Issue 1127 in lilypond: Piano staff centred dynamics

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Enhancement Priority-Low Bounty

New issue 1127 by PhilEHolmes: Piano staff centred dynamics
http://code.google.com/p/lilypond/issues/detail?id=1127

Alexander Kobel, Kieren MacMillan and others have requested the ability to  
centre dynamics accurately between the piano staves.  Alexander has offered  
a 50 Euro bounty and Kieren has offered to supplement this.

This "solution" was suggested by Kieren:

"After thinking about it a bit, it seems to me that the current (*wicked
awesome*, BTW) skyline coding could come to the rescue here...  =)

IMO, the ultimate algorithm for a piano-with-centered-dynamics situation
might be as follows:

1. At any given point requiring a dynamic/hairpin, the grob-box containing
the dynamic/hairpin is inserted between the skylines of the two surrounding
Staff contexts.

2a. If this insertion can be done without the dynamic/hairpin box touching
either skyline, the two Staff contexts remain unaffected.
2b. If the dynamic/hairpin grob-box touches either skyline, the lower Staff
context is pushed down until the grob-box no longer (or just barely)  
touches the skylines.
[In other words, this context would be "super-skylined" or "flatline-able",
with a minimum height of 0 where a Staff context has a minimum height of 4.]

3a. The dynamic/hairpin grob-box #'padding would be user-settable.
3b. There would also be a setting (default = ##f) which would force all
dynamic grob-boxes within a single system to be aligned on the same  
vertical axis."