[HarfBuzz] Can I only reshape broken clusters?

[kelvinsthirteen at gmail.com]

isn't that less accurate than what i’m doing here? since at least we are accounting for changes in ligature width or kerning

> On Jul 1, 2016, at 12:10 AM, Behdad Esfahbod <behdad at behdad.org> wrote:
> 
>> On Thu, Jun 30, 2016 at 9:06 PM,  <kelvinsthirteen at gmail.com> wrote:
>> 
>> 
>>> On Jun 30, 2016, at 11:41 PM, Behdad Esfahbod <behdad at behdad.org> wrote:
>>> 
>>> No, it wouldn't be safe necessarily.  That's exactly what the
>>> unsafe-to-break API is about, but that's not finished yet.  For now,
>>> you have to reshape the entire new string.
>> 
>> That’s O(n^2) in terms of the amount of shaping that has to be done per paragraph based on the length of the paragraph text, and not workable in practice
> 
> What Pango (and possibly other systems) does is to shape the full
> paragraph, then find line-break location, then reshape the
> just-decided line but continue with the rest of the paragraph as if
> the shaping wouldn't change the width much.
> 
>>>> On Thu, Jun 30, 2016 at 8:31 PM, Kelvin Ma <kelvinsthirteen at gmail.com> wrote:
>>>> If I have the string A = 'affifibcd' and the master list of shaped glyphs
>>>> 
>>>> [a 0] [ffi 1] [fi 4] [b 6] [c 7] [d 8]
>>>> 
>>>> and I wanted to shape the substring A[2:] ('fifibcd'), could I simply take
>>>> my preshaped glyphs after the cluster at or above (ceiling) i = 2 and only
>>>> reshape the segment A[2:6]?
>>>> 
>>>> So I would reuse the glyphs
>>>> 
>>>> [fi 4] [b 6] [c 7] [d 8]
>>>> 
>>>> and reshape the segment A[2:6] = 'fifi' to get
>>>> 
>>>> [fi 2] [fi 4]
>>>> 
>>>> and add them together (dropping the last glyph in the reshaped segment) to
>>>> get
>>>> 
>>>> [fi 2]  [fi 4] [b 6] [c 7] [d 8]
>>>> 
>>>> ?
>>>> Would this be the same result as reshaping the entire segment A[2:]? Would
>>>> this still work for RTL text, or a substring that’s on the left-hand side of
>>>> the parent string like A[:5] = 'affif'?
>>>> 
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>>> 
>>> 
>>> 
>>> --
>>> behdad
>>> http://behdad.org/
> 
> 
> 
> -- 
> behdad
> http://behdad.org/