On Thu, 2 Jan 2020 20:20:34 +0000 Richard Wordingham via Unicode <unicode@unicode.org> wrote:
> There's a project whose basis I can't find to convert Indian Indic > rendering at least to use the USE. Now, according to the > specification of the USE, visarga, anusvara and cantillation marks > are all classified as vowel modifiers, and are so ordered relative to > one another in the Indian Indic order: left, top, bottom, right. So, > the problem should already be solved for Grantha, and, if the plans > come to fruition, will work with a font whose Devanagari script tag > is 'dev3'. However, I may have overlooked a set of overrides to the > USE categorisations. I've now knocked up a partial* representation* of a Devanagari dev3 and a Grantha font (which I'm dubbing 'Mock Indic 3'). The supported orders of COMBINING DIGIT ONE and VISARGA, as in Firefox on Linux, are: dev2: कः꣡ <U+915 LETTER KA, U+903 VISARGA, U+A8E1 COMBINING DEVANAGARI DIGIT ONE> dev3: क꣡ः <U+0915, U+A8E1, U+0903> Grantha: (1) 𑌕𑍧𑌃 <U+11315 LETTER KA, U+11367 COMBINING GRANTHA DIGIT ONE, U+11303 VISARGA> (2) 𑌕𑌃𑍧 <U+11315, U+11303, U+11367> The second Grantha spelling is enabled by a Harfbuzz-only change to the USE categorisations. It treats Grantha visarga and spacing anusvara as though inpc=Top rather than inpc=Right. As I am using Ubuntu 16.04, this override isn't supported in applications that use the system HarfBuzz library, such as my email client. We are now establishing incompatible Devanagari font-specific encodings fully compliant with TUS! Richard. * Partial = much is not handled * Representation = glyphs are wrong, merely showing arrangement. (I've actually re-used a Tai Tham font.)