[BRLTTY] Multi-column characters (was: Re: 6.5 soon)

[Dave Mielke]

[quoted lines by Aura Kelloniemi on 2022/02/01 at 23:22 +0200]

>What do you mean by "corresponding?" Do you mean that Linux should add padding to a nearest narrow character.

I meant on the lines above/below the wide character at the same column.

>What if a line contains only wide characters?

Then I'd think that there'd be no need for padding.

> > My opinion is that there should be a common shared memory rendering of the screen content. Then other platforms, e.g. Chrome OS, could also benefit.
>
>I don't know how that would work permission-wise.

Group acess to tty, i.e. same as is used for the vcs devices now.

>I have planned to suggest that brlapi provided a simple interface through
>which terminal emulators could provide screen content to BRLTTY and accept
>input events from BRLTTY. Terminal emulators could then load brlapi with
>dlopen so that that the brlapi dependency would remain optional (which is
>probably important for distribution packagers). 

My positiion is that it needs to be as easy as possible so that other apps will actually use it. I favour a shared memory approach because that's general, i.e. not braille-specific.

>Does this mean that chinise braille is implemented using Contracted braille in
>BRLTTY?

Yes.

>If so, then standard braille glyph width of 1 cell holds as long as
>contraction is disabled. 

No, because computer braille isn't typically defined for such languages. The very nature of the braille requires a contraction table approach.

>But there are other options too – like padding at the
>next word boundary (it works often in tables, but not always).

Cells often contain more than one word. To me, it's impossible to get it right without actually knowing where a column starts.

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