Outline

• Introduction to GUI and Tkinter
• Basics about Tkinter
• grid for Tkinter
• a temperature conversion application

GUI

• GUI stands for graphical user interface.
• Tkinter is a popular python GUI, which is the standard Python interface to the Tcl/Tk GUI toolkit.
  • Tcl: (Tool Command Language) is a very powerful but easy to learn dynamic programming language, suitable for a very wide range of uses, including web and desktop applications, networking, administration, testing and many more.
  • Tk: is a graphical user interface toolkit that takes developing desktop applications to a higher level than conventional approaches. Tk is the standard GUI not only for Tcl, but also for other applications.
• Advantage of Tkinter:
  • Tkinter is most likely already installed in a recent version of Python
  • A vast collection of well known widgets are available in Tkinter, including all the most common ones like buttons, labels, checkboxes etc.
  • Code to each widget is straightforward

Basics about Tkinter

• package: tkinter
• initialize a window object from the Tk class.
• use the mainloop() to maintain the window open
• the rest of the widget code should be inside of the following chunk of code

from tkinter import *

window = Tk()
window.title("My first GUI progrom")
window.minsize(width=500, height=800)

window.mainloop()

label

• pack is one of the layout, which packs widgets relative to the earlier widget.

# Label
my_label = Label(text="I am a Label", font = ("Arial", 24, "bold"))
my_label.pack()
# my_label.pack(side = "left")
# my_label.pack(side = "bottom")
# my_label.pack(expand = True)

my_label["text"] = "New Text"
my_label.config(text="New Text")

entry

input = Entry(width = 10)
input.insert(END, string="Some text to begin with.")
input.pack()
print(input.get())

button

def button_clicked():
    new_text = input.get()
    my_label.config(text=new_text)

button = Button(text = "Click Me",command = button_clicked)
button.pack()

text

#Text
text = Text(height=5, width=30)
#Puts cursor in textbox.
text.focus()
#Adds some text to begin with.

text.insert(END, "Example of multi-line text entry.")
#Get's current value in textbox at line 1, character 0
print(text.get("1.0", END))
text.pack()

Spinbox (optional)

def spinbox_used():
    #gets the current value in spinbox.
    print(spinbox.get())
spinbox = Spinbox(from_=0, to=10, width=5, command=spinbox_used)
spinbox.pack()

Scale (optional)

def scale_used(value):
    print(value)
scale = Scale(from_=0, to=100, command=scale_used)
scale.pack()

Checkbutton (optional)

def checkbutton_used():
    #Prints 1 if On button checked, otherwise 0.
    print(checked_state.get())
#variable to hold on to checked state, 0 is off, 1 is on.
checked_state = IntVar()
checkbutton = Checkbutton(text="Is On?", variable=checked_state, command=checkbutton_used)
checked_state.get()
checkbutton.pack()

Radiobutton (optional)

def radio_used():
    print(radio_state.get())
#Variable to hold on to which radio button value is checked.
radio_state = IntVar()
radiobutton1 = Radiobutton(text="Option1", value=1, variable=radio_state, command=radio_used)
radiobutton2 = Radiobutton(text="Option2", value=2, variable=radio_state, command=radio_used)
radiobutton1.pack()
radiobutton2.pack()

Listbox (optional)

def listbox_used(event):
    # Gets current selection from listbox
    print(listbox.get(listbox.curselection()))

listbox = Listbox(height=4)
fruits = ["Apple", "Pear", "Orange", "Banana"]
for item in fruits:
    listbox.insert(fruits.index(item), item)
listbox.bind("<<ListboxSelect>>", listbox_used)
listbox.pack()

layout

• pack():
  • relative to the earlier widget
• place():
  • specify the exact coordinate
• grid(): (recommended)
  • flexible, relative coordinate

place

from tkinter import *

window = Tk()
window.title("My first GUI progrom")
window.minsize(width=500, height=800)
window.config(padx=100, pady = 100)

# Label
my_label = Label(text="I am a Label", font = ("Arial", 24, "bold"))
my_label.pack()
my_label.config(padx=100, pady = 100)

my_label["text"] = "New Text"
my_label.place(x=0,y=0)

grid

• grid() locates widgets in a two dimensional grid using row and column absolute coordinates.

grid

from tkinter import *

window = Tk()
window.title("My first GUI progrom")
window.minsize(width=500, height=800)
window.config(padx=100, pady = 100)

# Label
my_label = Label(text="I am a Label", font = ("Arial", 24, "bold"))
# my_label.pack()
my_label.config(padx=100, pady = 100)

my_label["text"] = "New Text"
my_label.grid(column=0, row=0)

grid

• button

def button_clicked():
    new_text = input.get()
    my_label.config(text=new_text)

button = Button(text = "Click Me",command = button_clicked)
# button.pack()
button.grid(column=1, row=1)

• entry

input = Entry(width = 10)
input.insert(END, string="Some text to begin with.")
# input.pack()
input.grid(column=2, row=2)

print(input.get())

Temperature converter

• formula:

\[(F − 32) × 5/9 = C\]

\[(32°F − 32) × 5/9 = 0°C\]

• example output:

• code:
  • https://caleb-huo.github.io/teaching/code/temperature_converter.py

Reference

• https://docs.python.org/3/library/tkinter.html
• https://www.udemy.com/course/100-days-of-code/