Re: Pedal gradual release

[Aaron Hill]

On 2019-01-20 4:28 am, Aaron Hill wrote:
> One option would be to exploit a Hairpin:
>
> %%%%
> sustainGradualRelease =
>   -\tweak shorten-pair #'(0 . 1.35)
>   -\tweak height #1
>   -\tweak style #'dashed-line
>   -\tweak self-alignment-Y #DOWN
>   -\tweak to-barline ##f
>   -\tweak stencil #(elbowed-hairpin '((0 . 0) (1 . 1)) #f)
>   \<
>
> sustainPedal = {
>   s4\sustainOn s s\sustainGradualRelease s s s\!\sustainOff
> }
> %%%%
>
> This is far from ideal, as a hairpin by default will attempt to align
> to the right extent of the musical column (unless the column has a
> rest, and then it aligns to the left).  The piano bracket aligns to
> the left, so setting shorten-pair is needed to have the hairpin meet
> the piano bracket.

This version calculates the correct width by pretending the hairpin is 
actually a piano pedal bracket and then customizing the stencil.  It 
also responds to the grow-direction of the hairpin so you can use it for 
gradually pressing and releasing the sustain:

%%%%
sustainGradual =
  -\tweak edge-height #'(0 . 1)
  -\tweak self-alignment-Y #DOWN
  -\tweak style #'dashed-line
  -\tweak stencil #(lambda (grob)
    (let* ((sten (ly:piano-pedal-bracket::print grob))
           (xex (ly:stencil-extent sten X))
           (yex (ly:stencil-extent sten Y))
           (cresc? (eqv? (ly:grob-property grob 'grow-direction) LEFT)))
      (ly:line-interface::line grob
        (car xex) (if cresc? (car yex) (cdr yex))
        (cdr xex) (if cresc? (cdr yex) (car yex)))))
  \etc

sustainGradualOn = -\sustainGradual \<
sustainGradualOff = -\sustainGradual \>


sustainPedal = {
  s4\sustainOn s s\sustainGradualOff s s s\!\sustainOff
  s s\sustainOn\sustainGradualOn s s\! s s\sustainOff
}
%%%%

There is an annoying alignment issue with the end of the dashed line not 
meeting the piano pedal bracket.  Still trying to track down the 
culprit.  (I suspect the piano pedal bracket itself is the one that is 
not correct.)

-- Aaron Hill