Fixing LSR 888: center-on-words ignoring punctuation

[Alexander Kobel]

Hi all,

yet another semi-feature request where I'm running out of knowledge...
I happily used LSR 888 (center lyrics without taking punctuation into 
account) for years and only now found out that the alignment is off 
under certain circumstances: The default algorithm seems to align lyrics 
on the center of the note*head* of the associated voice. Which seems the 
right thing to do. However, center-on-words aligns on the center of the 
*entire note* - in particular, this yields different results on quavers 
with stems up and "outward flags". At least, neither dots nor 
accidentals are taken into account...

Even more ugly, the alignment is totally off on chords with two adjacent 
notes (shifting one note). I know that this should be a forbidden 
situation for vocal music, but sometimes there is a reason for writing 
such chords instead of two separate voices (e.g., soprano and alto 
notated on a common staff in a homorhythmic piece, with one of the 
voices splitting for a cluster on just a few notes).
In such a rare case, I do not like the default algorithm's choices 
either (and I'd prefer alignment on the center of the noteheads of the 
chord); but center-on-words does even /way/ worse.

I attach a "test case" (including a full copy of the core of 
http://lsr.di.unimi.it/LSR/Snippet?id=888), where one would expect 
center-on-words to do exactly nothing, but you can notice the slight 
offsets on the "nonius scale" of lyrics.

Anyone got an idea where to start to fix that? I think one would have to 
figure how to get the note-column-extent without flags; but I have no 
clue how to approach that.


Thanks in advance,
Alexander

center-on-words-alignment.ly
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