Re: Why is NonMusicalPaperColumn.line-break-system-details.extra-offset "upside down"?

[Jean Abou Samra]

Le 01/01/2022 à 21:30, Kieren MacMillan a écrit :
> Hi all,
>
> (Happy New Year!)
>
> Is there a logical reason that for most tweaks negative extra-offset values 
> move the associated grob vertically lower on the page, but with 
> NonMusicalPaperColumn.line-break-system-details it moves the associated system 
> *higher* on the page?
>
> I offer it would be better if extra-offset had a consistent behaviour/effect.


Within a system, positive Y offsets move higher because
that is how we humans tend to think. However, page spacing
all works with Y offsets going down. That might be a little
more convenient a convention because systems are placed with
increasing Y offsets. It's easy to fix the direction of the
Y part of paper systems' extra-offsets ...

diff --git a/scm/page.scm b/scm/page.scm
index 01c167c6e2..d4807ab189 100644
--- a/scm/page.scm
+++ b/scm/page.scm
@@ -249,7 +249,7 @@ of layout settings just like markups inside the music"
                  (extra-offset (ly:prob-property system 'extra-offset 
'(0 . 0)))
                  (x (+ (ly:prob-property system 'X-offset 0.0)
                        (car extra-offset)))
-                 (y (+ (ly:prob-property system 'Y-offset 0.0)
+                 (y (- (ly:prob-property system 'Y-offset 0.0)
                        (cdr extra-offset)))
                  (is-title (paper-system-title?
                             system)))


... but it is trickier to design a convert-ly rule to
fix existing user files.

Regards,
Jean