Re: slanted typewriter font / txicodevaristt yields a spurious space before a closing parenthesis in the text

[Vincent Lefevre]

[Cc'ed back to bug-texinfo]

On 2022-09-06 21:39:33 +0100, Gavin Smith wrote:
> On Mon, Sep 05, 2022 at 02:40:44AM +0200, Vincent Lefevre wrote:
> > Commit 18389820e7059724edfcd616e8bfafb376c5b9e1 introduced
> > a regression. Consider
> > 
> > @code{(@var{b},@var{p})}
> > 
> > Previous this commit, the text contains "(b,p)" as expected.
> > But since this commit, I get "(b,p )", with a space between "p"
> > and the closing parenthesis.
> > 
> > This affects the text obtained with the pdftotext utility, but
> > also, with various PDF viewers, searching for text and copying
> > text.
> 
> I believe it is something to do with the italic correction.  This
> can be seen for other inputs: @i{aaaaaaaaaal}a appears to generate
> a space between the l and the a when it is copied from the PDF.
> 
> I'm struggling to understand this - I don't understand when it inserts
> a space and when it doesn't.  Here is a plain TeX input:
> 
> \font\ttsl=cmsltt10
> {\ttsl p\/})
> 
> ({\ttsl p\/})
> 
> \end
> 
> In the PDF output, the second line appears to have a space after the
> p while the first doesn't.  (This might be a problem with the PDF
> readers I used - I checked evince and xreader.)  Visually they look
> the same apart from the opening bracket at the start.  Also copying
> and pasting has a space in both - so probably a PDF reader bug.
> 
> Maybe there is some issue with the italic corrections for the ttsl
> font.  If I have time I will check older versions of texinfo.tex to
> see if the problem existed there.

Actually this is not just a text issue. This is also visually
different: alignment has been broken.

For instance, consider

@code{(@var{b},@var{p})(@var{b},@var{p})(@var{b},@var{p})(@var{b},@var{p})}@*
@code{12345678901234567890}

With texinfo.tex 2020-02-11.09 (currently used for MPFR), alignment
is perfect: I get

  (b,p)(b,p)(b,p)(b,p)
  12345678901234567890

(with "b" and "p" in italics), where the last characters of each
line are vertically aligned. This is still true with texinfo.tex
2022-08-13.11 (commit f0c48d71fa1c08f9c10547835f1a4a71e830af0f).
But 2022-08-13.12 (commit b3abe7731dd2aaaf33007155d0bbeeb53bcae141),
slanted typewriter is no longer used.

Slanted typewriter was re-added in texinfo.tex 2022-08-26.23
(commit 18389820e7059724edfcd616e8bfafb376c5b9e1), mentioned above,
but with additional spacing.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)