Re: Need help documenting Text alignment

[Mats Bengtsson]

Valentin Villenave wrote:
> Greetings,
>
> I'm having a hard time trying to properly document the markup
> alignment properties, can anyone give me a hand?
>
> It takes place here:
> http://kainhofer.com/~lilypond/Documentation/user/lilypond/Text-alignment.html
>
> - \center-align works differently from \right-align, does it?
>   
Perhaps it's time to continue the thread from 
http://lists.gnu.org/archive/html/bug-lilypond/2006-01/msg00163.html ?
> - what's the difference between \center-align and \column?
>   
\column is left aligned. More precisely, \column aligns each line on its 
own alignment point, see below.
> - what is \dir-column for?
>   
I hope you have looked at the implementation file for the markup 
commands, scm/define-markup.scm.
It seems that the documentation string for this particular markup 
command contains also an example,
which for some reason does not appear in Appendix B.6.2. As you can see 
there, it's identical to \column,
except that you can specify the stacking direction.
> - what is \hcenter for? is it like \hcenter-in without padding?
>   
It sets the horizontal alignment point. Example:
\relative{
c''^\markup{\column{I \left-align Left I \hcenter Center I \right-align 
Right I }}
}

> - what are \halign and \general-align for?
>   
\halign generalize \left-align, \hcenter and \right-align.
\general-align is even more general and can set both vertical or 
horizontal alignment.
See 
http://lists.gnu.org/archive/html/lilypond-user/2007-02/msg00656.html 
for one
explanation of why it can be useful (you can also view it as a feature 
request to include
commands also for vertical bottom and top alignment).
> - does \hspace take vertical space as well?
>   
From the implementation, it seems to extend from -1 to 1, which 
explains some of the
vertical alignment issues that have appeared on the mailing list over 
the years.
> - is \null equivalent to \hspace #0?
>   
No, \null doesn't have any vertical extent.
> - what's is \pad-x for? (difference with the other pad-* commands?)
>   
Isn't the documentation fairly clear? You just pad in the horizontal 
direction but keep the
vertical extent as it is.
> I'd welcome examples too -- if any of you has enough time to help me.
>   
Searching the mailing list archives (and LSR code) should bring up some 
examples for most
of the commands.

   /Mats