Re: vcenter help

[James E. Bailey]

Am 15.08.2008 um 19:36 schrieb Neil Puttock:

> 2008/8/15 James E. Bailey <address@hidden>:
>
> > Thanks, I think I've got a hang of it, (I was actually looking for
> > \hcenter), but now I have another question. Is there any situation  
> > where
> > \center-align and \hcenter are exclusive? Aside from \hcenter needing
> > \column, I couldn't find any difference.
>
> They're completely unrelated; \hcenter doesn't `need' column, it's
> used to align an object to its centre *relative* to another object.

Ah, okay, that makes sense.
> The example for \hcenter in B.8.2 uses \column as a convenience to
> show the alignment relative to the arrow.
When I try it without the column, they aren't centered (assuming I  
wanted to superimpose to markup objects on top of each other).

> > \markup {
> > \hcenter \column {
> >   { "One line of text." }
> >   { "Another line of text." }
> > }
> > }
>
> This doesn't work, since \hcenter comes before \column; it has no
> reference point to work with. If you swap them round, this behaves
> just like \center-align.
Yes, I knew that, I just switched them as I was typing it.

And I think I've figured it out. \center-align aligns all object along  
the center axis. \hcenter aligns an objects center axis to the left  
axis of the reference point.
\markup {
  \column {
    one
    \hcenter
    two
    three
  }
}

Can I suggest this (or something similar) be the example for B.8.2? It  
expresses very clearly, using terms from a previous example exactly  
how \hcenter differs from \center-align.