Re: Undesired MultiMeasureRest X position when clef change at end of measure

[Owain Evans]

> On 11 Oct 2020, at 16:33, Thomas Morley <thomasmorley65@gmail.com> wrote:
> 
> Am Sa., 10. Okt. 2020 um 16:14 Uhr schrieb Owain Evans <owaine1@live.com>:
>> 
>> Hi Bug-Lily,
>> 
>> MultiMeasureRest and  "clef change at end of measure" events in different 
>> staffs but same measure: undesired MultiMeasureRest X position.
>> 
>> MultiMeasureRest needs to be centered in this case.
>> I.e. The rest's centring between the two barlines presides over the addition 
>> of the clef symbol.
>> 
>> Gould p. 160: says "When the rest bar contains a clef, key signature or time 
>> signature, place the rest at the centre of the remaining blank space.
>> 
>> 
>> \version "2.20.0"
>> {
>>  \new StaffGroup
>>  <<
>>    \new Dynamics { s1-great s1-no s1-great s1-great }
>>    \new Staff  \relative c'' { \clef bass R1 \clef treble | g4 f e d \clef 
>> bass | c,,1 | R1 | }
>>    \new Staff  \relative c'' { R1 | R1 | R1 \clef bass | R1 | }
>>>> 
>> }
>> 
>> I am correcting this with:
>>        \once \override score.MultiMeasureRest.X-offset = 1.5 %but ofcourse 
>> varies
>> 
>> Many thanks,
>> 
>> Owain Evans
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> 
> Hi Owain,
> 
> per default left/right spacing of a MultiMeasureRest (MMR) is done
> according to left/right break-alignment (a clef change belongs to it).
> This is done score-wide, thus the spacing of MMRs is equal for all of
> them even if only in one Staff a clef change happens.
> 
> You can affect this by overriding the spacing-pair-property:
> 
> work-around =
> \once \override MultiMeasureRest.spacing-pair = #'(staff-bar . staff-bar)
> 
> {
>  \new StaffGroup
>  <<
>    \new Dynamics { s1-great s1-fixed s1-great s1-great }
>    \new Staff
>      \relative c'' {
>            \clef bass R1 \clef treble | g4 f e d \clef bass | c,,1 | R1 |
>      }
>    \new Staff
>      \relative c'' { R1 | \work-around R1 | R1 \clef bass | R1 | }
>>> 
> }
> 
> Alas, I'm undecided whether it's a bug or not, look at the output of:
> 
> <<
>  \new Staff { R1 R \clef bass R }
>  \new Staff { R1 \work-around R R }
>>> 
> 
> The MMRs don't line up, no surprise. Though, I seem to remember some
> users prefer this, but other users want the MMRs to be aligned.
> And we have the demonstrated and documented override to fulfill both wishes.
> Admittedly the documentation is poor and hard to find, perhaps we
> should created a snippet in NR or at least i Documentation/snippets
> 
> Cheers,
>  Harm

Hi Harm,

I appreciate your time on this.
Your solution with a constant variable is the way.
I would put `Score` in the work-around, i.e.:

work-around =
\once \override Score.MultiMeasureRest.spacing-pair = #'(staff-bar . staff-bar)

as the two rests are not vertically aligned otherwise.

I would always centre these rests and ignore the space created by the clef (my 
first example of “great” I’d now say “no”).
It’s much more noticeable on shorter measure lengths i.e. 2/4 vs 4/4

I think it is best not left as a bug, but this left in the searchable archive. 
It’s more flexible and less opinionated. And especially that there are already 
different opinions.

My reasoning is looking through scores, they are not consistent at all. I even 
found a 1930s Durant edition convention on irregular time signatures of 7/4 
where the rest placement is deliberately off centre (unless a typo error).

But please understand my logic for a staff event (clef change) to affect a 
score event (MMR) of perhaps multiple staffs, just seems up-side-down.

but sincere thanks,

Owain