Re: Issue 1228 in lilypond: \override RestCollision #'positioning-done = #merge-rests-on-positioning

[lilypond]

Comment #1 on issue 1228 by wbsoft: \override RestCollision  
#'positioning-done = #merge-rests-on-positioning
http://code.google.com/p/lilypond/issues/detail?id=1228

This file, merge-rests.ily, implements merging of simultaneous rests and  
multi-measure rests.

It works only for two voices (but this is acceptable and documentable).

The normal rest merging is as in LSR #336, I added support for multimeasure  
rests using the following algorithm:
- for every MMRest, record the StaffSymbol and the NonMusicalPaperColumn  
the MMrest resides in, on the moment 'Y-offset is requested.
- if there is already a MMRest found in this StaffSymbol and  
NonMusicalPaperColumn, delete that one and return 0
- if there wasn't a MMRest in this StaffSymbol and NonMusicalPaperColumn,  
store this one and return the default value from  
ly:staff-symbol-referencer::callback

I use a weak key hash so the storage will be gc'ed as soon as the staff  
symbol is gc'ed. the hash is enclosed in a (let ()) expression outside the  
function body so the global namespace is not polluted.

It seems to work well on some files I tested it on. The usage is documented  
in the file. Please give feedback as this is my first try at some more  
complicated Scheme stuff. :-)



Attachments:
        merge-rests.ily  4.2 KB