[HarfBuzz] Glyphs with negative advance width

[Olivier Berten]

I don't know if it helps but with this font, ICU and InDesign zero the
coeng (U+17D2) while uniscribe doesn't (string ពុម្ព). but the font doesn't
have OpenType features...

Olivier


2013/6/14 Olivier Berten <olivier.berten at gmail.com>

> FYI the same happens with this font after khmer character  ុ (glyph
> "vowelU") in string ពុម្ព
>
> By the way, it's not only Uniscribe since InDesign and LibreOffice (ICU)
> seem to deal the same way with it.
>
> Olivier
>
>
> 2013/6/14 Behdad Esfahbod <behdad at behdad.org>
>
>> Ok, negative vs positive is not the bug.  Uniscribe zeroes mark widths for
>> Khmer but we don't.  I tried to figure out whether Uniscribe does it by
>> Unicode category or GDEF, but couldn't build a test font...
>>
>> At any rate, we need to figure out and do the same.  Jonathan, any
>> comments?
>>
>> behdad
>>
>> On 13-06-13 05:31 PM, Olivier Berten wrote:
>> > After khmer character  ិ(glyph "uni17b7") in the string និង
>> >
>> > Olivier
>> >
>> >
>> > 2013/6/13 Behdad Esfahbod <behdad at behdad.org <mailto:behdad at behdad.org
>> >>
>> >
>> >     Ok, I'll take a look.  Can you send me the font?
>> >
>> >     That said, The HarfBuzz API uses signed integers for advance.  So
>> I'm not sure
>> >     why this is happening.  Where do you observe this behavior again?
>> >
>> >     b
>> >
>> >     On 13-06-13 05:16 PM, Olivier Berten wrote:
>> >     > Well... Harfbuzz will be the only one behaving that way then...
>> >     > That font is rendered fine by Adobe, Microsoft, LibreOffice, ...
>> and
>> >     fontforge
>> >     > as well as ttx/fontTools gives a negative advance width... I
>> guess this
>> >     > doesn't push fixing the font ;-)
>> >     >
>> >     > Olivier
>> >     >
>> >     >
>> >     > 2013/6/6 Behdad Esfahbod <behdad at behdad.org <mailto:
>> behdad at behdad.org>
>> >     <mailto:behdad at behdad.org <mailto:behdad at behdad.org>>>
>> >     >
>> >     >     Hi Olivier,
>> >     >
>> >     >     Thanks for the report.  I'm hesitant to make HarfBuzz return
>> >     negative advance
>> >     >     values as that can confuse downstream users.  If this doesn't
>> prove
>> >     to be a
>> >     >     major issue, I think we should ignore it for now.
>> >     >
>> >     >     behdad
>> >     >
>> >     >     On 13-06-01 05:40 PM, Olivier Berten wrote:
>> >     >     > Hi!
>> >     >     >
>> >     >     > Although it isn't complying with the TrueType/OpenType
>> specifications,
>> >     >     > some fonts have some glyphs with negative advance width.
>> >     >     >
>> >     >     > Advance width (in htmx) is defined as USHORT/uint16 but it
>> seems
>> >     >     > everybody else reads it as SHORT/int16.
>> >     >     >
>> >     >     > In the attached font, glyph "uni17b7" (khmer character  ិ)
>> has a
>> >     >     > negative advance width. You can try it with the string
>> និងសមភាព
>> >     >     >
>> >     >     > I wouldn't call this a bug in harfbuzz since it's a font
>> bug but for
>> >     >     > compatibility reasons, it might be useful to change it...
>> >     >     >
>> >     >     > Olivier
>> >     >     >
>> >     >     >
>> >     >     >
>> >     >     > _______________________________________________
>> >     >     > HarfBuzz mailing list
>> >     >     > HarfBuzz at lists.freedesktop.org
>> >     <mailto:HarfBuzz at lists.freedesktop.org>
>> >     <mailto:HarfBuzz at lists.freedesktop.org
>> >     <mailto:HarfBuzz at lists.freedesktop.org>>
>> >     >     > http://lists.freedesktop.org/mailman/listinfo/harfbuzz
>> >     >     >
>> >     >
>> >     >     --
>> >     >     behdad
>> >     >     http://behdad.org/
>> >     >
>> >     >
>> >
>> >     --
>> >     behdad
>> >     http://behdad.org/
>> >
>> >
>>
>> --
>> behdad
>> http://behdad.org/
>>
>
>
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