Lab Exercise 9
- Download widget_demo.py and HelloGui.py from the usual
place and run them. Read the code and make sure you understand how it
works. widget_demo.py demonstrates the basic use of widgets.
HelloGui.py demonstrates the usual structure of an interface that
inherits from Gui. It also displays an object diagram and a
class diagram that demonstrate the relationships among the objects
and classes you will be working with.
- Download MyWorld.py from the usual place. It is an example
of how you can use inheritance to customize the behavior of
existing classes without having to modify the original. This module
contains three class definitions:
- extends TurtleWorld and overrides setup,
allowing you to customize the Gui features for the World.
- extends Turtle, although at the moment it
doesn't override anything.
- extends TurtleControl and overrides
setup, again so you can customize the Gui features for the turtle.
As usual, you should read over the code and make sure you understand
- The purpose of this lab exercise is to encourage you to play
around and get familiar with the GUI elements in Tkinter. You
might find it useful to try the following exercises, although you
don't have to do them all.
You can also experiment with rearranging the widgets, but for now you
probably don't want to spend much time adjusting their layout or
appearance. We will play with the geometry manager more next week.
- Add a button to MyWorld.setup that draws an item on
the canvas when it is pressed.
- Copy the draw method from Turtle into MyTurtle
and then modify it so that your Turtles look different from those
- Add a new method to the MyTurtle class, like dance,
and then add a button to the MyTurtleControl panel so that
when the button is pressed, it invokes the new Turtle method.
- While you are at it, modify your Turtles so that their `pen
color' is their current color.
- Add an entry to the Turtle control panel and put the integer
1 into it. Then modify the Turtle so that when it moves, it draws
a line with the line width specified in the entry.
- Add up and down buttons that increment and decrement the
contents of the line width entry.
- Replace the pen up and pen down buttons with a single
check button that controls whether the pen is down.
- Replace the menubutton that controls the turtle color with
a sequence of radiobuttons or a listbox.