[BRLTTY] Clickable links, virtual consoles etc. (Was Re: Footsteps towards better accessibility in Linux)

[Dave Mielke]

[quoted lines by Nicolas Pitre on 2025/05/09 at 17:40 -0400]

>Most sighted people will tell you that such a small character font on a 
>Full HD monitor is visually too tiny to be practical.

Well ... I think we need to wonder, then, why his default is 480x135. Also, even if a regular monitor would create characters that are rather small, large monitors will probably be easy to read. What I know is that when I've had a regular monitor connected to my 240x67 cofigurtion, no sighted person has ever complained that it was too small.

>Possibility #1: make all legacy values 0

As also with possibilities #2 through #4, anyone who's still running an old release of brltty would have an immediate, not-so-obvious probem. I myself don't like this kind of non-backward compatibility.

>Possibility #2: To make it safer, we could instead do this:
>  - byte 0: legacy screen rows = 1
>  - byte 1: legacy screen columns = 1
>  - byte 2: legacy cursor x position = 0
>  - byte 3: legacy cursor y position = 0

As unexpected as it might be, that'd still be a valid set of values.

>Possibility #3: saturate the legacy header to signify presence of the 
>extended header:
>  - byte 0: legacy screen rows = 255
>  - byte 1: legacy screen columns = 255
>  - byte 2: legacy cursor x position = 255
>  - byte 3: legacy cursor y position = 255

Better, as at least the cursor would be out-of-bounds, but still not backward compatible.

>Possibility #4: open /dev/vcsa with O_LARGEFILE to enable the new 
>header.

No guarantee that an older (maybe even the current) implementation of vcsa doesn't silently ignore it.

>Possibility #5: create an ioctl to affect the header type.

I like this one as we have to ask for it and will be told that it isn't supported by a previous implementation.

>I'd still use the legacy header with 1,1,0,0 as a marker to flag out mistakes.

I think that's unnecessary and adds needless copmlication.

I'd also like to be able to know the real colour rather than just a set of VGA colour attributes.

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