Xianino: Experiment in microtonality without leaving your keyboard!

==Introduction==

In its current state Xianino is configurable only though python code.
You will need to modify xianino.py to change the midi output device,
key mappings or scale. In a future addition I hope that these parameters
will be accesible through the interface at runtime. This project was
inspired by an email request for help using FretFind from a blind 
Russian microtonalist named Eugene. An ideal GUI for Xianino would be 
usable via screen readers and other accessibility tools. 

==Architectural Overview==

Scale
A Scale is a callable object that transforms a scale step or index 
into a frequency. There are currently two implementations of Scale
included in Xianino: ETScale and ScalaScale. ETScale produces an
equal temperament scale (dividing the octive into equal steps).
ETScale(12) produces a common 12 tone ET scale. ScalaScale allow 
much more flexibilty in specifying the scale steps. Please refer
to the Scala documentation for the scale syntax. The Scala website
also provides a large library of scale files for your use.
http://www.huygens-fokker.org/scala/scl_format.html

MidiBrain
The MidiBrain object manages all MIDI communication. An output device
must be selected for use. The MidiBrain object responds to requests
to play a frequency. It chooses a MIDI channel that is not currently
producing sound and tunes the channel using pitch bend messages so
that the channel is able to produce the requested frequency. If no
channel is avalable it raises a NoFreeChannel exception. When it 
receives a request to silence a frequency it returns the channel back
to the usable pool. This method of microtonal tuning is widely 
compatible but it limits the available poliphony.

Piano
A Piano object handles user interaction turning key presses into
frequencies and sending requests to the MidiBrain object. Two 
implementations of Piano are available with Xianino, TKPiano and 
PGPiano, which utilize Tkinter and Pygame respectively. Piano
objects have two important configurable attributes: keys and 
scale. Piano.scale should be set to a Scale object as described
above. Piano.keys should be assigned a character string representing
playable keys. Order of the keys in the string translates to the index
passed to the Scale object. Using these to attributes it is possible 
to assign arbitrary frequencies to keys on the keyboard.

==Examples==

Assign whole available keyboard to the notes of the 12tet scale A=440

piano.keys = '''zxcvbnm,./asdfghjkl;'qwertyuiop[]\`1234567890-='''
piano.scale = ETScale(12, 25.5)

Assign two 12 tone scales that vary slightly
one to the Z key row (as white keys with black keys in the A key row above)
another to the W key row (similarly)

scale = '''two 12 tone chromatic scales
25
100.
200.
300.
400.
500.
600.
700.
800.
900.
1000.
1100.
1200.
0.
112.
204.
316.
386.
498.
590.
702.
814.
884.
996.
1088.
1200.'''
piano.scale = ScalaScale(scale, 55.0)
piano.keys = 'zsxdcvgbhnjm,w3e4rt6y7u8io'

Three major scales extracted from 12tet, 19tet and 31tet respectively

scale = '''3 major scales (12tet, 19tet and 31tet)
23
200.
400.
500.
700.
900.
1100.
1200.
0.
189.473684210526
378.947368421053
505.263157894737
694.736842105263
884.21052631579
1073.68421052632
1200.
0.
193.548387096774
387.096774193548
503.225806451613
696.774193548387
890.322580645161
1083.87096774194
1200.'''
piano.scale = ScalaScale(scale, 55.0)
piano.keys = 'zxcvbnm,asdfghjkqwertyui'

Assign the alphabet keys to play the notes of the alphabet song

scale = '''alphabet song
25
0.
700.
700.
900.
900.
700.
500.
500.
400.
400.
200.
200.
200.
200.
0.
700.
700.
500.
400.
400.
200.
700.
500.
400.
200.'''
piano.scale = ScalaScale(scale, 55.0)
piano.keys = 'abcdefghijklmnopqrstuvwxyz'