Tkinter

As with most other modern Tk bindings, Tkinter is implemented as a Python wrapper around a complete Tcl interpreter embedded in the Python interpreter. Tkinter calls are translated into Tcl commands, which are fed to this embedded interpreter, thus making it possible to mix Python and Tcl in a single application. The official Python release uses Tcl/Tk 8.6 (rather than the more up-to-date 9.0).

There are several popular GUI library alternatives available, such as Kivy, Pygame, Pyglet, PyGObject, PyQt, PySide, and wxPython.

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()

Widget

The generic term for any of the building blocks that make up an application in a graphical user interface.

• Core widgets:
  • Containers:
    • frame
    • labelframe
    • toplevel
    • paned window.
  • Buttons:
    • button
    • radiobutton
    • checkbutton (checkbox)
    • menubutton.
  • Text widgets:
    • label,
    • message
    • text
  • Entry widgets:
    • scale
    • scrollbar
    • listbox
    • slider
    • spinbox
    • entry (singleline)
    • optionmenu
    • text (multiline)
  • Canvas (vector and pixel graphics)

Tkinter provides three modules that allow pop-up dialogs to be displayed: tk.messagebox (confirmation, information, warning and error dialogs), tk.filedialog (single file, multiple file and directory selection dialogs) and tk.colorchooser (colour picker).

Python 2.7 and Python 3.1 incorporate the "themed Tk" ("ttk") functionality of Tk 8.5. This allows Tk widgets to be easily themed to look like the native desktop environment in which the application is running, thereby addressing a long-standing criticism of Tk (and hence of Tkinter). Some widgets are exclusive to ttk, such as the combobox, progressbar, treeview, notebook, separator and sizegrip.

Frame

In Tkinter, the Frame widget is the basic unit of organization for complex layouts. A frame is a rectangular area that can contain other widgets.

Child and parent

When any widget is created, a parent-child relationship is created. For example, if you place a text label inside a frame, the frame is the parent of the label.

Below is a minimal Python 3 Tkinter application with one widget:

#!/usr/bin/env python3 from tkinter import * root = Tk() # Create the root (base) window w = Label(root, text="Hello, world!") # Create a label with words w.pack() # Put the label into the window root.mainloop() # Start the event loop

For Python 2, the only difference is the word "tkinter" in the import command will be capitalized to "Tkinter".

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.