Re: Double-underline markup

[Thomas Morley]

Am Sa., 19. Okt. 2019 um 14:45 Uhr schrieb David Kastrup <address@hidden>:
>
> Thomas Morley <address@hidden> writes:
>
> > Am Sa., 19. Okt. 2019 um 13:35 Uhr schrieb David Kastrup <address@hidden>:
> >>
> >> Thomas Morley <address@hidden> writes:
> >
> >> > Iiuc, you recommend to fix \underline to make it work with most simple
> >> > input like:
> >> >
> >> > \markup {
> >> >   \override #'(offset . 12) \underline
> >> >   \override #'(offset . 10) \underline
> >> >   \override #'(offset . 8) \underline
> >> >   \override #'(offset . 6) \underline
> >> >   \override #'(offset . 4) \underline
> >> >   "underlined"
> >> > }
> >> >
> >> > I'll have a look.
> >>
> >> No, to have it work with most simple input like
> >>
> >> \markup
> >>   \underline
> >>   \underline
> >>   \underline
> >>   \underline
> >>   \underline
> >>   "underlined"
> >
> > Ok, understood. I'll give it a try...
>
> I mean, I might well be too naive about this.  If the underline is
> occuring in a fixed position with regard to the baseline, there are only
> a few obvious avenues to have multiple underlines work:
>
> a) change the baseline.  That's not really acceptable when mixing
> underlined and non-underlined text
> b) change a property (akin to offset but probably unique to \underline
> to avoid unexpected interactions) for the sake of additional
> underline calls.  That would result in the _innermost_ \underline call
> ending up lowest.
> c) somehow affect bounding box/outline in a manner that can be
> interpreted for moving the whole next underline to a different position
> while retaining the baseline.  That's sort of the handwavy "do magic"
> option that may or may not be workable at all.
>
> --
> David Kastrup

I first tried to tackle the increasing widths of subsequent calls of
\underline and observed a so far not mentioned problem:
\underline increases the width of the returned stencil, so that
word-space adds its value to the _increased_ borders. This is better
visible with increased thickness:

\markup
  \column  {
    \line
      \override #'(thickness . 10)
      \override #'(offset . 7)
        { This is a \underline underlining test }
    \line { This is a \underline underlining test }
  }

See attached image (the experimental code used there is not mature yet
and thus not posted here, p.e. appropriate y-offset is not coded)

The spacing of words looks uneven with default underline.
With the experimental code word-space is not affected, but the line
extends into this space.

Admittedly this is all more obvious with (very) thick lines, which is
likely a rare use-case.

Anyway, should I accept the uneven spacing or the lines sticking into
the space, provided by word-space?

I'd very much appreciate opinions



Thanks,
  Harm

atest-92-underline.png
Description: PNG image