[Indic-computing-devel] Re: About your Telugu font (Bharathi)

[Keyur S. <key...@ya...>]

hi,

--- K Nagarajan <kn...@wi...> wrote:

> 
> > About Bha - you are  correct,  till now I put all my
> efforts  on fixing the
> > rules, so that syllables are rendered correctly (except
> for drutvamu - like
> > in  word -  samskruthi,  where  in 2nd  syllable  it 
> supposed  to  display
> > sa+ka_vattu+vowelSignRU,      but     this      font   
> is      displaying
> > sa+VowelSignRU+ka_vattu;  in VOLT proof reader it
> displays correctly but in
> > real app, such as wordpad, IE it is not)

This is probably because you have encoded rules without
considering reordering of character. Let me give an example
with Devanagari script :

When we type Ka Halant Ra, then it turns into 'Kra', with
Ka as base glyph and Vattu glyph attached to it. However,
the rules for vattu is put as in GSUB table :
'Ra Halant -> Vattu' instead of 'Halant Ra -> Vattu'

This is required to minimize the number of all
theoratically possible combination rules. So in VOLT proof
reader, you have to type the sequence after reordering,
viz., 'Ka Ra Halant' to check rules for the syllable 'Kra'.

Also the word Sanskruthi in Hindi/Sanskrit is written using
VOWEL SIGN VOCALIC R attached to KA. Vattu is not used.
However if you use Vattu then it should be formed by the
following substitution rules :

Word : Samskruthi
Syllable : Skru

Input sequence :
Sa Halant Ka Halant Ra VowelSignU

Reordered sequence :
Sa Halant Ka Ra Halant VowelSignU

Step-1 : Apply 'half' feature
HalfSa Ka Ra Halant VowelSignU

Step-2 : Apply 'blwf' feature
HalfSa Ka Vattu VowelSignU

Step-3 : Apply 'vatu' feature
HalfSa Kra VowelSignU

Step-4 : Apply GPOS features ...

This way, you get the glyhs for HalfSa, Kra, and
VowelSignU.

There are alternative ways to substitue glyphs, but the
abovementioned is cleaner approach used in quality fonts.

> I guess we can have a somewhat bigger font (more memory)
> rather than lesser quality.

I agree. I also prefer medium-range font having number of
glyphs between 200 and 500.

> Thanks. I will see if I can compact the font with just
> Telugu in it, otherwise I will ask your help :-)

Be careful! If you add or delete any glyph in the font then
all the opentype rules will be disturbed and font will
become useless. So you should just remove mapping of
Unicode values to the glyphs that you don't want. In
OpenType font, tables should be added to the font ONLY
after you finish with the glyph set; otherwise it can
create many problems for you. Take backup of your font
before doing any experiment.

Regards,
Keyur



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