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Re: [Groff] The \D request in nroff and troff modes
From: |
Anton Shepelev |
Subject: |
Re: [Groff] The \D request in nroff and troff modes |
Date: |
Thu, 15 Jul 2010 18:52:13 +0400 |
Hello, Werner.
Many thanks for the info. I see that the problem
lies deeper than I had thought.
> It's obvious that the values 0..23 are somehow
> 'assigned' to character cell 0, and for orthogo-
> nality we have to assign position 24 already to
> character cell 1.
This is indeed only meet and logical. The 24th unit
is not a boundary between cells, but the first 'bit'
of the next cell. The boundary has no size and is
between the 23rd and 24th units.
> Another complication is that everything which
> specifies a length is rounded internally to be
> multiples of either \n[.H] or \n[.V]. In nroff
> mode this means that a horizontal length of 12u is
> still one character cell, but 13u is rounded up to
> be two character cells.
Hmmmm. But shouldn't 12u round to zero and 13u to
one (this would make lines one symbol shorter). Does
grotty 'see' the rounded values?
> Does this explain why a single horizontal line is
> one character cell too long?
> <...>
> BTW, if you always shorten horizontal lines by a
> small correction value, the above tables look like
> this:
So this is done generally to help tbl draw tables
properly? If it is so, then it keep tbl device-inde-
pendent but makes the \D request tbl-dependent...
Anton