Re: drawing commands have no impact on diversion height

[Steve Izma]

On Thu, Jun 08, 2023 at 08:30:53PM -0500, G. Branden Robinson wrote:
> Subject: Re: drawing commands have no impact on diversion height
> At 2023-06-08T14:29:04-0400, Steve Izma wrote:
> 
> > *But* the ending of the diversion seemed to swallow the EOL of the
> > diversion's last output line, or the .br, or something. As a result,
> > the first line after the diversion acts as if it's a continuation of
> > the input to the diversion (see attached PS file). If I add a .br
> > immediately after the .DD, I get the expected results, but that seems
> > unnecessary and unpredictable to me, almost as if a .chop got silently
> > applied by .di
> 
> There might be a confounding factor.  Note the part about diversions.
> 
> 5.11 Manipulating Spacing
> =========================
> 
> A break causes the formatter to update the vertical drawing position at
> which the new text baseline is aligned.  You can alter this location.
> 
>  -- Request: .sp [distance]
>      Break and move the next text baseline down by DISTANCE, or until
>      springing a page location trap.(1)  (*note Manipulating
>      Spacing-Footnote-1::) If invoked with the no-break control
>      character, 'sp' moves the pending output line's text baseline by
>      DISTANCE.  A negative DISTANCE will not reduce the position of the
>      text baseline below zero.  Inside a diversion, any DISTANCE
>      argument is ignored.  The default scaling unit is 'v'.  If DISTANCE
>      is not specified, '1v' is assumed.

Branden,

Thanks for pointing this out, but I think I have lost track of
the discussions on this list about recent changes to
documentation. The above section looks like it's from the GNU
Troff Manual, but it's not in the version I have, which is "The
GNU implementation of troff", edition 1.23.0. Where would I find
the above?

In any case, I'm sure I've not seen this discussion of DISTANCE
being ignored within a diversion, although many times I've been
confounded trying to control the vertical space at the beginning
of a diversion.

As well, I'm not sure that this cautionary note about .sp
addresses the issue with the .br command apparently being
ignored. Does anyone have more insight about this?

I will also experiment with the \n[.h] register to see if it
keeps track of drawing motions that go below the baseline.

        -- Steve

-- 
Steve Izma
-
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