simple_gui.py

import tkinter as tk

# create a window
window = tk.Tk()
# create a widget
greeting = tk.Label(text="Hello, Tkinter")
# use the Label widget's .pack() method
greeting.pack()
# event loop
window.mainloop()

• Displaying Text and Images With Label Widgets
• Displaying Clickable Buttons With Button Widgets
• Getting User Input With Entry Widgets
• Getting Multiline User Input With Text Widgets
• Assigning Widgets to Frames With Frame Widgets
• Adjusting Frame Appearance With Reliefs
• Understanding Widget Naming Conventions

widgets are the key element of the Python GUI framework Tkinter
widget are the elements through which users interact with the program
each widget in Tkinter is defined by a class
some of the widgets available

two kinds of widgets

label = tk.Label(
    text="Hello, Tkinter",
    foreground="white",  # Set the text color to white
    background="black"  # Set the background color to black
)

label = tk.Label(text="Hello, Tkinter", fg="white", bg="black")

label = tk.Label(
    text="Hello, Tkinter",
    fg="white",
    bg="black",
    width=10,
    height=10
)

button = tk.Button(
    text="Click me!",
    width=25,
    height=5,
    bg="blue",
    fg="yellow",
)

import tkinter as tk

window = tk.Tk()
label = tk.Label(text="Name")
entry = tk.Entry()
label.pack()
entry.pack()

window.mainloop()

name = entry.get()

entry.delete(0)

entry.delete(0, 4)

entry.delete(0, tk.END)

entry.insert(0, "Python")

>>> window = tk.Tk()
>>> text_box = tk.Text()
>>> text_box.pack()

.get() takes two arguments

1. the line number of a character - index is 1-based
2. the position of a character on that line - index is 0-based

# get first letter of the first line
>>> text_box.get("1.0")
'H'

# can use string slicing
>>> text_box.get("1.0", "1.5")
'Hello'

# to get all the text from the text widget
>>> text_box.get("1.0", tk.END)
'Hello\nWorld\n'

# delete the first character of 'Hello'
>>> text_box.delete("1.0")

# delete the 'ello'
>>> text_box.delete("1.0", "1.4")

# .get() shows the first line still contains a newline
>>> text_box.get("1.0")
'\n'

# to delete entire contents
>>> text_box.delete("1.0", tk.END) 

1. insert text at the specified position if there's already text at or after that position
2. append text to the specified line if the character number is greater than the index of the last character in the text box

# insert lines 1 and 2
>>> text_box.insert("1.0", "Hello")
>>> text_box.insert("2.0", "World")

# the text is inserted at the end of the first line
>>> text_box.get("1.0", tk.END)
HelloWorld

# to delete entire contents
>>> text_box.delete("2.0", tk.END) 
>>> text_box.get("1.0", tk.END)
Hello

# Text widget does not automatically add newlines
# to add a second line
>>> text_box.insert("2.0", "\nWorld")

# best way to append text is using tk.END
# just append to last line
>>> text_box.insert(tk.END, "Put me at the end!")
to append as new line
>>> text_box.insert(tk.END, "\nPut me at the end!")

import tkinter as tk

window = tk.Tk()
frame = tk.Frame()
# create a Label and assign it to the frame
label = tk.Label(master=frame, text='Hello World!')
# 'pack' it all together
label.pack()
frame.pack()

window.mainloop()

import tkinter as tk

window = tk.Tk()

frame_a = tk.Frame()
frame_b = tk.Frame()

label_a = tk.Label(master=frame_a, text="I'm in Frame A")
label_a.pack()

label_b = tk.Label(master=frame_b, text="I'm in Frame B")
label_b.pack()

frame_a.pack()
frame_b.pack()

window.mainloop()

if the master argument is omitted when creating a new widget instance, then the widget will be placed inside of the top-level window by default

import tkinter as tk

window = tk.Tk()

frame_a = tk.Frame()
label_a = tk.Label(master=frame_a, text="I'm in Frame A")
label_a.pack()

frame_b = tk.Frame()
label_b = tk.Label(master=frame_b, text="I'm in Frame B")
label_b.pack()

label_c = tk.Label(text="I'm not in a frame!")
label_c.pack()

# Swap the order of `frame_a` and `frame_b`
frame_b.pack()
frame_a.pack()

window.mainloop()

