(["#e9c46a","#e76f51","#264653","#2a9d8f","#e85d04","#a2d2ff","#06d6a0","#4d908e"])

        # Using pack() to stretch out the frame to the size of the window
        mainframe = ttk.Frame(master=root, relief="groove")
        mainframe.pack(fill="both", expand=True)

        # Use place() to center the button horizontally and vertically in the frame
        # Use a lambda function to be able to pass arguments to the called function
        button = ttk.Button(master=mainframe, text="Change Colors", command=lambda: self.change_frame_color(mainframe, style, colors))
        button.place(relx=0.5, rely=0.5, anchor="center")

        root.mainloop()

    # Using type hinting with method arguments
    def change_frame_color(self, objFrame: ttk.Frame, style: ttk.Style, colors: cycle) -> None:
        # First, apply a style to frame since we're using ttk package
        objFrame.configure(style="Mainframe.TFrame")
        # Second, configure the style with a background color
        style.configure("Mainframe.TFrame", background=next(colors))


tktest = TKTEST()

Changing the frame's color with each button press: