LIS 559 July 21 Week 11

1
LIS 559 July 21 - Week 11

• Summer 2006
• Margaret Kipp
• mkipp_at_uwo.ca
• x88687
• NCB 235

2
Concepts

• Graphics
• Python graphics module Tkinter
• Namespaces
• Global Variables
• Local Variables
• Databases
• http//publish.uwo.ca/mkipp/teaching/library.mdb

3
Basic GUI Programming Tasks

• specify how you want the UI to look what the
  user will see
• decide what the UI will do how the UI will react
  to the user
• connect how the UI looks to how it works i.e.
  make the widgets react to the user's input (e.g.
  pressing a button)
• write code that waits for user input

4
Definitions

• UI
• User Interface, what the user sees, until now we
  have been writing command line UIs
• GUI
• graphical user interface accessed via a mouse or
  keyboard shortcuts, consists of icons, windows,
  entry boxes, buttons, etc.
• Widget
• an element of a GUI, can include windows, entry
  boxes, buttons, radio boxes and check boxes (and
  more)
• Container
• frame to hold widgets

5
Definitions (cont.)

• Events
• input events like mouse clicks or keyboard input
• Event Handlers
• a function that responds to events, e.g.
  responding to mouse clicks or keyboard input
• Bindings
• connects an event handler to an event associated
  with a specific widget, e.g. binding a single
  click on a close button to a closeWindow function
  that closes the window the button is in
• Event Loop
• code that waits for user input

6
Example (without graphics)

• The following example illustrates the use of an
  event loop, event handlers and binding the event
  handlers to an event (user input) all without
  using Tkinter
• http//www.ferg.org/thinking_in_tkinter/tt000.py
• This is very similar to the text based menus we
  have been writing

7
Python Graphics

• Modules
• Tkinter is a popular python graphics module
• Importing
• from Tkinter import
• this is a new form of the import statement, using
  this format we do not need to say
  Tkinter.Button() or Tkinter.Label() instead we
  can just say Button() or Label() when we want a
  button or label

8
Main Programme

• Every Tkinter programme will have at minimum the
  following lines
• from Tkinter import import the module
• root Tk() create the main window
• root.mainloop() display the main window and
  wait for input
• By itself this code doesn't actually do anything
  useful though, we need to add containers and
  widgets.

9
Widgets and Containers

• A container holds a widget or widgets.
• Containers
• Frame
• A widget is an element of a GUI like a button or
  checkbox.
• Widgets
• Label
• Button
• Entry
• Text
• Radiobutton
• Checkbox

10
Containers

• Frame is the name of the most commonly used
  container in Tkinter
• from Tkinter import
• root Tk() create the main window
• container Frame(root) create a frame and
  associate it with the main window
• container.grid() put the frame into the main
  window and make it visible
• root.mainloop() display main window and wait
  for input

11
Containers (cont.)

• Containers aren't interesting without widgets.
• Notice that the window has now shrunk down to the
  size of the title bar.
• This is because the container is empty.
• If we put widgets in it it will grow again.
• It is also possible to specify the size and title
  of the window using the following syntax
• root.geometry("200x100") this is height x width
  and it is a string
• root.title("Tkinter Test")

12
Widgets

• Widgets are objects that can be placed in a
  container (e.g. buttons)
• Each widget has attributes such as the displayed
  text, size, border, background, etc
• Each widget has a grid() function to place it in
  the frame in a specific location
• e.g. widget.grid(row0, column1)

row 0 column 0
row 0 column 1
row 1 column 0
row 1 column 1
13
Labels

• Labels
• a label is a Tkinter widget
• labels are used to display text
• label1 Label(container, text "this is a
  label") create a new label with text and
  associate it with the Frame object container
• label1.grid() make the label visible
• It is also possible to set the text later
• label1"text" "this is a label too"

14
Buttons

• Buttons
• buttons are used to accept user input
• button1 Button(container, text"Submit",
  commanddoSomething)
• button1.grid()
• command refers to the function that will be
  called when the user presses the button
  doSomething is a function you must define
• e.g. def doSomething() pass

15
Example Button Click Counter

• The following example shows the use of a label
  and a button. The button reacts to user clicks by
  counting the number of times the user has clicked
  it.
• http//publish.uwo.ca/mkipp/teaching/buttonclick.
  py
• Note the update_count function that simply
  increments the counter keeping track of the
  clicks and updates the label on the button.

16
Entry

• Entry
• entry widgets are used to accept user input, they
  are single line
• entry1 Entry(container) create a new text
  entry box and associate it with the Frame object
  container
• entry1.insert(0, "This is an entry box.") use
  END for the end of the entry box
• entry1.grid() make the entry box
• userinput entry1.get() gets the value

17
Example Text Entry Field

• The following example shows the use of a label
  and a button. The button reacts to user clicks by
  counting the number of times the user has clicked
  it.
• http//publish.uwo.ca/mkipp/teaching/entryfield.p
  y
• Note the getName function that simply gets the
  value in the Entry field and prints it.

18
Text

• Text
• text widgets are used to accept user input, they
  are multiline
• text1 Text(container) create a new text entry
  box and associate it with the Frame object
  container
• text1.insert(END, "This is some text.")
• text1.grid() make the text box visible
• text1.get(index1, index2) gets all text between
  index1 and index2
• text1.see() moves to the end

19
Radiobutton

• Radiobutton
• radiobuttons are used to accept user input, only
  one can be selected at a time
• radio1 Radiobutton(container, text"Yearly",
  variablefrequency, value"Yearly",
  commanddoSomething).grid(row3, column1)
• Like a button, radiobuttons have an associated
  function (doSomething) they also have an
  associated variable which is set when the user
  selects it.

20
Checkbox

• Checkbox
• checkboxes are used to accept user input,
  multiple checkboxes can be selected
• check1 Checkbutton(container, text"Books",
  variablelikesBooks, commanddoSomething)
• check1.grid(row4, column1)
• Like a radiobutton have an associated function
  (doSomething) also have an associated boolean
  variable which is set when the user selects it.

21
Some Attributes

• Widgets have common attributes
• background"green" (or bg)
• borderwidth2
• height10
• highlightbackground"red"
• highlightcolor"yellow"
• highlightthickness3
• reliefsunken (sunken, flat, raised)
• width30
• font(('MS', 'Sans', 'Serif'), '8')
• and many more...
• http//www.pythonware.com/library/tkinter/introduc
  tion/

22
Example User Survey

• The following example demonstrates a very simple
  user survey.
• http//publish.uwo.ca/mkipp/teaching/usersurvey.p
  y
• This survey illustrates the use of radiobuttons,
  checkboxes, entry fields and buttons.

23
Example Database Access GUI

• The following example is a simple graphical
  interface to an MS Access database.
• http//publish.uwo.ca/mkipp/teaching/queryDB.py
• Notice the combination of the graphics code and
  the database access code.