[HarfBuzz] Kerning at the end of a line vs. line breaks

[Behdad Esfahbod]

On 12-10-23 10:43 PM, Konstantin Ritt wrote:
> 2012/10/23 Behdad Esfahbod <behdad at behdad.org>:
>> > On 12-10-17 08:22 PM, Lóránt Pintér wrote:
>>> >>
>>> >> This could work, but I would basically have to shape the whole text twice.
>>> >> That doesn't sound right. Or does it?
>> >
>> > It actually is what you need to do, and what Pango does for example.  Now, I
>> > like to add API to HarfBuzz that would improve this, and you would essentially
>> > just need to reshape the cluster at the linebreak position, but for now, you
>> > need to reshape each line.
> Are you saying about re-introducing the Unicode Segmentation algorithm
> implementation to Harfbuzz? Hope you're not :)

No.  Unicode segmentation algorithm is not really helpful here.  What HarfBuzz
can tell you is this: for each position in the text, it can tell you whether
breaking the string here and shaping the two sides separately and
concatenating the resulting glyphstrings will result in the same glyphstring
that you get if you shape the full string.  No other code can tell you that,
since it depends on how the font lookups work.

behdad

> Konstantin