Re: Inserting ே and க்ஷ without the dotted circle

[Random832]

Shakthi Kannan <shakthimaan@gmail.com> writes:

> Hi,
>
> I am using fonts-lohit-taml-classical 2.5.3-2 font on a Ubuntu 14.10
> system. With Tamil Unicode character and GNU Emacs 24.5.1, I am able to
> enter  ே and க்ஷ (க்ஷ = க + ் + ஷ) separately.
>
> #1 I have a word where I need both the characters put together, but,
> without the dotted circle. How can this be done?
>
> I can open the font sources using FontForge:
>
>
> https://fedorahosted.org/releases/l/o/lohit/lohit-tamil-classical-2.5.3.tar.gz
>
> and when I click on U+0BC7, I see the glyph for ே, but, without the dotted
> circle. But, the definition in Unicode has the dotted circle:

The dotted circle in the Unicode tables means that this is a combining
mark - specifically, in this case, that the glyph will appear to the
left of the preceding glyph that it is composed with.

To get the behavior I assume you want, you should enter U+0BC7 after the
others, i.e.:

0B95 0BCD 0BB7 0BC7, for this result: க்ஷே
= க + ் + ஷ + ே 

Note that this may not appear correctly in some terminals when you run
text-mode Emacs - it doesn't in mine.

>
>   http://www.charbase.com/0bc7-unicode-tamil-vowel-sign-ee
>
> #2 Where is this behaviour defined for such characters?

The Unicode standard provides information on how Indic scripts should be
rendered. Version 1.0 is available at the link below; I don't know if
any later version exists.

http://www.unicode.org/versions/Unicode1.0.0/V2appA.pdf

The dotted circle is generally used in charts to illustrate where a
combining character would be placed relative to preceding characters,
and in rendering to show an ill-formed sequence (i.e. the preceding
consonant cluster is missing).

> #3 Suppose I add a new glyph to one of the available Unicode slots in the
> font sources, where in Emacs should this be defined in order to use the
> same?

I am not sure what layer is responsible for doing this rendering, so I
don't know if there's anything you need to do or can do at the font level.