[HarfBuzz] Corner case wrt to repeating Malayalam vowel sign OO

[Jonathan Kew]

On 28/2/13 01:09, Behdad Esfahbod wrote:
 > On 13-02-27 05:41 PM, Cibu Johny (സിബു) wrote:
 >>
 >> When
 >> ​MALAYALAM ​
 >> VOWEL SIGN OO is repeated after a consonant, third one is displayed 
separately
 >> with a dotted circle. It should have behaved like the second OO 
sign. Sample
 >> text: കോോോ
 >>
 >> ​If there is a imposed upper limit for the count of repeating vowel 
signs,
 >> something close to 10 would be useful.​
 >
 > Right...  We used to have no limit, but to be closer to Uniscribe we 
limited
 > consonants to about 5 per syllable, and matras to 4.  Now, split 
matras count
 > two each.
 >
 > I'll go ahead and lift the limit again.
 >

I wonder whether it really makes sense to allow multiple matras in -all- 
positions. I believe I've seen Devanagari examples similar to Cibu's 
Malayalam comic, where a right-matra is repeated to suggest a loooooong 
sound. But left-reordering matras? Split matras? Above- or below-matras? 
The idea of repeating these indefinitely when writing seems much less 
plausible.

Cibu, the example you showed looks like it does not actually repeat a 
split-vowel matra; rather, it appends a repeated U+0D57 "Malayalam AU 
length mark". Do people actually repeat the full range of matras in 
their entirety, and if so how are repeated matras written on all the 
various sides of the base? Or is this practice restricted to "trailing" 
(right-attached) signs that can reasonably be appended to the cluster 
without affecting the rest of the glyphs?

JK