[DejaVu-bugs] [Bug 18614] Mono Sans: accent with Russian letters causes letters collapsing

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=18614





--- Comment #1 from Ben Laenen <bl.bugs at gmail.com>  2008-11-19 04:02:21 PST ---
Could you post a screenshot?

In Linux I have two behaviours strangely enough: in KDE I get accents on е and
и (which looks correct for me with my limited knowledge of Cyrillic) while in
Pango it's on the letters behind them (р and с). My first guess is that the
latter is caused by having no anchors on the letters to attach the accents to.
But that doesn't cause your problem.

Now, there are some things going on behind the scenes for combining diacritics:
because it's a monospaced font we have to make the combining diacritics the
same width as normal letters (or it wouldn't be recognized as monospaced
anymore). But combining diacritics have to be zero-width, and some opentype
rule does that: it removes the width from the diacritic (to be precise: it says
that the next letter has to be rendered X pixels left of where it would be
without the rule, with X the width of a letter in the font).

However, this goes terribly wrong if the font renderer "thinks" it is smarter
than the font (after all, that rule can't be found in a lot of fonts, given the
sparcity of monospaced fonts that support combining diacritics, even if it has
to be there to be correct), so the renderer says "combining diacritic doesn't
look zero width, I'll do that for you", but it then forgets to not apply the
opentype rule that already corrects the width. Result: the next letter is moved
left twice the letter width and therefore coincides with the letter that has
the accent on it.

So, I'm quite sure that the problem here lies with the renderer in Microsoft.


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