Re: Proportionally-Spaced Fonts and Spatial Information

[Bill Haneman <billh taistealai ireland sun com>]

On Wed, 2002-09-11 at 00:42, John J. Boyer wrote:
> Hello,
> There is a discussion on the blindprogramming list about screenreaders for 
> Linux GUI's. It was pointed out that it is important to convey spatial 
> information, especially when using Braille. Without considerable care, the 
> user can wind up with an inaccurate idea of where the cursor is located 
> and of the screen layout in general.
> How is this problem being handled in Gnopernicus?

Hi John:

I can't speak for gnopernicus' internal handling of proportional fonts,
but I can confirm that our accessibility API provides per-glyph
bounding-box information for objects which implement the AccessibleText
interface. 

This covers all non-trivial text on the screen, including text-entry
fields, freeform text, and labels; however there are a few cases,
notably pushbuttons, in which we expose the text in the button's
"accessible name" attribute rather than implementing the full-featured
AccessibleText API.  This was a judgement call which may or may not have
been the right thing to do, since it means that pushbutton text can't be
located as accurately on the screen by AT.  On the other hand, the
button's own bounding box information is readily available, so the loss
of information should not be serious in most cases.

One can imagine cases involving very long pushbutton-text, etc. where
the result of approximating glyph positions from the button's bounding
box would be unsatisfactory, but perhaps they are degenerate cases. 
Should this prove to be a problem in "actual" practice, after we have
gained more end-user feedback from gnopernicus and our AT "SPI"
(service-provider-interface), we can add the AccessibleText interface
implementation to pushbuttons at some later date.

regards,

-Bill

> Thanks.
> John
> 
> 
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