[BlindRUG] Text-based progress bars and screen readers?

[Liz Hare]

Hi Henrik,

On a Mac with VoiceOver

> Detailed questions:
> 
> In R, we have utils::txtProgressBar() for producing progress bars in
> the terminal.  Like other solutions, it works by outputting a
> single-line of symbols where the number of symbols relative to the
> width of the terminal reflects the amount of progress.  Calling:
> 
> example("txtProgressBar", package="utils")
> 
When running this example, all the resulting text is spoken, with VoiceOver interrupting itself. You'd have to review the screen to get an idea of what's going on.

> Q1. The screen reader will read out every single symbol as is, i.e. a
> sequence of 20 equal signs (the symbol used by default) will be a long
> repetitive readout.  Here is an example of such a progress bar at
> length 20:
> 
> ====================
> 
> Here is the same progress bar of length 40:
> 
> ========================================
> 
> How well do these convey progress when used with a screen reader?
> 

These are not read reliably.

> Q2. Some progress bars will append to the existing output as it grows.
> This means that there will be 80 equal signs outputted if the maximum
> width is 80.  Other solutions will rewrite the whole line at each
> update, which is down by skipping back to the first position and
> outputting the whole line.  If each of the 80 steps is outputted, I
> can imagine the screen reader will first render a progress bar of
> length 1, then redo the same of length 2, and so on.  That is a lot of
> voiced output if that is what happens.  Is that the case?

This could cause the screen reader to interrupt itself constantly.

> Q3. Other progress bars output includes both a visual bar and textual
> information.  Here is an example of a progress bar at 40% completion:
> 
>  |============                  |  40%
> 
> How does this kind of progress bar work with screen readers?


Being able to go back up a line and read the number (40%) is the best!

Liz