• tk.FLAT - default, has no border effect
• tk.SUNKEN - creates a sunken effect
• tk.RAISED - creates a raised effect
• tk.GROOVE - creates a grooved border effect
• tk.RIDGE - creates a ridged effect

import tkinter as tk

# a dictionary of border attribute values
border_effects = {
    "flat": tk.FLAT,
    "sunken": tk.SUNKEN,
    "raised": tk.RAISED,
    "groove": tk.GROOVE,
    "ridge": tk.RIDGE,
}

window = tk.Tk()

for relief_name, relief in border_effects.items():
    frame = tk.Frame(master=window, relief=relief, borderwidth=5)
    frame.pack(side=tk.LEFT)
    label = tk.Label(master=frame, text=relief_name)
    label.pack()

window.mainloop()

>>> tk.Label(text="Hello, Tkinter").pack()

• The .pack() Geometry Manager
• The .place() Geometry Manager
• The .grid() Geometry Manager

application layout in Tkinter is controlled with geometry managers

• .pack()
• .place()
• .grid()

1. computes a rectangular area called a parcel
   parcel is just tall (or wide) enough to hold the widget
   fills the remaining width (or height) in the window with blank space
2. centers the widget in the parcel unless a different location is specified

import tkinter as tk

window = tk.Tk()

frame1 = tk.Frame(master=window, width=100, height=100, bg="red")
frame1.pack()

frame2 = tk.Frame(master=window, width=50, height=50, bg="yellow")
frame2.pack()

frame3 = tk.Frame(master=window, width=25, height=25, bg="blue")
frame3.pack()

window.mainloop()

• tk.X to fill in the horizontal direction
• tk.Y to fill in the vertical direction
• tk.BOTH to fill in both directions

import tkinter as tk

window = tk.Tk()

frame1 = tk.Frame(master=window, height=100, bg="red")
frame1.pack(fill=tk.X)

frame2 = tk.Frame(master=window, height=50, bg="yellow")
frame2.pack(fill=tk.X)

frame3 = tk.Frame(master=window, height=25, bg="blue")
frame3.pack(fill=tk.X)

window.mainloop()

• tk.TOP
• tk.BOTTOM
• tk.LEFT
• tk.RIGHT

import tkinter as tk

window = tk.Tk()

frame1 = tk.Frame(master=window, width=200, height=100, bg="red")
frame1.pack(fill=tk.Y, side=tk.LEFT)

frame2 = tk.Frame(master=window, width=100, bg="yellow")
frame2.pack(fill=tk.Y, side=tk.LEFT)

frame3 = tk.Frame(master=window, width=50, bg="blue")
frame3.pack(fill=tk.Y, side=tk.LEFT)

window.mainloop()

import tkinter as tk

window = tk.Tk()

frame1 = tk.Frame(master=window, width=200, height=100, bg="red")
frame1.pack(fill=tk.BOTH, side=tk.LEFT, expand=True)

frame2 = tk.Frame(master=window, width=100, bg="yellow")
frame2.pack(fill=tk.BOTH, side=tk.LEFT, expand=True)

frame3 = tk.Frame(master=window, width=50, bg="blue")
frame3.pack(fill=tk.BOTH, side=tk.LEFT, expand=True)

window.mainloop()

import tkinter as tk

window = tk.Tk()

frame = tk.Frame(master=window, width=150, height=150)
frame.pack()

label1 = tk.Label(master=frame, text="I'm at (0, 0)", bg="red")
label1.place(x=0, y=0)

label2 = tk.Label(master=frame, text="I'm at (75, 75)", bg="yellow")
label2.place(x=75, y=75)

window.mainloop()

1. layout can be difficult to manage
   especially true if the application has lots of widgets
2. layouts created with .place() aren't responsive
   don't change as the window is resized

import tkinter as tk

window = tk.Tk()

for i in range(3):
    for j in range(3):
        frame = tk.Frame(
            master=window,
            relief=tk.RAISED,
            borderwidth=1
        )
        frame.grid(row=i, column=j)
        label = tk.Label(master=frame, text=f"Row {i}\nColumn {j}")
        label.pack()

window.mainloop()

two types of padding are external and internal
external padding adds some space around the outside of a grid cell
controlled with two keyword arguments to .grid()
extra padding around the Label widgets gives each cell in the grid space between the Frame border and the text in the Label

1. padx - adds padding in the horizontal direction
2. pady - adds padding in the vertical direction

import tkinter as tk

window = tk.Tk()

for i in range(3):
    for j in range(3):
        frame = tk.Frame(
            master=window,
            relief=tk.RAISED,
            borderwidth=1
        )
        frame.grid(row=i, column=j, padx=5, pady=5)
        label = tk.Label(master=frame, text=f"Row {i}\nColumn {j}")
        label.pack(padx=5, pady=5)

window.mainloop()

