Re: FVS Assignment for A

On Mon, 10 Aug 2015 00:17:10 +0900
<jrmt@almas.co.jp> wrote:

> > We have a formal problem here.  How should <NA, A, NA, MVS, A,
> > FVS1> be rendered?  One might naively expect it to be rendered the
> > FVS1> same as <NA, A, NA, MVS, A>.
> It should be same with <NA, A, NA, MVS, A>. 

> It is defined as "isol" in the MVS model ds00.pdf which we discussed
> last month.

But <A-isolate, FVS1> is to be rendered as default isolated E!  That is
agreed by all fonts and definitions.  The purpose of free variation
selectors is to overrule the decisions of the basic context rules.

------------ 
> What I am talking is we need this kind on mapping separately in the
> individual font or define it common to all font?

Each font has its own mappings.  For example, in one font identical
glyphs corresponding to different codepoints may have different
PostScript names.  Another font might have no PostScript names.

-------------
> After this forum complete and getting conclusion, I think the glyph
> set TR120 will be updated.

You're right in principle if you're talking about TR170.  Someone (you?)
posted a set of example words, and I can't find the link.  I want to
check the spelling of the name Ng.  I've a suspicion it's actually an
isolated ANG.

> Actually, I have not seen TR170 yet.
It's available at http://i.unu.edu/pub/techreports/report170a.tgz .

------------------

> The Variant Form mapping rule is the core.

I disagree.  The context rules are the core.  The job of the variant
form mappings is to overrule the results when they are inadequate.

------------------

> Just look one cooperation here:
> 1. Replacing final <BA, A> with < Final_BA_A glyph> one step
> 
> 2.  Replace BA before A with the <Medial_BA_A glyph>
>     Replace the A with the <Final_A> by context
>     Replace <Final_A> after <Medial_BA_A glyph> with
> <Final_A_UNENCODED_2>
> 
> Which is simple and cheap?

The second - fewer glyphs to write the hinting code for!

Additionally, in the OpenType scheme 'Replace the A with <Final_A> by
context' would be part of a whole set of changes 'Replace X with
<Final_X>' defined as part of the "fina" feature.  The font does not
need to define the context for this change; that is the job of the
OpenType layout engine.

Richard.

Received on Sunday, 9 August 2015 18:01:15 UTC