[BRLTTY] Slow cursor routing

[Dave Mielke]

[quoted lines by Vikash Kesarwani on 2018/06/05 at 13:24 +0530]

>    Since it takes some time to move cursor, so braille window keeps
>changing, and so does my braille display.
>    So when I move cursor from one position to other, braille display
>refreshes multiple times, before it reaches
>    on the final cursor position. So I was wondering if it is possible to
>know when cursor routing has finished, then
>    I can block the braille display update until the cursor routing has
>finished. This will make the braille display
>    refresh only once. Though this is a workaround, but it still will be
>better experience, in my opinion.

No, that'd be a much worse experience. Time isn't the only thing that matters.
Consider, for example, why user interfaces show things like spinners while long
operations are taking place. Those are inefficient, too, but they provide
valuable feedback.

If a braille user were to press a routing key and then "see" no change for a
while, he'd wonder what might've gone wrnog. Allowing him to observe the cursor
moving provides at least two types of very helpful feedback. One is that he
knows that nothing has gone wrong, and the other is that he can estimate when
it'll finish.

Cursor routing is done by a separate process which doesn't force a rewrite of
the braille display each time the cursor moves. Also, if cursor routing were
really as slow as you're describing for all Linux users, then I'm sure there'd
have been a major protest a very long time ago. I think it's worth
investigating, therefore, why it seems to be so slow in your particular case.

Cursor routing is a centralized process. No individual driver, unless there's a
very good reason, should be messing with how it works, how it's presented, etc.
If there really is a problem with cursor routing then it should be fixed in
that one central place for everyone.

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