[Konsole-devel] Re: bidi in konsole

[Waldo Bastian]

On Monday, September 30, 2002, at 09:59 , cuco el-cuco wrote:

> Hi,
>
> You have disabled the bidi rendering in konsole (cvs
> snapshots). I would like to add an options for
> enabling it back in runtime.
>
> I will change the config dialog, add a key on the
> config files and h0opefully no more... ;)
>
> do you mind if I put it on the head (it will be in
> kde3.1)?
>
> Do you want me to send patches first to you? or just
> putting them is cvs is ok?

Bidi rendering in konsole is broken by design, that is why it is 
disabled. It will be possible to do a proper bidi implementation once 
someone can explain to me how bidi is supposed to work in conjunction 
with e.g. vt100 terminal emulation.

The idea is that konsole maintains a grid that represents the screen and 
on each position in thiis grid a single character is shown. To properly 
support bidi, we must place bi-directioonal text properly in this grid, 
The previous, incorrect implementation, places bidirectional text always 
from left to right in the grid, but takes bidi into account when 
painting the screen. The result is that bidirectional text sometimes 
appears correctly but konsole does not know about the biderectional 
aspect and only knows aboout the grid. The characters on the screen now 
longer correctly correspond to the characters in the grid. This becomes 
visible when you try to select text.

Currently (on sep 30 at least) in CVS bidi painting is disabled so all 
characters are painted on the screen as they are present in the grid, 
What has to be done is that bidi has to be taken into account when 
placing the characters in the grid. Unfortunately I don't know how that 
should behave exactly.

Cheers,
Waldo (back from holiday)