Re: Stem.stem-begin-position not giving desired output on beamed stems (tablature)

[Thomas Morley]

Hi Carl,

2016-12-14 8:14 GMT+01:00 Carl Williams <address@hidden>:
> Hi Everyone,
>
> First time using a mailing list.
> I've raked through the documentation pages all today and yesterday (and 
> learnt a lot), but still couldn't solve this.
>
> So I want to create (ukulele) tablature where all the stems and beams are 
> above the staff.
> I use the \override Stem.stem-begin-position to set the unbeamed stems above, 
> but I think it aught to affect the beamed stems too (they are stems too after 
> all!). bug?

I don't think so.
If I understand correctly, beamed stems are not really calculated on
their own, but mostly rely on the calculations of the beam.
Thus you need to make some effort to have it work.

> Does anyone know any workarounds?

Maybe something at the lines of:

\version "2.18.2"

testFunc =
#(define-music-function (parser location beg-end-beam-pos)(list?)
"Takes a list containing values for
- the stem-start in Y-direction
- the stem-length
- the positions of a possible beam.
TODO: The relationship between those values currently escapes me.
      It should be possible to calculate the beam-positions, if the other values
      are known.
"
#{
  \stemUp
  \override Beam.after-line-breaking =
   #(lambda (grob)
     (let ((stems (ly:grob-array->list (ly:grob-object grob 'stems))))
       (ly:grob-set-property!
         grob 'positions (cons (last beg-end-beam-pos) (last beg-end-beam-pos)))
       (for-each
         (lambda (stem)
           (ly:stem::calc-stem-begin-position stem)
           (ly:grob-set-property!
             stem 'length (second beg-end-beam-pos))
           (ly:grob-set-property!
             stem 'stem-begin-position (first beg-end-beam-pos)))
         stems)))
  \override Stem.stem-begin-position = #(first beg-end-beam-pos)
  \override Stem.length = #(second beg-end-beam-pos)
#})

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXAMPLES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

{
  \testFunc #'(5 6 5.25)
  c''8[ d'']
  c''16[ d'']
  c''32[ d'']
  \autoBeamOff
  c''8 d''16 e''32
}


\new TabStaff \with {
  stringTunings = #ukulele-tuning
} {

  \relative c' {
      \testFunc #'(4.6 5 4.75)
    \tabFullNotation
    r8 g'\4 c,4 e2 |
    a1 |
    g8\4 c, e a c,[ c] a'8 a |
  }
}

2016-12-15 1:24 GMT+01:00 Carl Williams <address@hidden>:
> I think the original issue of Stem.stem-begin-position not working for 
> beamed-stems should be fixed. If it's not a bug, I call it a feature request.
>

Probably.
Added as
https://sourceforge.net/p/testlilyissues/issues/5012/

Cheers,
  Harm