Python Programming for Biology: Bioinformatics and Beyond

26

Graphical interfaces

Contents

An introduction to graphical user interfaces

Widgets and graphics libraries

GUI construction

Python GUI examples

Using Tkinter

Using Python Qt

An introduction to graphical user interfaces

At some stage when writing your own programs there may come a time when you want

others to be able to use what you have created without them necessarily having to know

anything  about  programming  or  Python.  Should  this  happen  the  next  step  is  to  consider

writing  a  more  friendly  interface  to  the  program.  Once  upon  a  time  in  computing

everything  was  text-based  and  the  user  had  to  type  commands  to  get  things  to  work.

Fortunately things have moved on and we are now usually presented with graphics and a

pointing device, either a mouse or a touch screen, and the user can interact with graphical

objects like menus and buttons.

When  building  a  graphical  user  interface  (GUI)  the  programmer  must  be  mindful  of

various factors, which are sometimes antagonistic, forcing us to make compromises. For

example,  the  designer  has  to  strike  a  balance  between  on  the  one  hand  giving  lots  of

functionality and on the other hand keeping things simple for novices and intuitive to use.

In  this  chapter  we  will  aim  to  give  some  general  advice  about  the  programming,  but  we

leave  you  to  make  the  tough  choices.  We  wish  to  be  clear  that  this  chapter  deals  with

making graphical interfaces that run on the users’ local computer. We will not venture into

the  world  of  Internet-based  applications,  although  these  are  becoming  increasingly

important, and the Pyjamas library,

1

which is available for Python programmers, works in

a remarkably similar way to the graphical libraries discussed here.