Creating GUI Using Tkinter

5.2  Creating GUI Using Tkinter

Creating a GUI Using Tkinter in Python

Tkinter is the standard Python library for creating Graphical User Interfaces (GUIs). It provides widgets like buttons, labels, text boxes, and more to build interactive applications.

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1. Basic Tkinter Window

A simple Tkinter window can be created with just a few lines of code.

import tkinter as tk

# Create the main application window
root = tk.Tk()

# Set window title
root.title("My First Tkinter App")

# Set window size
root.geometry("400x300")

# Run the Tkinter event loop
root.mainloop()

Explanation:

• tk.Tk() initializes the main window.
• title("My First Tkinter App") sets the window title.
• geometry("400x300") sets the window size.
• mainloop() starts the GUI event loop.

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2. Adding Widgets (Labels, Buttons, Entry)

import tkinter as tk

root = tk.Tk()
root.title("Simple GUI")
root.geometry("400x300")

# Create a Label
label = tk.Label(root, text="Hello, Tkinter!", font=("Arial", 16))
label.pack(pady=10)  # Add some padding

# Create an Entry Field
entry = tk.Entry(root, width=30)
entry.pack(pady=10)

# Function to handle button click
def on_button_click():
    user_text = entry.get()  # Get text from entry
    label.config(text=f"Hello, {user_text}!")  # Update label

# Create a Button
button = tk.Button(root, text="Click Me", command=on_button_click)
button.pack(pady=10)

root.mainloop()

Explanation:

• Label displays text.
• Entry allows text input.
• Button executes a function when clicked.
• pack() is used to arrange widgets.

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3. Using Grid Layout

Instead of pack(), you can use grid() for better layout control.

import tkinter as tk

root = tk.Tk()
root.title("Grid Layout Example")

# Create widgets
tk.Label(root, text="Name:").grid(row=0, column=0, padx=10, pady=10)
name_entry = tk.Entry(root)
name_entry.grid(row=0, column=1, padx=10, pady=10)

tk.Label(root, text="Age:").grid(row=1, column=0, padx=10, pady=10)
age_entry = tk.Entry(root)
age_entry.grid(row=1, column=1, padx=10, pady=10)

# Button to print input values
def submit():
    print(f"Name: {name_entry.get()}, Age: {age_entry.get()}")

tk.Button(root, text="Submit", command=submit).grid(row=2, column=0, columnspan=2, pady=10)

root.mainloop()

Explanation:

• grid(row, column) places widgets in a table-like structure.
• columnspan=2 makes the button span two columns.

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4. Message Box (Popup Dialogs)

import tkinter as tk
from tkinter import messagebox

def show_message():
    messagebox.showinfo("Greeting", "Hello, Tkinter!")

root = tk.Tk()
root.title("Message Box Example")

tk.Button(root, text="Show Message", command=show_message).pack(pady=20)

root.mainloop()

Explanation:

• messagebox.showinfo() creates a popup message.

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5. File Dialog (Open/Save Files)

import tkinter as tk
from tkinter import filedialog

def open_file():
    file_path = filedialog.askopenfilename()
    if file_path:
        print("Selected File:", file_path)

root = tk.Tk()
root.title("File Dialog Example")

tk.Button(root, text="Open File", command=open_file).pack(pady=20)

root.mainloop()

Explanation:

• filedialog.askopenfilename() allows users to select a file.

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6. Building a Simple Calculator

import tkinter as tk

root = tk.Tk()
root.title("Simple Calculator")

entry = tk.Entry(root, width=30, borderwidth=5)
entry.grid(row=0, column=0, columnspan=4, padx=10, pady=10)

# Function to handle button clicks
def button_click(number):
    entry.insert(tk.END, number)

def clear():
    entry.delete(0, tk.END)

def calculate():
    try:
        result = eval(entry.get())
        entry.delete(0, tk.END)
        entry.insert(tk.END, str(result))
    except:
        entry.delete(0, tk.END)
        entry.insert(tk.END, "Error")

# Button layout
buttons = [
    ('7', 1, 0), ('8', 1, 1), ('9', 1, 2), ('/', 1, 3),
    ('4', 2, 0), ('5', 2, 1), ('6', 2, 2), ('*', 2, 3),
    ('1', 3, 0), ('2', 3, 1), ('3', 3, 2), ('-', 3, 3),
    ('0', 4, 0), ('.', 4, 1), ('=', 4, 2), ('+', 4, 3)
]

for text, row, col in buttons:
    tk.Button(root, text=text, width=5, height=2, command=lambda t=text: button_click(t) if t != '=' else calculate()).grid(row=row, column=col)

tk.Button(root, text="C", width=5, height=2, command=clear).grid(row=4, column=3)

root.mainloop()

Explanation:

• Uses grid() to place buttons in a calculator layout.
• eval() computes the mathematical expression entered by the user.
• lambda allows passing values dynamically to functions.

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7. Adding a Menu Bar

import tkinter as tk

def open_file():
    print("Open file clicked")

root = tk.Tk()
root.title("Menu Bar Example")

menu_bar = tk.Menu(root)

# File menu
file_menu = tk.Menu(menu_bar, tearoff=0)
file_menu.add_command(label="Open", command=open_file)
file_menu.add_command(label="Exit", command=root.quit)
menu_bar.add_cascade(label="File", menu=file_menu)

root.config(menu=menu_bar)

root.mainloop()

Explanation:

• menu.add_command() adds menu items.
• menu_bar.add_cascade() adds dropdown menus.

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Summary

Feature	Code
Basic Window	tk.Tk()
Label	Label(root, text="Hello")
Button	Button(root, text="Click Me", command=function)
Entry (Text Box)	Entry(root)
Grid Layout	widget.grid(row=0, column=0)
Popup Message	messagebox.showinfo("Title", "Message")
File Dialog	filedialog.askopenfilename()
Calculator	eval(entry.get())
Menu Bar	Menu(root)