"""
This program demonstrates Python GUI using tkinter.
Input:
None
Output:
None
Global variables:
root (tkinter.root): top-level window
text_table tkinter.Text: prints Hello World.
References:
https://www.tutorialspoint.com/python/python_gui_programming.htm
https://www.python-course.eu/python_tkinter.php
https://wiki.python.org/moin/EscapingHtml
"""
from tkinter import *
root = None
text_table = None
def create_root():
"""Creates top-level window.
Args:
None
Returns:
None
Modifies:
global root
"""
global root
root = Tk()
root.title("Example")
def create_canvas():
"""Creates fixed size canvas.
Args:
None
Returns:
None
"""
canvas = Canvas(root, height=100, width=300)
canvas.pack()
def create_button_print():
"""Creates text - print button.
Args:
None
Returns:
None
"""
button = Button(
root, text="Print Hello World !!!", font=("Helvetica", 8),
command=lambda: display_text()
)
button.place(relx=0.07, rely=0.1, relheight=0.2, relwidth=0.35)
def create_button_clear():
"""Creates text - clear button.
Args:
None
Returns:
None
"""
button_clear = Button(
root, text="Clear Screen", font=("Helvetica", 8),
command=lambda: text_table.destroy()
)
button_clear.place(relx=0.62, rely=0.1, relheight=0.2, relwidth=0.3)
def create_exit_button():
"""Creates exit button.
Args:
None
Returns:
None
"""
button = Button(
root, text="Exit", font=("Helvetica", 8), command=root.destroy
)
button.place(relx=0.72, rely=0.65, relheight=0.2, relwidth=0.2)
def display_text():
"""Creates text table..
Args:
None
Returns:
None
Modifies:
global text_table
"""
global text_table
text_table = Text(root, font=("Helvetica", 12), fg='blue', bd=5)
text_table.insert(END, "Hello World !!!")
text_table.pack(side=RIGHT)
text_table.place(relx=0.08, rely=0.6, relwidth=0.38, relheight=0.30)
def main():
"""Main function of the program"""
create_root()
create_canvas()
create_button_print()
create_button_clear()
create_exit_button()
root.mainloop()
if __name__ == "__main__":
main()
