Re: Lyrics break estimation of vertical spacing

[Joe Neeman]

On Wed, 2010-03-24 at 16:08 -0400, Boris Shingarov wrote:
> > The skylines are used as part of VerticalAlignment, to figure out how
>   > far apart the children of VerticalAlignment (ie. VerticalAxisGroups for
>   > staves, lyrics, etc) need to be. Once we compute the translations of the
>   > children of VerticalAlignment, we can compute the height of
>   > VerticalAlignment (and thus the height of System). 
>  
> I understand that this is the general idea how it is supposed to be. 
> What happens in reality, is that pure_height() of the VerticalAxisGroup,
> calling ly:hara-kiri-group-spanner::y-extent in Scheme land,
> calling back Hara_kiri_group_spanner::pure_height(), ultimately
> ends up in Axis_group_interface::cached_pure_height(). 
> That function, unite()'s the begin_of_line_pure_height() and
> the rest_of_line_pure_height(),
Right, but in align-interface.cc:118, we throw away that unite()d extent
in favour of a begin_of_line_extent and a rest_of_line_extent.

> which are simply measured from
> the middle line of the staff, no translations.
Right, the positions of the staff lines relative to each other are not
yet computed, so each extent is relative to its own staff.

Cheers,
Joe