application.py

import tkinter as tk

BUTTON_START_NAME = "Start"
BUTTON_PAUSE_NAME = "Pause"
BUTTON_RESET_NAME = "Reset"

BUTTON_ENABLED = "normal"
BUTTON_DISABLED = "disabled"

BUTTON_WIDTH = 10
BUTTON_FONT = ("Arial", 16)

LABEL_FONT = ("Helvetica", 32)

class Application(tk.Frame):

    def __init__(self, tkinter, view):
        super().__init__(tkinter)
        self.tkinter = tkinter
        self.view = view
        self.tkinter.title("TKimer")
        self.tkinter.protocol("WM_DELETE_WINDOW", self.view.handle_quit)
        self.pack()
        self.create_widgets()

    def create_widgets(self):
        self.lbl_time = tk.Label(self, text="", font=LABEL_FONT)
        self.lbl_time.pack(side="bottom")

        self.btn_start = tk.Button(self)
        self.btn_start["text"] = BUTTON_START_NAME
        self.btn_start["font"] = BUTTON_FONT
        self.btn_start["width"] = BUTTON_WIDTH
        self.btn_start["command"] = self.view.handle_start
        self.btn_start.pack(side="left")

        self.btn_reset = tk.Button(self)
        self.btn_reset["text"] = BUTTON_RESET_NAME
        self.btn_reset["font"] = BUTTON_FONT
        self.btn_reset["width"] = BUTTON_WIDTH
        self.btn_reset["command"] = self.view.handle_reset
        self.btn_reset.pack(side="left")
        self.btn_reset["state"] = BUTTON_DISABLED

    def update_widgets(self, time_string, is_running, is_idle):
        start_name = BUTTON_PAUSE_NAME if is_running else BUTTON_START_NAME
        reset_state = BUTTON_DISABLED if is_idle else BUTTON_ENABLED
        self.lbl_time["text"] = time_string
        self.btn_start["text"] = start_name
        self.btn_reset["state"] = reset_state