Guidelines for bounding boxes?

[Patrick McCarty]

Hi,

Are there any guidelines LilyPond adheres to for creating bounding
boxes?

For example, when I adjusted the bbox for the \eyeglasses markup
command, I _underestimated_ the bbox.  Should I have slightly
_overestimated_ instead?  Attached is a PNG displaying the bbox.

Also, in the case of Metafont glyphs, there doesn't appear to be a
clear convention: some bounding boxes are underestimated, but others
are overestimated.

I've attached examples of various cases.  The "longa" example uses the
glyph "noteheads.sM2neomensural".


Thanks,
Patrick

eyeglasses-bbox.png
Description: PNG image

f-clef-bbox.png
Description: PNG image

longa-bbox.png
Description: PNG image

period-bbox.png
Description: PNG image