Re: Help with page breaking code

[David Kastrup]

Keith OHara <address@hidden> writes:

> David Kastrup <dak <at> gnu.org> writes:
>
>> #(define-markup-command (ugly layout props) ()
>>   (ly:make-stencil (ly:stencil-expr (interpret-markup layout props "x"))
>>    '(0 . 0) '(0 . -100)))
>
>> \markup \ugly
>> \markup *
>
> The page-breaker seems to be allowing for a markup that has something 100
> staff-spaces away from its baseline.
>
> The page-spacing seems to be doing its job, given the page-breaks, and
> realizing that \ugly actually requires no space.
>
> Page_breaking::compute_line_heights()
> looks at the individual ends of the y-extent of a line of markup, and
> uses the first line to initialize a set of variables that remember some
> things about the previous line.

That sounds to me like a problem of absolutistic tallying.  The cutters
for start of page and end of page keep separate and independent tallies
of the paper roll, and use their own tallying methods.  With -inf.0,
they don't manage resynchronizing ever.  But issue 3341
<URL:http://code.google.com/p/lilypond/issues/detail?id=3341> suggests
that resynchronization is flaky even in straightforward situations
involving forced breaks.

-- 
David Kastrup