Tkinter

Definitions

from tkinter import *

def calculate():
    price = float(entry_price.get())
    qty = float(entry_qty.get())
    total = price * qty
    label_result.config(text="Total: " + str(total))

app = Tk()
app.title("Facturation App")

Label(app, text="Prix").pack()
entry_price = Entry(app)
entry_price.pack()

Label(app, text="Quantité").pack()
entry_qty = Entry(app)
entry_qty.pack()

Button(app, text="Calculer", command=calculate).pack()

label_result = Label(app, text="")
label_result.pack()

app.mainloop()

Process

There are four stages to creating a widget

Create

Create it within a frame

Configure

Change the widget's attributes.

Pack

Pack it into position so it becomes visible. Developers also have the option to use .grid() (row=int, column=int to define rows and columns to position the widget, defaults to 0) and .place() (relx=int or decimal, rely=int or decimal, define coordinates in the frame, or window).

Bind

Bind it to a function or event.

These are often compressed, and the order can vary.

Simple application

Using the object-oriented paradigm in Python, a simple program would be (requires Tcl version 8.6, which is not used by Python on MacOS by default):

#!/usr/bin/env python3
import tkinter as tk


class Application(tk.Frame):
    """Application holds state for the whole app."""
    def __init__(self, root=None):
        tk.Frame.__init__(self, root)
        self.grid()
        self.createWidgets()

    def createWidgets(self):
        self.medialLabel = tk.Label(self, text="Hello World")
        self.medialLabel.config(bg="#00ffff")
        self.medialLabel.grid()
        self.quitButton = tk.Button(self, text="Quit", command=self.quit)
        self.quitButton.grid()


app = Application()
app.root = tk.Tk()
app.root.title("Sample application")
app.mainloop()

• line 1: Hashbang directive to the program launcher, allowing the selection of an appropriate interpreter executable, when self-executing.
• line 2: Imports the tkinter module into your program's namespace, but renames it as tk.
• line 5: The application class inherits from Tkinter's Frame class.
• line 7: Defines the function that sets up the Frame.
• line 8: Calls the constructor for the parent class, Frame.
• line 12: Defining the widgets.
• line 13: Creates a label, named MedialLabel with the text "Hello World".
• line 14: Sets the MedialLabel background colour to cyan.
• line 15: Places the label on the application so it is visible using the grid geometry manager method.
• line 16: Creates a button labeled “Quit”.
• line 17: Places the button on the application. Grid, place and pack are all methods of making the widget visible.
• line 20: The main program starts here by instantiating the Application class.
• line 21: Creates main window app.root as a Tk object.
• line 22: This method call sets the title of the window to “Sample application”.
• line 23: Starts the application's main loop, waiting for mouse and keyboard events.