Re: SMuFL name mapping update, 9 July

[Owen Lamb]

On 7/10/2021 9:38 PM, Werner LEMBERG wrote:
> > > * Regarding `noteheads.uM2`, I don't see a problem with removing the
> > >     hard-coded stems.
> > That's good to hear.  If we do, though, we'll have to reconcile
> > breve/longa sidebars with Lily's customizable stems.  I'm thinking
> > we keep our breve glyphs for SMuFL compatibility, but in LP itself
> > we draw breves and longas as noteheads.s0 with primitive sidebars.
> You mean with ligatures?

No--maybe I didn't explain very well.

If we're going to remove our longa glyphs, we'll need to find a new way 
to draw them. The first possible solution would be to draw a font's 
breve notehead, then add a primitive stem to it the way we do for all 
other stemmed notes (which is a primitive drawing, not a glyph, so not a 
ligature). This, however, is a recipe for ugliness: a particular breve 
glyph's hardcoded sidebars are hardly guaranteed to line up with every 
possible custom LilyPond stem. (This issue is probably why we've 
hard-coded longa stems in the first place.)

To that end, I suggest drawing not only stems, but also the sidebars of 
longas, as well as breves for consistency, as primitive lines by default 
(again, not glyphs, so not ligatures). noteheads.s0 would serve as the 
notehead glyph for longas, breves, and semibreves. noteheads.sM1 would 
become unused by default, although we can certainly keep it around for 
SMuFL compatibility. For those SMuFL fonts that involve stylized breve 
sidebars, we should allow something like \useBreveGlyphs to override the 
new default behavior.

And... as I ramble on about this, it occurs to me that this should 
probably be handled as a totally separate enhancement issue. SMuFL 
doesn't care about longas, so we might as well give our longa "notehead" 
glyphs custom names for now and leave any feature enhancements (i.e. 
custom longa stems) for another day. I keep trying to overcomplicate 
things...

> By the way, it certainly makes sense in the forthcoming documentation
> of the LilyPond → SMuFL mapping to describe which glyphs are only
> approximations based on similar shapes, and which ones are truly
> identical.  In other words, please preserve all comments, probably
> augmented with links to discussions, etc., etc.  It seems that this
> project deserves a small database...
Noted. I'll see about restoring the failed matchups I deleted and go 
from there. (Thank goodness for Git!)

Owen