4. tkinter geometry Hello World

The geometry managers allows you to arrange widgets within a root.
The Hello World example below has 3 versions which use the pack, grid and place geometry managers.
See: https://tkdocs.com/tutorial/grid.html
See: https://www.geeksforgeeks.org/python-pack-method-in-tkinter/?ref=lbp

4.1. Hello World - pack

widget.pack()
positions widgets relative to each other.
By default, widgets are stacked vertically from the top of the container.
Below is a sample Hello World using the pack layout.
../_images/hello_world_pack.png 
import tkinter as tk

# Create the main application window
root = tk.Tk()
root.title("hello world - pack")
root.geometry('300x200')

# define widgets
label = tk.Label(root, text="Hello World!")
button = tk.Button(root, text="Quit", command=root.destroy)

# place widgets using pack
label.pack()
button.pack()

# Start the main event loop
root.mainloop()

4.1.1. Code details

Overall, this code creates a simple Tkinter application with a window,
a label displaying "Hello World!", and a button that allows the user to quit the application.
import tkinter as tk: imports the Tkinter library and assigns it an alias (tk).
By doing this, you can use the tk prefix to access various Tkinter classes and functions throughout your code.
root = tk.Tk(): Here, the Tk() constructor initializes the main application root.
You can customize this window by setting properties such as its title, size, and other attributes.
root.title("hello world - pack"): sets the title of the application window to "hello world - pack".
You can replace this string with any other title you'd like for your application.
root.geometry('300x200'): The geometry() method defines the initial size of the root.
In this case, the window will be 600 pixels wide and 400 pixels tall.
label = tk.Label(root, text="Hello World!"): A label widget is created with the text "Hello World!".
Labels are used to display static text or messages in the GUI.
The label variable holds a reference to this widget.
button = tk.Button(root, text="Quit", command=root.destroy): A button widget is created with the label "Quit".
When this button is clicked, the root.destroy() method is called, which closes the application root.
The button variable holds a reference to this widget.
label.pack(): The pack() method is used to put the label widget into the root.
button.pack(): The pack() method is used to add the button widget vertically into the root.
root.mainloop(): starts the main event loop, which keeps the application running and responsive.
It listens for user interactions (such as button clicks) and updates the GUI accordingly.
Any code after it will not run until the tkinter window is closed.

4.2. Hello World - grid

widget.grid(row=row_index, column=column_index)
The grid() method is used to position widgets within a container using a grid-based layout.
Widgets are placed in rows and columns.
Specify the row and column indices where the widget should appear.
Below is a sample Hello World using grid layout.
../_images/hello_world_grid.png 
import as tk


# Create the main application window
root = tk.Tk()
root.title("hello world - grid")
root.geometry('300x200')

# define widgets
label = tk.Label(root, text="Hello World!")
button = tk.Button(root, text="Quit", command=root.destroy)

# place widgets
label.grid(row=0,column=0)
button.grid(row=1,column=0)

# Start the main event loop
root.mainloop()

4.2.1. Code details

Overall, this code creates a simple Tkinter application with a window,
a label displaying "Hello World!", and a button that allows the user to quit the application.
label.grid(row=0, column=0): The grid() method is used to place the label widget
in the first row (row 0) and first column (column 0) of the window's grid layout.
button.grid(row=1, column=0): Similarly, the button widget is placed
in the second row (row 1) and first column (column 0) of the grid layout.

4.3. Hello World - place

widget.place(x=x_value, y=y_value)
The place() method is used to precisely position widgets within a container using the (x, y) coordinate system. Here's how it works:
In absolute positioning, specify the exact x and y coordinates of the widget using the x and y parameters.
Below is a sample Hello World using place method to position widgets.
../_images/hello_world_place.png 
import tkinter as tk


# Create the main application window
root = tk.Tk()
root.title("hello world - place")
root.geometry("300x200")

# Define widgets
label = tk.Label(root, text="Hello World!")
button = tk.Button(root, text="Quit", command=root.destroy)

# Place widgets using x and y coordinates
label.place(x=50, y=20)
button.place(x=70, y=42)

# Start the main event loop
root.mainloop()

4.3.1. Code details

Overall, this code creates a simple Tkinter application with a window,
a label displaying "Hello World!", and a button that allows the user to quit the application.
label.place(x=250, y=0): The place() method is used to place the label widget
at (x, y) = (250, 0) in the root.
button.place(x=270, y=22): The place() method is used to place the label widget
at (x, y) = (270, 22) in the root.