1. index - the index of the grid column or row to be configured or a list of indices to configure multiple rows or columns at the same time
2. weight - determines how the column or row should respond to window resizing, relative to the other columns and rows
   set to zero by default
3. minsize - sets the minimum size of the row height or column width in pixels

import tkinter as tk

window = tk.Tk()

for i in range(3):
    window.columnconfigure(i, weight=1, minsize=75)
    window.rowconfigure(i, weight=1, minsize=50)

    for j in range(0, 3):
        frame = tk.Frame(
            master=window,
            relief=tk.RAISED,
            borderwidth=1
        )
        frame.grid(row=i, column=j, padx=5, pady=5)
        label = tk.Label(master=frame, text=f"Row {i}\nColumn {j}")
        label.pack(padx=5, pady=5)

window.mainloop()

import tkinter as tk

window = tk.Tk()
window.columnconfigure(0, minsize=250)
window.rowconfigure([0, 1], minsize=100)

label1 = tk.Label(text="A")
label1.grid(row=0, column=0)

label2 = tk.Label(text="B")
label2.grid(row=1, column=0)

window.mainloop()

• n or N - to align to the top-center part of the cell
• e or E - to align to the right-center side of the cell
• s or S - to align to the bottom-center part of the cell
• w or W - to align to the left-center side of the cell

import tkinter as tk

window = tk.Tk()
window.columnconfigure(0, minsize=250)
window.rowconfigure([0, 1], minsize=100)

label1 = tk.Label(text="A")
label1.grid(row=0, column=0, sticky="n")

label2 = tk.Label(text="B")
label2.grid(row=1, column=0, sticky="e")

window.mainloop()

import tkinter as tk

window = tk.Tk()
window.columnconfigure(0, minsize=250)
window.rowconfigure([0, 1], minsize=100)

label1 = tk.Label(text="A")
label1.grid(row=0, column=0, sticky="ne")

label2 = tk.Label(text="B")
label2.grid(row=1, column=0, sticky="sw")

window.mainloop()

• ns - fill cell vertically
• ew - fill cell horizontally
• nsew - fill cell completely

import tkinter as tk

window = tk.Tk()

window.rowconfigure(0, minsize=50)
window.columnconfigure([0, 1, 2, 3], minsize=50)

label1 = tk.Label(text="1", bg="black", fg="white")
label2 = tk.Label(text="2", bg="black", fg="white")
label3 = tk.Label(text="3", bg="black", fg="white")
label4 = tk.Label(text="4", bg="black", fg="white")

label1.grid(row=0, column=0)
label2.grid(row=0, column=1, sticky="ew")
label3.grid(row=0, column=2, sticky="ns")
label4.grid(row=0, column=3, sticky="nsew")

window.mainloop()

• Using Events and Event Handlers
• Using .bind()
• Using command

# Assume that this list gets updated automatically
events = []

# Create an event handler
def handle_keypress(event):
    """Print the character associated to the key pressed"""
    print(event.char)

while True:
    if events == []:
        continue

    event = events[0]

    # If event is a keypress event object
    if event.type == "keypress":
        # Call the keypress event handler
        handle_keypress(event)

1. maintains a list of events that have occurred
2. runs an event handler any time a new event is added to that list

import tkinter as tk

window = tk.Tk()

def handle_keypress(event):
    """Print the character associated to the key pressed"""
    print(event.char)

# Bind keypress event to handle_keypress()
window.bind("<Key>", handle_keypress)

window.mainloop()

.bind() takes at least two arguments

1. An event that’s represented by a string of the form "<event_name>"
   event_name can be any of Tkinter’s events
2. An event handler which is the name of the function to be called whenever the event occurs

def handle_click(event):
    print("The button was clicked!")

button = tk.Button(text="Click me!")

