Hi Gilberto,
Well, I've found this :
\version "2.19.15"
beamLength =
#(define-music-function (parser location myLength) (number?)
(define (myBeamLength grob)
(let* ((beam (ly:beam::print grob))
(beam-extent-x (ly:stencil-extent beam X))
(beam-length-x (interval-length beam-extent-x))
(beam-thickness (ly:grob-property grob 'beam-thickness))
(beam-positions (ly:grob-property grob 'positions))
(mrkp (markup #:beam (* beam-length-x (+ 1 (/ myLength 100)))
0 beam-thickness))
(new-Beam (ly:stencil-translate-axis
(ly:stencil-translate-axis
(grob-interpret-markup grob mrkp) -0.025 X)
(car beam-positions)
Y))) new-Beam))
#{
\once\override Beam.stencil = #myBeamLength
#})
\relative c' {
\beamLength #10
c8[c c c c c c c]
\stemDown
%% limitation: shows only one beam
\beamLength #6
c16[c c c c c c c c c c c c c c c]
\once\override Staff.BarLine.bar-extent = #'(-7 . 2)
}
but, as you can see, it's limited to one beam... :(
Any help from schemers ?
TIA,
Pierre