a simple stopwatch using python and tkinter

Here’s a Python program that implements a simple stopwatch with start, stop, and reset functionality using tkinter.

The stopwatch counts in seconds and milliseconds and updates every 100 milliseconds.

Code

import tkinter as tk

# Initialize the main window
root = tk.Tk()
root.title("Stopwatch")
root.geometry("300x200")

# Global variables for time and state
counter = 0
running = False

# Update the timer display
def update_time():
    if running:
        global counter
        counter += 1
        time_display = f"{counter//600}:{(counter//10)%60:02}.{counter%10}"
        label.config(text=time_display)
        root.after(100, update_time)

# Start the stopwatch
def start():
    global running
    if not running:
        running = True
        update_time()

# Stop the stopwatch
def stop():
    global running
    running = False

# Reset the stopwatch
def reset():
    global counter, running
    running = False
    counter = 0
    label.config(text="0:00.0")

# Display label for the stopwatch
label = tk.Label(root, text="0:00.0", font=("Helvetica", 40))
label.pack(pady=20)

# Buttons for start, stop, and reset
start_button = tk.Button(root, text="Start", command=start, width=10)
start_button.pack(side="left", padx=10)

stop_button = tk.Button(root, text="Stop", command=stop, width=10)
stop_button.pack(side="left", padx=10)

reset_button = tk.Button(root, text="Reset", command=reset, width=10)
reset_button.pack(side="left", padx=10)

# Run the main event loop
root.mainloop()

Explanation of the Code

1. Initialize the Main Window:
   • root = tk.Tk(): Creates the main application window.
   • root.title(“Stopwatch”): Sets the window title to “Stopwatch”.
   • root.geometry(“300×200”): Sets the size of the window to 300×200 pixels.
2. Global Variables:
   • counter: Holds the current time in tenths of a second (i.e., each increment is 100ms).
   • running: A boolean flag indicating whether the stopwatch is currently running.
3. update_time() Function:
   • This function is responsible for updating the time displayed on the label.
   • It checks if running is True; if so, it:
     • Increments counter by 1 (which represents 0.1 seconds).
     • Formats counter to display minutes, seconds, and tenths of a second.
       • counter//600 calculates the minutes.
       • (counter//10)%60 calculates seconds, ensuring it resets every 60 seconds.
       • counter%10 calculates tenths of a second.
     • label.config(text=time_display): Updates the label with the formatted time.
     • root.after(100, update_time): Schedules the update_time function to run again after 100 milliseconds, creating a loop.
4. Start, Stop, and Reset Functions:
   • start():
     • Starts the stopwatch if it’s not already running.
     • Sets running = True and calls update_time() to start updating the timer.
   • stop():
     • Stops the stopwatch by setting running = False.
   • reset():
     • Stops the stopwatch (running = False).
     • Resets counter to 0.
     • Updates the label text to “0:00.0”.
5. Creating the Display Label:
   • label = tk.Label(…): A Label widget that displays the current time.
   • text=”0:00.0″ initializes the label with “0:00.0” (0 minutes, 0 seconds).
   • font=(“Helvetica”, 40) sets the font size for visibility.
6. Creating the Start, Stop, and Reset Buttons:
   • Each button is created using tk.Button(…), specifying the button’s text, command, and width.
   • start_button, stop_button, and reset_button trigger start(), stop(), and reset() respectively when clicked.
   • side=”left” arranges the buttons horizontally in the window.
7. Run the Main Loop:
   • root.mainloop() starts the tkinter event loop, keeping the application window open and responsive.

How It Works

• Starting the Stopwatch:
  • Clicking “Start” sets running = True and begins incrementing counter every 100 milliseconds.
• Stopping the Stopwatch:
  • Clicking “Stop” sets running = False, stopping further updates until “Start” is clicked again.
• Resetting the Stopwatch:
  • Clicking “Reset” stops the stopwatch and resets counter to 0, updating the display to show “0:00.0”.

Summary

This Python program provides a basic stopwatch with start, stop, and reset functionality using tkinter for the GUI.

The update_time() function continuously updates the display, while the start, stop, and reset functions control the stopwatch state.

The program is a simple example of using tkinter for GUI-based timing applications.