Re: [OT?] Visual vs. logical order editing (was RE: Thia for Tamil

--- In qalam@yahoogroups.com, Marco Cimarosti
<marco.cimarosti@...> wrote:

> Richard Wordingham wrote:
> > So how do you do visual order?
>
> In order to correctly display Indic text, the controlling software should
> have two copies of the string being edited: the "back store", which

contains

> characters in logical order, and the "visual store", which contains
> character (or, rather, glyphs codes) in visual order.

> etc.

You make it sound as though one needs to rewrite the operating system!

To give a concrete example, how do I get IE to accept visual order? (I
do not have a copy of its source code, let alone of Windows.)

> In logical-order input, when a reordrant character is typed, the

software

> inserts it in the "back store" and generates a fresh "visual store".
>
> In visual-order input, the process is reverted: when a reordrant

character

> is typed, the software inserts it in the "visual store" and generates a
> fresh "back store".

What would be done to the "back store" once you had entered a pre-
posed character? I don't think this is a stupid question. It would have to
be able to distinguish the sequence <consonant with inherent vowel> +
<preposed vowel just entered> from the normal "back store" content of
<consonant with inherent vowel> + <preposed vowel which will visually
precede>.

> Logical-order input only needs one function to generate a "visual store"
> from a "back store" (i.e., to turn logical into visual order). Visual-order
> input needs that function as well (to initialize the display at the
> beginning of editing) but also needs the reverse function, to generate a
> "back store" from a "visual store" (i.e., to turn visual into logical
> order), and that's why visual order is more complicated.

Richard.