136. Creating GUI Applications with Tkinter

Creating GUI (Graphical User Interface) applications in Python is straightforward with the Tkinter module, which is part of the Python standard library. Tkinter provides a set of tools to create windows, buttons, labels, and other UI components for desktop applications.

1. Basic Window Example

This simple example demonstrates how to create a basic window using Tkinter.

import tkinter as tk

# Create the main window
window = tk.Tk()
window.title("My First Tkinter Application")

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

# Run the window
window.mainloop()

Explanation:

• tk.Tk(): Creates the main window.

• window.title(): Sets the title of the window.

• window.geometry(): Specifies the dimensions of the window.

• window.mainloop(): Keeps the window open and waits for user actions.

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2. Adding Labels and Buttons

This example shows how to add a label and a button to the Tkinter window. When the button is clicked, the label text changes.

import tkinter as tk

# Function to update label text
def update_label():
    label.config(text="Button Clicked!")

# Create the main window
window = tk.Tk()
window.title("Label and Button Example")

# Add a label to the window
label = tk.Label(window, text="Hello, Tkinter!", font=("Arial", 14))
label.pack(pady=20)

# Add a button that updates the label when clicked
button = tk.Button(window, text="Click Me", command=update_label)
button.pack(pady=20)

# Run the window
window.mainloop()

Explanation:

• Label: A widget to display text.

• Button: A widget that triggers a function when clicked (using the command attribute).

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3. Text Entry Box

This example adds a text entry box where users can type their name and a button that greets them.

import tkinter as tk

# Function to greet the user
def greet_user():
    name = entry.get()
    greeting_label.config(text=f"Hello, {name}!")

# Create the main window
window = tk.Tk()
window.title("Text Entry Example")

# Add a label
label = tk.Label(window, text="Enter your name:", font=("Arial", 12))
label.pack(pady=10)

# Add a text entry box
entry = tk.Entry(window, font=("Arial", 12))
entry.pack(pady=10)

# Add a button to greet the user
button = tk.Button(window, text="Greet Me", command=greet_user)
button.pack(pady=10)

# Label to display the greeting
greeting_label = tk.Label(window, text="", font=("Arial", 14))
greeting_label.pack(pady=20)

# Run the window
window.mainloop()

Explanation:

• Entry: A widget for single-line text input.

• get(): Method used to retrieve the text entered in the entry widget.

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4. Using Frames for Layout Management

In this example, we use a frame to organize widgets in a structured manner.

import tkinter as tk

# Create the main window
window = tk.Tk()
window.title("Frame Example")

# Create a frame to hold the widgets
frame = tk.Frame(window)
frame.pack(pady=20)

# Add a label inside the frame
label = tk.Label(frame, text="This is inside a frame", font=("Arial", 14))
label.pack()

# Add a button inside the frame
button = tk.Button(frame, text="Click Me", command=lambda: label.config(text="Button Clicked!"))
button.pack(pady=10)

# Run the window
window.mainloop()

Explanation:

• Frame: A container widget that allows you to organize other widgets inside it.

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5. Adding Checkbuttons

This example demonstrates how to add checkboxes (Checkbuttons) to the Tkinter window.

import tkinter as tk

# Function to display selected options
def show_selection():
    selection = "You selected: "
    if var1.get() == 1:
        selection += "Option 1 "
    if var2.get() == 1:
        selection += "Option 2 "
    if var3.get() == 1:
        selection += "Option 3"
    label.config(text=selection)

# Create the main window
window = tk.Tk()
window.title("Checkbutton Example")

# Define variables for checkbuttons
var1 = tk.IntVar()
var2 = tk.IntVar()
var3 = tk.IntVar()

# Add checkbuttons
check1 = tk.Checkbutton(window, text="Option 1", variable=var1)
check1.pack()

check2 = tk.Checkbutton(window, text="Option 2", variable=var2)
check2.pack()

check3 = tk.Checkbutton(window, text="Option 3", variable=var3)
check3.pack()

# Add a button to show selected options
button = tk.Button(window, text="Show Selection", command=show_selection)
button.pack(pady=20)

# Add a label to display the selection
label = tk.Label(window, text="", font=("Arial", 12))
label.pack()

# Run the window
window.mainloop()

Explanation:

• Checkbutton: A widget used to display checkboxes that can be selected or deselected.

