Re: \textLengthOn in polyphony and over MultiMeasureRests

[Urs Liska]

Hi Torsten,

thanks for these explanations.


Am 29.07.2018 um 19:22 schrieb Torsten Hämmerle:
> Trevor Bača-2 wrote
> > Torsten, how are you achieving the text centered above the pair of half
> > notes in the original example (ie, in the measure top-headed with
> > "Minima")? Try as I might, I can't get it!
>
> Hi Trevor,
>
> You've got me there! ;)
>
> Standard \textLengthOn will push away neighbouring notes and you won't get
> the markup text to neatly and symmetrically align with the barlines without
> some tweaking.
>
> \textLengthOn just sets the following two properties:
>
>    \override TextScript.extra-spacing-width = #'(-0.0 . 0.4)
>    \override TextScript.extra-spacing-height = #'(-inf.0 . +inf.0)
>
> By adapting extra-spacing-width, we can actually set the left and right
> "margins" of the text. This way, we can attach the TextScript to the second
> note and make it overlap the first note.
>
> Finally (this is not necessary, though) I've shifted both notes to the right
> by using extra-offset to better match the original.
>
> <http://lilypond.1069038.n5.nabble.com/file/t3887/textlength-modified.png>
>
> %%%%%%%
> {
>    \override TextScript.self-alignment-X = #CENTER
>
> % custom version of \textLengthOn:
>    \override TextScript.extra-spacing-width = #'(2.6 . 0.4)    % default:
> #'(-0.0 . 0.4)
>    \override TextScript.extra-spacing-height = #'(-inf.0 . +inf.0)
>
> % Shift NoteHead and Stem to the right
>    \override NoteHead.extra-offset = #'(5 . 0)
>    \override Stem.extra-offset = #'(5 . 0)
>
>    R1
>    \bar "||"
>    c''2 c''^\markup \line { \typewriter "#'extra-offset" "trickery" }
>    \bar "||"
> }
> %%%%%%
>
> HTH,
> Torsten

So if I see correctly this means your essentially doing a regular 
\textLengthOn that would push the neighboring notes away but prevent 
that by manually setting a "negative padding". And this has to be 
adjusted to the content around the element with the markup on it. Which 
makes it even less likely to get a decently working solution as a 
*function* that automatically determines the widths to set. I can 
imagine going through the note columns of the current system/measure and 
do some calculations, but earlier intense experiments with this area (I 
had to create manually drawn slur replacments) make be doubt that the 
width values needed for this are available at the point where I still 
can change the extra-spacing-width.

Plus: it seems this approach is problematic when more than one other 
note is in the area covered by the text (see attached PNG):

%%%%%%%
{
  \override TextScript.self-alignment-X = #CENTER
  \override TextScript.extra-spacing-width = #'(5 . 0.4)
  \override TextScript.extra-spacing-height = #'(-inf.0 . +inf.0)

  R1
  \bar "||"
  c''4 c'' c''2^\markup \line { \typewriter "#'extra-offset" "trickery" }
  \bar "||"
}
%%%%%%

Best
Urs, who is trying further ...

document.png
Description: PNG image