[HarfBuzz] Beginner question: What are cluster levels?

[Jonathan Kew]

On 6/1/16 14:17, Behdad Esfahbod wrote:
> On 16-01-05 09:17 PM, Jamie Dale wrote:
>> I actually just wrote something to give me very similar information since I
>> realised that my basic "this is a ligature" flag wasn't enough data, so each
>> of my glyphs now contains the number of characters that the glyph was composed
>> from. This, along with the cluster index of the glyph from the source text,
>> and the reading direction of the glyph, allow me to work out which characters
>> formed the glyph.
>
> Correct.  That's pretty much the only way to do it.
>


Don't forget the added complication that there may be multiple glyphs 
with the same cluster value. E.g. given the text

   <U+0915, U+094D, U+0915, U+093F, U+0915>

you're very likely to get two glyphs with cluster index zero, as in 
something like

   [imatra=0 | kka=0 | ka=4]

but it's not at all clear from this how you'd determine which characters 
formed each glyph.

JK