Re: Bug? Accidentals from tied notes having stencils that occupy space

[Thomas Morley]

2018-04-02 19:21 GMT+02:00 Stefano Troncaro <address@hidden>:
> Hi everyone,
>
> I've experienced that in certain situations, when notes with accidentals are
> tied, the accidental grobs have stencils that seem to be hidden (not shown
> but occupy space) which creates very awkward spacing.
>
> I made this snippet to showcase this:
>>
>> \version "2.19.80"
>> \language "english"
>>
>> \paper {
>>   ragged-right = ##t
>> }
>>
>> %Tied accidentals have the same placement as the untied ones,
>> %even though that with ties there should be less grobs occupying space
>> \score {
>>   \relative c'' {
>>     <cs gs>1 <es cs gs cs,> \break
>>     <cs gs>~ <es cs gs cs,> \break
>>     <es cs>~ <es cs gs cs,> \break
>>     <cs cs,>~ <es cs gs cs,> \break
>>   }
>> }
>>
>> %Checking that there are accidental grobs for each notehead
>> \score {
>>   \relative c'' {
>>      <cs cs,>~
>>     \override Accidental.before-line-breaking =
>>     #(lambda (grob)
>>        (pretty-print grob))
>>     <es cs gs cs,>
>>     %Output:
>>     %#<Grob Accidental >
>>     %#<Grob Accidental >
>>     %#<Grob Accidental >
>>     %#<Grob Accidental >
>>     %Showing there are 4 accidental grobs instead of only the required 2
>>   }
>> }
>>
>> %Deleting the tied accidentals "fixes" placement, shouldn't this be
>> default?
>> \score {
>>   \relative c'' {
>>      <cs cs,>~
>>     \override NoteColumn.before-line-breaking =
>>     #(lambda (nc)
>>        (let* ((nhds (ly:grob-array->list (ly:grob-object nc 'note-heads)))
>>               (accs
>>                 (filter ly:grob?
>>                   (map
>>                    (lambda (nhd)
>>                      (ly:grob-object nhd 'accidental-grob))
>>                    nhds)))
>>               (stils
>>                (list
>>                  ly:accidental-interface::print
>>                  #f
>>                  ly:accidental-interface::print
>>                  #f)))
>>          (for-each
>>           (lambda (acc stil)
>>             (ly:grob-set-property! acc 'stencil stil))
>>           accs
>>           stils)))
>>     <es cs gs cs,>
>>   }
>> }
>>
>
> I'm fairly confident that the accidental grobs shouldn't be taking up space
> in those cases. But maybe this is intended by design and I'm failing to see
> it's use.
>
> So, is this a bug?



Hi,

in general I'd agree calling it a bug of type ugly.

Looking for an even worse example I found:

chrd = < cis~ dis~ eis~ fis gis~ ais~ bis >1
\relative c' { \chrd q }

Though, according to common type-setting rules accidentals of tied
notes have to be repeated at line-start.

chrd = < cis~ dis~ eis~ fis gis~ ais~ bis >1
\relative c' { \chrd \break q }

This _is_ correct!
So it should be clear that simply deleting accidental-stencils via
'before-line-breaking is not the way to go.

I observed the following interesting behaviour.
If you set
AccidentalPlacement.positioning-done = ##t
i.e. don't let Lilypond place the accidentals, only _two_ accidentals
are printed.
Uncommenting the break will print all accidentals, as wished.


chrd = < cis~ dis~ eis~ fis gis~ ais~ bis >1
\relative c' {
  \chrd
  %\break
  \override Staff.AccidentalPlacement.positioning-done = ##t
  q
}

Ofcourse now no placement happens and all clashes.
Also this means it doesn't matter, whether accidental-grobs or their
stencils are present or not.
Rather that the default-procedure, i.e.
ly:accidental-placement::calc-positioning-done should be improved,
imho.


Cheers,
  Harm