Request to include optional conjuncts in Noto Sans/Serif Malayalam

[cibu]

Traditional cursive ligatures and open forms are specified in Unicode version 13.0 Chapter 12.9, Sections Requesting Traditional Ligatures and Requesting Open Forms of Conjuncts in page 511. Essentially, it says:

<Consonant, ZWJ, VIRAMA, Consonant> produces traditional cursive form and <Consonant, ZWNJ, VIRAMA, Consonant> non-cursive open form.

For example, consider following forms of the /kra/ conjunct:

KA (U+0D15)	VIRAMA (U+0D15)	RA (U+0D30)

Evidently, cursive forms would mean a lot more ligatures to be added to the reformed orthography fonts like Noto Sans Malayalam. There are some traditional orthography fonts like Rachana available for Malayalam. Here is a screenshot of the some additional ligatures listed by FontForge:

Please keep in mind Rachana does not implement the requested feature. These ligatures or conjuncts are available by just <Consonant, VIRAMA, Consonant> as it is a traditional orthography font. 

 It is easy to see that there are an additional 1000+ ligatures needed in Noto Malayalam to implement the optional ligatures. Please see a list of such ligatures provided by the FreeFont project. However, some of these ligatures share common subscript shapes as component glyphs. This means, each of these ligatures need not be drawn separately, instead, they can share the subscript glyph drawing. Their anchored positions need to be adjusted per base glyph, though. For example, consider the glyphs LLL-KA and S-KA sharing the same subscript -KA (ക).

Once the subscripts are drawn and counted separately, then the number of additional drawing requirements would nearly halve to 600+ new glyphs to fully implement this requested feature.

[marekjez86]

@cibu : thanks