button.bind("", handle_click)

import tkinter as tk

def increase():
    value = int(lbl_value["text"])
    lbl_value["text"] = f"{value + 1}"

def decrease():
    value = int(lbl_value["text"])
    lbl_value["text"] = f"{value - 1}"

window = tk.Tk()

window.rowconfigure(0, minsize=50, weight=1)
window.columnconfigure([0, 1, 2], minsize=50, weight=1)

btn_decrease = tk.Button(master=window, text="-", command=decrease)
btn_decrease.grid(row=0, column=0, sticky="nsew")

lbl_value = tk.Label(master=window, text="0")
lbl_value.grid(row=0, column=1)

btn_increase = tk.Button(master=window, text="+", command=increase)
btn_increase.grid(row=0, column=2, sticky="nsew")

window.mainloop()

import tkinter as tk

def fahrenheit_to_celsius():
    """Convert the value for Fahrenheit to Celsius and insert the
    result into lbl_result.
    """
    fahrenheit = ent_temperature.get()
    celsius = (5 / 9) * (float(fahrenheit) - 32)
    lbl_result["text"] = f"{round(celsius, 2)} \N{DEGREE CELSIUS}"

# Set up the window
window = tk.Tk()
window.title("Temperature Converter")
window.resizable(width=False, height=False)

# Create the Fahrenheit entry frame with an Entry
# widget and label in it
frm_entry = tk.Frame(master=window)
ent_temperature = tk.Entry(master=frm_entry, width=10)
lbl_temp = tk.Label(master=frm_entry, text="\N{DEGREE FAHRENHEIT}")

# Layout the temperature Entry and Label in frm_entry
# using the .grid() geometry manager
ent_temperature.grid(row=0, column=0, sticky="e")
lbl_temp.grid(row=0, column=1, sticky="w")

# Create the conversion Button and result display Label
btn_convert = tk.Button(
    master=window,
    text="\N{RIGHTWARDS BLACK ARROW}",
    command=fahrenheit_to_celsius
)
lbl_result = tk.Label(master=window, text="\N{DEGREE CELSIUS}")

# Set up the layout using the .grid() geometry manager
frm_entry.grid(row=0, column=0, padx=10)
btn_convert.grid(row=0, column=1, pady=10)
lbl_result.grid(row=0, column=2, padx=10)

# Run the application
window.mainloop()

import tkinter as tk
from tkinter.filedialog import askopenfilename, asksaveasfilename

def open_file():
    """Open a file for editing."""
    filepath = askopenfilename(
        filetypes=[("Text Files", "*.txt"), ("All Files", "*.*")]
    )
    if not filepath:
        return
    txt_edit.delete("1.0", tk.END)
    with open(filepath, mode="r", encoding="utf-8") as input_file:
        text = input_file.read()
        txt_edit.insert(tk.END, text)
    window.title(f"Simple Text Editor - {filepath}")

def save_file():
    """Save the current file as a new file."""
    filepath = asksaveasfilename(
        defaultextension=".txt",
        filetypes=[("Text Files", "*.txt"), ("All Files", "*.*")],
    )
    if not filepath:
        return
    with open(filepath, mode="w", encoding="utf-8") as output_file:
        text = txt_edit.get("1.0", tk.END)
        output_file.write(text)
    window.title(f"Simple Text Editor - {filepath}")

window = tk.Tk()
window.title("Simple Text Editor")

window.rowconfigure(0, minsize=800, weight=1)
window.columnconfigure(1, minsize=800, weight=1)

txt_edit = tk.Text(window)
frm_buttons = tk.Frame(window, relief=tk.RAISED, bd=2)
btn_open = tk.Button(frm_buttons, text="Open", command=open_file)
btn_save = tk.Button(frm_buttons, text="Save As...", command=save_file)

btn_open.grid(row=0, column=0, sticky="ew", padx=5, pady=5)
btn_save.grid(row=1, column=0, sticky="ew", padx=5)

frm_buttons.grid(row=0, column=0, sticky="ns")
txt_edit.grid(row=0, column=1, sticky="nsew")

window.mainloop()

from tkinter import *

root = Tk()
root.geometry('700x450')

class My_widget(Frame):
    def __init__(self, parent, label_text, button_text, button_name):
        super().__init__(master = parent)

        # set up the grid
        self.rowconfigure(0, weight=1)
        self.columnconfigure((0,1), weight=1, uniform='z')

        # create widgets
        Label(self, text=label_text).grid(row=0, column=0, sticky='nsew')
        Button(self, text=button_text, command=lambda: self.change(button_name)).grid(row=0, column=1, sticky='nsew')

        self.pack(expand=True, fill='both', padx=10, pady=10)

    def change(self, name):
        root.title(name)

My_widget(root, 'Label Text 0', 'Button Text 0', 'button_0')
My_widget(root, 'Label Text 1', 'Button Text 1', 'button_1')
My_widget(root, 'Label Text 2', 'Button Text 2', 'button_2')

root.mainloop()