Re: Proportionally-Spaced Fonts and Spatial Information

[Peter Korn <peter korn sun com>]

Hi John,

> 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.

Please feel free to forward my reply to the blindprogramming list (as well
as invite them to join this list, where a lot of the UNIX GUI Accessibility
discussions are taking place).

> How is this problem being handled in Gnopernicus?

The GNOME Accessibility framework provides calls for getting the bounding
rectangle of every character of text rendered to the screen in graphical
elements that implement the AccessibleText interface.  While this today
isn't every piece of text, it's an awful lot of it (notable exceptions are
things like the "OK" string in some buttons, in which case you can calculate
a reasonable guesstimate of each character of that small string by assuming
a monospaced font inside the bounding rectangle of the object).

Given this base information, Gnopernicus has a mode in which is renders
lines of text to the Braille display using the character width information
in order to convey spatial information about that line relative to lines
above and below.  The folks at BAUM who are developing Gnopernicus have
already implemented this feature in their Windows product Galileo, and they
are a very Braille-focused company.  

There are three ways in which a "line" of Braille can be presented -> within
a particular window or dialog box; within an application (rare); and across
the entire desktop.  The first way is slated for the 1.0 release of
Gnpoernicus.  The second and third were not possible until a bug fix in the
GNOME underpinnings that only happened in the last few days.  Those "Braille
line" presentations are not expected for version 1.0.  Perhaps, though, you
(or some other programmer) has some spare cycles you would like to
contribute to the open source gnopernicus effort, so that we might see that
feature sooner...?


Regards,

Peter Korn
Sun Accessibility team