Re: \parenthesize script on cross-staff-beamed note fails

[Thomas Morley]

2015-08-15 15:45 GMT+02:00 Thomas Morley <address@hidden>:
> 2015-08-15 14:22 GMT+02:00 Malte Meyn <address@hidden>:
>> Am 15.08.2015 um 10:43 schrieb Malte Meyn:
>>>
>>> Hi list,
>>>
>>> in the following example, the \parenthesize command doesn’t respect the
>>> width of the parenthesized script (same problem for other scripts like
>>> fermata).
>>>
>>> %%%%%%%%%%%%%%%%%%%
>>> \version "2.19.25"
>>>
>>> <<
>>>    \new Staff = "upper" {
>>>      s4
>>>    }
>>>    \new Staff {
>>>      b16-\parenthesize-> b b
>>>      \change Staff = upper
>>>      b
>>>    }
>>>  >>
>>> %%%%%%%%%%%%%%%%%%%
>>>
>>> Malte
>>>
>> Problem: \parenthesize uses ly:relative-group-extent to compute the X-extent
>> of the accent (see output-lib.scm). This function looks for the cross-staff
>> property and ignores all things that have this set to true
>> (axis-group-interface.cc).
>>
>> According to the internals reference 3.2.45 (grob-interface) the cross-staff
>> property is used for things that have a Y-extent that depends on inter-staff
>> spacing. So why are cross-staff things ignored in general and not only when
>> a == Y_AXIS in Axis_group_interface::relative_maybe_bound_group_extent?
>
>
> ly:relative-group-extent can't be the single problem.
> In the snippet below I redefined it.
>
> All instances of
> programming error: Improbable offset for stencil: inf staff space
> are fixed then and the visual output is ok, but
> programming error: Grob direction requested while calculation in progress.
> stil occurs - loads more of same kind, if I add other stuff.
>
> \version "2.19.25"
>
> #(define (ly:relative-group-extent elements common axis)
>   "Determine the extent of elements relative to common in the axis direction."
>   (let* ((elts
>             (cond
>               ((ly:grob? elements) (list elements))
>               ((ly:grob-array? elements) (ly:grob-array->list elements))
>               ((every ly:grob? elements) elements)
>               (else '())))
>          (exts
>         (map
>           (lambda (g) (ly:grob-extent g common axis))
>           elts))
>          (ext
>            (reduce
>          interval-union
>          (car exts)
>          (cdr exts))))
>     ext))
>
> %% c/p from output-lib.scm to provide
> %% a compilable snippet
> #(define (parenthesize-elements grob . rest)
>   (let* ((refp (if (null? rest)
>                    grob
>                    (car rest)))
>          (elts (ly:grob-array->list (ly:grob-object grob 'elements)))
>          (get-friends
>            (lambda (g)
>              (let ((syms (ly:grob-property g 'parenthesis-friends '()))
>                    (get-friend (lambda (s)
>                                  (let ((f (ly:grob-object g s)))
>                                    (cond
>                                      ((ly:grob? f) (list f))
>                                      ((ly:grob-array? f)
> (ly:grob-array->list f))
>                                      (else '()))))))
>                (apply append (map get-friend syms)))))
>          (friends (apply append elts (map get-friends elts)))
>          (x-ext (ly:relative-group-extent friends refp X))
>          (stencils (ly:grob-property grob 'stencils))
>          (lp (car stencils))
>          (rp (cadr stencils))
>          (padding (ly:grob-property grob 'padding 0.1)))
>     (ly:stencil-add
>      (ly:stencil-translate-axis lp (- (car x-ext) padding) X)
>      (ly:stencil-translate-axis rp (+ (cdr x-ext) padding) X))))
>
> %% adding a color for indication purpose
> %% otherwise c/p from output-lib.scm
> #(define-public (parentheses-item::print me)
>   (let* ((elts (ly:grob-object me 'elements))
>          (y-ref (ly:grob-common-refpoint-of-array me elts Y))
>          (x-ref (ly:grob-common-refpoint-of-array me elts X))
>          (stencil (parenthesize-elements me x-ref))
>          (elt-y-ext (ly:relative-group-extent elts y-ref Y))
>          (y-center (interval-center elt-y-ext)))
>     (ly:stencil-translate
>      (stencil-with-color stencil red)
>      (cons
>       (- (ly:grob-relative-coordinate me x-ref X))
>       (- y-center (ly:grob-relative-coordinate me y-ref Y))))))
>
> <<
>   \new Staff = "upper" {
>     s4
>   }
>   \new Staff {
>     \override ParenthesesItem.stencil = #parentheses-item::print
>     b16-\parenthesize->-3 b b
>     \change Staff = upper
>     b
>   }
>>>
>
>
>
> Cheers,
>   Harm

Only thing I've found to circumvent
programming error: Grob direction requested while calculation in progress.
is to use \voiceXxx and sometimes adding direction-indicators:

<<
  \new Staff = "upper" {
    s4
  }
  \new Staff {
    \override ParenthesesItem.stencil = #parentheses-item::print
    \voiceOne
    b16-\parenthesize _> _- -3 b b
    \change Staff = upper
    \voiceTwo
    b
  }
>>