On Sun, Nov 22, 2015 at 2:44 PM, David Kastrup <[email protected]> wrote:
> Thomas Morley <[email protected]> writes:
>
> > Though, why it is that arbitrary?
> >
> > Look at this variation and the attached image:
> >
> > \version "2.19.29"
> > #(define test-nmbrs
> > (let ((nmbrs (circular-list 1 2 3 4)))
> > (lambda (grob)
> > (let ((n (car nmbrs)))
> > (set! nmbrs (cdr nmbrs))
> > (grob-interpret-markup grob (number->string n))))))
> >
> > {
> > \repeat unfold 8 {
> > \once \override TextScript.stencil = #test-nmbrs
> > c''4^\markup "foo"
> > }
> > }
>
> Well, it is exactly 2 variants of 1, 2, 3, 4 each. I suspect that the
> order of grob evaluation at some point when a system is printed depends
> on the order of memory addresses.
>
> Find that point and you'll likely also have the culprit for various
> other stuff behaving non-deterministically, like what is drawn on top of
> what and other things frequently turning up in "make check".
>
>
Here's something interesting.
Setting the stencil during 'before-line-breaking or 'after-line-breaking
works for the short example that Harm provided. In longer examples,
after-line-breaking goes astray after several lines. Compare:
\version "2.19.29"
#(define test-nmbrs
(let ((nmbrs (circular-list 1 2 3 4)))
(lambda (grob)
(let ((n (car nmbrs)))
(set! nmbrs (cdr nmbrs))
(set! (ly:grob-property grob 'stencil)
(grob-interpret-markup grob (number->string n)))))))
{
\repeat unfold 200 {
%% works:
\once \override TextScript.before-line-breaking = #test-nmbrs
%% jumbling after 3 lines:
% \once \override TextScript.after-line-breaking = #test-nmbrs
c''4^\markup ""
}
}
%%%
In any case, the output of these variants is notably less screwed-up than
the original, where jumbling happens almost immediately.
My question would be: when does the evaluation of a grob's stencil normally
happen? My guess is this normal evaluation is happening based on a
haphazard input, that using 'before-line-breaking and 'after-line-breaking
is forcing a later evaluation, at a time when grobs have been better
arranged by timing.
(Please understand that this is largely a guess. I'm finding the code
incredible hard to follow.)
DN
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