Tkinter Lesson 1 Notes: Graphical User Interfaces

• Some basics
  • Python uses the Tkinter module to make graphical user interfaces
  • Before you can make a GUI, you must import Tkinter.
  • A GUI can be created interactively in IDLE (and is a lot of fun to watch)
• Starting Out
  from Tkinter import *
root = Tk()
# creates an instance / object of class Tk
root.title("My Title")
# displays a nice title on the window
root.mainloop()
# keeps displaying the window until we kill it.
  • You can name the instance of Tk() anything you want, but "root" seems to be a standard convention for the main window.
  • Creating an instance of the Tk() class makes a window.
  • The root.mainloop() command is needed for programs not run from within IDLE. If you add this to the end of a program run in IDLE it will hang. If you don’t add this to a program run outside of IDLE, the window will flash on, then disappear.
• Short List of Tk() Methods
  • x = Tk()
    Creates an object (or instance) of class Tk. This makes your initial "master" window.
  • x.title('Text here')
    Displays a title in the top of the window frame
  • x.mainloop()
    Sets up a processing loop for catching changes on the screen
  • x.destroy()
    Destroys the window.
• Putting Widgets in Windows
  • An item inside a window is called a widget
  • To add a widget to a window:
    • Create a widget (label, button, entry box, etc.)
    • For each widget, designate the master window it belongs to.
    • Finally, send the widget to a geometry manager to be placed in the window.
  • These steps can be done on a single line, but for clarity we will break it up.
• Creating Widgets
  • Widgets are classes.
  • Tkinter has a number of defined widget classes, including:
    Label, Button, Entry, Menu, Checkbutton, Radiobutton, Message, Text, Canvas, Scrollbar
  • To create a new widget, assign an instance to the widget class. The first argument must always be the name of the master window root = Tk()
widget1 = Label(root)
widget2 = Button(root)
• The grid() Geometry Manager
  • This lesson uses the grid() geometry manager.
  • A geometry manager is responsible for arranging the different widgets in a window.
  • When grid() is invoked without any arguments, it places each new widget on a new row by itself.
  • No widget will appear in the window until it is properly sent to the geometry manager
  • To send a widget for grid() to place in the window, type the widget name and then grid() btn = Button(root, text = “Enter”)
btn.grid()
• A Label() Widget
  from Tkinter import *
  root = Tk()
  lbl = Label(root, text = "Howdy")
  #note that "Label()" is capitalized
  # the first argument must be the name of the master window to which the label belongs
  lbl.grid()
  # grid is our geometry manager. We are telling grid to add the label to the window.
  root.mainloop()
  # The mainloop() keeps the window open and running until we kill it.
  # If you are running in IDLE, do not add the mainloop() line.
  
  
• A Button() Widget
  from Tkinter import *
  root = Tk()
  btn = Button(root, text = "Click Me")
  #note that "Button()" is capitalized
  # The first argument must be the name of the master window it belongs to.
  btn.grid()
  root.mainloop()
  
  
  • Note that this button does not do anything except look like a button. We'll make it useful in a later lesson.
• The state Option
  • state = NORMAL
  • Designates whether the widget is ACTIVE, NORMAL, or DISABLED.
  • A DISABLED widget cannot be clicked or edited
  • Note that the option is in all caps and is not a string.
  • btn = Button(root, text = "No Way", state = DISABLED)
btn.grid()
• An Entry() Widget
  from Tkinter import *
  root = Tk()
  a-label = Label(root, text = "Name: ")
  name = Entry(root, width = 30)
  # Entry creates a line to type text
  # width sets how wide the line is
  a-button = Button(root, text = "Enter")
  a-label.grid()
  name.grid()
  a-button.grid()
  root.mainloop()
  
  
• Hiding Entry() Text
  • show = "x"
  • An option for Entry() that hides what the users types, displaying instead the character you choose.
  • password = Entry(root, show = “*")
password.grid()
• Standard Widget Options
  • Since Label(), Entry(), and Button() are all subclasses of the Widget class, they inherit some common properties.
  • The following are options that can be used with any of these widgets.
  • To use an option, include it in the () when you first create the object.
• Widget Color Options
  • background = 'color'
  • bg = 'color'
  • foreground = 'color'
  • fg = 'color'
  • highlightcolor = 'color'
  • highlightbackground = 'color'
  • bg and fg are abbreviations for "background" and "foreground"
  • Colors may be entered as keyword names ('red', 'blue', 'gray80', etc.) or hex codes (#FF0000)
  • Gray colors can be called as percents. gray80 is 80% gray, which is darker than gray50 (50% gray).
  • Color names are not case sensitive
  • A list of named colors is here.
• relief Options
  • relief = RAISED
  • Determines type of border around a widget
  • Choices are: RAISED, SUNKEN, FLAT, RIDGE, GROOVE, and SOLID
  • Note the value uses all caps and is not a string
  • In the sample, the relief is applied to a Label() widget
  • Label(root, relief = RAISED)
• border Options
  • borderwidth = 2
  • Sets the width of the border
  • Abbreviated bd
  • In the sample, the border is applied to a Label widget with solid relief.
  • Label (root, relief = SOLID, borderwidth = 2)
  • Label (root, relief = SOLID, bd = 2)
• justify Option
  • justify = CENTER
  • Sets the alignment of text in the widget
  • Options are LEFT, RIGHT, and CENTER
  • Note the option is in all caps and is not a string.
  • Entry(root, justify = CENTER)
• font Option
  • font = (‘name’, size, ‘extra’)
  • First argument is the name of the font. This argument is not case sensitive.
  • Second argument is the font size
  • If ‘italic’ or ‘bold’ is desired, enter those words as the last arguments
  • If font does not exist, default font will be used.
  • Label(root, text = “Hello”, font = (“Arial”, 12, “bold”))
    
• Sample Code:
  from Tkinter import *
  root = Tk()
  root.title("A Rigged Quiz")
  q_test = “What is your favorite \n subject at school?”
  question = Label(root, text = q_text, font = ('Lucida Handwriting', 14), fg = 'blue')
  question.grid()
  answer1 = Button(root, text = "Programming")
  answer1.grid()
  answer2 = Button(root, text = "Math", state = DISABLED)
  answer2.grid()
  answer3 = Button(root, text = "Science", state = DISABLED)
  answer3.grid()
  answer4 = Button(root, text = "English", state = DISABLED)
  answer4.grid
  root.mainloop()
  # Do not include the last line if running in IDLE