Re: Font kerning

[David Bellows]

> making something like shelf{}full omit the ff ligature only
somewhat reliably: if there is a hyphenation pass over the paragraph in
question, TeX will create the ff ligature in the "reconstitution pass".

As an aside, the selnolig package exists for LuaTeX that automatically
removes select ligatures like with "shelfful".

On Mon, Feb 7, 2022 at 2:36 PM David Kastrup <dak@gnu.org> wrote:
>
> Valentin Petzel <valentin@petzel.at> writes:
>
> >> Am Montag, 7. Februar 2022, 22:47:30 CET schrieb:
> >>> Valentin Petzel <valentin@petzel.at> writes:
> >>> >> Am Montag, 7. Februar 2022, 21:30:21 CET schrieb:
> >>> >>> Thanks to all for your answers. The trick suggested by Valentin
> >>> >>> works for me.
> >>> >>>
> >>> >>> Anyway it looks like there’s no option to directly adjust letter
> >>> >>> spacing, something like \kern macro in LaTeX, right?
> >>> >
> >>> > No. As Lilypond is a music typesetter, not a  text typesetter, the text
> >>> > typesetting options in Lilypond are quite rudimentary. This means that
> >>> > Lilypond has no interface for these things. So kerning in Lilypond 
> >>> > markup
> >>> > usually means taking two markups and putting them next to each other 
> >>> > with
> >>> > some (potentially negative) distance.
> >>>
> >>> Which is pretty much what \kern does in TeX.  The difference between
> >>> a \kern and \hspace in TeX is that \hspace indicates a possible
> >>> breakpoint (and when a break happens there, it will get removed),
> >>> and \hspace can take flexible glue specifications.  And I am not
> >>> sure but \kern may be transparent to hyphenation.
> >>>
> >>> LilyPond's \hspace takes no flexible glue specifications and cannot
> >>> become a breakpoint either, and hyphenation is not a thing.  So I
> >>> have no idea what your "No." is supposed to mean.
> >
> > Hello David.
> >
> > TeX takes care of text output entirely by itself, while Lilypond delegates
> > this to Pango. This makes handling certain things quite a bit more awkward 
> > in
> > Lilypond. So while \hspace does work similarly to \kern it does not really
> > have the same function.
> >
> > In TeX we could for example do
> > This is a Test\kern0.2pt word
> > for what Lilypond would need
> > { This is a \concat { Test \hspace #0.1 word } }
>
> That has nothing to do with how \hspace works but rather how \line
> breaks things into pieces.  The equivalent to
> \markup { This is a Test \hspace #0.1 word }
> would be
> This is a Test \kern0.2pt\relax word
>
> \concat is LilyPond's way of omitting spaces.
>
> You'll also find that TeX's way of grouping kernable material is rather
> awkward, making something like shelf{}full omit the ff ligature only
> somewhat reliably: if there is a hyphenation pass over the paragraph in
> question, TeX will create the ff ligature in the "reconstitution pass".
>
> > Thus my "no" means to say that there is in fact not such a direct way
> > to adjust letter spacing in Lilypond.
>
> --
> David Kastrup
>