[tex-live] Bug#773668: okular shows "jumping" letters in pdf documents generated using pdflatex with russian babel

Reinhard Kotucha reinhard.kotucha at web.de
Tue Dec 23 01:21:16 CET 2014

On 2014-12-22 at 10:55:20 +0000, Robin Fairbairns wrote:

 > Martin Schröder <martin at oneiros.de> wrote:
 > > 2014-12-21 20:09 GMT+01:00 Askar Safin <safinaskar at mail.ru>:
 > > > Steps to reproduce:
 > > > * Create the following file tex.tex:
 > > > \documentclass[a4paper]{article}
 > > > \usepackage[russian]{babel}
 > > > \begin{document}
 > > > Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed ...
 > > > \end{document}
 > > > * pdflatex tex.tex
 > > > * okular tex.pdf
 > > > * Adjust zoom until you will see ugly "jumping" letters (i. e. one
 > >   letter is up, and the following letter in the same word is down). For
 > >   example, on my laptop with screen resolution 1600 x 900 pixels and
 > >   physical size 214.8 cm x 381.9 cm zoom 100 % will go
 > > >
 > > > What I see? Well, "jumping" letters. I see something like this:
 > > > "LOrEm IpSum DOlOr SIT AmEt ...". See screenshot:
 > > > http://picpaste.com/y-gh3PH69b.png  .
 > > 
 > > I can not reproduce this with TL2014 and okular 4.14.3.
 > however, the snapshot is exactly what one would expect with bitmap fonts
 > and pdf viewer that can't/won't deal with bitmap fonts.
 > (takes rather a lot of enlargement to be sure...)

The resolution of the PNG file is much too low, of course.  But as far
as I understand the problem exists only at low resolutions.  In this
case it's quite helpful to provide a screenshot of xmag(1), the X11
magnifying glass.

Robin, I'm not sure that bitmap fonts are involved.  You get similar
results with Type 1 fonts if they are not hinted properly or the font
rendering engine doesn't support hinting properly.  I suppose that
Okular is based on Freetype and thus can't imagine that hints are
ignored or processed improperly.  

In order to know which fonts are actually used, the output of
pdffonts(1) would be extremely heplful.

Due to the low resolution of the screenshot it's hard to determine
which font is actually used.  But despite the low resolution the
letter "t" does not look like the letter "t" in Computer Modern.
If fonts are substituted silently, everything can happen.

Askar, could you send me the PDF file which is not displayed properly?

Don't expect an answer from me before Dec 26, I don't have access to
my computer during the holidays.


Reinhard Kotucha                            Phone: +49-511-3373112
Marschnerstr. 25
D-30167 Hannover                    mailto:reinhard.kotucha at web.de

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