Re: DurationLine avoiding RehearsalMarks

[Thomas Morley]

Am Fr., 15. Apr. 2022 um 12:52 Uhr schrieb Jean Abou Samra <jean@abou-samra.fr>:
>
>
>
> Le 15/04/2022 à 11:45, Thomas Morley a écrit :
> > Am Fr., 15. Apr. 2022 um 10:39 Uhr schrieb Jean Abou Samra 
> > <jean@abou-samra.fr>:
> >>
> >>
> >> Le 15/04/2022 à 10:13, Thomas Morley a écrit :
> >>> Am Mi., 13. Apr. 2022 um 17:57 Uhr schrieb Jean Abou Samra 
> >>> <jean@abou-samra.fr>:
> >>>> Le 13/04/2022 à 17:03, Thomas Morley a écrit :
> >>>>> Am Di., 12. Apr. 2022 um 11:54 Uhr schrieb Jean Abou Samra 
> >>>>> <jean@abou-samra.fr>:
> >>>>>> Le 12/04/2022 à 11:16, Thomas Morley a écrit :
> >>>>> [...]
> >>>>>>> In many details DurationLine was tailored after Glissando and
> >>>>>>> Glissando _is_ effected by the breathing sign.
> >>>>> [...]
> >>>>>
> >>>>>> Well, if the goal is to have DurationLine similar to Glissando,
> >>>>>> how about reusing line-spanner-interface code? I haven't reviewed
> >>>>>> the code very thoroughly, but I assumed there was a difference
> >>>>>> warranting a different code path. If you put
> >>>>>> ly:line-spanner::calc-{left,right}-bound-info in
> >>>>>> DurationLine.{left,righ}-bound-info, that gives you X values for free
> >>>>>> in the bound info properties. Would that solve the problem?
> >>>>> If I go for ly:line-spanner::calc-{left,right}-bound-info then
> >>>>>
> >>>>> \layout {
> >>>>>       \context {
> >>>>>         \Voice
> >>>>>         \consists Duration_line_engraver
> >>>>>       }
> >>>>> }
> >>>>>
> >>>>> { b1\- }
> >>>>>
> >>>>> errors with
> >>>>>        "programming error: extremal broken spanner's bound has no parent
> >>>>> vertical axis group"
> >>>>> More complex examples may add:
> >>>>>        "programming error: bound item has no parent vertical axis group"
> >>>>> Both coming from `ly:line-spanner::calc-right-bound-info' based upon
> >>>>> `Line_spanner::calc_bound_info' in /lily/line-spanner.cc
> >>>>>
> >>>>> As a mere user I'd say: "Nice error-message, but why should I care...?"
> >>>>>
> >>>>> As a programmer, I doubt the example above can be made working with
> >>>>> ly:line-spanner::calc-right-bound-info.
> >>>>> At least, I don't know how.
> >>>> Oh, I'm sorry, I missed that detail of my own code. A DurationLine will
> >>>> always be horizontal, thus you can and should use
> >>>> ly:horizontal-line-spanner::calc-{left,right}-bound-info (with 
> >>>> 'horizontal'
> >>>> in the name).  The difference is that the functions without 'horizontal'
> >>>> try to compute vertical positions. This falls apart here, for 
> >>>> understandable
> >>>> reasons: the right bound of your DurationLine is a NonMusicalPaperColumn,
> >>>> so how would one tell where the line should end vertically?
> >>> Using ly:horizontal-line-spanner::calc-{left,right}-bound-info makes
> >>> for huge simplifications.
> >>> Alas, it introduces a minor and reintroduces a major problem.
> >>>
> >>> The minor: the X-value depends now on attach-dir. For the start of the
> >>> DurationLine this is ofcourse RIGHT. But if starting at a skip,
> >>> left-bound is PaperColumn there we would want LEFT. Can be fixed by
> >>> accurate conditions. Count it as done.
> >>>
> >>> The major: `ly:horizontal-line-spanner::calc-right-bound-info' and
> >>> `unbroken-or-last-broken-spanner?' (and friends) don't agree what's
> >>> the last part of the spanner.
> >>> To illustrate:
> >>>
> >>> \version "2.23.7"
> >>>
> >>> \layout {
> >>>     \context {
> >>>       \Voice
> >>>       \consists "Duration_line_engraver"
> >>>     }
> >>> }
> >>>
> >>> {
