Re: [frogs] bend implementation

[Marc Hohl <marc@xxxxxxxxxx>]

Carl Sorensen schrieb:
> On 1/11/10 3:41 AM, "Marc Hohl" <marc@xxxxxxxxxx> wrote:
>
>   
> > I am planning to implement bends.
> >
> > The more I think about it, Carls proposal to handle bends with some kind of
> > "auto beam" mechanism is a brilliant idea.
> >     
>
> Wow, I haven't had a "brilliant" idea for years!  Thanks for the compliment.
>   
My approach was to use the left and right note and try to compute everything
correctly while somehow take care of everything happening before or after
the spanner, while you propose a more global structure which should be 
able to
take care of everything more elegantly.

Moreover, I finally have some kind of starting point: I can try to 
understand how engravers
work, especially the auto beam mechanism.
>   
> > As I can see it now, there will be two new engravers necessary:
> > 1) a pointed slur engraver which handles the normal staves
> > 2) a bend arrow engraver for the tab staves
> >     
>
> My initial thought was to have one engraver that would change its output
> depending on the context in which it was placed.  That would avoid code
> duplication.
>
> But I could see doing it the other way as well.
>   
When we can handle the whole story with one engraver, even better!
>   
> > (for a more detailed description, please visit
> >
> > http://lists.lilynet.net/tablatures/
> >
> > and have a look at
> >
> > tablature Feature Request Examples - Part 2)
> >
> > As bends are somewhat "fundamental" actions which interact with e.g. the
> > TabNoteHead, I think that besides the possibility do create engravers in
> > scheme,
> > this should be done in c++, right?
> >     
>
> I'm not sure, because I've not really understood the capabilities of the
> Scheme engravers.
>
> If I were doing it, I'd do it in c++, because I want to have some static
> variables in the engraver, and I don't know if I can do that in scheme.
>   
Ok, so I concentrate on this.
>   
> > I am not a very fast and skilled programmer, so I appreciate any kind
> > of help in this task. I am looking at the engraver sources, and while I
> > think
> > I begin to understand, I am still struggling with the fundamental concepts.
> >
> >     
>
> Me too, but I think I just learned something over the weekend when comparing
> the fretboards engraver with the tab-note-head engraver.
>
> An engraver needs to listen to events, and then it needs to process music.
> When process music is called, all of the events at that time step should
> have already been received.
>
> This doesn't sound like much, but it was a key piece I was missing.
>
> If you can ask some more specific questions, maybe we can get answers.
>
> Look at some simple engravers (fretboards, chord-name) as well as some more
> complicated engravers.  This might help you get a feel.
>   
Ok, I'll do.

Thank you

Marc


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