Re: vim :hardcopy equivalent

[G. Branden Robinson]

At 2024-07-24T10:15:47+0200, me.groff@mro.name wrote:
> to keep it simple I went without macros and figured out the commands
> from https://www.gnu.org/software/groff/manual/groff.html without
> further help.

I'm glad the manual proved adequate here!  I've spent several years
attempting to improve it for our users.

> For now I may go with https://mro.name/2024/brief-dina4.roff
> 
> Having an automatic header line on subsequent pages would be a plus,
> but isn't worth to RTFM e2e.

groff's Texinfo manual covers that too.

The subsection/node "Page Location Traps" discusses how to do this and
offers a simple example of the setup and use of header and footer traps.

I'll reproduce the material (in "info" format) from my working copy
here.  I think it's pretty close to what's in groff 1.23.0's manual (and
therefore what's on the GNU website), but there may be improvements or
corrections here--I can't remember, since there have been over 1,300
commits to groff Git since 1.23.0 was released.


5.28.1.1 Page Location Traps
............................

A "page location trap" is a vertical position trap that applies to the
page; that is, to undiverted output.  Many can be present; manage them
with the 'wh' and 'ch' requests.

 -- Request: .wh dist [name]
     Plant macro NAME as page location trap at DIST.  The default
     scaling unit is 'v'.  Non-negative values for DIST set the trap
     relative to the top of the page; negative values set the trap
     relative to the bottom of the page.  It is not possible to plant a
     trap less than one basic unit from the page bottom: a DIST of '-0'
     is interpreted as '0', the top of the page.(1)  (*note Page
     Location Traps-Footnote-1::) An existing _visible_ trap (see below)
     at DIST is removed; this is 'wh''s sole function if NAME is
     missing.

     A trap is sprung only if it is "visible", meaning that its location
     is reachable on the page(2) (*note Page Location
     Traps-Footnote-2::) and it is not hidden by another trap at the
     same location already planted there.

     A macro package might set headers and footers as follows; this
     example configures vertical margins of one inch to the body text,
     and one half-inch to the titles.  Observe the use of the no-break
     control character with 'sp' request to position our text baselines,
     and the page number character '%' used with the 'tl' request.

          .\" hdfo.roff
          .de hd                  \" page header
          '  sp .5i
          '  tl '\\*(Ti''\\*(Da'  \" title and date strings
          '  sp .5i
          ..
          .de fo                  \" page footer
          '  sp .5i
          .  tl ''%''
          .  bp
          ..
          .wh 0   hd             \" trap at top of the page
          .wh -1i fo             \" trap 1 inch from bottom

     To use these traps, copy the above (or load it from a file with the
     'so' or 'mso' requests), then set up the strings it uses.

          .so hdfo.roff
          .ds Ti Final Report\"
          .ds Da 21 May 2023\"
          .ti
          On 5 August of last year,
          this committee tasked me with the investigation of the
          CFIT (controlled flight into terrain) incident of
          .\" ...and so on...

I notice now that those claims about the margin sizes might be off by
one vee; in my experience, a "margin" measures an extent of whitespace
(or "negative space"), whereas the `sp` request positions the _text
baseline_, and since glyphs are nearly always drawn at least in part
_above_ the text baseline, text formatted at a vertical position of 0.5i
from the top of the page actually encroaches into a "top margin" of one
half-inch.

Often that's a fairly subtle point, but when trying to format a document
to a national standard, it's important to use precise measurements, lest
ruler-wielding enforcers come around to rap one's knuckles.

So I will review this material for correctness.

Let me know if this was of assistance, and if I can offer more.

Regards,
Branden

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