> >>>    \override DurationLine.bound-details.right.foo =
> >>>      "I am last part (bound-details)"
> >>>    \override DurationLine.bound-details.right-broken.foo =
> >>>      "I am not last part (bound-details)"
> >>>
> >>>    \override DurationLine.after-line-breaking =
> >>>    #(lambda (grob)
> >>>      (pretty-print
> >>>        (if (unbroken-or-last-broken-spanner? grob)
> >>>            "I am last part (unbroken-or-last-broken-spanner?)"
> >>>            "I am not last part (unbroken-or-last-broken-spanner?)"))
> >>>      (pretty-print
> >>>        (assoc-get 'foo (ly:horizontal-line-spanner::calc-right-bound-info 
> >>> grob))))
> >>>
> >>>    b1\-
> >>> }
> >>>
> >>> =>
> >>> "I am last part (unbroken-or-last-broken-spanner?)"
> >>> "I am not last part (bound-details)"
> >>>
> >>> The problem occurs if we have a broken DurationLine with end-items
> >>> running to the very end of the score.
> >>> To fix it one would again need something like:
> >>>
> >>> {
> >>>     \override DurationLine.bound-details =
> >>>     #(grob-transformer 'bound-details
> >>>       (lambda (grob orig)
> >>>        (if (end-broken-spanner? grob)
> >>>            (cons
> >>>              (cons 'right-broken
> >>>                (cons '(end-style . arrow) (assoc-get 'right-broken orig)))
> >>>              orig)
> >>>            orig)))
> >>>     b1\-
> >>>     \break
> >>>     s1
> >>>     \break
> >>>     s1
> >>>     \bar "|."
> >>> }
> >>>
> >>> Or like \lastEndStyle which you cleared with
> >>>
> >>> commit 46671d13257f6ad68d1778a1cc850e59116c856a
> >>> Author: Jean Abou Samra <jean@abou-samra.fr>
> >>> Date:   Wed Dec 29 00:16:46 2021 +0100
> >>>
> >>>       Fix broken spanner functions
> >>>
> >>>       They were broken (pun intended) on spanners of which one bound is a
> >>>       non-musical column at a system boundary.  For example,
> >>>       unbroken-or-last-broken-spanner? would return false on a spanner
> >>>       running to the NonMusicalPaperColumn at the end of a score.  This
> >>>       fixes the known issue with duration lines running to the end of the
> >>>       piece, and will be needed in a refactoring of spanner-placement
> >>>       treatment for balloon-interface.
> >>>
> >>>       While at it, document these functions.
> >>>
> >>> This is unfortunate. Any chance making
> >>> `ly:horizontal-line-spanner::calc-right-bound-info' and friends
> >>> identify the last spanner-part correctly, i.e. like
> >>> `unbroken-or-last-broken-spanner?'
> >>> ?
> >>
> >>
> >> Ah, this one is showing up again. Yes, this is not too hard to
> >> fix (but please allow me some time).
> >>
> > No problem.
> > If you don't mind I'll open an issue for it with the code-example above.
> > Meanwhile I found a different workaround, without the need to have the
> > apply an extra override.
> > If testings suceed, I'll upload a patch with the new code for DurationLine.
> > The workaround could be removed later easily.
>
>
> The attached patch fixes it for me.
>
> Thanks,
> Jean

Will test in the evening, real life will occupy me the afternoon.
Though, at first glance:
I fear using "unbroken-or-first-broken-spanner?" will not cover middle
part(s) of a multiple broken spanner.
Shouldn't it be "unbroken-or-not-last-broken-spanner?"
?
To be defined as:
(define-public (unbroken-or-not-last-broken-spanner? spanner)
  "Is @var{spanner} either unbroken or not the last of its broken
siblings?"
  (check-broken-spanner
   #t
   (lambda (siblings)
     (not (eq? spanner (last siblings))))
   spanner))

Though, not tested.

Thanks,
  Harm