• IntVar(): A special type of variable used with checkbuttons to store the state (checked or unchecked).

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6. Radio Buttons for Single Choice

In this example, we use radio buttons to allow users to choose one option from a set.

import tkinter as tk

# Function to display the selected option
def show_choice():
    choice = var.get()
    label.config(text=f"You selected: {choice}")

# Create the main window
window = tk.Tk()
window.title("Radio Button Example")

# Define the variable to store selected choice
var = tk.StringVar()

# Add radio buttons
radio1 = tk.Radiobutton(window, text="Option 1", variable=var, value="Option 1")
radio1.pack()

radio2 = tk.Radiobutton(window, text="Option 2", variable=var, value="Option 2")
radio2.pack()

radio3 = tk.Radiobutton(window, text="Option 3", variable=var, value="Option 3")
radio3.pack()

# Add a button to display the selected option
button = tk.Button(window, text="Show Choice", command=show_choice)
button.pack(pady=20)

# Add a label to display the result
label = tk.Label(window, text="", font=("Arial", 12))
label.pack()

# Run the window
window.mainloop()

Explanation:

• Radiobutton: A widget that allows the user to select one option from a list.

• StringVar(): A special type of variable used with radio buttons to store the selected value.

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7. Canvas for Drawing Shapes

This example shows how to use a canvas to draw shapes and lines in a Tkinter window.

import tkinter as tk

# Create the main window
window = tk.Tk()
window.title("Canvas Example")

# Create a canvas widget
canvas = tk.Canvas(window, width=400, height=400, bg="white")
canvas.pack()

# Draw shapes on the canvas
canvas.create_rectangle(50, 50, 150, 150, outline="black", fill="blue")
canvas.create_oval(200, 200, 300, 300, outline="red", fill="green")
canvas.create_line(50, 200, 300, 50, fill="purple", width=2)

# Run the window
window.mainloop()

Explanation:

• Canvas: A widget used for drawing shapes, lines, and images.

• create_rectangle(): Draws a rectangle on the canvas.

• create_oval(): Draws an oval on the canvas.

• create_line(): Draws a line on the canvas.

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8. Using Messagebox for Alerts

This example uses Tkinter's built-in messagebox module to show alert dialogs.

import tkinter as tk
from tkinter import messagebox

# Function to show an alert message
def show_alert():
    messagebox.showinfo("Information", "This is an alert message!")

# Create the main window
window = tk.Tk()
window.title("Messagebox Example")

# Add a button to trigger the alert
button = tk.Button(window, text="Show Alert", command=show_alert)
button.pack(pady=20)

# Run the window
window.mainloop()

Explanation:

• messagebox.showinfo(): Displays an informational alert box.

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9. Grid Layout

This example demonstrates the use of grid layout to organize widgets in a table-like structure.

import tkinter as tk

# Create the main window
window = tk.Tk()
window.title("Grid Layout Example")

# Add labels and buttons in a grid layout
tk.Label(window, text="Name:").grid(row=0, column=0)
tk.Entry(window).grid(row=0, column=1)

tk.Label(window, text="Age:").grid(row=1, column=0)
tk.Entry(window).grid(row=1, column=1)

tk.Button(window, text="Submit").grid(row=2, column=0, columnspan=2)

# Run the window
window.mainloop()

Explanation:

• grid(): A layout manager that places widgets in a table-like structure. Widgets are arranged by specifying their row and column positions.

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These are just a few examples of what you can do with Tkinter. You can create complex, interactive applications by combining different widgets and layout options, such as menus, dialogs, and event handling.