Created attachment 51074 [details]
Misplaced combining diacritics in Dejavu Sans and DejaVu Serif

I've hijacked a previous post, as this is problem is more widespread than the original poster realized. Combining diacritics on all versions of DejaVu do not place correctly for large or capital letters.  In addition, the tittle is not removed on the lowercase "i" when a diacritic is added.  Attached PDF is from Libreoffice/Linux showing the worst offeders.  On Windows/MSOffice, Aigue and Grave (u0300 and u0301) place correctly on only the simple vowels (AEIOU), but not the rest of the raised diacritics.  Compare to ttf-sil-charis (available in universe) in the attached PDF, where they all place correctly.  

I would be excited to have DejaVu as an out-of-the-box font that would work well for Cameroonian languages (mostly roman characters with the diacritics listed in the pdf), but this issue is holding us back and keeping us using the SIL fonts.  I was surprised not to find a reference to this already on bugzilla. versions of DejaVu do not place correctly for large or capital letters.  In addition, the tittle is not removed on the lowercase "i" when a diacritic is added.  Compare to ttf-sil-charis (available in universe) in the attached PDF, where they all place correctly.

Vertical placement is the priority, then we can talk horizontal placement.

I'm excited to see the complex diacritics like macron-grave included in the list. We would be excited to have DejaVu as an out-of-the-box font that would work well for Cameroonian languages (mostly roman characters with the diacritics listed in the pdf), but this issue is holding us back and keeping the country dependent on using our SIL fonts.

If this is something that must be done manually for letters and diacritics, I'm willing to do some of the work myself if someone will point me in right the direction or utility.

~Matthew Lee
Linguistic Technology Specialist
SIL Cameroon

(In reply to comment #2)
> I've hijacked a previous post, as this is problem is more widespread than the
> original poster realized. Combining diacritics on all versions of DejaVu do not
> place correctly for large or capital letters.  In addition, the tittle is not
> removed on the lowercase "i" when a diacritic is added.  Attached PDF is 

I have a workaround for the "i" issue. There is a Unicode character "dotless i" (and even a "dotless j") to which you can add combining diacritics :-)

from
> Libreoffice/Linux showing the worst offeders.  On Windows/MSOffice, Aigue and
> Grave (u0300 and u0301) place correctly on only the simple vowels (AEIOU), but
> not the rest of the raised diacritics.  Compare to ttf-sil-charis (available in
> universe) in the attached PDF, where they all place correctly.  
> 
> I would be excited to have DejaVu as an out-of-the-box font that would work
> well for Cameroonian languages (mostly roman characters with the diacritics
> listed in the pdf), but this issue is holding us back and keeping us using the
> SIL fonts.  I was surprised not to find a reference to this already on
> bugzilla. versions of DejaVu do not place correctly for large or capital
> letters.  In addition, the tittle is not removed on the lowercase "i" when a
> diacritic is added.  Compare to ttf-sil-charis (available in universe) in the
> attached PDF, where they all place correctly.
> 
> Vertical placement is the priority, then we can talk horizontal placement.
> 
> I'm excited to see the complex diacritics like macron-grave included in the
> list. We would be excited to have DejaVu as an out-of-the-box font that would
> work well for Cameroonian languages (mostly roman characters with the
> diacritics listed in the pdf), but this issue is holding us back and keeping
> the country dependent on using our SIL fonts.
> 
> If this is something that must be done manually for letters and diacritics, I'm
> willing to do some of the work myself if someone will point me in right the
> direction or utility.
> 
> ~Matthew Lee
> Linguistic Technology Specialist
> SIL Cameroon

This is very weird. This always used to work before. But I wonder if something else changed: I have the same problem in anything making use of Pango, but if I use a Qt/KDE program everything is rendered the way it should... In FontForge all looks well too.

(In reply to comment #4)
> This is very weird. This always used to work before. But I wonder if something
> else changed: I have the same problem in anything making use of Pango, but if I
> use a Qt/KDE program everything is rendered the way it should... In FontForge
> all looks well too.

Yes, Firefox also does it fine. So it's a rendering engine-specific problem.

Well, either a bug in Pango triggered by DejaVu, or a bug in DejaVu which most renderers can handle. Bugs like this are extremely hard to pinpoint, given the enormous size of the Opentype tables in our font.

For now I'd say that Pango gets in trouble from the moment substitutions have to happen (the diacritic gets replaced by an uppercase variant, or i with the dotless i).

Charis does it differently: it has all these combinations as ligatures.

Serif and Mono seem to work fine here using pango-view (pango-1.28.4).

Sans rendered Å and I̊ with the ring touching the base letters, though.

I looked closer, using the pdftotext output from the attached pdf, and i᷄ 
is wrong here, too, with sans and mono.  Serif still gets it right, though.

Sans and mono each fail to do the /i → /dotlessi glyph substitution
before adding the combining char’s glyph; sans additionally adds the
U+1D4C above the i’s dot; mono adds it which it should had it done the
substitution.

It seems like the GPOS/GSUB tables and the mark attachment points are
off in sans and mono, but correct in serif.

*** This bug has been marked as a duplicate of bug 44023 ***