[Peter Ahlstrom]

...Except wow, the font embedding screws up the font's character encoding. The font wasn't showing correctly, so I opened the subsetted font up in FontForge and the characters are all wacky. Characters are assigned these names:
! : carriage return
# : space
& : exclam
( : quotedbl

etc. I'm going to change the encoding of the original font and then subset it again and see what happens.

OK, I did that, and it did not help. When I opened the subsetted font in FontForge, it said the encoding was UnicodeBmp. So I took the original font and changed its encoding from Glyph Order to UnicodeBmp, then put that in my ePub and ran the plugin again. The result was exactly the same: character names still screwed up.

I don't know how to fix this, but at least now I know which characters I need for the subset, so I'm just going to do it manually in FontForge...

Note: the other Sigil plugin that subsets fonts did not have this problem, but it goes by all the characters in the whole ePub, not the spots where that particular font is actually used.

EDIT: Well, never mind that, this plugin also does not base the subsetting on where that particular font is actually used. Guess I'll just go back to my wholly manual method.