PyFLTK - an underrated gem for GUI projects

aum aum at
Mon Nov 7 01:23:40 CET 2005

Hi all,

I've been doing a fair bit of python gui programming on and off, jumping
between different widget sets along the way, from anygui, to pythoncard,
to tkinter/PMW, then to wxPython/wxGlade, and have now settled on a python
gui API that seems to get barely a mention - PyFLTK.

PyFLTK ( is a SWIG-generated Python
wrapper around the multiplatform FLTK widget set ('Fast Light Tool Kit'
- In recent months, this wrapper has
stabilised to the point where it's fit for production projects.

A recent development that's given PyFLTK even more power is the
companion utility program, 'flconvert', which takes gui layout files
(created with the FLTK 'fluid' gui designer program) and turns them into
importable Python modules that Simply Just Work.

Every widget set has its place, and I feel this applies in no small part
to PyFLTK.

To me, wxPython is like a 12-cylinder Hummer, with fuzzy dice hanging
from the mirror, fridge and microwave in the back, and DVD consoles on
every seat, towing a campervan - absolute power and luxury, giving 8mpg
if you're lucky.

wxPython has the cost of a massive disk and memory footprint. A 'hello,
world' turned into a windoze exe with py2exe weighs in at around 15MB,
and takes 6-10 seconds to load up on a 2GHz Athlon box, about as long as
Photoshop! For large and intricate apps, wxPython is a logical choice,
but for smaller progs it's serious overkill IMHO.

Whereas PyFLTK feels more like an average suburban 4-door sedan giving
70mpg, nothing too flash, but easy to drive, easy to park and generally
comfortable, and easy to look after. The widget set is pretty simple,
but covers all the basics and includes good rich-text features in
listboxes, as well as an html viewer that supports html2.0 and parts of

Some of the things I'm liking about PyFLTK include:
 - way less code to get things done
 - some nice automagic, for instance in setting up tiling (similar to
   wx's splitter windows)
 - an absolute minimum of 'voodoo programming' (which was a constant
   bugbear for me with tkinter)
 - apps compile small, and start up fast
 - a really good designer program - fltk's 'fluid' program is light
   years ahead of wxglade imho

Also, FLTK's intuitive, semantically clear API makes it really
approachable for newcomers. One can write a 'hello, world' in 5 lines:

  import fltk
  label = "something here" # to stop string being gc'ed
  w = fltk.Fl_Window(100, 100, 300, 200, label)

So I hope this humble message might inspire some folks to have a serious
look at pyfltk. For many situations, PyFLTK can take you to break-even
point quickly, and deliver net savings in time and effort after that.



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