[bug #66323] [gropdf] rendering differences between PostScript and PDF output?

[anonymous]

Follow-up Comment #25, bug #66323 (group groff):

Thanks. By comparing what your dump does and what my attempts didn't, I
managed to get an equivalent setup locally for -Tpdf as I have for -Tps (not
that it didn't fight me every step of the way). As a bonus, ps2pdf(?) no
longer spends minutes unpicking the chinese font.

The test dataset was obtained by appending
.br
.ft CR
\Z'Symbola'\h'4c' 😩😖🙄
.br
\Z'DejaVuSans'\h'4c' ⨝⋈▷
.br
\Z'STIX-Regular'\h'4c' ⟕⟖⟗
.br
.ft CR
\Z'TW-Sung-98_1'\h'4c'
不用烤箱，教你在家做面包，简单一蒸，蓬松宣软
.br
\Z'topaz'\h'4c' ␤
.br

This is the sum total of all the fonts I use. Might as well try them all :)

I'm attaching:
-Tps created on bookworm 1.24.4 — I'd consider this the most correct
baseline — with
  sed -e 's/[😩😖🙄]/\\f[Symbola]\\z&\\fP\\ \\ /g' -e 'y/⨝/⋈/' -e
's/[⨝⋈▷]/\\f[DejaVuSans]\\z&\\fP\\ \\fC\\ \\fP/g' -e
's/[⟕⟖⟗]/\\f[STIX-Regular]\\z&\\fC\\ \\ \\fP/g' -e
's/[一-拿挀-矿砀-賿贀-鼀]/\\f[TW-Sung-98_1]\\z&\\fP\\ \\ /g' -e
's/␤/\\f[topaz]␤\\fP/' n3363.mom | pdfmom -Tps -K utf-8 -t | ps2pdf - - >
newpdf6ps6.pdf

-Tpdf created on bookworm 1.24.4 with
  sed -e 's/[😩😖🙄]/\\f[Symbola]\\z&\\fP\\ \\ /g' -e 'y/⨝/⋈/' -e
's/[⨝⋈▷]/\\f[DejaVuSans]\\z&\\fP\\ \\fC\\ \\fP/g' -e
's/[⟕⟖⟗]/\\f[STIX-Regular]\\z&\\fC\\ \\ \\fP/g' -e
's/[一-拿挀-矿砀-賿贀-鼀]/\\f[TW-Sung-98_1]\\z&\\fP\\ \\ /g' -e
's/␤/\\f[topaz]␤\\fP/' n3363.mom | pdfmom  -K utf-8 -t  > newpdf94.pdf

-Tpdf created on sid with groff HEAD
(ddbbe95e27fd3f2aa633d719c95e921a178fd25a) with
  sed -e 's/[😩😖🙄]/\\f[Symbola]\\z&\\fP\\ \\ /g' -e 'y/⨝/⋈/' -e
's/[⨝⋈▷]/\\f[DejaVuSans]\\z&\\fP\\ \\f(CR\\ \\fP/g' -e
's/[⟕⟖⟗]/\\f[STIX-Regular]\\z&\\f(CR\\ \\ \\fP/g' -e
's/[一-拿挀-矿砀-賿贀-鼀]/\\f[TW-Sung-98_1]\\z&\\fP\\ \\ /g' -e
's/␤/\\f[topaz]␤\\fP/' n3363.mom | pdfmom  -K utf-8 -t  > newpdf95c.pdf

As I have it configured, -Tps and -Tpdf use the exact same metrics and the
exact same font files.

The trends I see are thus:

newpdf6ps6.pdf has everything, but neither -Tpdf outputs have STIX or
TW-Sung-98_1 characters.

On -Tpdf, the на pair is overkerned. (And I'd say it's /over/kerned not just
"more kerned", it definitely looks weird.)

On -Tpdf everything's, like, inconsistently shifted around by like 1pt. This
is blameless but still weird.

groff HEAD justifies (fills? whatever the nomenclature is) the "all comments
were applied" line differently so it breaks it mid-word earlier. Conversely
with the polyomino link line.

groff HEAD -mom spaces the 2.2.1. heading. Good!

I can't attach site-font/ because it blows the max file size many times over,
so it's at
https://lfs.nabijaczleweli.xyz/0025-groff-Tpdf-fonts/site-font.tar.zst. This
is for groff HEAD on sid. This should ease testing significantly.

(file #56544, file #56545, file #56546)

    _______________________________________________________

Additional Item Attachment:

File name: newpdf6ps6.pdf                 Size: 78KiB
    <http://file.savannah.gnu.org/file/newpdf6ps6.pdf?file_id=56544>

File name: newpdf95c.pdf                  Size: 37KiB
    <http://file.savannah.gnu.org/file/newpdf95c.pdf?file_id=56545>

File name: n3363.mom                      Size: 14KiB
    <http://file.savannah.gnu.org/file/n3363.mom?file_id=56546>


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