User manual

pygame.display.update() So far, all the graphic elements have been drawn only virtually. But this line

restructures the graphic display genuinely. It is updated simultaneously. Therefore, you can’t see any

flickering when the individual pointers are drawn in sequence.

for event in pygame.event.get():

if event.type == QUIT or (event.type ==

KEYUP and event.key == K_ESCAPE):

mainloop = False

We are still within the if query, where once per second, the relatively performance-hungry query attempts

to detect any system events to verify whether the user wanted to close the window of the clock within the

last second or has pressed the

[Esc] key. If that is the case, the variable mainloop is set to False and the

loop will not be restarted.

pygame.quit() This last line terminates the PyGame module first, so that the graphical window closes and

then the entire application.

10 Graphical dialog fields for program control

There is no modern program that requires some interaction with the user and is running in pure text mode.

Graphical user interfaces, where you click on buttons, instead of having to enter data via the keyboard are

abundant.

Python itself has no graphical user interface for programmes, but we have got several external modules,

similar to the PyGame described earlier which are particularly meant for creating graphical interfaces. One

such modules is the famous

Tkinter

, which produces the graphical interface

for Python, and is also of use

for various other programming languages.

The structures of the graphical toolkit Tk are slightly different from Python and may look a bit unfamiliar at

first. So let’s start with a very simple example: An LED is switched on and off by buttons in a dialog box.

Components required:

1x breadboard

1x LED red

1x 220-ohm series resistor

2x connecting wire