Re: How to really center a text above a note?

[Mats Bengtsson]

A hint is to look at how the alignment is done for articulations, i.e. 
Script layout objects, where the X-offset property is the function 
script-interface::calc-x-offset defined in scm/output-lib.scm.
It doesn't work to use that function directly for TextScript objects, 
but you can probably use it as a building block or at least as 
inspiration for a similar function for TextScript objects.

I figured this out when comparing to version 2.8, where the X-offset of 
Script objects indeed was calculated using 
ly:self-alignment-interface::centered-on-x-parent and yes, I have 
already tried to just replace this by script-interface::calc-x-offset in 
the code given below, so the solution is not that simple.

   /Mats

Trevor Bača wrote:
> Second: there used to be a (somewhat more) direct way of specifying 
> the point-on-notehead to which TextScripts would make reference during 
> positioning. Here're some settings from 2006:
>
>
> %%% BEGIN X-PARENT CENTERING SNIPPET %%%
>
> \version "2.9.16"
>
> textScriptCenterOnParent = \override TextScript #'X-offset =
>
>       #(ly:make-simple-closure
>         `(,+ ,(ly:make-simple-closure (list
>  ly:self-alignment-interface::x-aligned-on-self))
>       ,(ly:make-simple-closure (list
>  ly:self-alignment-interface::centered-on-x-parent))))
>
> \new Staff {
>  \textScriptCenterOnParent
>  \override TextScript #'self-alignment-X = #left
>  c'4_\markup { MMM }
>  \override TextScript #'self-alignment-X = #center
>  c'4_\markup { MMM }
>  \override TextScript #'self-alignment-X = #right
>  c'4_\markup { MMM }
> }
>
> %%% END X-PARENT SNIPPET %%%
>
>
> These are settings that I put together in September 2006 ...
>
>    http://lists.gnu.org/archive/html/lilypond-user/2006-09/msg00088.html
>
> ... and, at that time, they worked great. See notehead-centering.png, 
> reattached here for convenience.
>
> (And I should also mention that I cobbled together the settings given 
> above by looking at the settings for OctavateEight in define-grobs.scm 
> rather blindly. But they worked great.)
>
> But running that same code now (2.13.2) produces bizarre results. See 
> weird-notehead-centering.png.
>
> So, thinking about Michael's statement here ...
>
> ML> I think the difference is that LyricTexts have NoteHeads as 
> grob-parents,
> while TextScripts have PaperColumns.
>
> ... is it possible that TextScripts *used to* have NoteHeads as 
> grob-parents (at least in 2.9.16) and have since changed to have 
> PaperColumns as grob parents, thus rendering the settings from 2.9.16 
> no longer functional?
>
> Or is something else now going that would prevent calls to 
> Self_alignment_interface::aligned_on_x_parent and centered_on_x_parent 
> from working as they did previously?
>
>
> Trevor.
>
>
> --
> Trevor Bača
> address@hidden <mailto:address@hidden>
>
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--
=============================================
        Mats Bengtsson
        Signal Processing
        School of Electrical Engineering
        Royal Institute of Technology (KTH)
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
       Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================