[kln2-devel] PianoKeyboard,NameButtonsBox,BaseMusicNote

[Marek W. <Mar...@fu...>]

Hi e-body.

I just wanted to let you all know, that I did some major changes
in the kln2. Parts which have already been there were almost not
modified, so what you are working on should be little affected
(although will have to be modified in future to get full
advantage of the changes). Please, report any problems.

===========================

First of all, I included a new class BaseMusicNote. This holds
many static functions for conversion of e.g. a form with
note+accidental to midi pitch, returning number of the note in
octave (0 for ANY C, 1 for ANY C# or Db and so on), returning
QString of a note name dependent on "enum Notation {English,
German}" and things like this. Extra methods of this kind will
have to be added in future. Please, for any such a conversion
needed, add a new method into BaseMusicNote.

I think we needed such an abstraction of a music note. Current
'Note' class is too much connected to staff canvas picture. And
many abstract note properties were scattered all through the
code.

==========================

Another change affects the structure of the code very much. Now,
let's think about future exercises. They re-use the same kinds
of widgets.

Example:
There is now a note-to-name exercise : you see a note in the
staff, and you choose it's name from namebuttons.

But there will be e.g. note-to-fret exercise : you see a note in
the staff (so the staff canvas is used again) and you should
find an appropriate PieceOfFret (a one-note place on the fretboard).

And there may be a fret-to-name exercise: you see a PieceOfFret
highlighted (fretboard reused) and should choose appropriate
namebutton (namebuttons reused).

Basically, what I am trying to say is : there will be only few
different elements just used in different configurations. In the
form in which it is written now it would be quite hard to
implement. The nameButtons, the staff canvas etc. are direct
properties of KLearnNotes2 class. Therefore, their
initialization makes the code quite complicated (anybody who
read KLearnNotes2 constructor knows, it takes a pen and a big
piece of paper to figure out which layout corresponds to which
widgets and where it is placed in the main window). This makes
any modifications quite complicated. Plus, all the elements have
to know about each other: did you noticed, that one of arguments
of ClickableView constructor is ...  KLearnNotes2* ??? And it
runs KLearnNotes2 class methods directly!  (grep for
"papcio->isStarted()"). I guess this is one of the best
candidates for the bottle of wine contest (do you remember my
introductory kln2-devel e-mail? :) .

Nope, that's not the way things should be done.
* All self contained elements should be extracted into separate
  classes (NameButtonBox, Staff, PianoKeyboard, GuitarFretboard
  etc.).
* They should not run each other methods directly; rather, they
  should emit signals informing about what an user is doing and let
  the exercise setup decide how to react on this (that is, to
  which slots of which objects connect these signals).

OK. So I did it for the two simplest examples: PianoKeyboard and
NameButtonBox. I also added examples of these to the
KLearnNotes2 constructor, so that you could see how they are
used (see the attached screenshot). I DO NOT INTEND TO KEEP THEM
DISPLAYED THIS WAY. This is added temporarily just to show you
what's new.

What to look at?
First of all, look at the end of KLearnNotes2 constructor. The
PianoKeyboard and NameButtonBox are created, added and set up
(signals are connected to some slots) just in few lines of code!
What a difference compared to the complicated setup of the old
buttons/canvas ! Basically, everything that deals with placement
of buttons/piano keys (="everything messy") is done in the
PianoKeyboard and NameButtonBox classes.

Second thing: you will see in standard output info about all
signals emitted (just click on the piano keys/nameButtons). As
you see, they are much more detailed than what is really used
right now, so more detailed user action handling will be quite
easy too.

And the third thing: new files musicwidget.{h,cpp} and
modifications of KLNfancywidgets.{h,cpp} are examples of usage
of BaseMusicNote class.

==========================

This is the very crude first version of the new classes. If you
look at the code you will see that many methods are not written
yet (they are just "{}"). RandomObject stuff should be handled
within the classes.  Also, I didn't write comments for all the
methods/members yet.

~Marek

PS: For those with slow i-net connection: updating
    Makefile.am  basemusicnote.cpp  klearnnotes2.cpp  musicwidget.h
    Makefile.in  basemusicnote.h    musicwidget.cpp
    KLNcanvasitems.cpp KLNcanvasitems.h KLNfancywidgets.cpp
    KLNfancywidgets.h globals.h
and, because of recent Mo's commits:
    klearnnotes2.h
in src/ should be enough.

-- 

     \/   /|\  Marek Wieckowski
  #####  | | |
 = . . =  \|/  Institute of Theoretical Physics
    U      |   Warsaw University
  / ~ \___ |
 <|   |    |
  > . <    |   http://www.fuw.edu.pl/~wiecko
 <<___>>   |   http://klearnnotes2.sourceforge.net