reported by Mike Brown
Subscripts and superscripts are way higher/lower in DejaVu Sans Mono than in
Bitstream Vera Mono
spotted with DejaVu TTF in Firefox on Windows
Cause: Positions and sizes of super- and subscripts set in TrueType tables are
not equal for DejaVu and Vera, but it is not known if Firefox uses them (more
information: http://sourceforge.net/mailarchive/message.php?msg_id=13818410 )
All Bitstream fonts that I have looked at have a bug in the subscriptyoffset. It
is entered as a negative value, when it should be positive. This is what it says
at Microsoft Typography:
"The Subscript Y Offset parameter specifies a font designer's recommended
vertical offset from the character baseline to the character baseline for
subscript characters associated with this font. Values are expressed as a
positive offset below the character baseline. If a font does not include all of
the required subscript for an application, this parameter specifies the
recommended vertical distance below the character baseline for those subscript
Values are expressed as a POSITIVE value below the baseline, i.e. values with a
negative value are ABOVE the baseline (>_<). I reported the bug to Bitstream, but
they didn't seem to be too concerned.
(In reply to comment #1)
> All Bitstream fonts that I have looked at have a bug in the
> subscriptyoffset. It is entered as a negative value, when it should be
That bug was fixed a long time ago in DejaVu. We now make use of the values
FontForge makes by default (but we should perhaps go back to the values
defined by Bitstream, except with the negative value made positive of course).
The subscripts in DejaVu are currently sitting on the baseline. That is one way
to design them, but then the subscriptyoffset should be zero. I prefer to have
subscripts bisect the baseline.
Created attachment 10475 [details]
DejaVu Superscripted Digits rendered with freetype2
Perhaps related to this more general bug about superscripts and
subscripts. We're observing some issues with the vertical offset
for superscripted digits 0 to 9. Display of a number as "1024 = 2¹⁰"
doesn't work very well with any of the DejaVu fonts.
Update: dejavu-ttf-2.19 same problem observed with the vertical offset
for superscripted digits 0 to 9.
Just another addition here - it's not just the offsets, but I'm seeing large differences in the *sizes* of the superscript numerals. It's particularly noticeable on Sans Mono in a small font. I use Sans Mono for my terminal windows at 8 or 10pt, and the 0 is quite a bit bigger than 4-9, and 1-3 are again bigger than the 0.
This is with version DejaVu 2.20 on Debian unstable.
Is it possible to use 'jstf' table to adjust?